单选题 . 
    Medical experts have suspected for many years that there is a strong link between what a person eats and cancer. They say a new study provides the first evidence that vitamins could reduce a person's chance of developing cancer. A team of Chinese and American scientists did the study. They are from American National Cancer Institute and the Cancer Institute of the Chinese Academy of Medical Sciences in Beijing. The Journal of the National Cancer Institute published the results of the study. About thirty thousand people between the ages of 40 to 69 took part in the study. They were from the Northern Central Chinese area of Linxian. Most of them took vitamins and minerals every day for five years.
    Linxian was chosen because the people there have an extremely high rate of cancer of stomach and esophagus. Researchers believe that fungus and molds in local foods may be partly responsible for the high cancer rate. Researchers divided those into eight groups. Seven of the groups received different mixtures of vitamins and minerals daily. The amounts of the vitamins and minerals were 1 to 2 times greater than what American health officials say is needed. The eighth group received sugar pills that had no effect. Those who seemed to gain the most received a mixture of a form of vitamin A called D-carotene, vitamin E and the mineral selenium. The vitamin and mineral are believed to prevent damage to cells caused by cancer-causing substances. Researchers reported a 13 percent drop in cancer rates in those who took D-carotene, vitamin E and selenium. They also found a 10 percent drop in the number of deaths caused by strokes from bursting blood vessels.
    Scientists warn that it is too soon to know if the effect would be the same among people in other countries. They note that the people in Linxian eat foods that lack necessary vitamins and minerals. Chinese officials will continue to record the health records of the people in Linxian for many years. For now officials reportedly are considering using the results of the study. They want to find a way to improve the health of people in Linxian and other small towns in China.1.  The results of the new study are unexpected.