| Safeguarding
Children's Health:
Defeating Disease Through
Vegetarian/Vegan Diets
A Major
New Health and Nutrition Report For Healthcare Professionals
and Parents
by Laura
Scott, MSc Nutrition – Vegetarian & Vegan Foundation Senior
Nutritionist
Introduction
by Professor Colin Campbell
and Dr Anne Griffiths MB ChB
Copyright:
The Vegetarian & Vegan Foundation
April 2002
Registered
Charity: 1037486
Contents
Introduction
Definitions
Food For Thought
National Diet and
Nutrition Survey: Young People Aged 4 to 18 Years
How
Animal Products Affect Children:
Allergies
Cancer
Chemicals
Colic
Crohn's Disease
Coronary Heart Disease (CHD)
Dental Health
Diabetes
Ear Infection
Eczema
Food Poisoning
Gastrointestinal Problems
Kidney Problems
Migraine
Overweight & Obesity
Rheumatoid Arthritis (Juvenile)
Sudden Infant Death Syndrome
(SIDS)
How
Animal Products Affect Adults:
Cancer:
Meat and Cancer
Fat and Cancer
Types of Cancer:
Breast Cancer
Colorectal Cancer
Endometrial Cancer
Non-Hodgkin's Lymphoma
Ovarian Cancer
Pancreatic Cancer
Prostate Cancer
Uterine Cancer
The Role of Fibre
in Cancer Prevention
The Protective
Nature of Fruits and Vegetables
Soya Products
The Very Best Anti-Cancer
Diet
Coronary Heart Disease (CHD):
Cholesterol & Saturated
Fat
Cow's Milk & CHD
A Vegetarian Diet
Can Reverse CHD
Fibre and CHD
Diabetes
Diverticular Disease
Fibromyalgia
Food Poisoning
Gallstones
Hypertension
Infertility
Kidney Disease
Lactose Intolerance
Overweight & Obesity
Osteoporosis
Premature Death
Rheumatoid Arthritis
Strokes
Children's Eating Habits:
Parental Food Choices
Food Advertising
Parental Incomes
But Eating Meat Is
Natural, Isn't It?
Vegetarian Vitality:
Protein
Carbohydrates
Fibre (NSP)
Fats
Calcium
Iron
Iodine
Zinc
Vitamin A
B Vitamins
Vitamin C
Vitamin D
Free Radicals
Antioxidants
The Adequacy
of Vegetarian Diets for Children
Conclusion
What Does the VVF Gain?
References
Introduction
Professor
Colin Campbell
Jacob Gould Schurman Professor Emeritus of Nutritional Biochemistry,
Cornell University, USA and long time senior science advisor
to the World Cancer Research Fund.
This
report – summarising the scientific evidence favouring the
health value of a plant-based diet for children – is well
done. I have been on several 'expert panels' responsible for
recommending health policy positions, both nationally and
internationally, and although some may be more voluminous,
none is more reliable. This well-referenced document draws
heavily on conclusions drawn by other institutions and panels,
who have represented considerable collective deliberation,
to synthesize their views into a logical and responsible report.
It is well nigh time to make clear to the public that even
conservative science is strongly trending in the direction
of a plant-based diet and a read of this report is a good
place to start.
Dr Anne
Griffiths MB ChB
Diploma from the Royal College of Obstetrics and Gynaecology
and Member of the Royal College of General Practitioners.
Has an MSc in Community Paediatrics and is Associate Specialist
at the East Paediatric Team, Newcastle upon Tyne, UK.
VVF has
brought together, in this report, the overwhelming evidence
that vegetarian and vegan diets are not only healthy for children,
but preferable to modern meat and dairy-based diets which
are a major cause of chronic ill-health and premature death.
Here we have the results from over 200 studies, which show
conclusively the links between meat and dairy consumption
with such diverse diseases as asthma, gastrointestinal problems,
cancer, coronary heart disease, hypertension, diabetes and
obesity.
This
information should now be disseminated so that as many parents
as possible can make informed choices about what they choose
to feed their offspring. Some of us have long-standing beliefs
about the importance of meat and dairy products in our diets.
We need to challenge these, as individuals and societies.
It is imperative that future generations reap the health benefits
that a shift towards a plant-based diet can bring. Vegetarian
and vegan diets need to be actively promoted as the best diet
for all stages of life: pregnant mothers, babies, toddlers,
children, adolescents, teenagers and adults. Meat has become
the so-called luxury we can ill afford.
Definitions
Vegetarian
– a person who eats no red meat, white meat, fish or other
aquatic animals (prawns, crabs, lobsters etc) or slaughterhouse
by-products such as gelatine, animal fat, lard or rennet.
Vegan
– a person who eats no animal products at all including red
and white meat, fish and other water creatures, dairy products
(eg cow's or goat's milk or derivatives such as yoghurt or
cheese) or eggs.
Food
For Thought
The latest
worldwide research on diet and health has led internationally
renowned health organisations such as the World Health Organisation
(WHO) to recommend a diet very different to the one the majority
of people in the West eat today. Diets should be based more
on foods such as fruits, vegetables and cereals and less on
meat, fat, sugar and salt if killer diseases such as coronary
heart disease, diabetes, obesity and cancer are to be reduced.
This report documents the evidence which backs up this assertion
and concludes that animal produce must be eliminated from
the diet as early as possible to promote a long, healthy life.
And the evidence is overwhelming.
Anthropological
studies show that the diet which fuelled most of human evolution
was low in fat, very low in sugar and high in fibre and other
complex carbohydrates (3), so it is no great surprise that
today's high-fat, high-protein, low-fibre diet causes so many
health problems and the dietary trends are spreading worldwide.
With increased prosperity, the global trend is towards an
increasingly unsuitable and unhealthy diet. In less developed
countries even modest increases in prosperity are accompanied
by major changes in dietary patterns and a dramatic increase
in the incidence of diet-related diseases. If such trends
continue, the WHO predict a massive rise in cardiovascular
disease and cancer in virtually every country in the world
(4). So concerned is this august body they are argue for intervention
on a mass scale to shift dietary patterns closer to
a safer diet (5).
Scientific
data suggest positive relationships between a vegetarian diet
and reduced risk for several chronic degenerative diseases
and conditions, including obesity, coronary artery disease,
hypertension, diabetes mellitus, and some types of cancer...
Vegetarians often have lower morbidity and mortality rates
from several chronic degenerative diseases than do non-vegetarians...Vegetarian
diets offer disease protection benefits because of their lower
saturated fat, cholesterol and animal protein content and
often higher concentration of folate, antioxidants such as
vitamins C and E, carotinoids and phytochemicals... vegetarian
diets have also been successful in arresting coronary artery
disease. American Dietetic Association Position Paper
on Vegetarian Diets, 1997 (182).
With economics and politics dominating food production systems
throughout the world, we need to listen to independent bodies
and their research to re-discover a diet that will give children
a chance at a long and disease-free future. It is essential
that healthcare professionals guide parents and guardians
and encourage them to actively promote the best diet for their
family. Although many families have information about food-related
issues this does not necessarily mean that the advice is followed
(6). It is VVF's hope that healthcare professionals the world
over will take heed of the research published here and promote
a diet that will help save lives.
National
Diet and Nutrition Survey: Young People Aged 4 to 18 Years
June
2000 saw the publication of a national diet and nutrition
survey. This survey looked into the eating habits of a representative
sample of over 2000 young people aged 4 to 18 years. For most
parents what this report reveals will come as no surprise
and makes for grim reading. Roughly 80% of kids are guzzling
away on white bread, savoury snacks, biscuits, chips and chocolate
confectionery. Roughly 60-75% had not eaten any citrus fruits
(oranges, kiwi fruits, berry fruits – all very rich in fibre
and vitamin C) or leafy green vegetables (eg broccoli and
greens rich in fibre and many minerals). Whilst girls were
more likely to eat some salad vegetables, boys more often
consumed convenience foods such as sausages, bacon, ham and
pizza. When interviewed 1% of boys and 5% of girls reported
to be vegetarian or vegan increasing to 10% of girls aged
15-18 years.
Protein
intakes for all ages considerably exceeded the government
recommended intakes (known as Reference Nutrient Intakes or
RNI for short). Carbohydrates (sugar and starch) are our primary
energy source but should be predominantly starchy foods like
bread, cereals, pasta and rice rather than sugar-laden processed
foods. Sugars in the form of table sugar, honey and in baked
goods contributed 17% of energy intakes with the RNI set at
only 11%. Fibre intake (the indigestible part of plant foods
that helps keep the body regular or NSP (Non-Starch Polysaccharides))
was some 10-11g per day – the RNI being 18g for adults with
children slightly less so relative to their body size. Not
surprising then that a third of children recorded not having
a daily bowel movement. Dietary saturated fats (mainly from
animal products) accounted for some 14% of daily fat intakes
with the RNI set at some 20% less than this at just 10-11%.
Dairy products contributed some 30% of this type of fat and
meat products contributed 17%. Saturated fat intakes are a
major contributor to cholesterol levels so with 20% higher
intakes of this type of fat then recommended it is of no surprise
that approximately 10% of boys and girls had cholesterol levels
at or above the recognised safe levels.
