calcium pills, high blood level of calcium

The latest flip-flop in health has to do with calcium. For decades, doctors, nutrition experts and registered dietitians have been urging women to take calcium supplements to strengthen their bones. A new study shows that advice was likely misguided.

Do Calcium Supplements Calcify Arteries?

In this trial, the Multi-Ethnic Study of Atherosclerosis (MESA), 5,448 adults who did not have heart disease were followed up for 10 years (Journal of the American Heart Association, October 11, 2016). Researchers had them fill out questionnaires about their diet and supplements. They also underwent scans of their coronary arteries to see how much calcification they had. This is a measure of heart attack risk.

The authors found that “calcium supplement use was associated with a 22% increase in risk in incident CAC” [coronary artery calcification]. When people take calcium pills, their blood levels rise rapidly. This can lead to what doctors call “calcium loading” or excessive calcium throughout the blood stream. This in turn appears to contribute to atherosclerosis.

Plaque in the coronary arteries contains much more calcium than cholesterol. That’s why scans for coronary artery calcification can help predict the risk of heart disease and future heart attacks. The authors speculate that calcium from supplements may also affect insulin metabolism, inflammation, cholesterol and triglycerides.

Calcium from Food Is Protective:

Not all calcium is dangerous. In fact, the results of the MESA study show that people who got the highest amounts of calcium from their diet were least likely to have calcified coronary arteries. They had a 27% reduced risk for hardened arteries.

What this means is that mom was right when she encouraged you to drink your milk, eat your yogurt and consume lots of green leafy vegetables. These dietary sources of calcium appear to be good for the circulatory system.

Are Calcium Pills Bad for Bones?

The assumption that calcium pills would strengthen bones and prevent osteoporosis appears to have been built on a house of cards. Because bones have a lot of calcium, people thought that taking supplements would make bones stronger. But excessive calcium disrupts a crucial hormone that regulates calcium flow in and out of bone tissue. Calcium loading seems to interfere with the normal activity of this parathyroid hormone. One possibility is that high calcium levels suppress natural bone remodeling, which is how bones stay strong (Nutrients, Oct, 2013).

Last year a meta-analysis involving 50 controlled trials and more than 12,000 study subjects concluded that calcium supplements “are unlikely to translate into clinically meaningful reductions in fractures” (BMJ, Sept. 29, 2015). In the same issue of the BMJ, a separate analysis found that “Evidence that calcium supplements prevent fractures is weak and inconsistent” (BMJ, Sept. 29, 2015).

The Handwriting on the Wall:

For decades thoughtful scientists have been warning that taking high-dose calcium pills is not a good way to build strong bones and prevent fractures. Here is what we wrote about this topic last year.

It must be especially frustrating for people who have been conscientiously trying to protect their bones to learn that instead they have may have been putting their hearts at risk. Calcium pills have other downsides as well. Research has been building that excess calcium may increase the risk for kidney stones (New England Journal of Medicine, Feb. 16, 2006) and severe constipation (Journal of Bone Mineral Research, March, 2012) in addition to a greater risk of heart attacks (BMJ, July 29, 2010) and dementia (Neurology, online Aug. 17, 2016). Read more about this most recent concern:

Are Calcium Supplements Bad for Women’s Brains?

Are Calcium Supplements Bad for Women’s Brains?

What Are We to Make of the Calcium Flip-Flop?

By now, it should be apparent that the calcium advice of the last 30 years leaves a lot to be desired. Not only is the benefit of supplements questionable, there is reason to be concerned about risks.

In 2010 we interviewed Walter Willett, MD, DrPH, Chairman of the Department of Nutrition and Frederick John Stare Professor of Epidemiology and Nutrition at Harvard University’s T. H. Chan School of Public Health. He and Michael Castleman suggested that a diet rich in vegetables would be a better approach to keeping bones healthy than calcium supplements. People don’t need pills to have strong bones. Here is a link to the one-hour Show 752: Bone Vitality. The MP3 download is $2.99.

What do you think about this calcium controversy? We would love to read your thoughts in the comment section below.

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  1. MFK

    Thanks in part to The People’s Pharmacy, some years ago I changed both my own supplement habits, and advice to my wellness-coaching clients, based on the earlier research and warnings.

    It is difficult for people when their doctors are not well-informed: women are told more supplemental calcium is helpful for their bones, and also being given Rx that weaken bones. There are so many good food sources for calcium—it is hard to see why someone should take an unnecessary supplement that is still questionable. However, magnesium citrate, vitamin D3, zinc — all in proper doses—are a different matter.

    The basics of good nutrition are re-validated with every study published…Michael Pollan says it succinctly: “Eat food. Not too much. Mostly plants.”

  2. Ethan
    Seattle, WA USA

    Am a 70 year old retiree, it is not the calcium pills that cause hardening of the arteries, but the staph bacteria that folks get by eating finger food without thoroughly washing their hands.

    Happened to see a brief presentation by a seasoned M.D., on one of the big morning news TV shows over 10 years ago, he said examination of deceased dying of hardening of the arteries found the calcium was adhering to the inside of the arteries
    due to the staph bacteria on the walls of the arteries. I believe his name was Isadore
    Rosenfield, a medical practictitioner somewhere around New York.

    My parents lived to near 100, but they both were careful about washing-up and using
    clean utensils to eat with. I know dysentery was areal problem when I was in the U.S.
    Army 46 years ago overseas due to failure of the riflemen to wash their hands, and
    use clean water in the field. Support personnel did not have this problem, however,
    since they were where there was plenty of clean water and it was easy to wash-up.
    Hope this helps. I think it is the correct reason for hardening of the arteries.
    A healthy retiree on the west coast near Seattle.

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