Researchers at the Institute for Aging Research (IFAR) at Hebrew SeniorLife, an affiliate of Harvard Medical School (HMS), have published a study that shows no evidence of a link between calcium intake and coronary artery calcification, reassuring adults who take calcium supplements for bone health that the supplements do not appear to result in the development of calcification of blood vessels.
The study followed participants from the Framingham Heart Study, the longest running medical study in history. The investigators examined 1,300 participants, both men and women with an average age of 60, who were asked about their diet and supplement use and then underwent CT scans of their coronary arteries four years later.
Study participants who had the highest calcium intake, from diet or supplements or both, had the same coronary artery calcification score as those who had the lowest calcium intake. The coronary artery calcification score represents the severity of calcified plaque clogging the arteries in the heart and is an independent predictor of heart attack.
This study addresses a critical question about the link between calcium intake and a clinically measurable indicator of atherosclerosis in older adults. There was no increased risk of calcified arteries with higher amounts of calcium intake from food or supplements.
In recent years, reports have raised concern regarding a potential adverse effect of calcium supplements on risk of heart attack in women. However, the Institute of Medicine (IOM) concluded that evidence from clinical trials does not support an adverse effect of calcium intake on risk of cardiovascular disease. They recommended the following guidelines for calcium intake considered safe and effective for bone health: 1,200 mg per day of calcium for women over 50 and men over 70 and 1,000 mg per day for men between 50 and 70. The guidelines say supplementation can be used if the minimum requirements are not being met through diet.
These findings add to the weight of the evidence that calcium supplements do not have adverse effects on cardiovascular disease risk. In fact, previous studies have shown that calcium has beneficial effects on blood pressure and blood cholesterol levels. There's also preliminary evidence to suggest that calcium plus vitamin D supplementation may improve blood glucose (sugar) control in people with type 2 diabetes.
While coronary artery calcification is indeed a risk factor for heart attack, there's no evidence that consuming calcium causes this condition. Calcification in arteries is the result of events happening in damaged arteries, not simply because calcium is circulating your bloodstream.
Furthermore, experts contend that the small increase in blood calcium that occurs after taking a supplement is unlikely to be large enough to cause calcification in artery walls, or any tissue in the body.
These new study findings offer assurance that people who take calcium at recommended levels for bone health can continue to do so safely. That said, it's always important that you discuss with your health care provider whether calcium supplements are appropriate for your health profile. People with chronic kidney disease, for example, should only take calcium as prescribed by their doctor.
Source: American Journal of Clinical Nutrition, November 7
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