In order to see if supplementation with specific vitamins and minerals could lower cancer rates, a joint team from the US National Cancer Institute in Maryland and the Cancer Institute, Chinese Academy of Medical Sciences in Beijing, People's Republic of China, gave 30,000 people in Linxian County in China aged between 40-69 one of four combinations of nutrients in doses roughly double the US Recommended Daily Allowance. The researchers then followed the study group over five years, to 1991.

This particular county was chosen because it has one of the world's highest rates of esophageal/gastric cancer and is known to have a low intake of certain nutrients found in fruits and vegetables in the inhabitants' diet of mainly grains.The study found a 13 per cent reduction in cancer deaths among the group receiving supplementation with beta carotene, vitamin E and selenium, a 10 per cent reduction in mortality from all causes and 21 per cent reduction in deaths from cancer in the stomach all striking results for so short a study period. Interestingly, the researchers also found a 38 per cent reduction in mortality from cerebrovascular disease (strokes).

Although the group taking the B vitamins riboflavin and niacin did not have a statistically significant drop in overall mortality, they did show a 14 per cent reduction in throat cancer and a 41 per cent drop in cataracts.

There were no significant effects among the groups taking vitamin C, or those receiving vitamin A and zinc, suggesting that antioxidants need to be working together.