The Benefits of Calcium

YOU'VE HEARD IT A MILLION TIMES: You need calcium to prevent osteoporosis. But a lack of this mineral means more than weak bones, says Robert P. Heaney, M.D., a calcium researcher and member of the Osteoporosis Research Center at Creighton University in Omaha, Neb. Key organs and bodily functions, like your heart and metabolism, need calcium to operate at their best. Yet only 21 percent of us are getting the recommended amount of calcium, according to federal government statistics.

Here are five important but little-known ways that getting more calcium can improve your health.

Benefit 1

Research suggests that if you don't get enough calcium in your diet, you're likely to be overweight, Heaney says. Of course, it's possible to be overweight even if you do get plenty of calcium, but Heaney points out that an adequate supply appears to make it easier to maintain a healthy weight.

The reason has to do with your body's response to a calcium deficit. When you're low, your body thinks you're starving and enters emergency mode, releasing parathyroid hormone from four glands in your neck. This hormone stimulates your bones to release some calcium into your bloodstream. Your kidneys also deliver a dose of a hormone called calcitriol, a form of vitamin D, to increase your ability to absorb calcium.

The trouble is that parathyroid hormone and calcitriol also stimulate the production of fat and inhibit its breakdown. As a result, your body stores fat and holds on to it stubbornly, even if you're on a low-calorie diet, explains Michael B. Zemel, Ph.D., head of the department of nutrition at the University of Tennessee at Knoxville. On the other hand, a high calcium intake suppresses these hormones so your body stores less fat and also breaks it down easily, he says.

In his research, Zemel found that calcium from low-fat or nonfat dairy products was more effective for weight loss than any other form.

Benefit 2

Calcium protects your heart.

If you're low on calcium, researchers say, you're more likely to have high blood pressure. Your body releases the hormone calcitriol in response to a calcium shortage, and calcitriol acts on the smooth muscle walls of your arteries, constricting them and elevating your blood pressure, says Heaney.

In fact, your calcium intake may be almost as important to blood pressure as your sodium intake, says Gene Spiller, Ph.D., the director of the Health Research and Studies Center in Los Altos, Calif., and co-author of Calcium: Nature's Versatile Mineral (Avery, 2000). He explains that an adequate supply of calcium helps muscles--including your heart muscle--do their work of contracting and relaxing. Calcium also appears to help your nervous system regulate the level of pressure in your arteries.

The benefits of calcium on heart health were confirmed in the Dietary Approaches to Stop Hypertension (DASH) study, published in the New England Journal of Medicine in 1997. The study found that a healthy diet that included two to three servings a day of low-fat, calcium-rich dairy foods like yogurt reduced systolic blood pressure by 5.5 points more than the control diet, and reduced diastolic blood pressure by 3 points more. "We don't want to oversell the importance of calcium [for heart health], because it's only a part of the puzzle," says Heaney. "But it's a very useful part."

Benefit 3

Calcium improves premenstrual moods.

A 1998 study led by Susan Thys-Jacobs, M.D., of St. Luke's Roosevelt Hospital in New York City, found that getting enough calcium can ease the symptoms of premenstrual syndrome (PMS). In this study of 497 women, published in the American Journal of Obstetrics and Gynecology, half took 600 mg supplements of calcium carbonate twice a day, while half took a placebo. The women who took calcium experienced significantly fewer symptoms in two months and improved even more after three months.

The explanation comes down (again) to calcium-regulating hormones. Your body suppresses the hormones if your calcium supplies are adequate, but releases these hormones if you're not getting enough. Women who suffer from PMS appear to have elevated levels of these hormones during their menstrual cycle. Thys-Jacobs explains that it's no accident that some of the symptoms of PMS, like cramping, irritability, and depression, are similar to the symptoms of a calcium-deficient state.

The good news for PMS sufferers is that consuming calcium appears to ease most of the symptoms. "We found that calcium is effective both on the emotional and physical side," Thys-Jacobs says. "It has a major effect on irritability, cravings, mood swings, breast tenderness, and other symptoms."

Benefit 4

Calcium protects against colon cancer.

Adequate calcium intake may reduce your overall risk of colon cancer and suppress the growth of polyps that can lead to cancer. Researchers don't know exactly why this happens, but Heaney says it may be linked to the excess calcium that's left in your intestines after your body absorbs what it needs. On its way through the colon, this unabsorbed calcium is believed to bind with cancer promoters so they're excreted together from the body. Studies have shown that both food sources of calcium and calcium supplements provide this protective effect.