Science: Vitamins and Supplements Don’t Work

Welcome to Impact Factor, your weekly dose
of commentary on a new medical study, I’m Dr. F. Perry Wilson. Thirty billion dollars. That’s how much Americans spend every year
on vitamins and supplements, and according to the most comprehensive analysis of their
effects, most of that money is being wasted. The “umbrella review”, appearing in the
Annals of Internal Medicine, is a comprehensive reporting of randomized trials of vitamins
and supplements that examined their effects on cardiovascular disease and overall mortality. Including only randomized trials was a great
choice – observational studies of vitamin and supplement usage are plagued by what’s
known as “healthy user bias” – individuals who choose to take vitamins often engage in
other healthful behaviors. Time and again, vitamins that looked promising
in observational studies failed in large randomized trials. I’m looking at you, Vitamin D.
Now we have all the best data surrounding vitamins and supplements in one place which
allows me to say the following: there is no high-quality evidence that any vitamin or
supplement has a beneficial effect on overall mortality. But ok, I’ll give you the details
The analysis included studies of 24 different interventions – I’ve listed most of them
here – comprising 277 randomized trials and nearly a million patients. And, basically, bupkis. The only intervention that had even moderate
quality evidence for protection against all-cause mortality was reducing salt-intake, which,
frankly, doesn’t sound like a vitamin or supplement to me. To give fair play to the other findings, there
was low quality evidence that omega-3 fatty acids might protect against myocardial infarction
and heart disease, and that folic acid might protect against stroke. There was moderate quality evidence that a
combination of calcium and our old friend vitamin D increased the risk of stroke. But all of these effects were pretty small. Why? Well, let’s remember that vitamins were,
by and large, identified via their deficiency syndromes. We know that vitamin C is vital for life because
without it people get scurvy. But there has never been much rationale as
to why a super-intake of any of these chemicals would give super-benefits to health. Now, to be fair, this is only looking at mortality
and cardiovascular outcomes. It remains possible that vitamins and supplements
might improve subjective quality of life. But you know what else improves quality of
life? Money – and based on this study, you might
want to save yours when you’re walking down the vitamin aisle.