Looking
at some specific vitamins, vitamin A intakes for 10-20% of
boys and girls were lower than recommended. Beta-carotene
intakes (the antioxidant or disease-busting form of vitamin
A only found in plant foods) were found to be actually zero
for 2% of boys and girls! Of particular importance here was
the observation that since girls aged 15-18 were most likely
to be vegetarian it was no surprise to find that this group
had a diet richer in total carotene than other younger girls.
Folate (a B-group vitamin rich in plant foods) was below the
RNI for 1-4% of all sex/age groups. Over half the vitamin
C intake was from fruit juice and soft drinks with 15% from
potatoes and only 10-13% from fruits and nuts. Whilst fruit
juices are rich in vitamin C they are devoid of any fibre
and thus a far better source of this vitamin is from whole
fruits and vegetables.
A number
of mineral intakes were also a cause for concern. The intake
of iron for girls above seven years was below the RNI with
the oldest age group having an intake of only 58% of the RNI.
Calcium intakes were likewise below the RNI for 11-18 year
olds and zinc intakes were below the RNI for all ages. Magnesium
intakes were some 20-50% below the RNI for various different
age groups – a mineral found principally in foods of plant
origin. Not surprisingly, given the sort of highly salted,
processed foods eaten by children, sodium (salt) intakes were
twice the RNI.
As far
as physical activity was concerned – a key determinant along
with diet for maintaining a suitable and stable body weight
– 40% of boys and 60% of girls had less than the recommended
one hour per day of moderate activity.
About
a quarter of all children reported to be unwell on at least
one day during the seven-day dietary recording period. Approximately
5% of children had been diagnosed as having food allergies
by their GP with double this percentage as reporting undiagnosed
unpleasant reactions to food.
What
this survey reveals is that young children are eating a diet
low in many of the vital health-promoting vitamins and minerals
needed to help combat disease and high in disease-promoting
foods such as high fat, high salt and high sugar convenience
foods. Much of their daily nutrient intakes are gained not
from the basic foods that provide them but from processed
cereal, meat and dairy products that are themselves laden
with harmful fats, sugar and salt. Fresh fruit and vegetable
intakes are woefully lacking in the diet. The consumption
of energy-giving starchy foods like unrefined cereals, breads,
pasta, rice – the very foods that our diets should be primarily
composed of – take a very poor secondary place in the diet.
Meat and dairy products still take centre stage at every meal
and children will undoubtedly suffer the consequences of this
type of diet sooner rather than later in terms of their health
and quality of life.
A recent
report from the Cancer Research Campaign paints a similarly
worrying picture of children's diets. One in 20 of the 2,635
children (aged 11-16) questioned by MORI claimed not to have
eaten any vegetables in the previous week, with one in 17
not eating any fruit. Compared with the recommended intake
of 35 portions of fruit and vegetables per week, most of the
children had eaten fewer than 13 portions (273). Vegetarian
children nearly always have higher fruit and vegetable intakes.
A very recent study found that vegetarian preschool children
had in several ways a more desirable nutritional profile than
those consuming meat products. The research revealed that,
compared to omnivore children, vegetarian children had lower
intakes of total and saturated fat, cholesterol and sodium
and higher intakes of beneficial nutrients like potassium
and vitamins beta-carotene (the precursor to vitamin A), C
and E. No surprises that these findings reflected a higher
consumption of fruits and vegetables than their meat-eating
counterparts (274).
How
Animal Products Affect Children
ALLERGIES
An allergy
is the term used to describe an adverse reaction to a substance
from the body's immune system – the body's defence against
foreign substances. Asthma (breathlessness with wheezing episodes),
eczema (areas of red, itchy, flaky skin), rhinitis (constant
runny or congested nose), hay-fever and urticaria (skin rashes)
are said to be classical allergies. Food allergy is also included
here where there is an immediate violent reaction to a food
– eg to peanuts. Food allergy is distinct from food intolerance
which is the term used to describe an adverse reaction to
a food where the involvement of the immune system is unproven
and reactions are usually slower. The most common food intolerance's
are to foods that are eaten very regularly – two of the most
common being cow's milk and wheat.
A recent
paper in the European Journal of Clinical Nutrition found
that a maternal diet rich in saturated fat during breastfeeding
may be a risk factor underlying the later development of allergies
(atopic sensitisation) of the infant. This was regardless
of whether the mother herself was atopic or not. The effect
of such a diet ends in infants whose sole source of energy
and nutrients is breast milk during the period of rapid growth
and development when the immune response is developing (1).
Along with certain processed foods, saturated fats are predominantly
found in foods based on animal products such as meat and cow's
milk.
One in
seven children (aged two to 15) now suffer from asthma – that's
over 1.5 million sufferers and over 1500 people die each year
in the UK as a result (7). There are many possible triggers
for an asthma attack, from animal hair, environmental pollution
to dust. Whilst food and drink are not considered common triggers
for people with asthma, the British Allergy Foundation estimate
that food and food additive allergy may be involved in 5-10%
of asthmatics (8). The National Asthma Campaign is also aware
that an allergy to dairy products can be a trigger for this
debilitating disease (2). According to Dr Nand Kishore Sharma,
a milk drinker can never cure his asthma. The
mucous-forming quality of cow's milk seems to trigger asthmatic
development (9).
In Sweden,
doctors prescribed a vegan diet to twenty-four asthmatic volunteers.
With only a few lapses, the volunteers followed the diet for
a year and their health assessed. After one year 92% of patients
reported an improvement in their condition and there was a
significant decrease in asthmatic symptoms. This means that
the decrease in symptoms was not down to chance or it just
happening anyway but attributed to the change in the diet
itself. In almost all cases, medication was withdrawn or drastically
reduced. Some of the volunteers that had also suffered from
rheumatic diseases found a lessening of these symptoms too
(11).
CANCER
Most
cancers affect adults rather than children – and diet is a
major contributory cause. However, there has been some research
on childhood cancers looking at the different types of variables
(a variable simply meaning any quality like age or type of
food consumed that varies in each individual) associated with
certain cancers. One study in particular found that brain
tumours in young people to be significantly associated with
(amongst other variables) maternal exposures during pregnancy
to frequent consumption of cured meat. Cured meat products
contain nitrosamines – the most potent nervous system cancer-causing
agents known – and cooking such meats means that relatively
high levels may be released in cooking fumes (12). In a separate
study, a statistically significant (ie not due to chance)
threefold increased risk of brain tumours in offspring was
associated with low maternal intake of vitamin C during pregnancy.
This means that there was an association for the offspring
of women having low intakes of vitamin C of having a three
times greater chance of brain tumour than women who had high
intakes of vitamin C. This effect remained even after adjustment
for other variables (13) – ie the association remained at
this increased risk level even after taking into account other
factors or variables that may have increased the risk for
brain tumours. A vegetarian diet is naturally high in this
antioxidant vitamin which can help to protect against cancer.
Meat and dairy foods contain no vitamin C.
Diet
has an enormous bearing on cancer according to the latest
research (14) and it is therefore crucial that children are
encouraged in healthy eating habits right from a very early
age and that includes the removal of meat and dairy products
from the diet. Indeed cancer specialist, Dr Rosy Daniel states
that the main foods to cut out of your diet to prevent cancer
are red meat and animal fats along with preserved foods and
food additives. Thus she states that: The best move
for those who feel inspired to 'go the whole way' is to become
completely vegan and eliminate animal products from the diet
altogether. (10). (See also Cancer section on how animal
products affect cancer rates in adults).
CHEMICALS
There
is growing concern about the effects of chemical pollutants
on both adults and children. Many harmful substances like
PCBs and dioxins are principally found in fatty foods – meat,
dairy, eggs and oily fish. This is because fatty tissue has
a tendency to 'soak up' and store these chemicals. Exposure
to PCBs and dioxins are linked to immune system damage, some
cancers and can negatively affect the intelligence of infants.
Nursing infants especially may be exposed to an array of chemical
pollutants from the breastmilk of their mothers. Hergenrather
and colleagues analysed samples of breastmilk from vegan mothers.
They found that the highest level of a number of chemicals
in the breastmilk of vegan mothers was lower than the lowest
level in the general population. For three chemicals, the
mean levels found in the vegan mothers were only 1 to 2% as
high as the average levels found in the non-vegetarian reference
population (17).
The theory behind these differing results involves a consideration
of food chains. Chemical pollutants that are fat-soluble accumulate
at each stage in the food chain. Thus foods from the top of
the chain like meat and dairy foods will have accrued and
concentrated a larger measure of chemicals compared to plant
foods at the very bottom
of the chain. Humans and thus nursing infants are regarded
as living at the top of the food chain. A nursing infant will
therefore be exposed to very high levels of chemicals accumulated
from the maternal diet. Eating foods lower down in the food
chain – plants – means that vegan mothers are likely to receive
less chemical contaminants in their diet and their breastmilk
will reflect this. Their nursing infants would, by extension,
be similarly less exposed to harmful chemicals (17).
