At least every 5 years, the U.S. Department of Agriculture and the U.S. Department of Health and Human Services are required by federal law to issue Dietary Guidelines for Americans. According to the law, these guidelines are supposed to be based on the best available science. Yet some of their recommendations don’t seem to have any basis in science at all. In particular, I think that their recommendations about calcium intake will make the problem of osteoporosis worse, not better.
Continue reading “High-Calcium Diets Probably Cause Osteoporosis”
The committee that put together the Dietary Guidelines for Americans, 2010 were trying to solve a nonexistent problem: calcium deficiency. Unfortunately, their suggested solution to this nonexistent problem would make some of our most serious real problems worse. If people follow these guidelines and eat more dairy foods, they will actually increase their risk for osteoporosis and several other common, serious health problems.
The human body is surprisingly good at maintaining calcium balance on a low-calcium diet. To find cases of true dietary deficiency of calcium, you have to look at people who were consuming extremely abnormal diets. Most cases involved babies who were being fed some bizarre substitute for breast milk. In reality, cases of rickets (soft bones) in children are nearly always due to a shortage of vitamin D, the sunshine vitamin.
When you think about it, most of the world’s large land animals manage to get enough calcium from their plant-based diet to grow an enormous skeleton. Nor does any species other than our own consume the milk of another species, or any milk at all after infancy. So why should we expect human beings to need dairy foods, or to need a calcium intake that can be achieved only through eating dairy foods or taking supplements? It makes no sense.
Scientists have known for decades that osteoporosis occurs mainly in countries where people eat a lot of dairy products and have a relatively high calcium intake. In fact, there’s reason to believe that eating too much animal protein and too much calcium actually causes osteoporosis.
The populations with a high risk for osteoporosis also have high rates of death from coronary artery disease. Fortunately, the same kind of diet that prevents heart attacks also helps to keep the bones strong. That means eating a low-fat, plant-based diet that includes plenty of fruits and vegetables.
It’s also important to get enough vitamin D. A few minutes of exposure to midday sun on the face and arms during the spring, summer, and fall should provide enough vitamin D for most light-skinned people in the United States. If you are dark-skinned, live in the far North, or have some other reason why you can’t go out in the sunshine, your doctor, physician assistant, or nurse practitioner can monitor your vitamin D levels and advise you about vitamin D supplements.
Women in the United States are continually pressured by their doctors and by the media to eat a high-calcium diet and take calcium supplements, supposedly to prevent osteoporosis. I resist this advice, because I’ve known for more than 20 years that osteoporosis is actually most common in the populations with the highest calcium intakes. Now, a study just published in the British Medical Journal warns that calcium supplements could also raise the risk of heart attack, which is the major cause of death in women in the United States.
I found out about the link between high calcium intakes and osteoporosis in the late 1980s, while I was editing a handbook for dietitians. The author wrote that osteoporosis is common only in societies where people eat a lot of dairy products. I was shocked by this information. Later on, I found that both the high protein content and the high calcium content of dairy foods are implicated in causing osteoporosis. For years, Harvard professor Mark Hegsted warned people that osteoporosis was a result of the same kind of diet that causes heart disease. He specifically warned that high calcium intakes probably make osteoporosis worse. Sadly, his warnings fell on deaf ears.
Reading the article in the British Medical Journal made me angry. The study it described was a meta-analysis, which means that it compiled the results of several clinical trials. The researchers found 15 clinical trials in which women were given either calcium or placebo, mostly for the prevention or treatment of osteoporosis. What angered me was the dates of the studies. The earliest one was published in 1989, the latest in 2008. Even by the time the earliest of those studies was done, there was already plenty of reason to believe that calcium supplements would have made the women’s osteoporosis worse, not better. In other words, human research subjects were subjected to unnecessary harm. That sort of thing is a huge violation of medical research ethics. It’s also illegal in civilized countries.
Medical researchers are supposed to do their homework before they start enrolling human beings in a clinical trial. By the time that first study was done, it was already obvious that high calcium intakes make osteoporosis worse, not better. Harvard professor Mark Hegsted explained the problem in an article published in 1986, before the first of the studies included in the meta-analysis.
It’s bad enough that the average doctor has had little to no training in nutrition or dietetics. What’s even worse is that some of the doctors who are doing nutrition studies evidently don’t bother to read the scientific literature on nutrition before they start experimenting on human beings.
According to the article in the British Medical Journal, there were 143 myocardial infarctions in the patients assigned to take calcium and 111 myocardial infarctions in the patients assigned to take a placebo. If these women had been given proper counseling on how to make themselves heart-attack-proof, all of these heart attacks could have been avoided.
Photo by German Tenorio