Taking calcium supplements to treat or reduce the risk of osteoporosis has been linked to a “significantly increased risk of heart attacks,” according to research by scientists at the University of Zurich, published Thursday in the prestigious journal Heart.

Prof. Sabine Rohrmann, of the cancer epidemiology and prevention division at the Swiss university’s Institute of Social and Preventive Medicine, and her team also found that “boosting overall dietary calcium confers no significant heart health benefit.”

Calcium supplements are commonly recommended to the elderly and to women who have gone through menopause, to prevent bone thinning.

The Swiss authors based their findings on almost 24,000 participants in one of the German arms of the European Prospective Investigation into Cancer and Nutrition (EPIC) study in Heidelberg. All the participants were between 35 and 64 years old when they joined the study, which lasted from 1994 to 1998.

In an editorial in the same journal, Prof. Ian Reid and Prof. Mark Bolland of the University of Auckland in New Zealand wrote that the safety of calcium supplements “is now coming under increasing scrutiny.” They pointed to previous research, showing a link between these supplements and kidney stones, as well as stomach and abdominal symptoms, and noted that while trial evidence suggested that calcium supplements cut levels of cardiovascular risk factors, this didn’t actually translate into fewer heart attacks and strokes.

The editorial writers also suggested that many women taking calcium supplements to ward off brittle bones were already healthier than those who didn’t, and that the overall protective effect was modest – in the order of just 10 percent.

They noted that eating food high in calcium, including milk products, green leafy vegetables and bony fish like sardines were greatly preferable to taking supplements. Calcium consumed in food, the New Zealand researchers wrote, is taken in small amounts spread throughout the day, so it is absorbed slowly. But bottled supplements cause calcium levels in the blood to soar above the normal range, and it is this flooding effect that might ultimately be harmful, they suggest.

“It is now becoming clear that taking this micronutrient in one or two daily doses is not natural, in that it does not reproduce the same metabolic effects as calcium in food,” they said. “Given that it is neither safe nor effective, boosting calcium intake from supplements should be discouraged.”

After receiving a copy of the article, the Health Ministry told The Jerusalem Post that calcium was a valuable nutrient and that health authorities around the world recommended it to strengthen and preserve the health of bones.

“There have been some epidemiological studies that analyzed data on the use of calcium in certain populations and found that there may be a statistical connection between the use of calcium supplements and the rise in prevalence of heart attacks,” the ministry statement said.

However, it added, “not enough scientific data has been accumulated to bring about a change in the positions of leading health organizations in the world, including Israel.”

The ministry, the US Food and Drug Administration and their European counterparts have not changed their recommendations on calcium consumption, but “they continue to follow the subject and will work to limit calcium supplements if adequate scientific data accumulate.”

The ministry statement concluded that it was “looking into the possibility of limiting the maximum permitted level of vitamins and minerals in general and other nutritional supplements to prevent overconsumption.”

Prof. Sofia Ish-Shalom, a veteran endocrinologist and head of Rambam Medical Center’s unit for bone and mineral metabolism, told the Post regarding the new research that it was “best to get calcium intake from food, but there are people – including many Jews and Arabs, apparently due to genetics – [who] develop lactose intolerance. They have difficulty digesting milk products.

If people do not get enough calcium from food, they can take supplements making a total – including food – of 1,000 to 1,200 milligrams of calcium per day if they are post-menopausal women or men over 60.

Teenagers should also get 1,200 mg., but other age groups should take less.”

There is not enough evidence, continued Ish-Shalom, that calcium supplements are dangerous to the heart, as not enough epidemiological evidence exists.

“There are self-reported events, but that is different from actual data on heart attacks,” she said. But she urged additional studies on the alleged connection.

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