When a recent study reported that calcium may increase your risk of cardiovascular disease, the ensuing wave of concern and controversy was inevitable. For millions of older men and women taking calcium to help maintain bone mass, the study caused undue alarm and a flurry of calls to doctors asking, “Should I stop taking calcium?”
Before you consider tossing your calcium supplements, you should know that there are some serious flaws in the design of this study--even the study authors acknowledge these defects.
Problems with Study Design
As the Council for Responsible Nutrition (CRN) points out, the original study wasn’t designed to measure cardiovascular events. Consequently, confounding factors were not equally distributed across the study groups, which resulted in misleading results.
For example, the calcium supplement group had a population with a greater incidence of high cholesterol at baseline, and also included more smokers who were more likely to smoke for a longer duration. (The association between smoking and heart disease is well-established.)
Also, the data on calcium intakes was incomplete. Study participants did not always provide the supplement brand name or dosage on food questionnaires so calcium intakes from supplements were inaccurate. Also dietary changes over time which affect total calcium consumption were not calculated.
In addition, calcium intake does not equal calcium absorption in the gut. Many factors can affect calcium absorption and utilization—including age, medical conditions and the presence of other nutrients necessary to use calcium in the body. So, drawing any associations between calcium intakes and CVD outcomes without accounting for these factors would be unreliable.
Taken together, these shortcomings in the study design render the association between calcium intake and increased risk of CVD questionable at best.
The flawed study design may explain why the study findings were inconsistent.
Greater dairy calcium intake—that is milk, cheese or ice cream and not supplements—actually had a significantly lower risk of heart attacks. However they found no link between either calcium supplements or food-based calcium intake and strokes or overall cardiovascular disease death. But they did find a link for heart attacks.
Sorting it Out
The bottom line is this: you need calcium at every stage of life, but it is particularly important as you get older as there is a greater risk of falls and fractures due to weak bones. Removing calcium supplements from your diet could put you at an even greater risk for these kinds of problems.
Nutrition experts advise consumers to be aware of how much calcium you get from your diet and then supplement with calcium if needed.
For best utilization, calcium--whether obtained through diet or supplements--should be consumed in small divided doses.
Also, calcium needs other nutrients including vitamins, protein and minerals--primarily magnesium--to be absorbed by your bones. This is why good bone-building supplement formulas contain vitamin D and vitamin K and the correct ratio of calcium to magnesium. The current ratio is 2 to 1 with newer evidence pointing to a 1 to 1 ratio.
If you do take a calcium-only supplement, most medical experts recommend that you take it with meals rather than in isolation.
As with any supplement, speak with your doctor or other healthcare practitioner to determine your own personal needs.
Council for Responsible Nutrition
New Hope 360
Drug Store News
Journal of Clinical Endocrinology and Metabolism