Daily doses of beta carotene, Vitamin E and selenium reduced cancer deaths by 13% in a study conducted in rural China by U.S. researchers, who caution that the results may not apply to the United States, where people eat a more well-balanced diet.
The five-year study, involving 29,584 people in an area where cancer rates are among the highest in the world, showed that some vitamins and minerals can be of benefit against cancer, according to the National Cancer Institute researchers.
“The study is the first randomized trial to show a significant reduction in cancer in a population supplemented with vitamins and minerals,” Dr. William J. Blot said Tuesday.
Blot added, however, that the results “don’t automatically translate to the situation in the United States.”
Blot and other cancer institute experts also said the single study does not present conclusive proof that vitamin and mineral supplements, such as in vitamin pills, give any protection against cancer.
“At this point in time, NCI recommends that Americans eat a well-balanced diet, low in fat, high in fiber, with plenty of fruits and vegetables, as a way to maintain good health and to reduce the risk of cancer,” said Dr. Peter Greenwald, director of the division of cancer prevention and control at the institute. “We do not have a recommendation now for vitamin and mineral supplements.”
The death rate from esophageal cancer among people ages 40 to 69 in the United States is 5 to 19 per 100,000. In Linxian, the area of China where the study was conducted, the rate is 470 per 100,000 among people of the same age.
In cooperation with the Chinese government, cancer institute researchers arranged for a study group of almost 30,000 adults, ages 40 to 69. They were divided into groups that received different combinations of vitamin supplements or placebos. Blot said the vitamin and nutrient doses were up to two times the U.S. recommended daily allowance.
The vitamin groups were:
* Retinol, a form of Vitamin A, and zinc, which helps metabolize retinol.
* Riboflavin and niacin, two B vitamins.
* Ascorbic acid, which is Vitamin C, and molybdenum, a nutrient.
* Beta carotene, a form of Vitamin A; alpha tocopherol, a form of Vitamin E, and selenium.
After five years and three months, Blot said, the group receiving beta carotene, Vitamin E and selenium “showed significant benefits.”
Total death rates from any cause were down 9% in that group and cancer mortality dropped 13%, he said. Stomach cancer deaths were reduced by 21% and stomach cancer was down by 16% when compared to those in the study taking other combinations of vitamins.