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Calcium — more than strong bones

Karen Miller | 6/13/2014, 10:02 a.m.
(Almond photo Luigi Chiesa)

People associate calcium with strong bones. That’s understandable. Ninety-nine percent of the body’s calcium is stored in the bones and teeth. But it’s that other 1 percent that’s a powerhouse. Calcium is the most common mineral in the body and is responsible for a number of essential functions in the body.

Without calcium, muscles would not contract, nerve cells would not communicate with each other, the heart would not beat normally. Blood clots because of calcium, and hormones, such as insulin — which regulates sugar in the blood — are secreted with calcium’s help.

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Dairy products, like milk, cheese and yogurt, are good sources of calcium.

So important are these functions that to keep a steady supply of calcium available, the body literally robs Peter to pay Paul and takes from its stash in the bones. A normal heartbeat trumps bone strength.

Calcium requires a bit of help to do its job. That’s where vitamin D comes in. Without an adequate supply of vitamin D, calcium is less likely to be absorbed by the digestive tract and instead is lost as waste products. That’s why calcium supplements typically contain a dose of the vitamin. The two work in unison to build a healthy body.

The daily requirements of calcium recommended by the Institute of Medicine vary by gender and age, and are highest for those nine to 18. These years provide the optimum window of opportunity to increase bone density, or bone strength.

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Foods high in calcium and exercise help young people reach peak bone density or strength.

Bones are far from lifeless matter, and in fact are in constant change removing the old and developing the new. During childhood and teenage years, bone development exceeds the pace of bone removal, resulting in larger, heavier and denser tissue. That’s why foods high in calcium and exercise — particularly weight bearing exercise —are recommended at an early age when bones are still growing. Weight bearing exercise, such as walking, creates stress on bones and induces them to grow bigger and stronger.

That does not mean that older adults no longer require calcium. In aging adults, particularly among postmenopausal women, bone removal exceeds formation, resulting in bone loss that increases the risk of osteoporosis.

According to the Osteoporosis Foundation, in the five to seven years following menopause, a woman can lose up to 20 percent of her bone density.

The good news is that it’s easy to get calcium from food — and not just milk and cheese. Other excellent sources are leafy green vegetables, such as kale, collard greens and broccoli as well as certain fish and seafood. In addition, calcium is added to foods, such as cereals and orange juice.

For more suggestions, visit the Office of Dietary Supplements.

Supplements can help if it is difficult to consume enough calcium in food. The two main forms of calcium dietary supplements are carbonate and citrate. Calcium carbonate is inexpensive, and is absorbed best when taken with food. Calcium citrate, on the other hand, is more expensive and is absorbed well on an empty or full stomach.

In addition, according to health experts, the body can absorb only about 500 milligrams of a calcium supplement at any one time. In other words, taking a higher dosage does not increase calcium intake. Those on 1,000 mg a day are advised to split the dose and take half at one time.

Whether you get calcium from food or supplement, consuming the recommended amount each day can promote good health and strong bones.

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Recommended daily allowances for calcium and vitamin D

Age Calcium
(milligrams)
Vitamin D (IUs)
1-3 700 600
4-8 1,000 600
9-18 1,300 600
19-50 1,000 600
51-70

1,000 (males)
1,200 (females)

600
70+ 1,200 800
14-18 pregnant / lactating 1,300 600
19-50 pregnant / lactating 1,000 600

Source: Institute of Medicine

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Good sources of calcium

Food Amount Calcium (milligrams)
Yogurt, plain, low fat 8 ounces 415
Sardines, with bones 3 ounces 325
Milk, non-fat 8 ounces 299
Collard greens, cooked 1 cup 266
Orange juice, fortified 6 ounces 261
Canned salmon 3 ounces 181
Almonds 1 ounce (24 nuts) 70

Source: National Institutes of Health Office of Dietary Supplements, Harvard School of Public Health