When It Comes to Calcium, the Advice Is to Keep Eating

Everyone knows that calcium is a requirement for strong bones and teeth. Less well known is that it plays an important role in maintaining the normal functions of the heart, nerves, muscles and other bodily systems.

Everyone knows that calcium is a requirement for strong bones and teeth. Less well known is that it plays an important role in maintaining the normal functions of the heart, nerves, muscles and other bodily systems.”The first thing you think about with calcium is bone, but it’s a mistake to stop there,” said Dr. Robert P. Heaney, a professor of medicine at Creighton University in Omaha and a founder of its Osteoporosis Research Center. “Low-calcium intakes have been implicated in disorders such as premenstrual syndrome, polycystic ovary syndrome, pre-eclampsia and mood disorders.” Insufficient calcium, experts say, has also been associated with obesity, precancerous colon polyps and cognitive decline in people 65 and over.Yet for all of calcium’s importance, only one American in five consumes an adequate amount. For women ages 19 to 50, the recommended dietary allowance for calcium is 1,000 milligrams a day. After age 50, the recommendation rises to 1,200 milligrams a day to compensate for the decline in estrogen that occurs with menopause and can contribute to osteoporosis. Experts agree that the best way to consume calcium, as well as other vitamins and minerals, is from food. “Calcium’s a nutrient,” Dr. Heaney said. “If you’re not getting enough calcium, chances are you’re not getting enough of other nutrients.” Dairy products are the best-known source of calcium, though other foods contain the mineral in varying amounts. “Broccoli is good, but you need bushels,” said Dr. Barbara Levine, a co-director of the Human Nutrition Program at Rockefeller University in Manhattan. Or, she said, “if you’re a sardines devote, you can take 35 sardines a day,” which would provide an amount equal to one cup of milk.There are more palatable ways to get your daily allotment, but even those require some effort. For example, you could drink four cups of milk or calcium-fortified juice a day, which provides the suggested 1,200 milligrams. Or you can eat either four 6-ounce containers of yogurt; a 6-ounce piece of Cheddar cheese; or seven 3-ounce cans of salmon (with bones, unfortunately).Many people, however, cannot digest milk products easily, and not everybody warms to the idea of eating multiple helpings of broccoli or sardines. This brings us to calcium supplements, which account for at least $700 million in sales annually, according to industry estimates.The two main kinds of calcium supplements are calcium carbonate and calcium citrate, which are distinguished by the compound that is used to combine with the calcium. The most widely available and inexpensive supplement is calcium carbonate, found in Os-Cal, Tums and Rolaids. But calcium carbonate can be hard to digest and should be taken with food. Calcium citrate, found in Citracal, may be more easily tolerated and taken any time, though it contains only half as much calcium as a comparable amount of calcium carbonate.Other supplements include calcium lactate, calcium gluconate and calcium phosphate. Dr. Levine warned against taking another supplement, coral calcium, because there is no evidence that it is a preferable form of the mineral. Some coral calcium supplements have been found to contain excessive amounts of lead, as have supplements containing bone meal or dolomite.Many calcium supplements are combined with other vitamins or minerals. Among the most common pairings is calcium with vitamin D, which helps the body absorb and use calcium, and calcium with magnesium, a mineral that is also important for bone health. It is not necessary to take these substances in the same pill as calcium, but some people find it more convenient.Experts recommend taking calcium supplements at intervals throughout the day instead of all at once because anything more than 500 milligrams will not be absorbed by the body. Overzealous consumers should be careful about taking more than 2,500 milligrams a day, which is not advised. Doctors say that excessive intake can cause kidney stones and other disorders. A full 99 percent of the ingested calcium, whether through food or supplements, goes into the skeleton, which reaches its peak density at around age 30. The remaining calcium circulates in the blood, where it facilitates functions like nerve transmission and muscle contraction, Dr. Levine said.”We can’t live without that 1 percent, but we always take it out from our bones, to keep that little bit in our blood at a very steady level,” she said. “Think of it as a healthy bank account. For instance, you want to be depositing calcium every day rather than withdrawing it.”When the body determines that there is insufficient calcium in the blood, calcium-recruiting hormones are stimulated to leach it from the bone, causing a loss of bone-mass density. If the withdrawn reserves are not restored soon enough, bones can become more brittle, leading to osteoporosis, perhaps the best-known ailment related to calcium deficiency.According to the National Osteoporosis Foundation, women are four times as likely to have the disease as men. Eight million women currently suffer from the disease nationwide. The Women’s Health Initiative is studying the role that calcium plays in maintaining skeletal health in older people. In 1994, it began a clinical trial of 37,000 women taking supplements containing calcium and vitamin D. Dr. Joan McGowan of the National Institute of Arthritis and Musculoskeletal and Skin Diseases, a division of the National Institutes of Health, says the study, which ends in 2005, is the largest calcium trial ever conducted. (Source: The New York Times, By SARA IVRY, 22 June)