Other investigational drugs are currently being evaluated by NCI, but it will be years before their preventive value is known. There are correlations between diet and exercise and prostate cancer, but few are strong and many are contradictory. For example, many researchers have stated that vitamins A and C protect against carcinoma of the prostate. At the same time, others have said that a high intake of these vitamins increases a man's risk for acquiring the disease. That confusion doesn't help you at all, but it is probably safe to say that a single multivitamin tablet a day is beneficial for most people.
Excessive vitamin doses, however, are at the very least wasteful, and quite often harmful.
A stronger association exists between prostate cancer and fat intake. Dietary fat is converted by the body to androgens, which, as we know, stimulate growth of cancer cells. Men who eat high-fat diets have a much higher rate of prostate cancer than those who adhere to diets low in fat and rich in yellow and green vegetables. This risk seems to be isolated to animal fats, which are broken down into chemicals that are carcinogenic, or cancer-causing, to prostate cells. This is one of the reasons why Asians have such a low incidence of prostatic carcinoma when compared to Americans.