Strong bones take a lifetime to make

September 11, 2002|by LYNN F. LITTLE

No bones about it, your body needs calcium and a fair amount of it. The National Academy of Sciences currently recommends that children ages 4 through 18 consume 1,300 milligrams of calcium daily to help build dense bones and promote maximum calcium retention later in life. From age 19 through 50 years, 1,000 milligrams of calcium are recommended daily to maintain calcium balance and reduce the risk of osteoporosis. After age 50, the recommended intake increases to 1,200 milligrams daily to minimize bone loss in later years and help keep osteoporosis in check.

Unfortunately, many of us don't even come close to meeting these guidelines. In fact, less than half of us do. Teens have the worst record. According to one study, 86 percent of teen girls and 65 percent of teen boys did not meet recommended levels. Adult women are not much better. On average, American women consume 500 to 600 milligrams of calcium daily; about half the amount recommended. While the body can adapt to some reduction in dietary calcium by increasing the efficiency of absorption, such adaptations typically are not enough.

Also, one's ability to compensate for low intake decreases with age, which makes getting adequate calcium even more important in later years when risk of osteoporosis is highest.

Most doctors and nutritionists recommend that people look first to food for their calcium. This is because food sources of calcium tend to supply other nutrients such as phosphorus, vitamin D and lactose that help the body absorb and use calcium. Supplements are best used to help boost calcium intake, but should not be the primary source of it.

Consider the following tips to increase your calcium intake.

Dairy products are the most concentrated sources of calcium. Milk contains 300 milligrams (mg) per cup; low-fat yogurt, 345-425 mg per cup; ricotta cheese, 340 mg per half-cup; and hard cheeses from 200-270 mg per ounce.
Good non-dairy sources of calcium include white beans and cow peas, 200 mg per cup; baked beans, 150 mg per cup; tofu made with calcium sulfate, 130 mg per half-cup; collard/mustard greens, 100 mg per half-cup; and broccoli, 80 mg per half-cup.

For those who are lactose-intolerant or who have lactose maldigestion, non-dairy calcium sources are very important.
Canned fish is another good source of calcium, if you can stomach the bones. A 3-ounce serving of salmon serves up 180 mg and sardines come in at 325-370 mg per 3 ounces.
To optimize bone retention of calcium, get moving! Activity that demands the skeleton to resist gravity and bear weight (walking, running, weight lifting) encourages calcium to stay in the bones.

Along with boosting calcium intake, make an effort to minimize calcium loss. Protein, caffeine and alcohol all play a role in increasing calcium loss in urine. In one study, it was found that the more protein the subjects ate, the more calcium they lost. Furthermore, animal protein led to an even greater loss of calcium than plant protein. One theory to explain this is that the body dumps calcium into the urine to neutralize the increased acidity that occurs when eating meat. So, for optimal bone health, watch your intake of animal protein, caffeine and alcohol.

If getting the recommended level of calcium through diet alone proves too difficult, many calcium supplements - each of which has advantages and disadvantages - are available on the market. Calcium carbonate and phosphate preparations have the highest concentration of calcium, about 40 percent. Calcium citrate contains 21 percent elemental calcium, but generally is better absorbed than calcium carbonate. Calcium lactate and calcium gluconate contain the least amount of calcium, 13 percent and 9 percent calcium, respectively.

To maximize absorption, some clinicians recommend consuming calcium on an empty stomach; calcium carbonate, however, is generally better tolerated and absorbed when consumed with a meal. Regardless of the form consumed, it's recommended that no more than 500 mg of calcium be taken at any one time. Calcium-fortified orange juice is an excellent alternative to pills. One cup generally contains the same amount of calcium as a cup of milk and is readily absorbed.

When selecting a calcium supplement, look for labels that state the supplement meets USP standards or has passed a 30-minute dissolution test. Avoid supplements made with bone meal or dolomite; they may be contaminated with lead. Also, don't pay more for claims of "natural" or sugar- or starch-free formulas. Calcium is calcium. Even flavored chewable calcium tablets are not significant sources of sugar or calories. Finally, it's best to take calcium supplements with plenty of fluids. If you can tolerate milk, it's an ideal accompaniment because the lactose and vitamin D in the milk help enhance absorption.

Calcium is needed in the body to slow calcium loss from bone as well as for everyday functions including muscle contraction, blood clotting, hormone secretion and nerve impulse transmission.

Fitting more calcium into your diet does not have to be costly or inconvenient. Read food labels to find out how much calcium is contained in your favorite foods. Aim for 100 milligrams or more per serving.

Lynn F. Little is a family and consumer sciences educator with Maryland Cooperative Extension, Washington County.

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