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.

Why did humans lose our tails? Blame a "jumping gene"


Most animals have tails, including almost all mammals. For some reason, we humans don’t. This difference has been the source of much speculation among scientists over the years, and many arguments have been made about why we don’t tails.

One line of reasoning goes like this: tails are very useful for animals that live in trees, but once our ancestors came down from the trees and started living on the open plain, they didn’t need those tails any more. But why lose them? Lots of animals don’t live in trees, and they still have tails.

Even among the primates, most species have tails, but chimpanzees, gorillas, orangutans, and bonobos–the great apes–don’t. In fact, one way to tell great apes apart from other apes is by the presence of a tail. We humans are simply great apes without so much hair. Or, as the English scientist Desmond Morris called us in his famous book, humans are “The Naked Ape.”

So why am I writing about this now? Well, in a newly published article in Nature, a group of scientists from NYU, led by Itai Yanai and Jef Boeke, seem to have figured out what made us lose our tails. It’s all due to a piece of DNA that copies itself and jumps around our genome.

It’s a bit geeky, but stay with me and I’ll try to explain.

It seems that sometime around the divergence of the great apes from other primates, about 15-20 million years ago, a “jumping gene” popped into a gene called TBXT in our ancestor. (The B in TBXT stands for brachyury, which means “short tail.”)

The jumping gene here is just a piece of DNA a few hundred letters long*, not really a gene all by itself. But once that jumping gene got into TBXT, it was in just the right position to make the cells in our ancestor produce a shorter version of TBXT. The shortened gene was missing one of its pieces, but it still worked – well, sort of. Our ancestors managed just fine, but they lost their tails.

(Aside: the piece that’s chopped out is called exon 6, for those who really want to know.)

Given that this happened over 15 million years ago, how did the scientists prove their hypothesis? Well, other mammals have the same gene, but they make a longer version. So the authors of the new paper created a version of the TBXT gene in mice that included the jumping gene–and, as predicted, some of the mice lost their tails entirely.

Admittedly, this doesn’t exactly prove that one jumping gene caused us to lose our tails. Without a time machine to take us back 15 million years (with a DNA sequencing machine in tow), we can’t truly prove what happened eons ago. But it’s a compelling story, because we know that our genomes, and those of other great apes, have this unique jumping gene that other mammals lack.

So now we know how we lost our tails. We still don’t know exactly why, though. Some scientists speculate that being tail-less might have helped us to walk upright, or that it might have been better to lose the tails once our ancestors stopped living in trees.

On the other hand, guinea pigs don’t have tails either, and they don’t walk on two legs. And koalas don’t have tails, even though they live in trees. Some of these questions may just have to remain a mystery.

*Technically, the jumping genes in this story are called Alu elements, and they occur all over our genome. Famed geneticist Haig Kazazian, a former Hopkins colleague who passed away just two years ago, explained in a 2004 paper that Alus are a form of “nonautonomous retrotransposon.”