The March Harvard Men's Health Watch recommends men not take a multivitamin because of recent studies linking multivitamins to prostate cancer but most especially, recent studies linking high consumption of folic acid to colon polyps.

The newsletter explains researchers speculate that high intakes of folic acid -- first added to grain products in the 1990s to help prevent neural tube defects in infants -- may have contributed to an increase in colorectal cancers in the mid-1990s. With folic acid being added to grain products, there is a good possibility combining a healthy diet with a multivitamin could boost a person's daily intake of folic acid to 1,000 mcg or more, the newsletter says.

For those who may no longer take a multivitamin, consider taking a vitamin D supplement, the newsletter suggests. The typical diet for most men and women doesn't supply enough of this crucial vitamin, and while sun exposure boosts vitamin D production, too much sun has health risks of its own, the newsletter says.