Boning up on calcium

It’s easy these days to worry about whether you’re getting enough calcium. Milk-mustache ads jump off magazine pages. Antacids (such as Tums) promise to deliver calcium while easing your upset tummies. And the supermarket is full of calcium-fortified foods. Do we really need all this reminding, not to mention the added calcium? And if you take supplements, do you know which kind works best?

Adequate calcium is unquestionably important to our overall health. It builds optimal bone mass early in life and slows age-related bone loss during adulthood. Calcium also plays an essential role in blood clotting, blood pressure and the normal functioning of our muscles and nervous system. Some studies even suggest that calcium in the diet has a positive effect on blood pressure and reduces risk for colon cancer.

Researchers agree that calcium is critical for bone health and helps limit bone loss in postmenopausal women. They point out, however, that we do not store up calcium so any gains we get from calcium supplementation last only as we take our supplements.

Some health experts worry that women will make calcium supplementation their primary hedge against osteoporosis and neglect other important ways of maintaining and improving bone health – such as getting exercise and taking adequate vitamin D. Calcium alone, no matter what the amount, cannot prevent osteoporosis. Osteoporosis is a multi-factorial condition involving genes, gender, race, estrogen status, weight, lifestyle factors, vitamin D levels and degree of physical activity.

Calcium Needs Over Time

Calcium needs are high during childhood and adolescence, when bone formation outpaces bone breakdown, and then again after reaching peak bone mass (at around age 35), when the process begins to reverse itself. After age 50, both men and women lose bone at a rate of approximately 0.5-1 percent per year. But because of the sudden drop in estrogen levels, women may experience more bone loss than that – as much as three percent of skeletal mass annually – the first five years after menopause.

Several factors contribute to age-related bone loss. As we get older, we absorb less calcium from our food and supplements. With age, we are also less able to absorb vitamin D – essential for proper calcium absorption – and are less able to produce it through exposure in sunlight. As we get older, we are more likely to also take medications that interfere with calcium absorption or that deplete the body’s calcium; these include corticosteroids (e.g. cortisone), anticonvulsants, diuretics (except thiazide), and antacids containing aluminum. All these factors underscore the need to make adequate calcium intake (as well as vitamin D) a priority as we get older.

How Much Calcium Should You Get?

It’s not easy to know how much calcium to get. Published recommendations have changed to incorporate new understanding of nutrition and nutrients. For example, the familiar Recommended Dietary Allowances (RDAs) for vitamins and minerals have undergone many changes. More recently, the US National Academy of Sciences (NAS) introduced the Dietary Reference Intake (DRI), a level of nutrient intake that research suggests may lower chronic disease risk. The DRI reflects the latest evidence-based research and is gradually replacing the RDA. The NAS also established a Tolerable Upper Intake Level (UL), which it considers the highest intake that poses no health risk.

Dietary Calcium

Most experts agree it’s better to get our nutrients from food than from supplements, because we don’t know yet all the nutrients found in foods, or how they work together. Fruits and vegetables, in particular, are beneficial to the bones. A wide range of foods are rich in calcium. Dairy products may be the most efficient way to get it: One cup of milk (whether whole, skim, or low-fat) has about 300 mg of calcium.

Other calcium-rich foods include broccoli, bok choy, kale, collard, mustard, turnip greens, pinto beans, tofu, figs, canned salmon, sardines with bones, and calcium-fortified orange juice. In the Philippines, our experts from the Food and Nutrition Research Institute (FNRI) recommend a wide array of food items, notably fish and shellfish, which offer the same if not a higher amount of nutrients than milk. They identified some of these food items as dilis, susong pilipit, kuhol, salinyasi and leafy vegetables like saluyot and malunggay.

Calcium Supplements

Even with a good diet, you may come up short on your daily calcium intake and need to consider a supplement. The question is, which one? A visit to the supplement aisle of a drugstore or health food store can be daunting. The elemental or actual calcium that you’re looking for comes in several preparations – carbonate, citrate, gluconate, lactate and phosphate. Many, but not all, come with vitamin D.

Not all labels make note of elemental calcium. But a calcium supplement that includes a number such as "500" or "600" in its title (e.g. Os-Cal 500), usually is an indication that each tablet contains 500 or 600 mg of elemental calcium. To figure out how much actual calcium you’re getting, read the label or the % Daily Value (a term used in food labeling that reflects recommended nutrient intake) of each tablet or serving. Be sure to note the serving size – it may be more than one tablet or capsule. The % Daily Value for all calcium supplement is based on a recommended daily intake of 1000 mg. Thus, a single 500 mg Os-Cal tablet is listed as 50% of Daily Value.

For the most part, calcium carbonate supplies more actual calcium per tablet than other forms. They are also generally the most economical and convenient supplements to use. However, stomach acid is needed to dissolve it and about 20 percent of those over age 60, and 40 percent of those over age 80, may not produce enough stomach acid to promote sufficient calcium carbonate absorption between meals. Therefore, calcium carbonate should always be taken with either food (which stimulates the secretion of stomach acids) or orange juice (which has a high acid content) to be certain that the calcium is absorbed by the body.

Calcium citrate is more readily absorbed than calcium carbonate, and can be taken anytime, but you have to take more, and it’s usually more expensive. Calcium citrate though, is less likely to cause constipation and other gastrointestinal side effects. Although acceptable, calcium gluconate, lactate and phosphate supplements are generally less convenient to use and more expensive than either calcium carbonate or calcium citrate. Calcium gluconate is too difficult to break down, while the other two contain less than 100 mg of calcium each – too little per pill to be practical for most people.

The body has a hard time absorbing more than about 500 mg of calcium at a time. So, try to spread your calcium intake – from both food and supplements – over the course of a day. And even if your calcium intake is stellar, remember that two other elements are essential for bone health: Vitamin D and weight-bearing exercise. Adequate vitamin D is essential for proper calcium absorption, and the stimulus of regular exercise is needed to build bone.