Chemical
pollutants are now a major problem in the sea and the inclusion
of fish in the diet is increasingly being seen as a risky
business. Sea pollution means that farmed salmon and other
oily fish like mackerel are now a reservoir of harmful toxins.
Though now illegal, PCBs were once widely used and stay in
the environment – including the seabed – for many years. These
toxins bind to organic matter on the sea floor which is eaten
and absorbed into the fatty tissue of small fish. These seabed
feeders are in turn eaten by larger fish which accumulate
the toxin load from these smaller fish. At each stage of the
food chain toxins will be concentrated and increase.
The problem
with chemical pollutants in the food chain is now extremely
worrying. European Commission (EU) guidelines on safety limits
for dioxins in foods means that a third of all Britons and
half of all under-five's could be exceeding these safety limits
(276, 277).
COLIC
According
to Dr Alan Gaby (President of the American Holistic Medical
Association) cow's milk is probably the most common cause
of infantile colic. So sensitive are some infants to cow's
milk that they develop colic, even when exclusively breast
fed, if their mother continues to consume any cow's milk in
her own diet. Gaby
describes one study in which colic was cured in 68% of 19
breast-fed infants simply by eliminating cow's milk products
from the mother's diet (20).
CROHN'S
DISEASE
Crohn's
disease often affects young people, causing pain after mealtimes
and can also bring on a fever and mild diarrhoea. It is a
chronic inflammatory bowel condition that affects 90,000 people
in the UK and rates are rising rapidly. The condition is thought
to be partly genetic but also partly dietary. Some researchers
believe that the problem starts when infections or food sensitivities
aggravate the digestive tract.
Crohn's
disease is rare in Africa and rural Asia where diets are low
in fat and high in fibre, more common in parts of Asia that
have a Westernised diet and most common in North America and
Northern Europe. A 19-year study in Japan suggests the strongest
independent dietary risk factor for Crohn's is an increased
intake of animal protein (22). The high fat, low-fibre, meat-based
diets are believed to play a big part. One study found that
when placed on a milk-free diet, one third of patients with
Crohn's disease noticed a beneficial effect (23).
A report
by Professor John Hermon-Taylor of St. George's Hospital Medical
School, London, strongly supports the belief that bacteria
responsible for Johne's disease (found in cattle) is the same
bacteria that causes Crohn's disease – Mycobacterium avium
subspecies paratuberculosis (MAP). Research is now suggesting
that pasteurisation of milk – heating it to 72 degrees for
15 or 25 seconds – may not be enough to kill the bacteria
(24).
CORONARY
HEART DISEASE (CHD)
Coronary
heart disease (CHD) results from narrowing of the arteries
and stiffening of the artery walls by hard fatty deposits
– principally cholesterol. Blood supply to the heart muscles
is then reduced and eventually they become short of blood,
leading to a heart attack. Dietary cholesterol is only found
in foods of animal origin and saturated fats (from processed
foods and animal products) cause the liver to produce more
cholesterol. The National Forum for Coronary Heart Disease
Prevention states that: in order to reduce the overall
risk of coronary heart disease, healthy eating patterns should
be established in childhood. The report continues: Children
continue to eat more than the recommended percentage of energy
in their diets from fat and consume less than the recommended
amount of fibre. Several studies indicate that there has been
no improvement in children's eating habits over the last ten
years, with fat consumption at up to 43% of energy. The typical
diet of school children in the UK is high in fat and sugar,
low in fibre, low in iron and calcium and possibly low in
folate. This means that children should be eating a diet which
contains more bread, cereals and other starchy foods; more
fruit and vegetables; and less fat, sugar and salty foods;
and which is richer in minerals and vitamins. (135).
A vegetarian diet is ideal for promoting a healthy start in
life and the sooner this diet is adopted, the better.
The
avoidance of meat is likely to reduce the risk of coronary
artery disease, because meat is the major source of saturated
fat. High consumption of red meat has adverse
health consequences: thus vegetarian diets tend to impart
health advantages. Dr Walter C Willett, chairman of
the Department of Nutrition at the Harvard School of Public
Health and Professor of Medicine at the Harvard Medical School,
one of the world's most distinguished experts on nutrition
(251).
A study
in the New England Journal of Medicine found that in autopsy
studies of 204 children and young adults, aged two to 39,
essentially all persons had fatty streaks in their aortas
(the main artery from the heart to the body's tissues). The
prevalence of fatty streaks in the coronary arteries (the
arteries that carry blood to the heart) increased with age
from approximately 50% at two to 15 years of age to 85% at
21 to 39 years. The study found that the same risk factors
that encourage heart disease in older people – high cholesterol
levels, overweight and high blood pressure – do the same in
the young (136). A more recent study echoes this statement
finding that early deposition of cholesterol in the walls
of the arteries (atherosclerosis) is influenced by these risk
factors for clinical Coronary Heart Disease (CHD) and that
the long-term prevention of CHD must begin in adolescence
or young adulthood (60).
The WHO
reaffirms the importance of introducing a healthy high-fibre,
low-fat diet early in a child's life, one of the major reasons
being that it is known that the atherosclerotic process leading
to heart disease starts in childhood (15).
But of
course it is not only diet that influences the development
of CHD. Exercise is also important. The National Forum for
Coronary Heart Disease Prevention discovered that children's
hearts are under a huge strain from a poor diet and lack of
exercise. Only 4% of boys aged 11-16 and less than 1% of girls
could sustain a heart rate of over 140 beats per minute for
periods up to 20 minutes which is the recommended level for
children (137).
DENTAL
HEALTH
As every
parent is more than aware, sugar in the diet is the most important
dietary determinant in the development of dental caries (tooth
decay). The properties of different foods, including their
stickiness and nutrient content can affect the rate at which
caries are formed. The foods that can help reduce dental decay
are starchy foods like rice, bread and potatoes and the less
refined the better. Thus when children are given carbohydrates
such as beans, oats, rice, wholemeal bread and fruit, they
will tend to develop fewer and smaller cavities than children
fed a more refined diet. Fresh fruit, even though it contains
fruit sugars (fructose) has a low cariogenic potential (138).
A typical vegetarian diet provides all these types of foods
for children in abundance.
DIABETES
Diabetes
mellitus is a group of disorders that all lead to elevation
of glucose (sugar) in the blood due to inaction of insulin
– a hormone produced by the pancreas that helps to take glucose
out of the blood and into the body's cells. There are two
types – Insulin-Dependent Diabetes Mellitus (IDDM) where there
is an absolute deficiency of insulin and Non-Insulin Dependent
Diabetes (NIDDM) where insulin
is still produced but insulin-sensitive cells become much
less sensitive to it.
Although
it is not a killer disease in itself, it is still a factor
in the development of premature heart disease, kidney failure
and blindness (25). Insulin-dependent diabetes mellitus (IDDM)
is on
the rise (26) but the correct diet may help prevent this disease
in some instances. (See Diabetes section on how animal products
affect adults).
There
is increasing evidence from a number of studies to show that
early exposure to cow's milk may be a trigger for IDDM. (139,222,227).
In particular that cow's milk may destroy pancreatic beta
cells (cells that secrete insulin) in genetically susceptible
hosts, thus potentially increasing the risk for IDDM (223).
In 1994,
Diabetes Care published a critical review and statistical
analysis of cow's milk and IDDM by Hertzel Gerstein MD. His
review showed that early cow's milk exposure may be an important
determinant of subsequent IDDM and may increase the risk by
about one and a half times. Dr Hertzel concluded that: "74-94%
of the variation in diabetes incidence across countries may
be related to differences in cow's milk consumption."
(27).
EAR
INFECTION
Diseases
of the middle ear are primarily a disease of childhood with
as many as 1.5 million cases in Britain every year (30). They
are often linked with a cold or other problems of the respiratory
system. The avoidance of dairy produce is recommended by some
nutritionists and may be particularly valuable (31).
According
to the British Allergy Foundation: ...the food intolerance
patient is often mildly addicted (often without realising
it) to the food or foods causing the problem. The child with
catarrh, recurrent ear infection, insomnia and irritability
who craves regular milk, cheese and yoghurt is a good example.
Night-time waking, only
settling after a drink of milk, is an even stronger clue!
The complete disappearance of symptoms with milk avoidance
(and recurrence with milk re-introduction) is then clear evidence
of the relationship. (36).
ECZEMA
An allergy
to cow's milk protein is the most common food allergy in childhood,
affecting between four and 75 babies in every 1000 (32). It
can cause a whole host of symptoms including eczema in a child
but can also play a part in the development of eczema in adult
life. A number of studies have therefore concluded that whole
cow's milk should not be given during the first year of a
baby's life in order to help prevent the onset of a number
of diseases and conditions in childhood and adulthood (33,34).
