To Your Health

A. Calcium is needed for many important body functions, including blood clotting, transmitting nerve impulses, and regulating heart rhythm, not to mention maintaining strong bones and teeth, where almost all of the calcium in the human body is found. Because most kidney stones are composed of calcium oxalate, it is commonly assumed that a high intake of calcium increases the risk of formation of such stones. The situation is just the opposite: Limitation of dietary calcium intake promotes formation of kidney stones. There are several dietary factors that can promote stone formation, such as excessive dietary protein, but calcium intake should not be restricted.

Most people think of calcium deficiency as a woman's problem, and that men are "immune" to osteoporosis. However, of the 25 million Americans with osteoporosis, every one in five is a man. A recent study estimates that 3-6% of non-Hispanic white American men 50 years of age or older have osteoporosis, and almost 10 times that number have osteopenia, the thinning of bones that comes before osteoporosis. While women tend to begin to lose bone density about 10-15 years earlier in life than men, after age 65 the rate of bone loss in men and women is about the same.

As is true for most chronic diseases, prevention works better than any cure. It is not necessary to avoid calcium supplements just because you have experienced kidney stones, but you should be careful to combine calcium supplements with magnesium. Since both magnesium and citrate work to keep calcium in solution, your calcium and magnesium supplements should be in the form of citrate salts. A combined dietary and supplemental calcium intake between 1,200 and 2,400 milligrams per day should be safe and beneficial.

Most Americans, when they think of good dietary sources of calcium, immediately think of milk and milk products. Despite heavy promotion by dairy interests, milk is not the best calcium source for everyone. The diets of many people around the world may supply as little as 300 milligrams of calcium per day, yet their incidence of bone fracture is quite low. Factors other than calcium consumption evidently come into play. For instance, calcium found in green leafy vegetables is naturally combined with magnesium and vitamins such as vitamin K that are helpful in maintaining bone health. In addition, many Americans of black, Asian, and Native American lineage are lactose intolerant and only tolerate fermented milk products, or require a pill that digests milk sugar when they use regular milk.

Adequate lifelong calcium intake along with adequate magnesium, potassium, zinc, vitamin D, vitamin K, moderate protein intake, avoidance of caffeine, and a reasonable amount of weight-bearing exercise seem to be the recipe for keeping bones healthy.