SCIENTISTS at the Hyderabad-based National Institute of Nutrition (NIN) say a healthy diet rich in spinach and other leafy green vegetables offers protection against cancer of the mouth. Their studies also show that certain vitamins and minerals taken regularly can retard the development of malignant oral cancers.

The team of scientists, led by NIN deputy director Kamala Krishnaswamy, who is also head of the institute's Food and Drug Toxicology Research Centre, studied the effects of diet and diet supplementation on the development and regression of lesions in the mouth. These lesions are associated with the eventual development of oral cancers, especially in women smokers in Andhra Pradesh's Srikakulam district.

Srikakulam has a high incidence of oral cancers caused by the peculiar habit of reverse smoking, where the smoker holds the lighted end of the cigarette or beedi inside the mouth, a common practice in the area. More than 30 per cent of such smokers have lesions, says Krishnaswamy. The researchers found that patients with lesions usually consumed fewer protective foods, like fruits and vegetables, on a regular basis.

Some 300 people with and without these lesions in the high risk group, were given a cocktail of vitamin A, riboflavin (vitamin B), zinc and selenium twice a week. After a year of this micronutrient supplementation, the researchers discovered that these lesions regressed in as many as 57 per cent of the patients. The scientists also found that signs of DNA damage, at the cell level, caused by reverse smoking, decreased in the treated group.

Interestingly, says Krishnaswamy, the supplements seemingly prevented the development of lesions in those high-risk members who did not have lesions prior to the trial. Some 38 per cent of those given placebos developed oral lesions, but only 12 per cent on mineral supplements developed them.