You probably need a lot more than you're getting
Most Americans don't meet the recommended dietary allowances for calcium intake set by the National Research Council. What's more, the NRC's calcium standards are themselves too low and are likely to be revised in the next three years, experts believe. In fact, an advisory panel of the National Institutes of Health recently urged that the RDA for calcium be increased to as much as 1,200 milligrams a day for children from 1 to 10 years old to as much as 1,500 milligrams a day for adolescents, young adults, and post-menopausal women, and to 1,000 milligrams a day for women from 25 to 50 years old. That represents increases of 25 to 50 percent over the standards established by the NRC in the past.
Such boosts are necessary, the panel of experts said, to lower the risk of osteoporosis, the brittle bone disease that is crippling 25 million Americans, especially postmenopausal women. The new recommendations are based on research showing that raising calcium levels to build greater bone mass, particularly in adolescents and older women, plays a critical role in fighting osteoporosis.
For both men and women, peak bone density is achieved during late adolescence. Around 35 years of age, bones begin to thin for both sexes. This process accelerates for women when estrogen levels drop at menopause. During their lifetimes, women lose about one-third of their bone mass while men lose about one-fifth. The more bone mass one develops as an adolescent, the more protected one will be from the inevitable loss that occurs with age. In one recent study of adolescent girls, raising calcium intake with supplements from 80 percent of the current recommended dietary allowance to 110 percent increased bone mass by more than 1 percent per year during adolescent growth. In another study, this time of men and women ages 50 to 79, those in the top third in terms of calcium consumption suffered 60 percent fewer hip fractures over the next 14 years than did the others.
Estrogen replacement therapy can be of great help to older women at a high risk of developing osteoporosis (see related story in the paper book, page 329). 
So can raising an older woman's intake of calcium significantly, through either diet or supplements.
Moreover, there is much evidence to suggest that calcium may reduce the risk of high blood pressure and high cholesterol levels as well as cut the chances of colon cancer. Colon cancer risk appears even lower when high calcium consumption is accompanied by high intake of vitamin D. Previous medical concern that too much calcium leads to kidney stones now appears unfounded except in the cases of a few men whose bodies overabsorb the mineral.
Meeting the higher calcium requirements now being advanced by experts will take effort. For adolescents and older women, who are being urged to eat 1,500 milligrams of calcium per day, it will take a cup of nonfat yogurt, two glasses of skim milk, two ounces of cheese, and one-third of a cup of fresh, cooked broccoli to reach the threshold.
Relying on natural food sources is preferable because the body absorbs calcium from foods more easily than from supplements, and the effectiveness of the mineral appears to be enhanced by being ingested along with other nutrients in the food, such as vitamin D, potassium, and magnesium.
"Calcium supplements are a viable option," says John P. Bilezikian, chief of endocrinology at Columbia University College of Physicians and Surgeons and chairman of the National Institutes of Health panel that is urging higher calcium standards, "but so are calcium-fortified foods."
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