Extra Calcium Benefits Women on Hormone Replacement Therapy

January 13, 1998

Contact:
Moira Saucer
(202) 872-1488

EXTRA CALCIUM BENEFITS WOMEN ON HORMONE REPLACEMENT THERAPY

A review of clinical trials published this week found that women who consumed high levels of calcium in conjunction with hormone replacement therapy (HRT) had much greater increases in bone mass than those who used either estrogen or calcitonin alone.

The researchers, who published their findings in the January 1998 American Journal of Clinical Nutrition, show that postmenopausal women on HRT benefit from additional calcium intakes either through diet or calcium supplements. "The beneficial effect of estrogen and an adequate intake of calcium appears greater than the sum of each effect alone...," said the scientific team, led by Jeri W. Nieves of the Clinical Research Center and Regional Bone Center, Helen Hayes Hospital, West Havershaw, NY and Columbia University, New York. While observing that more research is necessary to determine optimal calcium consumption to be used in conjunction with HRT, the study found a clear benefit at total calcium intakes of 1200 to 1500 milligrams (mg) of calcium per day.

The reviewers evaluated 31 clinical trials investigating the impact of calcium intake on estrogen therapy for postmenopausal women and 7 similar clinical trials with calcitonin instead of estrogen. Twenty of the estrogen trials increased calcium intakes through modification of diet or calcium supplementation and 11 used estrogen alone without increased calcium. Of the seven trials involving calcitonin, six used a calcium supplement in conjunction with calcitonin, and one used calcitonin alone. Annual bone mass increases for those on estrogen and extra calcium averaged 2.4 percent in the femoral neck, 2.1 percent in the forearm, and 3.3 percent in the lumbar spine. Increases in bone mass from HRT alone were 0.9

percent in the femoral neck; 0.4 percent for the forearm, and 3.3 percent in the lumbar-spine. While less data was available for those taking only calcitonin, the review found that bone mass of the spine did increase two percent, or two-fold, for those on calcium supplements and calcitonin but decreased by 0.2 percent for those in the one study given calcitonin alone.

An accompanying editorial by Bess Dawson-Hughes, MD, of the U.S. Department of Agriculture's Human Nutrition Research Center on Aging at Tufts University, observes that "The meta-analysis of Nieves et al supports the position that calcium is an important component of a regimen that includes antiresorptive therapy for the prevention and treatment of osteoporosis." Added Dawson-Hughes, "It also supports the notion that the calcium intake requirement of women treated with estrogen may not be lower than the average women."

A consensus conference held by the National Institutes of Health in 1994 concluded that estrogen use lowers the calcium requirement. However, in its recent recommendations on optimal intakes for calcium, the National Academy of Sciences' Food and Nutrition Board concluded that the evidence did not support different calcium recommendations for postmenopausal women on estrogen therapy. The FNB recommends that men and women ages 51 and older consume 1,200 mg of calcium a day, a 50 percent increase over the previous RDA of 800 mg of calcium.

"This study clearly shows that hormone replacement therapy is not optimal -- calcium is necessary for maximum protection against osteoporosis," said CRN Director of Nutritional and Regulatory Science John Hathcock, Ph.D.

Bone loss is an indicator of osteoporosis, a chronic disease in which the body loses bone mass over the years due to low calcium intake and absorption. If the loss is sufficient, bones become thin, brittle and often break. In fact, 90 percent of hip fractures in the United States are due to osteoporosis. A growing base of scientific research indicates that increased calcium intake can help to reduce bone loss significantly and maximize bone mass for postmenopausal women. A recent double-blind, placebo controlled study, led by Dawson-Hughes, found that a daily calcium and vitamin D supplement given to older people reduced bone loss and the rate of fracture significantly.

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