Calcium is Not the Magic Bullet

By Wendy Gordon

In most people's minds, healthy bones are inextricably linked with calcium. The use of calcium supplementation as the primary tool for osteoporosis prevention has increased significantly since 1987, the year when the National Institute of Health increased their recommended daily intake of calcium to 1500mg/day for women over 50.

This obsession with calcium, while not totally misplaced, typifies Western medicine's reductionist approach to physiology. Bones are not merely inert hunks of calcium. They are living tissue, constantly forming and reforming via a complex interplay of minerals, vitamins, and hormones.

Osteoporosis is the excessive demineralization of bone. Bone density generally begins to decline in both sexes past the age of 35. Women lose bone mass most rapidly in the decade after menopause, but by the age of 75 the gap closes and both sexes are equally prone to fracture. Bone is composed of two types of tissue: the solid cortical tissue that makes up the outside of bone, and trabecular tissue, an interconnecting honeycomb structure that comprises the spongy interior.

There is no denying that osteoporosis is a serious problem. Hip fractures (the most common manifestation) are incapacitating, sometimes even fatal. Back problems due to vertebral degeneration and compression are also painful and debilitating. What is doubtful is that mainstream medicine's limited approach, based on calcium loading and drugs, is remotely effective. Nor are the results of bone density machine tests particularly consistent or reliable. The incidence and morbidity associated with osteoporosis is increasing worldwide. Ironically, the rate of osteoporosis is lowest in countries with the lowest calcium intake; as calcium intake increases so does the incidence of osteoporosis. These studies don't factor out numerous other nutritional and lifestyle factors, but obviously calcium is not the magic bullet.

An analysis of 49 separate studies published between 1986 and 1989 showed a small positive correlation between calcium intake and bone mass, especially in premenopausal and early postmenopausal women. Other studies indicate that calcium supplementation of 1000mg/day significantly slows bone loss in healthy post menopausal women. What wasn't clear was whether this denser bone mass actually prevented fractures. Although decreased bone mass is the hallmark of osteoporosis, qualitative changes in bone matrix are also present, which could result in "brittle bones" more susceptible to fracture. Women with postmenopausal osteoporosis also have significantly lower levels of transferrin (a plasma protein that transpor ts iron to the bone marrow), prealbumin (a hepatic protein that is an accurate indicator of malnutrition), retinolbinding protein (which transports vitamin A) and fibronectin (a glycoprotein involved in wound healing).

Clearly we need a broader-based perspective!

Phosphorus accounts for approximately half of bone mass. The mineral is required to merge calcium into bone, in the form of calcium phosphate. If insufficient phosphorus is ingested along with calcium, the body will cannibalize its own phosphorus stores to make up the difference. A study published in the June 2003 Journal of the American College of Nutrition shows that as calcium intake increases without a corresponding increase in phosphorus, total phosphorus levels fall. Calcium supplementation in the U.S. has increased substantially over the past 20 years, but phosphorus intake has remained relatively the same. Older women tend to have the lowest phosphorus intakes.

Some nutrition experts now recommend that people take their calcium in the for m of calcium phosphate, but others believe that phosphor us actually exacerbates the problem. Western societies, where the incidence of osteoporosis is highest, consume the most phosphorus. Phosphorus is an end product of protein digestion, and soft drinks contain a lot of phosphorus. However, digestion of complex carbohydrates also produces lots of phosphorus byproducts. Go figure.

Magnesium comprises only a small fraction of bone matter, but plays an impor tant role in maintaining the optimal level of calcium in the body. Magnesium regulates the amount of calcium that is let into the cell. Deficiencies not only lead to calcification of bone, they promote calcium deposits elsewhere in the body, such as calcium oxalate kidney stones and calcium deposits in the arteries. Magnesium supplementation, like calcium, increases bone density. Some researchers and doctors suggest magnesium supplements from 300-1000mg/ day. But again, magnesium requirements are highly individualized and excessive magnesium could disrupt a delicate balance. Too much magnesium (as anyone who's taken Milk of Magnesia) knows causes loose stools. Whole grains, nuts, green leafy vegetables, and seeds are naturally high in magnesium.

Fluoride increases bone mass, but too much causes brittle bones. Fluoridated water or even use of fluoridated toothpaste should be sufficient. Silicon, boron, and manganese, all trace minerals found readily in whole, unprocessed foods, all appear to strengthen bone.

Chromium and copper also contribute to healthy bones, although an overly high ratio of copper in proportion to chromium weakens trabecular bone. Sugar (both from refined and natural sources) and alcohol increase chromium requirements, so overconsumption of these substances may play a role in osteoporosis. Vitamin C and zinc increase calcium absorption, while vitamin E prevents calcium deposits in the ar teries.

Then there's vitamin D, which in its active hormone-like form in the body, promotes calcium absorption. Vitamin D levels have been on the decline due to our indoor lifestyles and fear of the sun. As I've stated in this column previously, most people, especially darker-skinned people in northern urban climes, could benefit from a half hour or so a day of unadulterated sunshine.

The sedentary lifestyle in industrialized societies probably plays just as significant a role in bone health as diet. Exercise such as walking, running, aerobics, and weight lifting clearly strengthen bone, among their many other benefits.

Hormones play an important role in bone mineralization, as evidenced by women's rapid bone loss after menopause. Unfortunately, postmenopausal hor mone supplements increase the risk of breast and cervical cancer. Whether or not the potential benefits outweigh the risk is again a personal decision, based on an individual's physiology and family medical history.

Approved in 1995, the drug Fosamax has become a very popular way to treat osteoporosis. Doctors are prescribing it to younger and younger women, even at the expense of dietary recommendations. Fosamax is a "biphosphonate" which works through the phosphorus pathway to inhibit bone resorption and soft tissue calcification. However, it is expensive, has many side effects (most notably digestive difficulties), and there is no proof it decreases the risk of fracture.

Obviously osteoporosis is a very complex subject where much more extensive research is needed and anyone who makes a definitive statement on how to treat it is lying. From my analysis of the research, I think younger women are fine eating a varied diet of whole foods and engaging in regular weight-bearing exercise. Women nearing or past menopause, especially those with a family histor y of osteoporosis, probably need something extra. But they are better off consulting a nutritionist or nutritionally sophisticated doctor for an individualized diet and exercise plan, rather than simply guzzling milk or gulping calcium pills. Drugs such as Fosamax should be a last resort.