Calcium is an element critical to many body functions, including bone growth and maintenance, muscle and nerve control, blood clotting, and blood pressure regulation. Bone mass is built until age 29 years or so. After that, you cannot build more bone by increasing your calcium intake, but you can help prevent bone loss by maintaining a good intake of calcium and vitamin D and exercising regularly.

Chronically low calcium intake decreases bone mass and increases the risk of osteoporosis and bone fracture. Osteoporosis is usually silent until people reach their later years. Children, adolescents, and adult women may find it challenging to include enough calcium in their diets. Those who have had prolonged bed rest, diet intensively, and/or inadequate vitamin D intake are also at risk to lose bone mass. Calcium deficiency is usually diagnosed in later years through bone density studies.

Daily calcium requirements: How much do you need?

Birth - 6 months: 210 mg
6 to 12 months: 270 mg
1 to 3 years: 500 mg
4 to 8 years: 800 mg
9 to 18 years: 1300 mg
19 to 50 years: 1000 mg
50+ years: 1200 mg

Daily vitamin D requirements: How much do you need?

Vitamin D is critical to the absorption of calcium from the gastrointestinal tract and in bone formation. From age 6 months through 24 years a person should have 400 IU (International Units) of vitamin D daily. Note that a cup of vitamin D fortified milk has 100 IU. From age 24 years until approximately age 50 years, 200 IU vitamin D is adequate, especially if you get 15 minutes of sunshine exposure three times a week, but there is no harm from taking supplements which contain 400 IU of vitamin D (a common dose in supplements). Healthy adults over 50 years should have at least 400 IU per day. Persons who are frail, housebound or have little sun exposure should have 600 - 800 IU of vitamin D daily. Avoid doses of vitamin D above 1000 IU, as this can be toxic, unless otherwise advised by your physician. .

Food Sources of Calcium

There are many excellent food sources of calcium. See table for calcium content in common foods. Note that one quart of milk contains 1200 mg of calcium, the daily requirement for adolescents and adults. Calcium in foods can be boosted with nonfat dry milk (one tablespoon contains 95 mg of calcium). Finally, note that caffeine, alcohol, and very high protein intake may increase calcium loss through urine.

Calcium Supplements

If your food intake of calcium is too low, take an over the counter calcium supplement. Multivitamins do not contain much calcium. The best researched calcium supplements are calcium carbonate and calcium citrate. Read labels carefully; insure adequate elemental calcium (i.e. the amount available for absorption by your body). See table for details.

Exercise and Bone Health

Exercising regularly will help maintain bone density, agility, and strength, making falls less likely and falls that do occur less likely to cause fracture. Exercise at least four times a week, thirty minutes each time. What type? "Weight bearing" is best: walking, jogging, dancing, etc. Water aerobics, swimming and bicycling are not weight bearing exercises but will help your cardiovascular health and muscle fitness.

Calcium Content in Common Foods

Note: When making soup from bones, add vinegar, 1 to 2 tablespoons during boiling. The acid in the vinegar will dissolve the calcium, enriching the soup stock with the calcium.

Commonly Available Calcium Supplements

If your dietary sources of calcium are insufficient, a supplement taken with meals is needed to ensure adequate intake. Read labels carefully to insure that you obtain adequate elemental calcium. Elemental calcium is the amount of calcium available for absorption from each tablet. In general, you must take several tablets or portions to receive the recommended daily allowance of calcium.