Q. Will taking calcium and vitamin D ease my PMS symptoms?

A. Premenstrual syndrome includes symptoms such as depression, irritability, stomach cramps, fatigue and headaches occurring a few days before the start of a woman's menstrual period. Many women experience mild versions of these symptoms. Medically, to be considered PMS, these symptoms have to be severe enough to interfere with normal activities or relationships. This medical definition affects 8 percent to 20 percent of women.

Studies suggest that blood calcium and vitamin D levels are lower in women suffering from PMS. Calcium supplements seem to reduce symptom severity. University of Massachusetts researchers decided to study whether calcium and vitamin D could prevent women from developing PMS in the first place. Their findings were reported in the June 13, 2005, issue of the Archives of Internal Medicine.

Over 10 years, the study followed 3,025 women ages 27 to 44 who were PMS-free. Calcium and vitamin D intake from diet and/or supplements were evaluated. By the end of the study, 1,057 of the women reported developing PMS.

The researchers observed a 40 percent lower risk of developing PMS in women with high intakes of vitamin D and calcium from food sources equivalent to four daily servings of skim or low-fat milk, fortified orange juice or yogurt. That is equivalent to about 1,200 milligrams of calcium and 400 IU of vitamin D each day.

The researchers found that skim or low-fat milk lowered the risk of developing PMS better than whole milk. Neither calcium nor vitamin D from supplements decreased risk.

Calcium and vitamin D may influence the development of PMS through their relationship with estrogen in the body. Levels of these nutrients fluctuate in response to changes in estrogen levels during ovulation and throughout each month.

A limitation of this study was that the researchers did not measure vitamin D intake from sunlight, a common source of the vitamin. Other limitations include difficulties differentiating between PMS cases and noncases, and too few participants taking large doses of calcium supplements. A large clinical trial is needed to really prove that calcium and vitamin D prevent PMS.

Even with these limitations, increasing your intake of calcium and vitamin D has benefits, such as strengthening bones and decreasing the risk of certain cancers. If you suffer from PMS, increasing calcium and vitamin D in your diet may be worth a try.

Amy Tousman is a registered dietitian with Straub Clinic & Hospital. Send your questions to Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Honolulu, HI 96802; fax 535-8170; or islandlife@honoluluadvertiser.com.