FOOD
POISONING
In 1999
a government report stated that an astonishing 9.5 million
people in the UK get food poisoning each year, at a cost of
£750 million to the National Health Service. Amongst
the groups most endangered by food poisoning are young children
– especially under one's but anyone can suffer. Eating animal
products causes 95% of all cases with meat being the main
culprit as the bacterial micro-organisms responsible thrive
on rotting flesh. Food poisoning can range from being quite
mild to a cause of death from a heart attack or stroke. Abdominal
pain is the first sign of poisoning with the pain becoming
excruciating and may lead to explosive diarrhoea. Although
the illness usually lasts for five to 10 days, most often
it is a further one to two weeks before someone feels well
again (35).
A very
recent report in the New Scientist detailed results of a study
from the Royal London School of Medicine which found that
a staggering one in 10 British children are carrying superbugs
resistant to one or more antibiotics. The proportion of adult
carriers could be even higher. The researchers found that
11% of seven and eight year olds in the study population contained
bacteria such as E. coli that were resistant to antibiotics
that the children themselves had never previously been given
(156). Once resistant, bacteria can easily spread from person
to person and they can be picked up from food and agricultural
sources. There is already strong evidence that feeding farmed
animals antibiotics can lead to resistant strains of bacteria
in the gut which can then be passed on to people by eating
infected animal products. Farm use of antibiotics have caused
antibiotic resistance to medical drugs in 3 types of food
poisoning (Salmonella, Campylobacter and Escherichia coli)
(41). Now researchers from the University of Illinois have
discovered that bacteria in the soil and water beneath pig
farms seem to be acquiring tetracycline resistance genes from
bacteria originating in the pigs' guts. Once transferred,
these resistance genes can persist and could potentially be
passed on to humans through drinking water (236).
Escherichia
coli (E. coli) is a normal inhabitant of the gastrointestinal
tract of humans and animals. Whilst this bacteria colonises
infants within hours after birth and performs vital functions
throughout
life, some strains cause a wide range of diseases. The most
serious form of E. coli is known as VTEC – verocytotoxin-producing
Escherichia coli. Another name for this strain is E. coli
0157. It has been known since 1983 that Haemolytic Uraemic
Syndrome (HUS) – a form of kidney disease – is a complication
of a VTEC bacterial infection. The bacteria sticks to the
gut and releases a chemical into the bloodstream which causes
renal (kidney) failure. It is most likely to affect the young
and the elderly. VTEC is now thought to be the biggest cause
of acute (short term) renal failure in children. Farmed animals,
in particular cattle, are thought to be the reservoir of infection
(35).
A
diet free of meat, fish, milk and eggs is by far the safest
and one that I highly recommend. Emanuel Goldman Professor
of Microbiology & Genetics (35).
GASTROINTESTINAL
PROBLEMS
Many
children display intolerance to the proteins (casein) in cow's
milk with symptoms initially restricted to diarrhoea and vomiting
(37). Cow's have a four-stomach digestive system ensuring,
amongst other things, that calves can deal with casein easily
– but cow's milk is clearly not designed for humans. Because
it cannot be readily absorbed by humans cow's milk remains
undigested in the gut and begins to putrefy. This putrefaction
in humans produces toxins and mucus and it clings as undigested
matter to the lining of the intestines, preventing the absorption
of vital nutrients in the body (29).
Although
chronic diarrhoea is usually the most common gastrointestinal
symptom of intolerance to cow's milk among children, a recent
study in the New England Journal of Medicine found other consequences
of feeding children cow's milk. This study reported on 65
children between 11 months and six years of age with chronic
constipation who had been treated unsuccessfully with laxatives.
Taking them off cow's milk and switching to soya milk cured
44 of the children. The authors concluded that in young children,
chronic constipation could be a manifestation of intolerance
to cow's milk (38).
A 1993
review study concluded that in some children whole cow's milk-induced
gastrointestinal blood loss appears sufficiently great to
be nutritionally significant and may contribute to the development
of iron deficiency anaemia (40).
Ideally
the infant should be exclusively fed human milk for the first
year of life... After the first year of life the child requires
no milk of any type. The child, like us adults, can thrive
without cow milk ever crossing his lips. Frank Oski
MD (1932-1996). Internationally recognised specialist in paediatric
nutrition and former Director, Department of Paediatrics,
Johns Hopkins University School of Medicine and Physician-in-Chief,
the Johns Hopkins Children's Centre (281).
KIDNEY
PROBLEMS
Along
with Haemolytic Uraemic Syndrome (discussed above under Food
Poisoning), Nephrotic Syndrome is another potentially serious
kidney disease that may be related to the consumption of animal
products. Nephrotic Syndrome is linked to cow's milk allergy.
Children with the disease suffer from protein deficiency and
severe fluid retention and may ultimately develop permanent
kidney damage. In one study, allergy to cow's milk was found
to be a cause of nephrotic syndrome in five out of the six
children studied. Elimination of cow's milk from their diet
resulted in a marked improvement (43).
MIGRAINE
Migraine
is a common condition characterised by recurring intense headaches
and affects around 10% of the population (44). Usually accompanied
by nausea, vomiting and visual disturbances, a migraine can
be terrifying, especially for young children. Meat, dairy
products and eggs can all trigger a migraine (as can citrus
fruits, wheat, nuts, coffee, tomatoes and chocolate). The
Elimination Diet recommends abstinence from these foods for
two weeks and then reintroducing them one at a time in order
to assess which food or foods trigger the migraine attack
(45).
OVERWEIGHT
AND OBESITY
The UK
government has recognised that the prevalence of overweight
and obesity in the population is increasing rather than declining
(46). Body Mass Index (BMI) provides an estimation of an individual's
level or risk of morbidity and mortality. BMI is calculated
by dividing a person's weight (kg) by the square of his or
her height (m). A BMI of 20-25 means that a person has a normal
weight. A BMI of 25-30 indicates a person is overweight and
a BMI of 30 and over indicates obesity. At least 10% of children
in this country could be regarded as overweight (47). Two
recent papers in the British Medical Journal make grim reading.
The first study reported trends in overweight and obesity
over 20 years in British children (four to 11 years) and found
that in 1994 an average of 10% of boys and 14.5% of girls
were overweight (39). A second study observed that one in
five nine-year olds and one in three 11-year old girls are
overweight (42). In 1998, the prevalence of obesity in England
had trebled compared to 1980 to 21% of women and 17% of men.
Currently, over half of women and about two thirds of men
are overweight or obese (48). It is therefore vital for current
as well as future health that weight problems are tackled
early on.
Psychological
damage can be inflicted early in childhood as a result of
being overweight and this damage can last a lifetime. Healthy
eating habits should be started early. The typical diet of
school children in the UK is high in fat and sugar, low in
fibre, low in iron
and calcium and possibly low in folate. Diet in childhood
may influence the development of dental disease, constipation
and other bowel disorders, nutritional anaemia, obesity and
overweight, and may increase the risks in adulthood of low
bone mass, coronary
heart disease, stroke and some cancers including breast and
bowel cancer. So states the National Forum for Coronary
Heart Disease Prevention (49).
The 1991
Bogalusa Heart Study showed that even mild obesity in childhood
is related to higher levels of blood pressure, insulin and
cholesterol and that to some extent these track into adulthood.
There is evidence that fatty deposits and the development
of atherosclerosis start in childhood and emphasise the need
for preventative cardiology in early life (50).
Research
is clear on how diet affects obesity: energy (food) intake
exceeds energy output. Meat and dairy products all contain
saturated fat. A much healthier source of energy comes from
complex, slow-releasing carbohydrates and the good news is
that vegetarians are on average leaner than omnivores (51,
52, 53, 54).
RHEUMATOID
ARTHRITIS (Juvenile)
Rheumatoid
Arthritis affects more than 750,000 people in the UK and one
child in every thousand has arthritis. Dairy products, meat
and eggs can all be common triggers for rheumatoid arthritis
(as can corn, nuts and citrus fruits) in children and adults
alike. In 1985 the Journal of the Royal Society of Medicine
reported on the case of a 14 year old girl who had first been
admitted to hospital at the age of eight due to pain and swelling
of the wrist. During the following years she had been hospitalised
nine times as the swelling and pain spread and been diagnosed
with juvenile rheumatoid arthritis (JRA). At 14 she again
presented at hospital and after tests, doctors advised her
to avoid dairy products and the swelling disappeared within
a week. By the end of three weeks the pain had also gone.
The arthritis was to return just three times in this girl's
life, each time after she'd eaten dairy products. Even a small
piece of milk chocolate was enough to cause the painful symptoms
to recur (61).
SUDDEN
INFANT DEATH SYNDROME (SIDS)
Researchers
are currently investigating a link between cow's milk and
SIDS, saying that some cot deaths may be as a result of an
allergic reaction to cow's milk. Research at Southampton University
has discovered certain proteins, released during an allergic
reaction, in the blood of babies who have died with no apparent
cause. Researcher Dr Andrew Walls said that cow's milk was
a promising line of research. Although the number
of babies dying from cot death has dropped in recent years,
it still kills nearly 10 babies a week and is the leading
cause of death among children aged under 12 months (62).
