Q. I take daily multivitamins but heard this may increase prostate or other cancers. What's your take?

This came from an article published May 16 in the Journal of the National Cancer Institute, in which nearly 300,000 men without prostate cancer were followed for five years.

Men who took multivitamins more than seven times a week had double the chance of dying from prostate cancer than men who did not take vitamins. The danger was even worse in those who also took micronutrients like selenium, beta-carotene or zinc.

Two consecutive reports from the Cancer Prevention Study-II studied nearly half a million men and also found that multivitamin use may increase fatal prostate cancers. The first found that men taking multivitamins for five or more years had more deaths from prostate cancer, and the second found that taking multivitamins 15 or more times a month marginally increased the risk for fatal prostate cancer.

However, the above reports were less-accurate observational studies. But even if you look at more accurate experimental (randomized) studies, you likewise find that beta-carotene, vitamin A or vitamin E, given singly or combined with other antioxidant supplements, actually increases death rates (mortality) from all causes, including cancers and heart disease. And Vitamin C neither worsens nor improves mortality, in accord with studies showing that it can act as both a pro-oxidant and an antioxidant, potentially causing either harm or good.

As described in an editorial to the May 16 article, while reactive oxygen species like free radicals may damage cells and cause disease, they also may help the body get rid of unwanted precancerous and cancerous cells. Taking extra antioxidants may reduce free radicals, but this may be harmful if this allows cancerous cells to grow. Antioxidant supplements in pills are synthetic and factory-processed. If you take extra antioxidants like beta-carotene or Vitamin E, either alone or perhaps even in multivitamins, it's no longer natural; it's like taking a drug and may throw off the balance of the micronutrients you ingest in the natural, correct proportions in your diet, causing cancer or other diseases.

And there's no evidence that taking several vitamins or supplements in combination is beneficial — in fact, this may only add to their individual toxicities.

The American diet provides 120 percent of the recommended daily amounts of beta-carotene, vitamin A and vitamin C, and vitamin E deficiency is nonexistent in the United States, yet one-third of adults take vitamin or mineral supplements because of heavy marketing, despite scientific studies showing potential harm.

Get your vitamins and antioxidants naturally from fruits and vegetables. It may save both your money and your life.

Dr. Landis Lum is a family-practice physician for Kaiser Permanente and an associate clinical professor at the University of Hawai'i John A. Burns School of Medicine. Send your questions to Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Honolulu, HI 96802; fax 535-8170; or write islandlife@honoluluadvertiser.com. This column is not intended to give medical advice.