Vegetarian and vegan diet
Vegetarians don't eat meat, poultry, game, fish, shellfish or food containing some animal by-products. Unlike vegans, they do eat dairy products and eggs.
According to the Vegetarian Society, around 2% of people in the UK are vegetarian, while less than 1% are vegans.
Raw foodists are vegans who eat mainly raw fruits, vegetables, pulses, sprouts and nuts.
There are also pescatarians, vegetarians who eat fish and seafood, and lacto-vegetarians, who eat dairy products but not eggs.
Fruitarians follow a diet that includes fruits, nuts, seeds and other plant food.
Reasons for becoming a vegetarian
Many adherents of vegetarianism and veganism - Beatle Paul McCartney and actor Alec Baldwin are just two celebrities who happily promote the cause - regard a flesh-free diet not only as more healthy, but as a more ethical way to live. They point to the cruel practices and the high environmental cost of raising animals for food as a few reasons for excluding meat from the diet.
Vegetarianism and health
Most doctors and nutritionists agree that a low-fat diet high in fruits, vegetables and nuts can be good for health. There is also widespread acknowledgement that reducing or eliminating red meat from the diet cuts the risk of heart disease and of bowel cancer.
Research has also shown that a plant-based diet can improve the health of people with type 2 diabetes. A study in 2004 and 2005 showed that people with diabetes who followed a low-fat vegan diet had less of a need for diabetes medications. They lost weight and their insulin sensitivity increased. They had improved glycaemic and lipid control.
Does being a vegetarian lower cancer risk?
Whether being a vegetarian or a vegan lowers cancer risk is less clear. This is mainly because of the diversity within the vegetarian population. Studies, however, have suggested that people who do not eat meat have a lower risk of prostate and gastrointestinal cancers.
Many of the cancer/vegetarian studies often conclude that diets rich in fibre, carotenoids (found in carrots, sweet potatoes and spinach), vitamins, minerals and isoflavones (found in soya beans and pulses) seem to protect against disease, including cancer. This is in concert with a health-conscious lifestyle.
A British study of 11,000 vegetarians and healthy eaters concluded that daily consumption of fruit was associated with a 20%-plus reduction in mortality from heart disease, cerebrovascular disease and cancers of the stomach, lung, pancreas, large intestine and rectum. Researchers, however, didn't account for the kind of diet practised by study participants (whether they ate dairy and fish or drank alcohol, for example). They also didn't check to see if their diets had changed over the course of the 17-year study.
A 1998 Dutch survey of 150,000 vegetarians concluded that the benefit of a vegetarian diet comes not just from excluding meat but in eating more whole grains, fruits and vegetables, pulses and nuts.
Researchers who conducted an 11-year study in Germany came to a similar conclusion. They examined the relationship between a vegetarian diet and colon cancer among 1,900 vegetarians. Researchers noted fewer deaths from cancers of the stomach and colon and even the lung in study participants - particularly among those who practised some form of vegetarianism for at least 20 years. They suggested, however, that other factors, such as body weight and amount of exercise, likely affected mortality rates in the vegetarians they studied.