Diet & Lifestyle Vegetarianism

• Introduction
• A healthy vegetarian diet
• Vegetarian diets tend to be lower in total fat
• The best dietary sources of complex carbohydrates & fibre
• Antioxidants
• The China Health Project
• Research
• Recommended reading from Cygnus Books

• Vegan diet 'cuts prostate cancer risk'

   

Introduction
A vegetarian diet is known to confer a wide range of health benefits. Research has shown vegetarians to suffer less heart disease, hypertension, obesity, diabetes, various cancers, diverticular disease, bowel disorders, gall stones, kidney stones, and osteoporosis (Dwyer, 1988). Vegetarian diets have also been used in the treatment of various illnesses, including rheumatoid arthritis and nephrotic syndrome.

Dickerson & Davies (1986) studied matched pairs of vegetarians and non-vegetarians with regard to their general health. It was found that the vegetarians made 22% of the visits to hospital out-patients of non-vegetarians, and spent a similarly reduced proportion of time in hospital.

return to top

A healthy vegetarian diet
A typical vegetarian diet closely matches expert dietary recommendations for healthy eating, being low in saturated fat and high in fibre, complex carbohydrates, and fresh fruit and vegetables.

The 1983 NACNE Report (National Advisory Committee on Nutrition Education) in the UK recommended a reduction in fat intake, particularly saturated fat, and an increased dietary proportion of polyunsaturated fats to saturated fats. An increased intake of complex carbohydrates and fibre and a decreased intake of sugar and salt were also recommended.

The World Health Organisation (1990) has similarly recommended a reduced intake of fat and increased consumption of complex carbohydrates. Increased consumption of fruit, vegetables, cereals and pulses is also recommended.

The nutritional guidelines from the World Health Organisation, the NACNE Report and other expert bodies form the basis of advice given on healthy eating by health professionals today.

return to top

Vegetarian diets tend to be lower in total fat
Taber & Cook (1980) found lacto-ovo vegetarians to consume an average of 35% of energy as fat, compared to omnivores consuming over 40% of energy as fat. A study of the diets of a group of French vegetarians found they had a daily intake of 25% less fat than non-vegetarians (Millet, 1989). Vegetarians also tend to eat proportionally more polyunsaturated fat to saturated fat compared with non-vegetarians. Animal products are the major sources of dietary saturated fat.

return to top

The best dietary sources of complex carbohydrates & fibre
The best dietary sources of complex carbohydrates and fibre (also called non-starch polysaccharides or NSPs) include wholegrain cereals, vegetables and pulses and so vegetarian diets tend to be high in these nutrients. Animal products contain no fibre or complex carbohydrate.

return to top

Antioxidants
Recent research has demonstrated the importance of protective antioxidant nutrients in the diet found in fresh fruit and vegetables. These antioxidant nutrients include the beta-carotene form of vitamin A, vitamin C and E. Many researchers now believe that these nutrients play a major role in reducing the risk of chronic diseases such as heart disease and cancer. A high consumption of fresh fruit and vegetables is a benefit of vegetarian diets.

All these factors contribute to the proven health of vegetarians although it is difficult to account for the exact contribution of each nutrient. All vegetarian diets are not necessarily healthy, for example if too high a proportion of high fat dairy products are consumed.

return to top

The China Health Project
The China Project on Nutrition, Health & Environment is a massive study involving researchers from China, Cornell University in Boston, and the University of Oxford, into the relationships between diet, lifestyles and disease-related mortality in 6500 Chinese subjects from 65 mostly rural or semi-rural counties.

The rural Chinese diet is largely vegetarian or vegan, and involves less total protein, less animal protein, less total fat and animal fat, and more carbohydrate and fibre than the average Western diet. Blood cholesterol levels are significantly lower. Heart disease, cancer, obesity, diabetes, and osteoporosis are all uncommon. Areas in which they are becoming more frequent are areas where the population has moved towards a more Western diet with increasing consumption of animal products.

The China Health Project has clearly demonstrated the health benefits of a diet based on plant foods. One of the Project’s coordinators, Dr Cohn Campbell of Cornell University, has stated that "We’re basically a vegetarian species and should be eating a wide variety of plant foods and minimising our intake of animal foods."

