Cardiovascular disease is the major cause of mortality in Britain,
being responsible for around 50% of all deaths. The majority of these deaths
are from coronary heart disease. Vegetarians suffer markedly lower mortality from coronary heart disease
compared to non-vegetarians (Key et al (1999). This reduced risk may
be related to the lower blood cholesterol levels of vegetarians.
Findings from the Oxford Vegetarian Study, a 12 year study of 6000
vegetarians and 5000 meat-eater found that the incidence of coronary
heart disease mortality was 28% lower in vegetarians compared with matched
omnivores, after all non dietary factors had been taken into consideration
(Thorogood, 1994).
Burr & Butland (1988) found vegetarians to suffer significantly
lower mortality from heart disease than health conscious non-vegetarians.
Mortality from ischaemic heart disease was 57% lower in vegetarians than
the general
population, and 18% lower than in non-vegetarians following a healthy
lifestyle. Deaths due to cerebrovascular disease was 43% lower in the
vegetarians compared with the general population.
A study of nearly 28,000 Seventh Day Adventists in California noted
a clear trend of increasing incidence of heart disease with rising frequency
of meat consumption (Snowdon, 1988).
The Coronary Artery Risk Development in Young Adults (CARDIA) Study
examined diet in relation to health in over 5,000 young adults aged 18
to 30. Vegetarians were found to have greatly improved cardiovascular
fitness and a lower risk of heart disease (Slattery, 1991). A low level
of meat consumption was linked to improved general health.
An eleven-year study of 1,900 German vegetarians has found mortality
from cardiovascular disease to be 61% lower in male vegetarians and 44%
lower in female vegetarians than the general population. For ischaemic
heart disease, mortality was reduced still further, to only one-third
of that expected (Claude-Chang, 1992).
The protective effect of a vegetarian diet is believed to be related
to the lower blood cholesterol levels seen in vegetarians. Repeated studies
have demonstrated the low blood cholesterol levels of vegetarians (Resnicow,
1991). Thorogood (1990) found vegetarians to have cholesterol levels
10% lower than health conscious meat-eaters. High blood cholesterol is
a primary risk factor in heart disease. Significantly, vegetarians have
lower levels of low-density-lipoprotein (LDL) cholesterol. This is the
cholesterol fraction particularly associated with heart disease.
Research has suggested that a 10% reduction in blood cholesterol may
be associated with a 30% reduction in the incidence of coronary heart
disease (Martin, 1986).
A recent collaborative analysis of 8,300 deaths among 76,000 men and
women in five prospective studies concluded that vegetarians have a 24%
reduction in mortality from ischaemic heart disease, this increased to
45% in the under 65s. When compared with regular meat eaters the vegetarians
showed 34% less mortality (Key, 1998)
The California Lifestyle Heart Trial has indicated that a low fat vegetarian
diet together with other lifestyle changes such as exercise and stress
management can in fact reverse the progress of heart disease, by reducing
cholesterol plaques in coronary arteries (Ornish, 1990).
Hypertension
Hypertension, or high blood pressure, can contribute to heart disease,
strokes and kidney failure. A number of studies have shown vegetarians
to have lower blood pressures than non-vegetarians (Sacks, 1974, Armstrong,
1977).
A
vegetarian diet has also been shown to reduce blood pressure in hypertensive
patients (Margetts, 1986).
The reason for the low blood pressure associated with vegetarian diets
is unclear. The relative leanness of vegetarians is one suggestion, as
is the effect of reduced sodium or increased potassium or calcium in
the diets of vegetarians.
Obesity
Vegetarians are leaner than non-vegetarians and their weights are
generally closer to desirable levels. The British Medical Association (1986)
has stated that vegetarians have lower rates of obesity. Appleby et al
(1998) as part of the Oxford Vegetarian Study concluded that non meat eaters
are thinner than meat eaters. This may be partly due to a higher intake
of dietary fibre, a lower intake of animal fat, and only in men a lower
intake of alcohol.
Diabetes
Snowdon (1985) found type II diabetes to be only half as common as
a cause of death amongst the largely vegetarian Seventh Day Adventist population
as in the general population. An
average vegetarian diet closely matches the British Diabetic Association's
recommendations for diabetic patients. Vegetarian diets tend to be
high in complex carbohydrates and dietary fibre, which has a beneficial
effect
on carbohydrate metabolism, lowering blood sugar levels. The leanness
of vegetarians also contributes to reduced incidence of diabetes. Diabetes
is often associated with raised blood cholesterol levels and a vegetarian
diet confers protection against this.
See also: The
EPIC OXFORD STUDY of the health of vegetarians