How
Animal Products Affect Adults
Many
diet-related diseases and conditions begin in childhood but
don't show themselves until much later. The 1997 Scientific
Conference on Preventative Nutrition: Paediatrics to Geriatrics
reported that similar dietary guidelines are appropriate for
children (aged over two years) as well as adults in order
to reduce the risk of cancer, heart disease, diabetes and
obesity. These include choosing a diet with plenty of wholegrain
products, vegetables and fruits and a diet low in fat, saturated
fat and cholesterol (64). When you consider that the main
source of saturated fats in the diet are processed foods and
animal products – both meat and dairy – the arguments in favour
of a vegetarian diet get stronger and stronger.
CANCER
Experts
worldwide now believe that over a third of cancer deaths –
and possibly many more – may be linked to diet.
The percentages
of cancer deaths attributable to various factors is shown
below (65):
Accepted Average
Food Additives 1%
Pollution 2%
Alcohol 3%
Occupation 4%
Tobacco 30%
Diet 35%
One quarter
of a million people in the UK discover they have cancer every
year and it kills one in four. If the two main risk factors
(diet and smoking) were noted and acted upon, it is estimated
that two thirds of cancers could be prevented. In 1981 Professor
Sir Richard Doll estimated that 35% of fatal cancers are linked
to diet. He currently estimates that 20-60% of cancers might
be reducible by practicable dietary means (66).
According
to the WHO, evidence suggests a direct relationship between
the risk of certain cancers and the level of total fat in
the diet and that it may prove necessary to lower the upper
limit for total fat [intake] from 30% to 25% or perhaps even
20% (67).
The EPIC
(European Prospective Investigation on Cancer) Project initiated
in 1993 is a multi-centred prospective study designed to investigate
the relation between diet, nutrition, various lifestyle factors
and the risk of cancer. Prospective studies record the diets
of subjects and track their health over the coming years.
The EPIC study is set against the background that the most
consistent result of epidemiological (population) studies
on food choices and cancer is that a diet rich in vegetables,
fruit and more generally, in plant foods is associated with
a reduced risk of many cancers (59). The study has 480,000
subjects in nine European countries including 60,000 participants
in the Oxford Study for the UK element of the project. Data
is now being prepared for analysis and the results will be
compiled over the next year (86). (See section under Colorectal
Cancer below for interim results from EPIC studies.)
MEAT
& CANCER
Way back
in 1892, Scientific American asserted that cancer is
most frequent among those branches of the human race where
carnivorous habits prevail. (68). More recently it has
been found that the very process of cooking meat, particularly
at high temperatures for long periods, produces carcinogens
which are thought to increase certain cancers (69). As animal
proteins are heated, they produce cancer-causing chemicals
called heterocyclic amines. This phenomenon occurs in all
meats and the level of heterocyclic amines is 15 times higher
in chicken than beef (70), suggesting that chicken can no
longer be viewed as a healthy food option.
Heterocyclic
amines are most strongly linked to colon cancer but have also
been linked to cancer of the breast, ovary and uterus. A 24-year
Finnish study of nearly 10,000 people found that fried meat
consumption was linked to higher risk of these hormone-related
cancers in women (71).
FAT
& CANCER
In 1996,
researchers at the American Institute for Cancer Research
(AICR) presented new evidence on how fat affects cancer. Dr
Laurence Kolonel from the University of Hawaii Cancer Research
Centre and his team believe that fats (mainly of animal origin)
in the diet produce bile acids in the intestinal tract that
seem to promote colon cancer. Apparently eating high-fibre
foods like fruits, cereals and vegetables can reduce the concentration
of these bile acids and help prevent colon cancer (72).
High-fat
diets also increase the amount of oestrogens (female sex hormones)
in the blood. It is known that many breast tumours are fuelled
by an excess of oestrogen. When women begin a low-fat diet,
their oestrogen levels drop sharply and vegetarians have significantly
lower oestrogen levels than omnivores (63,73,74).
Researchers
in New York tested the effect of low-fat diets on immunity
and found that people with a low-fat diet had more 'natural
killer' cells than those on a high-fat diet. These cells seek
out and destroy any abnormal cells that may turn cancerous.
The authors of this paper state: The enhanced natural
cytotoxicity may be one of the factors contributing to the
lower cancer risk shown by vegetarians. (75).
TYPES OF CANCER
BREAST
CANCER
Breast cancer has now taken over lung cancer as the most commonest
cancer in the UK. In 1980 there were 25,000 cases each year
but now there are 40,000 women each year being diagnosed with
the disease. Asian countries have a much lower rate of breast
cancer than Western countries but when Japanese girls are
raised on Westernised diets, their rate of breast cancer increases
dramatically. In the 1940s when breast cancer in Japan was
rare, less than 10% of calories came from fat while today's
Western diets have up to three or four times that amount (78).
A Japanese study found the risk of breast cancer was eight
and a half times higher in affluent women consuming meat every
day than poorer women who did not eat meat daily (16).
Researchers
in Buffalo, New York calculated what they believed to be the
degree of risk posed by fat in the diet. For a woman with
metastatic breast cancer where the disease has spread to other
parts of the body, the risk of dying from the disease at any
point in time increases 1.4-fold for each 1000g of fat consumed
monthly (79). This means that the typical Western diet could
lead to about a 40% higher risk of dying of breast cancer
at any given point, compared to a low-fat vegetarian diet
(80). The relationship between dietary habits and breast cancer
was studied in 240 women aged 50-65. Results suggested that
diets that are low in fat, high in fibre, carbohydrates and
Vitamin A seem to help the prognosis while alcohol slightly
worsens it (81). The World Cancer Research Fund echoes this
view. The advice given in their information leaflets is that
research has shown that cancers of the breast are more common
in overweight women and a diet to lower cancer risk is low
in fat, high in vegetables, fruits and wholegrains (82). Well-balanced
vegetarian diets typically incorporate this way of eating
as a matter of course. A diet rich in vegetable products,
especially fibre, may lead to a later menarche (onset of menstruation)
which is thought may lessen the risk of developing breast
cancer later in life (83).
The association
of cooked meat and thus exposure to heterocyclic amines formed
during high-temperature cooking may also play an important
role in the risk of breast cancer. This was the conclusion
of a paper by Zheng et al who conducted a case-control study
among members of the Iowa Women's Health Study. This study
looked at a group of 41,836 women who had been followed over
the years from 1986 for mortality, cancer incidence and diet
eaten. During 1995 to 1996 Zheng and colleagues looked at
all members of the original group who had been diagnosed with
breast cancer (the cases), compared them to a random sample
of women from the original group who were free of cancer (the
controls) and looked at the intake and preparation of meats
consumed by both groups over the years. This analysis found
that risk of breast cancer was elevated with increasing intake
of well done to very well done meat (56).
The role
of cow's milk as a possible risk factor for breast cancer
has also been investigated. There is increasing speculation
that one particular hormone – Insulin-Like Growth Factor-1
(IGF-1) – may have a major role to play. IGF-1 is a naturally
occurring compound that stimulates growth in children and
declines as a child ages. IGF-1 also encourages breast cancer
cells to multiply and cow's milk contains about 30 micrograms
of IGF-1 in every litre (84). A recent paper published in
1997 in Medical Hypotheses put forward the view that regular
cow's milk ingestion after the age of weaning may produce
enough IGF-1 in mammary tissue to cause the cell cycle to
supersede its boundaries of control, thus increasing the risk
of breast cancer (18). A study published in The Lancet found
that pre-menopausal women with even small increases in blood
levels of IGF-1 have up to seven times the breast cancer risk
of women with lower levels (85).
Professor
Jane Plant was diagnosed as having breast cancer in 1987 and
had five recurrences. She began to research the disease and
came to the conclusion that cow's milk had a major part to
play. Seven years on, and after removing dairy products from
her diet, the cancer has never returned. Her book on the subject
presents the argument that cutting out cow's milk dramatically
reduces the body's exposure to antibiotics, biologically active
chemicals and a powerful cocktail of hormones thought likely
to promote breast – and prostate – cancer (19).
COLORECTAL CANCER
Colorectal cancer (also called bowel cancer) refers to cancer
in the colon (first part of the large intestine) and rectum
(last part of the large intestine). In 1991 in England and
Wales over 27,700 people had large bowel cancer (248). In
the Harvard Nurse's Health Study, it was found that women
who ate more animal fat had a greater risk of bowel cancer
(76) and similar results have been found for men. In one prospective
study the dietary risk factors for colorectal adenomas – precursors
of cancer – found a positive association with saturated fat
but a negative association with fibre (77).
Contrary
to claims that white meat is somehow healthier than red meat
a 1998 prospective study (whereby subjects diets are recorded
and their health tracked over the coming years) identified
both red meat and white meat (fish and poultry) intake as
important dietary risk factors for colon cancer. Researchers
at Loma Linda University examined eating habits of 32,000
men and women between 1976 and 1982 and monitored cancers
over the six years. Among those who avoided red meat but ate
white meat less than once a week, colon cancer risk was 55%
higher than for those who avoided both kinds of meat. Those
who had white meat at least once a week had more than a three-fold
risk of suffering colon cancer. Conversely eating legumes
such as beans, peas or lentils at least twice a week was associated
with 50% lower risk compared to never eating these foods (21).