References

• Abelow, B J et al. (1992) Cross-cultural association between dietary animal protein and hip-fracture. Calcified Tissue International v.50 p.14-18.
• British Medical Association (1986). Diet, nutrition and health. BMA, London.
• Claude-Chang, J et al. (1992) Mortality pattern of German vegetarians after 11 years of follow-up. Epidemiology v.3 (5) p.395-401.
• D’Amico, Get al. (1992) Effect of vegetarian soy diet on hyperlipidaemia in nephrotic syndrome. The Lancet v.339 p.1131-34.
• Dickerson, J & Davies, J. (1986) Consequences for health of a vegetarian diet, Postdoctoral thesis, University of Surrey.
• Doll, R. (1990) Symposium on diet and cancer. Proc of the Nutrition Society v.49 p.119-31.
• Gear, J Set al. (1979) Symptomless diverticular disease and intake of dietary fibre. The Lancetv.1 p.511-14.
• Hall, R H. (1992) A new threat to public health: organochlorines and food. Nutrition & Health v.8 p.33-43.
• Key, T J et al. (1998) Mortality in vegetarians and non-vegetarians: a collaborative analysis of 8,300 deaths among 76,000 men and women in five prospective studies. Public Health Nutrition
• Martin, M J et al. (1986) Serum cholesterol, blood pressure and mortality: implications from a cohort study of 361 662 men. The Lancet p.933-6.
• Millet, Petal. (1989) Nutrient intake and vitamin status of healthy French vegetarians and non-vegetarians. Am .inI Clinical Nutrition v.50 p.718-27.
• Mills P K et al. (1988) Dietary habits and past medical history as related to fatal pancreas cancer risk among Adventist men. Cancer v.61 (12). p.2578-85.
• Sabate, J et al. (1992) Lower height of lacto-ovo vegetarian girls at pre-adolescence: an indicator of physical maturation delay. .inI Am Dietetic Association v.92 (10) p.1263-64.
• Sacks, FM et al. (1974) Blood pressure in vegetarians. Am .inI Epidemiology v.100 p.390-8.
• Slattery, Met al. (1991) Meat consumption and its associations with other diet and health factors in young adults: the CARDIA study. Am .inI Clinical Nutrition v.54 p.930-35.
• Snowdon, D. (1985) Does a vegetarian diet reduce the occurrence of diabetes Am .Jnl Public Health v.75 p.507-12.
• Snowdon, D. (1988) Animal product consumption and mortality because of all causes combined, coronary heart disease, stroke, diabetes, and cancer in Seventh Day Adventist. Am .inI Clinical Nutrition v.48 p.739-48.
• Taber, LA. & Cook, R A. (1980) Dietary and anthropometric assessment of adult omnivores, fish-eaters and Iacto-ovo-vegetarians. .inI Am Dietetic Association v.76 p.21-29.
• Willett, WC et al. (1990) Relation of meat, fat and fibre intake to the risk of colon cancer in a prospective study among women. New England Jnl of Medicine v.323 p.¹ 664-72.
• World Health Organisation (1990). Diet, nutrition and the prevention of chronic diseases. WHO, Geneva.

A vegan diet might lower the risk of developing prostate cancer, say researchers.

They have found that men who eat a vegan diet have lower levels of a growth factor that is associated with prostate cancer than either meat-eaters or vegetarians.

The research's publication comes after controversy about claims that dairy-free diets prevent breast cancer.

Earlier studies have suggested that the risk of prostate cancer is increased by high levels of the growth factor IGF-I.

Other research has shown that prostate cancer rates are generally low in countries with a low consumption of meat and dairy products.

The new study, by the Imperial Cancer Research Fund's Cancer Epidemiology Unit in Oxford, reveals IGF-I levels are 9% lower in vegans than in meat-eaters.

First evidence

Dr Tim Key, senior scientist at the charity, said: "Previous studies have shown that men with prostate cancer have higher levels of IGF-I and that even small differences in the circulating level are predictive of prostate cancer risk.

"Our study shows that the circulating level of IGF-I is different in vegan men than it is in non-vegans, including vegetarians.

"The lower levels of IGF-I found in vegan men might reduce their risk of prostate cancer."

There has been much coverage in the media about the possible effect of a dairy-free diet on breast and prostate cancer risk.

However, until now there has been no scientific evidence to prove the anti-cancer benefits of a vegan diet.

Dr Key said: "More research is needed before it would be possible to say whether having a vegan diet reduces a man's risk of prostate cancer."

The study, carried out in 696 British men, also found IGF-1 levels were lower in vegetarians than meat-eaters.

The men in the study were taken from a larger European study (EPIC), which is looking at the relationship between diet and cancer to follow-up and check for prostate cancer in men with different dietary habits.