a diet containing substantial amounts of vegetables and fruits can prevent about two million cancer cases in the world every year. The American Institute for Cancer Research ( aicr ) and the World Cancer Research Fund, Washington, usa, have announced the study recently. Paul Talalay and his colleagues at the Johns Hopkins University School of Medicine, Baltimore, usa, found that young broccoli seedlings are chockfull of natural compounds which help prevent cancer ( Proceedings of National Academy of Sciences usa , Vol 94, No 19).

An active ingredient of vegetables called sulphoraphane is known to have anti-cancer properties. The chemical is present in various plants of the Brassica family such as cauliflower and cabbage. But broccoli contains more amount of the chemical than other vegetables.Talalay and his colleagues found that sulphoraphane present in these vegetables increases the levels of protective phase ii enzymes inside the cells. These enzymes detoxify carcinogens before they could cause cancer.

The levels of this chemical vary widely among the plants. Findings show that gram for gram three-day old broccoli plants contain 20-50 times more sulpho-raphane than adult plants. When rats were fed with daily doses of sprout- derived sulphoraphane for five days, they developed significantly fewer and smaller tumours after being fed a potent carcinogen. The compound reduced the incidence of breast tumours in rats by about 60 per cent. Unlike vitamin e and other anti-oxidants that attack cancer-causing molecules directly, sulphoraphane works indirectly by boosting body's cancer-fighting defences.

The researchers found that the sprouts do not have any phase i enzymes which are present in the adult plants. These enzymes enhance tumour growth. Based on established epidemiological studies on diet and cancer, the team also computed the required quantity of the vegetable. Talalay estimates that a person would have to eat more than 800 gm of broccoli every week to reduce the chances of colon cancer by 50 per cent. The same risk can be reduced by taking less than 10 gm of sprouts every day.

According to the researchers, even after knowing that vegetables prevent lung, colon and several other cancers, most people do not like to eat broccoli and cauliflower. A survey has shown that they consume less than the recommended five daily servings of vegetables and fruits. In India, the average consumption of vegetables is far less than 200 gm per day when the minimum recommended quantity is about 400 gm. Most people avoid taking vegetables such as broccoli and cauliflower mainly because of their bitter flavour and flatulent side-effects.

Recently, while releasing the aicr's diet-cancer report in New Delhi, John Potter of the Fred Hutchinson Cancer Research Center, Seattle, usa , said, "It is clear that diet can play a major role in cancer prevention". He added that the task of following these dietary recommendations should be easy in India as relevant dietary habits already exist in the country.