A paper in the American Journal of Epidemiology in 1998 makes
two very interesting points. Firstly that it is the overall
dietary intake pattern that is important with greater emphasis
on fruits and vegetables that is associated with lower risk
for colon cancer. Secondly that 'substituters' (people who
use low-fat dairy products instead of high-fat ones, margarine
instead of butter, poultry instead of red meat and wholegrains
instead of refined grains) were at reduced risk for colon
cancer but the reduction was not significant. The authors
conclude that this was because many adopting these 'substituter'
so-called 'healthier' diets were not increasing their vegetable
consumption and this aspect of the diet is important in significantly
reducing colon cancer risk (55).
Fibre
or non-starch polysaccharides (NSP) are major constituents
of a plant-based diet and it has been long thought that high-fibre
diets offer a measure of protection against colon cancer.
The reason for this centres around the digestion of dietary
fat. Fat is broken down in the body by the secretion from
the gallbladder of bile acids made in the liver. Bacteria
in the intestines turn these bile acids into cancer-promoting
substances (mutagens) called secondary bile acids. Meat –
unlike plant foods – fosters the growth of bacteria that cause
these disease-causing acids to form. Fibre actually changes
the type of bacteria that are present in the intestine so
the production of carcinogenic (cancer-causing) secondary
bile acids is reduced (88). Fibre may also help both by diluting
the presence of such harmful acids in the faeces and by greatly
speeding up their passage through the colon.
Jerome
J DeCosse, a surgeon at Cornell Medical Centre in the US gave
a high-fibre grain supplement to patients with recurring polyps
of the colon. Polyps are small growths that may go on to become
cancerous but within six months in this study, the polyps
became smaller and fewer in number (90). Virtually every food
that comes from a plant contains fibre while food from animal
sources contains no fibre at all.
However
it may not be simply a matter of increasing fibre and still
eating meat that will help reduce risks of colon cancer. A
study by O'Keefe et al in 1999 found that the low prevalence
of colon cancer in black Africans was not so much explained
by dietary 'protective' factors including fibre but may be
influenced by the absence of 'aggressive' factors such as
excess animal protein and fat as well as differences in colonic
bacterial fermentation (57).
Preliminary
results from the EPIC study on the link between meat consumption
and colorectal cancer are showing that a high intake of red
meat and particularly of processed meat, are associated with
a moderate but significant increased risk of colonic cancer
(89). Overall first results suggest that frequent consumption
of beef, veal, pork and lamb is associated with a 20-40% increase
in colorectal cancer risk (87). This contradicts a recent
review paper by Key, Davey and Appleby which found no association
between a vegetarian diet and a reduced risk of colonic cancer
(225).
ENDOMETRIAL
CANCER
A population-based case-control study of dietary factors and
endometrial cancer published in 1993 revealed that women eating
the most animal fat and animal protein had more than three
times the risk of developing this particular cancer. High
consumption of meat, eggs and fresh fish were all associated
with elevated risk (105).
NON-HODGKIN'S
LYMPHOMA
Non-Hodgkin's lymphoma – a form of cancer – occurs more frequently
in individuals with a suppressed immune system. Some types
of dietary fat and protein have been linked with a decreased
immunological response. A recent study published in 1999 found
that greater dietary intake of certain meats and fats was
associated with a statistically significant increased risk
of this form of cancer. Intakes of beef, pork or lamb were
all implicated (113).
OVARIAN
CANCER
Dr Daniel Cramer of Harvard University found that in a case-control
study a higher intake of dairy products was linked to a higher
risk of ovarian cancer. In particular the milk sugar found
in cow's milk – lactose – was thought to be the problem when
it is broken down in the body to galactose. It is thought
that the galactose damages the ovary (94). This of course
means that if it is the milk sugar not the milk fat causing
this particular problem a switch to low-fat cow's milk products
may not help to lessen ovarian cancer. Ovarian cancer also
seems to be more common in countries with a higher total fat
intake (95).
PANCREATIC
CANCER
Risk factors for pancreatic cancer were evaluated in a 20-year
cohort study between 1966 and 1986. A cohort study is one
in which two groups of people are selected on the basis of
differences in their exposure to a particular agent – in this
case dietary habits including meat consumption. This study
of over 17,500 men in the United States revealed – after adjustment
for other risk factors – that those who ate meat were three
times more likely to develop cancer of the pancreas than those
with low meat consumption (96).
International
comparison studies have shown that as Japan's diet has Westernised,
so the incidence of pancreatic cancer has increased. One particularly
pertinent aspect of this Westernised diet is in terms of animal
fat consumption that previously was very low. Consumption
has steadily increased from a daily level of 6.5 grams of
animal fat per person in 1955 to 27.6 grams in 1987 and animal
protein consumption has doubled in these 30 years (98).
PROSTATE
CANCER
One in 12 men will develop prostate cancer at some point in
their lives. The number dying from the disease has almost
tripled in the past 30 years to 9,500 in 1998. By 2015, it
is expected to overtake lung cancer to become the most common
male cancer. Professor Jonathan Waxman who founded the Prostate
Cancer Charity believes that dietary factors are very strongly
implicated. The rise in meat consumption since World War Two
is the main culprit but eating dairy products can also increase
your chances of getting it due to the hormones in cow's milk.
Vegetarians are half as likely to get it as non-vegetarians
(91).
Research
has shown that men who consume diets based on animal products
tend to have more testosterone and oestrogens compared to
men who eat plant-based foods. This increase may be due to
over-production of these hormones in the body or, since fibre
in the diet is essential for the normal excretion of sex hormones,
a lesser ability to get rid of them. This hormonal boost can
affect the prostate and, according to the Physicians Committee
for Responsible Medicine, is probably the reason for increased
cancer risk among those on a meat-based diet (101).
IGF-1
(Insulin-Like Growth Factor-1) – found in cow's milk – is
already known to encourage breast cancer cell growth and may
also be a risk factor for prostate cancer. A very recent study
reported in the British Journal of Cancer found that vegan
men had a significant 9% lower IGF-1 concentration compared
to meat eaters and that this might reduce their risk of prostate
cancer (97). Other studies have likewise found that cow's
milk consumption is also very strongly implicated as a risk
factor for prostate cancer (256, 257, 258).
An important
study published in 2001 in the prestigious American Journal
of Clinical Nutrition also gives weight to the theory that
dairy products are risk factors for prostate cancer. A high
calcium intake, mainly from dairy products, may increase risk
by lowering concentrations of a form of vitamin D (actually
a hormone) thought to protect against cancer of the prostate.
Results here showed that men consuming two and a half or more
servings of dairy products (a serving being 140 grams of cheese,
170 grams of yoghurt or 75 mls of cow's milk) a day appeared
to be almost a third more likely to develop prostate cancer
then those eating the lowest amounts (less than half a serving
per day). The authors concluded that their results supported
the hypothesis that dairy products and calcium are associated
with a greater risk for this particular cancer (269).
Earlier
in 1999 Grant used an ecologic (multi-country analysis) approach.
Here mortality data from a particular year for various age
groups in a number of countries (41 in this example) were
compared with national consumer macronutrient supply values
for a range of foods. Grant found that the non-fat portion
of cow's milk had the highest association with prostate cancer.
For an association to be causal (ie in this instance that
the non-fat portion in milk actually causes prostate cancer)
a number of criteria need to be satisfied including strength
of the association, consistency and most important of all
a likely mechanism to link the suspected agent with the observed
effect. Grant concluded that for cow's milk the most likely
mechanism may be related to calcium with high intakes suppressing
conversion of one form of vitamin D to another form which
has an anti-tumour effect for prostate cancer (270).
In 1993,
American researchers analysed data from the prospective cohort
Health Professionals Follow-up Study looking at diet and subsequent
disease patterns. Of all the foods studied red meat represented
the food group with the strongest positive association with
advanced prostate cancer (99).
A lower
risk of prostate cancer is associated with diets higher in
rice, soya bean products and green and yellow vegetables (100).
Not surprising then that vegetarians have been found to have
low rates of prostate cancer (102) and increasing consumption
of beans, lentils, fruits and vegetables are all associated
with significantly decreased prostate cancer risk (103).
UTERINE
CANCER
Uterine cancer is linked to diets that are high in fat and
obesity (104). Vegetarians have been shown to eat a diet that
is lower in dietary fat and have lower body weights than non-vegetarians
(107).
THE
ROLE OF FIBRE IN CANCER PREVENTION
Eating
high fibre foods can reduce the concentration of destructive
bile acids and help prevent cancer from developing by sweeping
away toxins in the intestines before cancers can form. The
link between higher fibre consumption and lower cancer risk
is clear and has been reaffirmed in many studies. Fibre first
received worldwide attention in the 1970s when international
studies showed that in countries where diets included large
amounts of fibre, there were fewer cases of colon cancer,
diverticulitis and other intestinal diseases, haemorrhoids,
hiatus hernia, appendicitis, varicose veins, gallstones and
heart disease. Since then, many scientists have reached similar
conclusions and have also found that diets high in soluble
fibre (eg oats, soya beans, fruits and vegetables) appear
to lower the risk of diabetes and may reduce levels of cholesterol
in the blood. The World Cancer Research Fund recommends adults
introduce children to fibre-rich foods at an early age to
ensure they grow up enjoying and eating these foods (106).
