Calcium and Vitamin D Supplements Still Don't Work, New Study Says

I think I’ll have to add calcium to my list of the Top Six Supplements You Should Not Take. Here’s why.

A year and a half ago, I reported on a very large study of 26,000 men and women that asked if vitamin D helps to prevent bone fractures, as many people (including some doctors) believe.

Well, it doesn’t. That study found that people who took vitamin D had exactly the same risk of bone fractures as those who didn’t. It didn’t matter how much vitamin D they took, nor did it help if they also took supplemental calcium: either way, vitamin D had no effect.

(Aside: everyone needs vitamin D, but most people get all they need from a normal diet. Alternatively, just 10 minutes of sunlight gives you about 4 times your daily recommended vitamin D requirement.)

Well, now there’s a huge new study, just out in the Annals of Internal Medicine, that followed over 36,000 older women, looking at the effects of a combination of vitamin D and calcium over a 22-year period. (That’s a really long time for a study, and kudos to the authors for their determination and effort.) The scientists leading the study looked not only at the effects of supplements on hip fractures, but also whether supplements changed the risk of dying from cancer or heart disease.

The results? Well, the study found no reduction in the risk of hip fractures, which isn’t surprising given that earlier studies found the same thing. But because it was such a lengthy study, following people for more than 20 years, they could ask something else: did vitamin D and calcium have any effect on mortality? Or to put it more bluntly, did the supplements prevent death?

Well, no. But the report was a bit more nuanced than that. It turns out that deaths from cancer went down a tiny bit, and deaths from heart disease went up a tiny bit.

First, though, let me explain the overall experiment. Approximately half the women in the study, just over 18,000, were assigned to take both vitamin D and calcium every day. They were given pills with 1000 mg of calcium carbonate (400 mg of elemental calcium) and 400 IU of vitamin D3 daily. The other half of the participants took placebo pills, but neither group knew whether their pills were placebos or not.

Over the course of 22 years, 1817 women taking supplements died of cancer, compared to 1943 women in the placebo group who died of cancer. That sounds kind of good, right? The study authors report that this result – 126 fewer deaths – was statistically significant (just barely), but there are good reasons to be skeptical of this “significance” claim.

On the other hand, 2621 women taking supplements died of heart disease, versus 2420 women in the placebo group. So there were 201 more deaths from heart disease among women taking vitamin D and calcium: not so good.

Combining both causes of death, we see that in the women taking supplements, there were 75 more deaths from either cancer or heart disease. The study also reported numbers for all causes of death, and there were still very slightly more deaths in the supplement group. (The annual death rate increased from 2.14% to 2.15% for those taking supplements, a non-significant change.)

So on the whole, taking supplements didn’t seem to provide any benefit at all, and it certainly didn’t reduce the risk of death.

Why would supplemental vitamin D and calcium increase the rate of heart disease, or decrease the rate of cancer? Well, first I should emphasize that it’s entirely possible that these supplements have no effect at all, and the difference in death rates must just be random variation. There have been multiple studies speculating on how vitamin D might help to prevent cancer, but the effect, if any, is very small. And as for heart disease, maybe, as the authors of the new study speculate, long-term calcium supplements create calcifications in coronary arteries, which would be a bad thing. For now, this is merely a hypothesis.

So here is my new list of the top 7 (no longer 6) supplements that you should not take:

1. Vitamin C
2. Vitamin A and beta carotene
3. Vitamin E
4. Vitamin B6
5. Multi-vitamins
6. Vitamin D
7. Calcium

You can read more about the first five, some of which can be downright bad for you, in The Top Five Vitamins You Should Not Take.

What’s left? Well, if you don’t have a deficiency, there’s no reason to take any supplemental vitamins at all. If you want to spend a little more money at the grocery, buy some fresh fruit instead. You’ll be healthier for it.

As a final caveat, I should point out that although routine supplementation is worthless and megadoses of vitamins can be harmful, if you think you have a vitamin deficiency, consult with your doctor. Serious vitamin deficiencies might be the result of other health problems that your doctor can help you address, and treatments for specific conditions or diseases may include vitamins.