The Calcium Conundrum: New Research on Calcium and Heart Health

Calcium, in partnership with vitamin D, is critical to our bone health, a message that doctors, pharmaceutical companies, and marketers of calcium supplements have broadcast loud and clear. What is less well understood is the effect of calcium on heart health. It does appear that people who get enough food-based calcium in their diets have slightly lower blood pressure, better cholesterol numbers, and are a little less likely to become diabetic. But most of us have never thought to question whether there is a difference between calcium from our diet and calcium that we get from a pill or from fortified foods.

Research has shown that our bones tend to use calcium from food sources more effectively than supplemental calcium, and that, despite the hype, supplemental calcium may reduce the risk of bone fracture by a very modest 10%. Nevertheless, since most people don't choose to include enough calcium-rich foods in their diets, supplements have become standard care. Now an analysis of 15 major trials of calcium supplements, published this month in the British Medical Journal, raises serious concerns about this common practice.

After combing through data involving approximately 12,000 individuals, the researchers from New Zealand, Scotland, and Dartmouth Medical School in the US, reported that those taking at least 500 mg of supplemental calcium daily appeared to have a 30% higher risk for heart attacks, and a slightly higher risk for stroke, when compared to those who took no calcium supplements. Notably, the analysis did not include people who took Vitamin D along with the calcium; it is not known whether this would make a difference.

Dietary calcium is a completely different matter. In fact, other studies have suggested a lower risk for heart problems in women who choose foods that are high in calcium. So what foods are best? A list of foods naturally high in calcium can be found on the USDA website (scroll down the page until you find the section on calcium). Happily, most are also extremely heart healthy: sardines, salmon, soybeans (including tofu products), collard greens (and many other green leafy vegetables), and even molasses. Of course, dairy products also provide plenty of calcium. The moral of the story? As with so many other high dose supplements, we continue to learn that it's really not nice to try to fool Mother Nature!