Calcium Supplementation

Revised August 2000

Dr. Charlie Booras, M.D.
by Charles H. Booras, MD

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Christine M. Booras, CPFT, LMT

What Is Calcium?

Calcium is a mineral that your body needs to build and maintain strong bones. It is not produced within the body so it must come from outside sources. It is an integral part in the war against Osteoporosis, along with regular weight-bearing exercise (such as walking) and hormone replacement therapy.

Why is it Important?

Everyone can benefit from strong bones. Since peak bone mass is reached between age 25-35, it is important to start calcium supplementation as early in life as possible (as in our teenage years). Developing strong bones early on helps prevent the weakening that naturally occurs later in life. Young female athletes, dancers, and those with low body weight are at risk for brittle bones.

How much do I need?

A simplified recommended daily allowance (RDA) for calcium is as follows…

Women under age 50 and Men under 65: 1200 mg of Elemental Calcium daily .

Women over age 50 and Men over 65: 1500 mg of Elemental Calcium daily.

Younger people: 1000 mg of Elemental Calcium daily (about three servings of milk, yogurt, or cheese).

Where can I find it?

Calcium may be obtained from two main sources: foods and supplements.

Food sources - the best sources of calcine are from foods, such as dairy products, but they can be high in fat so go for the low fat versions (like 1 or 2% milk). Other good sources are found in nuts, tofu, smelt, sardines, salmon & shrimp. Smaller amounts are found in various other vegetables, fruits, proteins & grains.

Supplements – Calcium is available in different combinations (calcium carbonate, citrate, lactate, gluconate, and phosphate). Each has a different rate of absorption as well as different effects on the gastrointestinal tract. You will likely find the widest selection at a health-food store. Buy a supplement labeled "USP." These letters on a label mean that the product meets the U.S. Pharmacopoeia's standard for dissolving and for dosage. Chewables are probably absorbed better since the dissolving process starts in your mouth.

Calcium citrate has the advantage of being absorbed when gastric acid secretion is low (very common after menopause and in those taking acid reducing medications). In addition, the citrate form is protective against the formation of calcium-rich kidney stones.

Elemental calcium

The RDA for calcium intake is based on the amount of elemental calcium in the supplement you take. You will need to look carefully at the packaging of you supplement to find out just how much elemental calcium you are getting. For example, TumsŪ contains "500mg" of calcium carbonate, but only 200mg of its calcium carbonate is in the elemental form. In order to get 1000 mg. of elemental calcium, you would need to take five TumsŪ per day, not just two.

Additional Minerals.

These minerals help to strength our bones and have other benefits as well. If you are at an increased risk for Osteoporosis, we recommend shopping for a calcium supplement that already contains these ingredients, or take them as an additional supplement.

  • Magnesium. Increases the absorption of calcium and helps control high blood pressure and palpitations. The RDA is 400 mg. a day.

  • Vitamin D. Useful in those who can not get about 15 minutes of sun each day. The ability to synthesize Vitamin D is reduced with aging. Take 400 IU a day before age 65 and then 800 IU a day thereafter.

You may also consider increasing your intake of the following...

  • Zinc: About half of all women consume less than the recommended dietary allowance (RDA) for zinc, which is 12 milligrams per day.

  • Fluoride. A fluoride intake of 1.5 to 4 mg. a day is considered safe and may increase calcium retention and reduce the incidence of dental cavities.

  • Others. Additional supplementation with manganese, copper, and boron will also help prevent osteoporosis. They can usually be found in a multivitamin / multimineral supplement.

How do I take supplements?

Your calcium is best taken with meals, such as a calcium rich food (milk or orange juice) and not with a high-fiber food (such as cereal). This increases the likelihood of absorption. The presence of other nutrients (such as vitamin D and certain amino acids) also promotes absorption. You should not take more than 500 milligrams at a time. If you're taking 1,000 milligrams a day, divide it into two doses. Calcium is also more efficiently absorbed at night, so take one of your doses before bedtime.

Blockers of Calcium Absorption

Alcohol, caffeine, smoking, excess phosphorus (in carbonated beverages) excess protein (ie. high protein diets), and antacids containing aluminum hydroxide all contribute to either depleting calcium from your bones or preventing absorption. Remember... everything in moderation!

Drug Interactions

If you are taking the antibiotic tetracycline, corticosteroids, or iron pills, talk with your doctor or pharmacist. Calcium can interact with these and other drugs.

A study published in the June 2000 issue of the prestigious Journal of the American Medical Society has demonstrated that initiation of supplementation with calcium carbonate can reduce the absorption of levothyroxine, a commonly used hormone for the treatment of hypothyroidism ("underactive thyroid"). You should talk to your doctor about having your thyroid tests repeated about one month after starting calcium supplementation. It is not known if this effect on thyroid hormone absorption occurs with use of other supplements besides calcium carbonate.

Quantities of foods containing 500 mg of Elemental Calcium:

  • Milk - 14 oz.

  • Calcium fortified Milk - 8 oz.

  • Vanilla milkshake - 12 oz.

  • Swiss cheese - 2 1/4 oz.

  • Cottage Cheese - 3 1/3 cups

  • Cheddar Cheese - 2 1/2 oz.

  • Yogurt, plain, low-fat - 10 oz.

  • Ice cream - 2 3/4 cups

  • Custard - 1 2/3 cups

  • Macaroni and cheese - 1 1/4 cups

  • Tofu - 1 3/4 cups

  • Cheese pizza - 3 slices

  • Sardines - 11 medium

  • Salmon (canned, with bones) - 9 oz.

Strategies to increase your calcium intake

The average calcium intake of menopausal women in the U.S. is only about 500 mg. a day. It takes a bit of thought to increase your calcium intake without excessively increasing your calories too. In addition to helping reduce bone loss, a high calcium intake is thought to be a protective factor against cancer of the colon, stroke, hypertension, Premenstrual Dysphoric Disorder (formerly Premenstrual Syndrome or PMS, and periodontal disease.

The best source of calcium is from your diet! A good strategy is to include 300-500 mg. of calcium containing foods with each meal and as a bedtime snack. If this is not possible at any meal, a calcium supplement should be used.

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