Portland, Ore.

A glass of milk, a slice of cheese or even a little calcium pill could prevent women from gaining too much weight when they're pregnant. At least that's what scientists at Oregon Health & Science University are investigating.

Researchers at OHSU have begun a clinical trial to see whether dietary calcium can help prevent excess weight gain during pregnancy and promote weight loss postpartum.

"For many women, excess weight gain during pregnancy and then the failure to lose the additional pounds during the postpartum period marks the beginning of obesity. During this time of rapid weight change, it would be a great benefit if calcium could help curtail excess weight gain and facilitate weight loss following pregnancy," said Daniel Hatton, Ph.D., associate professor of behavioral neuroscience, OHSU School of Medicine and the principal investigator of the study.

Jane Harrison-Hohner, M.S., nurse practitioner and study coordinator, thinks that pregnancy is a perfect time to test the effects of calcium on weight regulation. "There are many positive aspects to increasing calcium consumption during pregnancy," she said. "It would be great if such a simple and safe intervention was able to help women contend with body weight issues as well as provide for the child's needs." Harrison-Hohner is an adjunct instructor in obstetrics and gynecology, OHSU School of Medicine.

The possibility that calcium may be beneficial in body weight regulation comes from several lines of evidence. Data from the National Health and Nutrition Examination Surveys have consistently shown a relationship between calcium consumption and body weight. The most recent survey shows that people who consume the lowest range of calcium consumption are six times more likely to be overweight than those in the highest range.

Clinical studies have shown that subjects placed on a weight-loss diet enriched with dietary calcium lose more body weight than those who eat the same amount of calories but with less calcium. Furthermore, the weight loss includes a significantly greater loss of body fat. The loss of body fat may result from the body burning more fat when there is greater calcium intake. In fact, calcium intake can account for as much as 10 percent of fat burned in a 24-hour period, according to Hatton.

The dosage used in this study is 1200 milligrams of elemental calcium. Harrison-Hohner stresses that this is an experimental study and people should consult their health care provider for more information before taking any supplement.

How calcium promotes fat burning is not known. Michael Zemel, a nutritionist at the University of Tennessee, thinks that it has to do with the actions of vitamin D. His data suggest that the active form of vitamin D, called calcitriol, causes fat cells to create more fat. Calcitriol levels are higher when you eat less calcium. Therefore, fat cells produce more fat on low calcium diets. By contrast, high-calcium diets suppress calcitriol and, as a consequence, promote the burning of fat.

IRB#7274

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