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).
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. Cancer is the second leading cause of death in Britain, accounting for 25% of all deaths. It has been estimated that diet may be linked to 30-70% of cancers (Doll, 1990). Certain cancers, such as colon, breast and prostate are clearly diet related (Cummings & Bingham, 1998).
Sir Kenneth Calman, Chief Medical Officer, has stated (1997) that "there is a relationship between eating red meat and cancer". The Oxford Vegetarian Study found cancer mortality to be 39% lower among vegetarians compared with meat-eaters (Thorogood, 1994). A study of 23,000 largely vegetarian Seventh Day Adventists found cancer mortality rates to be 50-70% of those of the general population for several cancer sites unrelated to smoking or alcohol (Phillips, 1975).Professor Nick Day of the University of Cambridge and the European Prospective Study into Cancer has stated that vegetarians may suffer 40% fewer cancers than the general population. The World Cancer Research Fund's dietary advice to minimise cancer risk involve reducing the intake of dietary fat and increasing the consumption.