Transcript: Are Calcium Supplements Effective?
There has been an assumption for decades that as a natural element, calcium supplements must intrinsically be safe, but calcium supplementation is neither natural nor risk-free. But, the same could be said for every medication on the planet. Yet, doctors continue to write billions of prescriptions for drugs every year because the hope at least is that the benefits outweigh the risks. So, what about the benefits of calcium supplements. Yes, heart attacks and strokes can be devastating, but so can hip fractures. The risk of dying shoots up in the months following a hip fracture. About one in five women don’t last a year after a hip fracture, and it may be even worse for men, on average apparently cutting one’s lifespan short by four or five years. And, unfortunately these dismal statistics don’t seem to be getting much better.
So, even if calcium supplements caused a few heart attacks and strokes, if they prevented many more hip fractures, then it might result in a favorable risk-benefit ratio. So, how effective are calcium supplements in preventing hip fractures? We’ve known that milk intake doesn’t appear to help, but maybe that’s because any potential benefit of the calcium in milk may be overshadowed by the increased risk of fracture and death associated with the galactose sugar in milk. So, what about just the calcium in a calcium supplement alone? Calcium intake in general does not seem to be related to hip fracture risk at all, and when people have been given calcium supplements, not only was there no reduction in hip fracture risk, an increased risk is possible. The randomized controlled trials suggested a 64% greater risk of hip fractures with calcium supplementation compared to just getting like a placebo sugar pill.
Where then did we even get this idea that taking calcium supplements might help our bones? It was this influential study, in 1992, that found that a combination of vitamin D and calcium supplements could reduce hip fracture rates 43%. But, this was done on institutionalized women, like in a nursing home, who were vitamin D deficient. They weren’t getting sufficient sun exposure. And, so, if you’re vitamin D deficient and you take vitamin D and calcium, no surprise your bones get better, but for women living independently, out in the community, the latest official recommendations for calcium and vitamin D supplementation to prevent osteoporosis are unambigious: Do not supplement. Why? Because in the absence of compelling evidence for benefit, taking supplements is not worth any risk, no matter how small. Now, this is not to say these supplements don’t play a role in treating osteoporosis, or that vitamin D supplements might not be good for other things, but if you’re just trying to prevent fractures, women living outside of institutions shouldn’t take them and perhaps even in institutions. In this study, instead of giving nursing home residents vitamin D and calcium supplements, they randomized them to sunlight exposure and calcium supplements, and those that got the calcium pills had significantly increased mortality, lived shorter lives than the sunshine only group.
Although calcium supplements don’t appear to prevent hip fractures, they may reduce overall fracture risk by like 10%. So, here’s how the risk-benefit shakes out. If a thousand people took calcium supplements for five years, we would expect 14 excess heart attacks, meaning 14 people would have a heart attack that would not have had a heart attack if they hadn’t started the calcium supplements. So, they were effectively going to the store and buying something that gave them a heart attack, plus ten strokes that otherwise would not have happened, and 13 deaths—people who would have been alive had they not started the supplements. But, that’s all balanced against the 26 fractures that would have been prevented. Now, it’s no fun falling down and breaking your wrist or something, but I think most people would look at risk benefit analysis and conclude that calcium supplements are doing more harm than good.
Given these findings, the use of these supplements should be discouraged, and individuals advised to obtain calcium from their diet instead. Calcium supplements have been associated with elevated risk of myocardial infarction (heart attacks), whereas dietary calcium intake has not. How much calcium should we shoot for? Interestingly, unlike most other nutrients, there’s no international consensus. For example, in the UK, the recommendation for adults is 700 mg a day, but across the pond in the US, it’s up to 1,200 a day. Whenever I see that kind of huge discrepancy between government panels, I immediately think scientific uncertainty, political maneuverings, or both.
Newer data, based on calcium balance studies in which researchers make detailed measurements of the calcium going in and out of people, suggest that the calcium requirement for men and women is lower than previously estimated. They found calcium balance was highly resistant to change across a broad range of intakes, meaning our body is not stupid. If we eat less calcium, our body absorbs more and excretes less, and if we eat more calcium, we absorb less and excrete more to stay in balance. Therefore, current evidence suggests that dietary calcium intake is not something most people need to worry about.
This may explain why in most studies, no relationship was found between calcium intake and bone loss anywhere in the skeleton, because the body just kind of takes care of it. Don’t push it too far, though. Once you get down to just a few hundred milligrams a day, you may get significantly more bone loss. Though there may not be great evidence to support the U.S. recommendations, the UK may have the right idea shooting for between 500 and 1,000 mg a day from dietary sources unless you’ve had gastric bypass surgery or something and need to take supplements. For most people, though, calcium supplements cannot be considered safe or effective for preventing bone fractures.
To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.
Please consider volunteering to help out on the site.