Can dietary supplements lower the risk of developing prostate cancer? Here’s a brief look at what’s known about some common vitamins and minerals.
Vitamin D. Sunlight promotes the body’s production of vitamin D. Early epidemiological studies showed higher rates of prostate cancer in regions where sunlight exposure is low compared with sunnier areas. However, this association does not prove that low vitamin D levels increase prostate cancer risk. To date, there is no solid evidence that higher vitamin D blood levels or higher vitamin D intake prevents prostate cancer.
Vitamin E and selenium. Both vitamin E and the mineral selenium have been evaluated for their potential to prevent or slow the progression of prostate cancer. Early studies that were not controlled suggested that men who took vitamin E supplements and selenium supplements had a reduction in the risk of developing prostate cancer. These studies prompted a large randomized trial called SELECT (Selenium and Vitamin E Cancer Prevention Trial). Findings from SELECT demonstrated an increased risk of prostate cancer among vitamin E users with lower levels of selenium at the start of the trial.
Folic acid. Studies have produced mixed results, with some showing an increased risk with high intakes of this B vitamin. Notably, a large 10-year study in the Journal of the National Cancer Institute in 2009 found that the risk of prostate cancer more than doubled in men taking folic acid supplements (1,000 micrograms a day). But folate from food seemed to reduce the risk slightly.
Calcium. A high calcium intake has come under scrutiny as a possible risk factor for prostate cancer, especially for men consuming 2,000 mg or more of calcium daily. However, a few studies have found no connection and others have shown a reduced risk. For now, experts say that a sensible approach is to limit calcium consumption to no more than 1,200 mg per day and to obtain it through food sources.