Dear Curious,

All body cells need calcium, but over 99 percent of the calcium in the body is used to strengthen bones and teeth. Calcium is also essential for blood clotting, muscle contraction, and nerve functioning. It's believed that a long-standing poor calcium intake contributes to osteoporosis, a condition where there's less bone mass throughout the body. This can lead to a decrease in height, hip fractures in old age, and eventual loss of teeth.

Although osteoporosis is a disease associated with older people, prevention of it starts as early as childhood. Adequate calcium intake is important for building strong bones that can benefit you for the rest of your life. From ages 9 through 18 years, the RDA for calcium is 1300 mg. because this period of growth is a critical time to build a greater bone mass that can help prevent osteoporosis. For adults aged 19 - 50, the RDA is 1000 mg. a day. After age 50, the RDA is 1200 mg.

Dairy products, such as milk, yogurt, and cheese, provide most of the calcium in the adult diet. Cottage cheese is an exception, since most of its calcium is lost in processing. For non-dairy sources, try calcium-fortified orange juice, leafy greens (e.g., spinach, kale, collards), tofu processed with calcium carbonate (check the label), almonds, sardines, and other small fish eaten with the bones. Some breakfast cereals and breakfast bars are fortified with calcium, too. Another good way to boost the calcium content of foods is to add nonfat powdered dry milk to items, such as puddings, cookies, soups, gravy, or casseroles. One tablespoon of nonfat powdered dry milk contains 52 mg. of calcium, so adding 2 to 4 tablespoons to a food item can significantly boost its calcium content. It's also a good idea to be sure that your foods contain Vitamin D because it helps with calcium absorption. Good sources include fortified milk, margarine, egg yolk, and tuna fish; it's also made in your skin when exposed to sunlight.

Another option is a supplement. Before going this route, estimate your calcium intake (via nutritive values of foods charts or with a nutritionist). The major risk of taking excess calcium supplements is poor absorption of other minerals and, occasionally, the development of kidney stones. If you're at Columbia, call x4-2284 to make an appointment with a nutritionist. Outside of Columbia, get a referral from your primary health care provider.

Women, in particular, need to be especially vigilant about their calcium intake. They make less bone than men, lose it at a faster rate, and live longer. Thus, women start their adult years with less bone and have a longer time to lose it. Women's bone loss begins at around age 30, and proceeds slowly and continuously until menopause (at approximately age 50). It often speeds up at menopause and continues at a high rate for the next 5 to 10 years.

For further information on calcium and osteoporosis, look at Calcium and Osteoporosis and Can drinking milk prevent osteoporosis? in Alice's Fitness and Nutrition archive.

Alice

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