Is it any wonder that people get frustrated when health advice gets turned upside down? Millions of women swallow several calcium pills daily because they have been told they need more of this mineral to keep their bones strong.
Over the past few years, however, evidence has been mounting that this practice carries unexpected risks. A recent study including nearly 24,000 German adults found that those taking calcium supplements were more likely to have heart attacks during the 11 years of follow-up (Heart, online May 23, 2012).
The researchers speculate that excess calcium circulating in the body may lead to calcification in blood vessels. Few people realize that the plaque that clogs coronary arteries is made up predominantly of calcium.
This isn’t the first study to show that extra calcium from supplements could be harmful for the heart. A study published last year in BMJ (online, April 19, 2011) also linked calcium supplements with cardiovascular complications. In this study, more than 16,000 women over the age of 40 were randomized to take both calcium and vitamin D or placebo. Those taking the supplements had about 20 percent more heart attacks and other vascular problems.
Results from 13 other studies of calcium with or without vitamin D were consistent: those taking supplements were slightly more likely than those on placebo to suffer a heart attack or stroke. The researchers estimated that if 1,000 people took calcium for five years, six of them would have a heart attack or stroke and only three fractures would be prevented. Such a risk/benefit ratio is not favorable.
An editorial titled “Calcium Supplements: Bad for the Heart?” in the journal Heart [June, 2012] reviews the medical literature on this controversial topic. Here is the executive summary from the editorial: calcium supplements have been linked to kidney stones, constipation and other more serious digestive complaints, coronary artery calcification, heart attacks and strokes. After considering all the data that has accumulated over the last several years the authors conclude:
“Thus, the consistent evidence is that calcium supplements do more harm than good and that other interventions are preferable for reducing the risk of osteoporotic fractures…We should return to seeing calcium as an important component of a balanced diet and not as a low-cost panacea to the universal problem of postmenopausal bone loss.”
Women aren’t the only ones who have been given confusing health advice. For years, middle-aged men have been urged to have their PSA (prostate specific antigen) blood levels checked annually. Doctors have used this marker to screen for prostate cancer.
Now the U.S. Preventive Services Task Force has recommended that PSA screening should no longer be done routinely. The problem is that the PSA test does not do a good job of discriminating between dangerous prostate cancer that could kill a man, small slow-growing tumors that will not be lethal, and normally enlarged prostates, which are common as men grow older.
One study included 180,000 men and lasted 11 years. It found that at most one death from prostate cancer might be prevented by screening 1,000 men. Screening itself is not risk-free: it can lead to biopsies and surgery, which may result in complications such as erectile dysfunction or incontinence.
Many urologists are outraged at the Task Force recommendation and will continue to encourage their male patients to be screened. This will leave men in the middle, wondering who to believe and what to do.
The same kind of confusion exists for many other health guidelines. Is severe salt restriction helpful or harmful? Scientists are not in agreement. Tight control of blood sugar with medication seems like a prudent approach for treating diabetes, but studies have shown that it may actually cause more harm than good.
Uncertainties will always exist in medicine. Perhaps it’s time for physicians to be more candid about the controversies and the lack of conclusive data behind many guidelines.
Should you wish to read more about the salt controversy, the calcium controversy and some of the other medical flip flops of the last decade, may we suggest our book, Best Choices from The People’s Pharmacy. We provide some common sense suggestions for many health conditions ranging from high blood pressure and high cholesterol to osteoporosis prevention and treatment.
The People's Perspective on Medicine