Osteoporotic bone. Are the mainstay treatments for osteoporosis prevention, calcium and vitamin D, truly useless?
Do osteoporosis guidelines overstate the benefits of calcium and vitamin D supplements? And is their continued presence due to vested interests and conflicts of interest? That’s the provocative argument made by Andrew Grey and Marc Bolland, two endocrinologists who recently detailed their analysis in The BMJ, in a paper entitled “Web of industry, advocacy, and academia in the management of osteoporosis” [PDF]. They introduce their case by noting:
For many years, recommendations for prevention and treatment of osteoporosis have included increasing calcium intake (by diet or supplements) and use of vitamin D supplements. Since the average dietary calcium intake in most countries is much less than that recommended by guidelines, many older people are advised to take calcium supplements to prevent osteoporosis. The recommendations have been implemented successfully: over half of older Americans take calcium and vitamin D supplements, either prescribed or over the counter, and bone health is the most common specific motivation for use of nutritional supplements. However, this behaviour does not reflect evidence that has emerged since 2002 that such supplements do not reduce the risk of fracture and may result in harm. Guideline bodies also continue to recommend calcium and vitamin D supplements. Here, we argue that change is made difficult by a complex web of interactions between industry, advocacy organisations, and academia.
Osteoporosis is a medical condition for which supplements have been considered an accepted part of conventional medicine for some time. Are conflicts of interest trumping good science? And are calcium and vitamin D supplements truly useless? Like many clinical questions, there is evidence to support a range of opinions, and it’s very difficult to state, with certainty, that one position is the correct one. Despite this, that’s the case that Grey and Bolland make in their analysis. Continue reading
Why take a drug, herb or any other supplement? It’s usually because we believe the substance will do something desirable, and that we’re doing more good than harm. To be truly rational we’d carefully evaluate the expected risks and benefits, estimate the overall odds of a good outcome, and then make a decision that would weigh these factors against any costs (if relevant) to make a conclusion about value for money. But having the best available information at the time we make a decision can still mean decisions turn out to be bad ones: It can be that all relevant data isn’t made available, or it can be that new, unexpected information emerges later to change our evaluation. (Donald Rumsfeld might call them “known unknowns.”)
As unknowns become knowns, risk and benefit perspectives change. Clinical trials give a hint, but don’t tell the full safety and efficacy story. Over time, and with wider use, the true risk-benefit perspective becomes more clear, especially when large databases can be used to study effects in large populations. Epidemiology can be a powerful tool for finding unexpected consequences of treatments. But epidemiologic studies can also frustrate because they rarely determine causal relationships. That’s why I’ve been following the evolving evidence about calcium supplements with interest. Calcium supplements are taken by almost 1 in 5 women, second only to multivitamins as the most popular supplement. When you look at all supplements that contain calcium, a remarkable 43% of the (U.S.) population consumes a supplement with calcium as an ingredient. As a single-ingredient supplement, calcium is almost always taken for bone health, based on continued public health messages that our dietary intake is likely insufficient, putting women (rarely men) at risk of osteoporosis and subsequent fractures. This messaging is backed by a number of studies that have concluded that calcium supplements can reduce bone loss and the risk of fractures. Calcium has an impressive health halo, and supplement marketers and pharmaceutical companies have responded. There are pills, liquids, and even tasty chewy caramel squares embedded with calcium. It’s also fortified in foods like orange juice. Supplements are often taken as “insurance” against perceived or real dietary shortfalls, and it’s easy and convenient to take a calcium supplement daily, often driven by the perception that more is better. Few may think that there is any risk to calcium supplements. But there are now multiple safety signals that these products do have risks. And that’s cause for concern. Continue reading
Calcium is good for us, right? Milk products are great sources of calcium, and we’re told to emphasize milk products in our diets. Don’t (or can’t) eat enough dairy? Calcium supplements are very popular, especially among women seeking to minimize their risk of osteoporosis. Osteoporosis prevention and treatment guidelines recommend calcium and vitamin D as an important measure in preserving bone density and reducing the risk of fractures. For those who don’t like dairy products, even products like orange juice and Vitamin Water are fortified with calcium. The general perception seemed to be that calcium consumption was a good thing – the more, the better. Until recently.
In a pattern similar to that I described with folic acid, there’s new safety signals from trials with calcium supplements that are raising concerns. Two studies published in the past two years suggest that calcium supplements are associated with an significantly increased risk of heart attacks. Could the risks of calcium supplements outweigh any benefits they offer? Continue reading