THE
PROTECTIVE NATURE OF FRUITS AND VEGETABLES
Fruits
and vegetables contain antioxidants such as beta-carotene
(the precursor to vitamin A), and vitamins C & E which
protect body cells against damage. The evidence is overwhelming
that an abundant intake of fruits and vegetables can play
an important role in reducing cancer risk (108). Members of
the cruciferous family – broccoli, Brussels sprouts, cabbage
and cauliflower – are widely regarded as potentially cancer
preventative foods. A number of papers have looked at the
issue and found strong evidence to support these beliefs (92,
93).
For these
reasons, it is recommended we all eat at least five portions
of different fruits and vegetables per day as well as more
starchy carbohydrates. One portion is equivalent to one medium
fruit like an apple, banana or orange, two smaller fruits
like kiwis or plums, a cupful of berry fruits, a large bowlful
of green salad or two
serving spoonfuls of most cooked vegetables and pulses like
beans and lentils.
The World
Cancer Research Fund (WRCF) states: The emphasis of
our meals needs to be reversed; it is plant foods that should
be the focal point of our dinner plate, not meat and dairy
products. (109).
The WCRF also has this to say about some important vitamins
and minerals from fruits and vegetables:
Beta-carotene
is the pigment that gives dark green, yellow and orange fruit
and vegetables their colour. In the body it is converted to
Vitamin A, which may well lower our risk of developing cancer,
especially lung cancer (167).
Vitamin
C is believed to protect against cancer of the oesophagus
and stomach. It is found almost exclusively in fruits and
vegetables (167).
Vitamin
E may help in the prevention of stomach and throat cancers
as well as other serious illnesses. It is present in moderate
levels in most fresh fruits and vegetables and at higher levels
in cereals (167).
Selenium
is a mineral that can probably protect against colon, breast
and possibly other cancers. Scientists say an adequate amount
passes into fruit and vegetables from the soil in which they
are grown (167).
SOYA
PRODUCTS
There
has been much publicity in the lay press – both negative and
positive – surrounding soya products and their effects on
the body – no less so than in the area of cancer. Some studies
point to the chemo-preventative nature of soya whilst other
studies seem to point to the opposite effect. On balance research
seems to be suggesting that soya foods can be a very valuable
part of a varied vegetarian diet.
Soya
beans contain all eight essential amino acids (building blocks
of protein), have strong antioxidant properties, are very
rich in soluble fibre, contain no cholesterol and are high
in the essential fats which are often lacking in many people's
diets. Studies have also demonstrated that soya lowers cholesterol
levels and the large amount of evidence linking soya to good
heart health has even led the FDA (the US Food and Drug Administration)
to allow health claims on food products containing soya.
Soya
beans are rich in a class of compounds called isoflavones.
These act as weak oestrogens – hence the name also given to
isoflavones – phytoestrogens or 'plant hormones'. Phytoestrogens
appear to have both antioestrogenic and oestrogenic effects
in the body – thus they act as oestrogen modulators. The prevailing
thought is that these plant hormones exert antioestrogenic
effects in a high-oestrogen environment (such as that exists
in pre-menopausal women) and oestrogenic effects in a low-oestrogen
environment (such as that existing in post-menopausal women).
Thus phytoestrogens appear to normalise oestrogen in the body.
At the present time the data so far produced is insufficient
to conclude that soya is protective against cancer but the
data certainly warrants further investigation of this relationship.
Indeed one important researcher in the field of soya states
that: given the nutrient profile and phytochemical contribution
of legumes, nutritionists should make a concerted effort to
encourage the public to consume more beans in general and
more soya foods in particular. (110).
A study published in The Lancet in 1991 of women in Singapore
found that soya protein had a significant protective effect
against breast cancer. This was in strong contrast to the
finding that red meat consumption was a significant predisposing
risk factor for this type of cancer (111). Soya beans are
a mainstay of Asian diets and may be one factor why cancer
levels are lower than in the West (112).
THE
VERY BEST ANTI-CANCER DIET
A landmark
study published in 1994 in the British Medical Journal found
that vegetarians suffer 40% less cancer mortality than the
population average, even with controls for smoking, body weight
and socio-economic status (114). In the words of Professor
Jane Plant a completely plant-only diet may confer even greater
advantages: Undoubtedly, the best anti-cancer diet would
be completely vegan. (58).
CORONARY
HEART DISEASE (CHD)
Coronary
Heart Disease (CHD) is the cause of nearly a quarter of all
deaths in England and persists as the UK's number one health
problem with one in three men and one in four women dying
from it. Treating CHD costs the NHS £500 million each
year (115). According to the WHO's report on diet, nutrition
and disease published in 1991, dietary factors clearly play
a role in CHD: All the available evidence suggests that,
for cardiovascular disease and cancer, diet has an influence
throughout the life cycle, even though the end-points are
manifested in the adult. (116).
World
renowned heart surgeon Christiaan Barnard performed the world's
first heart transplant in 1967. After 30 years of surgery
he has come to the conclusion that most heart attacks are
unnecessary – we have the power to prevent them. He states
that our diet lacks sufficient fruits and vegetables, is not
properly balanced and that we should live like the people
of Crete. Here heart disease is almost unknown, and along
with other dietary norms fruit and vegetables are the mainstay
of the diet and their consumption of meat is 32% less than
in northern Europe (121). This is of course the typical 'Mediterranean'
diet that has many elements to it that support a far more
healthier way of eating. Indeed two recently published articles
in the British Medical Journal detailing the results of the
WHO World Health Report 2000 clearly show that many of the
countries performing best in terms of health of their populations
are characterised by such diets (265, 266). A well-balanced
vegetarian diet – by its very nature – is very much along
the lines of a Mediterranean-type diet typified as it is by
higher intakes of plant foods especially fruits and vegetables
and of course zero meat consumption.
A number
of studies have demonstrated that a vegetarian diet can lead
to a much reduced risk of heart disease. A key paper published
in 1998 concluded from a collaborative analysis of 76,000
men and women in five prospective studies that vegetarians
have a lower risk of dying from ischaemic heart disease (IHD)
than non-vegetarians (122). A similar review study in 1999
actually put a figure to this decreased risk. Here, compared
with non-vegetarians, Western vegetarians were found to have
a lower BMI, a lower plasma cholesterol concentration and
lower mortality from ischaemic heart disease by about 25%.
These findings led the authors to state that the evidence
available suggests that widespread adoption of a vegetarian
diet could prevent approximately 40,000 deaths from IHD in
Britain each year (123). Faced with such clear evidence as
this and a cash-strapped NHS it is a surprise that a vegetarian
diet is not available by prescription! Indeed a recent comprehensive
review of the beneficial and adverse effects of vegetarian
diets in various medical conditions makes this exact point.
The authors conclude that: The burden of modern lifestyle
diseases is enormous when the costs of investigation, diagnosis,
treatment and primary and secondary prevention are included.
Thus, dietary intervention with a vegetarian diet seems to
be a cheap, physiological and safe approach for the prevention,
and possibly management of modern lifestyle diseases.
Dr M Segasothy, NT Clinical School of Medicine of Flinders
University, Australia (239).
A new
piece of research published this year in the Journal of Clinical
Pathology gives a clue as to one of the reasons why a vegetarian
diet may lead to lower heart disease risk. Scottish researchers
found that levels of salicylic acid in the blood of vegetarians
were up to one and a half times significantly higher than
in meat eaters. Some vegetarians had levels up to 12 times
higher (253). Salicylic acid is the main component of aspirin
– widely prescribed to reduce the risk of heart attacks –
which helps fight the inflammation that causes most cardiovascular
illness. Salicylic acid is also present in fruits and vegetables
suggesting a high dietary intake may produce some of the same
good effects as aspirin. Dr John Paterson who helped conduct
the research states there is also evidence that aspirin can
protect against bowel, breast and lung cancer as well as Alzheimer's
disease. It may be that salicylic acid in the diet can
help prevent these diseases. (252).
Another
reason why vegetarians have a reduced risk of heart disease
is thought to be caused by factors in the diet having a beneficial
effect on vascular dilatory responses. Impairment of the ability
of blood vessels to dilate or relax is an important early
event in the lead up to plaques forming in vessels. A recent
study reported in Atherosclerosis found that the vascular
dilatory responses of vegetarians are better than omnivores.
Just as importantly these effects are dependent on diet alone,
independent of other known risk factors for atherosclerosis
(clogged up arteries) such as smoking, diabetes, hypertension
and ageing (261).
CHOLESTEROL
& SATURATED FAT
Whilst
not the only factor in the causation of CHD cholesterol is
still considered a prime indicator of risk for this disease.
