Calcium is the one nutrient that comes to mind when most people think of preventing osteoporosis, a loss of bone mass that often increases with age »»]]>

Calcium is the one nutrient that comes to mind when most people think of preventing osteoporosis, a loss of bone mass that often increases with age and can lead to fractures. Calcium is an important nutrient for building bone and for slowing the pace of bone loss that comes with age. But it’s not the single magic bullet for preventing osteoporosis, and some scientists suggest that too much calcium or dairy products may be unhealthy. Keep in mind that there are other nutrients and foods that help keep your bones strong — most importantly vitamin D, but also vitamin K, fluoride, and possibly fish.

The dietary reference intakes (DRI) for calcium is 1,000 mg a day for adults up to age 50 and 1,200 mg a day for people over 50, when bone loss accelerates. With age, the intestines absorb less calcium from the diet and the kidneys seem to be less efficient at conserving calcium. As a result, your body uses more of the calcium stored in your bones for a variety of important metabolic functions.

Scientific studies have yielded different results regarding how much calcium you really need for preventing age-related bone loss. For example, a report in the American Journal of Clinical Nutrition in 2003 found that calcium intake during youth pays dividends many decades later. In this study of 3,215 women, those women over age 50 who, as children, drank very little milk (less than one serving a week) were twice as likely to fracture a hip as women who had consumed more than one serving a day. But calcium intake during adulthood may not have the same benefit. Seven studies done in the United States and Europe that have followed thousands of people for many years have found no correlation between a high intake of calcium in adulthood and fewer bone fractures. For example, in the Nurses’ Health Study and the Health Professionals Follow-Up Study, people who drank two or more glasses of milk a day were no less likely to break a hip or forearm as people who drank one glass or less a week.

Men should be aware that some preliminary findings suggest that high calcium intake from milk may increase the risk of prostate cancer. For women, studies have suggested a possible link between calcium from milk and increased risk of ovarian cancer. In both cases, the risk came from milk specifically, so even if research confirms the danger, it’s not clear whether the culprit is calcium or something else about milk.

Other foods and nutrients can help guard against osteoporosis. In building bone, calcium has an indispensable assistant: vitamin D. This vitamin helps the body absorb calcium, and some researchers think that increasing vitamin D can help prevent osteoporosis. But many people don’t get enough vitamin D. A study of people admitted to Massachusetts General Hospital in Boston found that more than half had a deficiency. This problem is most common among people who live in northern regions of the country, because they don’t spend much time in the sun. Exposure to sunlight prompts the skin to manufacture vitamin D. If you don’t make enough vitamin D yourself, you can also get it from milk and other dairy products, fortified breakfast cereals, eggs, and vitamin supplements.

Other substances may help fight osteoporosis. The Nurses’ Health Study found that women who got more than 109 mcg of vitamin K a day were 30 percent less likely to break a hip than women who got less. To get enough vitamin K, eat one or more servings daily of dark green lettuce, broccoli, spinach, brussels sprouts, or kale. Vitamin K helps regulate calcium and build bone. Additionally, some studies show that isoflavones in soy can slow bone loss and therefore might help prevent osteoporosis.

Fluoride is another substance that may play a role in building bone. Fluoride has been tested in many experiments over the last few decades with contradictory results. While some studies have shown that fluoride builds bone, several trials in the 1980s indicated that taking fluoride supplements did not reduce spinal fractures. But more recent research has shown that a newer slow-release version increases bone density and reduces spinal fractures. Fluoride therapy is used in several countries to treat osteoporosis, and the FDA is considering its use here. Whether the fluoride normally added to public drinking water reduces bone fractures remains a controversial question.

A word of caution: Don’t take fluoride supplements on your own. Taking too much fluoride can actually be bad for your bones by making them brittle. The amounts of fluoride added to drinking water are safe.

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