Calcium: Good; Calcium Supplements: Not So Much

While calcium consumed while eating food aided heart health, supplements were not correlated with similar benefits.

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After years of hearing that we should consume more calcium and supplement our diets with calcium pills, a new study questions that advice and suggests that calcium supplements may increase the risk of having a heart attack.

Calcium supplements have been widely accepted by physicians and the public as a safe and natural way to prevent osteoporosis. Is it time to take a second look at this philosophy?

Dietary calcium is absorbed in low doses throughout the day while calcium supplements cause a spike in blood calcium levels which may ultimately deposit too much of the mineral in the body at one time, causing harm.

A large study of nearly 24,000 people was undertaken to determine if calcium supplements reduce the risk factors for cardiovascular disease. The participants' use of dietary supplements, their diet, and their health were studied during the 11 years of research. Study subjects were between the ages of 35 and 64 when they joined the study.

During the course of the research, led by Swiss and German researchers, there were 354 heart attacks and 260 strokes in the group with 267 deaths. Those whose diets included a moderate intake of calcium (820 mg per day) from both dietary sources and supplements had a 31 percent lower risk of having a heart attack than those in the bottom 25 percent of calcium intake. However, people who consumed more than 1,100 milligrams of calcium per day did not have a significantly lower risk of heart attack, and the level of calcium intake had no effect on the risk of stroke.

When researchers looked further, they found that those who took vitamin/mineral supplements regularly were 86 percent more likely to suffer a heart attack than people who took no supplements, and those who only took calcium supplements had twice the risk of heart attack than those who took no supplements.

The authors of the study concluded that increasing dietary calcium may not provide significant cardiovascular benefits, but calcium supplements might raise the risk of heart attack and should be taken with caution.

In an editorial that accompanied the study, New Zealand professors Ian Reid and Mark Bolland call the safety of calcium supplements "under increasing scrutiny." They address previously published research that links calcium supplements to an increased risk of kidney stones and gastrointestinal symptoms (especially constipation), as well as an increased risk of hospitalization for acute abdominal conditions. They point to the fact that dietary calcium is absorbed in low doses throughout the day while calcium supplements cause a spike in blood calcium levels which may ultimately deposit too much of the mineral in the body at one time, causing harm. Taking calcium in one or two daily doses does not replicate natural dietary calcium intake and does not have the same metabolic effects in the body as calcium provided from food.

Many people, particularly post-menopausal women, take calcium supplements hoping to minimize the loss of bone density and reduce their risk of osteoporosis. The findings from this study add to the increasing body of evidence that calcium supplements may increase the risk of a cardiac event while providing only minimal benefit.

Americans over the age of 50 are advised to consume 1,000 to 1,200 milligrams of calcium per day. Doctors regularly recommend supplements that meet or exceed those amounts, particularly for post-menopausal women and others at risk for osteoporosis.

Until more research is done and the issue is more clear, perhaps it is time to return to recommending a balanced diet that provides adequate calcium instead of encouraging patients to pop a pill to meet their calcium needs.

The report was published online in the journal, Heart.

This article originally appeared on, an Atlantic partner site.

Presented by

Beth Fontenot is a registered dietitian and a licensed dietitian/nutritionist. She serves on the Louisiana Board of Examiners in Dietetics and Nutrition and writes for

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