Dietary cholesterol is not an essential nutrient since the
liver can make all that it needs. Cholesterol is transported
in the bloodstream and supplied to different body tissues
by five major classes of lipoprotein, (fat and protein complexes)
the two most important being low-density lipoproteins (LDL-cholesterol)
and high-density lipoproteins (HDL-cholesterol). LDL-cholesterol
transports cholesterol to the arteries and plays a significant
role in the metabolic processes leading to atherosclerosis.
HDL-cholesterol – 'good cholesterol' – carries cholesterol
to the liver so the body can get rid of it. Since LDL-cholesterol
accounts for most of the total cholesterol in the blood, elevated
total serum cholesterol is therefore regarded as a reliable
indicator of the risk for developing atherosclerosis and CHD
(120).
The foremost
dietary determinant of total serum cholesterol is the intake
of saturated fat. This type of fat is found principally in
foods of animal origin and is particularly rich in the fatty
portion of meat, eggs and milk products. Studies have suggested
that whereas saturated fats elevate serum cholesterol levels,
polyunsaturated fats (and possibly monounsaturated fats) actually
lower levels (124). This is echoed by research showing that
replacement of saturated fatty acids with almonds or walnuts
(typical vegetarian staples which are high in polyunsaturated
fats) lowers both total cholesterol levels and LDL-cholesterol
levels. Compared with a reference population this study found
that there were significant reductions of 7% and 10% respectively
with almonds and 5% and 9% reductions respectively when walnuts
were used in place of saturated fat (267). Saturated fat encourages
the body to make more cholesterol than it needs and seems
to prevent it from getting rid of the excess, leading to the
narrowing of the arteries (118). Approximately 15% of dietary
energy (calories) in the UK diet comes from saturated fat.
Experts recommend that this be reduced to just 11% (125).
A very recent literature review makes the point that the advice
to reduce consumption of eggs – a major source of dietary
cholesterol – may still be important in the prevention of
coronary heart disease. The paper's authors also state that
other major sources of dietary cholesterol – dairy fats and
meat – are already considered as increasing the risk of heart
disease because of their saturated, cholesterol-rich profiles
and should likewise be reduced (268).
The WHO
report in 1991 states: Population data clearly associate
a decrease in saturated fatty acid intake with a progressive
fall in cardiovascular disease mortality... A value of 10%
of energy has thus been fixed as the maximum upper limit for
saturated fatty acids... Saturated fatty acids are not essential
nutrients... The lower limit for saturated fatty acids is
therefore zero. (127).
This
statement is lent support when one considers that from a public
health standpoint, 'lean' red meat diets and white meat diets
are both largely ineffective in reducing serum cholesterol
concentrations. Hardly suprising when one considers that unlike
fat, cholesterol is located mainly in the lean portion of
meat. Low-fat vegetarian diets that forgo all meats can achieve
serum total and LDL-cholesterol concentration falls of 23%
and 32% respectively. These stand in stark contrast to many
cholesterol-lowering programs that see serum cholesterol concentrations
fall by only 5 to 6% (126). A recent study by Ashton and colleagues
also highlights the greater benefits of plant sources of protein
compared to protein from lean meats. Replacement of lean meat
with tofu (soya bean curd) in this study found significantly
lower total cholesterol and triglyceride (fat) levels compared
with the lean meat diet (237).
There
is increasing evidence to suggest that vegans may have an
even greater advantage. Thorogood et al found that differences
in total cholesterol concentration suggest that not only the
incidence of coronary heart disease may be 24% lower in lifelong
British vegetarians but 57% lower in lifelong vegans (131).
COW'S
MILK AND CHD
There
is increasing speculation that cow's milk products may be
playing a role in the high rates of CHD in Western countries.
Research by Sacks et al has found that dairy products were
the major sources of dietary saturated fat and cholesterol
and that ingestion of fatty dairy products raises the LDL-cholesterol
levels in the subjects followed (128). Way back in 1982 Segall
made the compelling point that in Switzerland a falling cardiovascular
mortality rate has been associated selectively with a fall
in milk consumption, amounting to 46%, between 1951 and 1976
(129).
The theory
that plasma homocysteine levels are directly associated with
cardiac disease risk is one gaining considerable ground. This
too may therefore be another factor why plant-based diets
reduce CHD risk. Homocysteine is an amino acid found in high
levels in foods of animal origin. A straightforward hypothesis
would be that a vegetarian diet and more so vegan diet would
have lower levels of this potentially damaging protein. Very
recently DeRose and colleagues in Preventive Medicine published
a study clinically demonstrating such an effect. In just one
week on a vegan diet, as well as lifestyle interventions,
subjects mean homocysteine levels fell 13% (130).
A study
by Grant into possible dietary associations with CHD in 1998
found that milk carbohydrate (lactose) had the highest statistical
association for CHD for males aged 35+ and females aged 65+.
Non-fat milk was found to have the highest association for
CHD for males aged 45+ and females aged 75+, while for females
65-74, milk carbohydrates (and sugar) had the highest associations.
A number of possible mechanisms have been put forward for
this, the most prominent of which is the plasma homocysteine
hypothesis. Animal proteins contribute to homocysteine (Hcy)
production and cow's milk lacks adequate B vitamins (vitamin
B6, B12 and folic acid) to convert Hcy to less harmful products.
Lactose and calcium in conjunction with Hcy from consumption
of non-fat milk may also contribute to calcification (hardening)
of the arteries (132).
A
VEGETARIAN DIET CAN REVERSE CHD
Not only
can a vegetarian diet lower the risks of getting heart disease
in the first place it can also halt and reverse even severe
CHD. Dr Dean Ornish and colleagues have demonstrated that
a near-vegan diet (no animal products allowed except egg white
and one cup per day of non-fat milk or yoghurt) caused a significant
overall regression of coronary atherosclerosis in patients
with moderate to severe coronary heart disease (119, 211).
The
Reversal Diet is a very low-fat vegetarian diet.. This is
what the patients in our study consumed, whose coronary heart
disease began to reverse. I am convinced that this is the
world's healthiest diet for most adults, whether or not they
have heart disease. Dr Dean Ornish, Director of Preventive
Medicine Research Institute, California, and the first clinician
to offer proof that heart disease can be halted or even reversed
on a vegetarian diet (282).
The evidence
for a protective effect of a vegetarian diet for heart health
is very clearly documented in an on-going landmark study –
The China Health Study. This is a comprehensive survey of
diet and mortality characteristics in 65 counties in rural
China overseen by Professor Colin Campbell. All the evidence
points to the conclusion that even small intakes of foods
of animal origin are associated with significant increases
in plasma cholesterol concentrations, which are associated,
in turn, with significant increases in chronic degenerative
disease mortality rates (117).
FIBRE
AND CHD
Fibre
or NSP (Non-Starch Polysaccharides) is a collection of indigestible
substances found in all plant cells. Hence virtually every
food that comes from a plant will contain it and is why vegetarians
have greater intakes than non-vegetarians do. Food from animal
sources contains no fibre whatsoever. There are two types
of fibre – soluble and insoluble. Soluble fibre is found in
fruits and vegetables and the richest sources are vegetable
protein foods like lentils, peas and beans. Oats are also
rich in this type of fibre. Soluble fibre dissolves in the
fluid of the gut and helps to maintain even blood sugar levels.
It is also known to reduce cholesterol levels in the body.
Insoluble fibre found in cereals, breads, rice, pasta as well
as fruits and vegetable adds bulk to waste products ensuring
easy passage of this waste through the digestive system.
According
to the National Food Survey the average intake of fibre in
the UK diet is 11.9 grams per person per day (133). Nutritionists
are in agreement that adult diets should contain an average
for the population of 18 grams of fibre per day (134).
Not surprisingly,
vegetarian diets are found to be far richer in fibre than
average meat-based diets (254).
DIABETES
Non-Insulin
Dependent Diabetes (NIDDM) is much more common than the childhood-onset
variety (IDDM). It is estimated that 150 million worldwide
people have NIDDM with 5% or 22.5 million adults in Europe
affected, including two million in the UK. The WHO estimates
that by 2025 there will be at least 300 million sufferer's
worldwide. The cost implications are truly staggering. In
Europe and the US 10-15% of total health care expenditure
goes on NIDDM and associated complications. This amounts to
£2bn a year in the UK (216). By maintaining an appropriate
weight, the risk of developing the disease is greatly diminished.
Once again vegetarians – who as a group are typically leaner
than omnivores – have a particular advantage in this aspect
of health.
NIDDM,
which usually starts in middle adulthood, is strongly associated
with an increased risk of CHD as well as kidney, nerve and
eye disorders. In pregnant diabetics the disease may have
an adverse effect on the foetus. Approximately 80% of NIDDM
sufferers are obese. The incidence rate is close to double
in people who are only moderately overweight (226).
Vegetarians
and vegans are less at risk from diabetes than meat-eaters
as a 21-year study in America found. Over 25,000 adult Americans
were studied and the results showed that people on meat-free
diets had a 45% reduced risk of developing diabetes compared
to the population as a whole. Meat consumption was po |