Vitamin D Supplementation Still Probably Doesn't Work
The results just keep showing that the popular supplement has few if any benefits
Vitamin D is a surprisingly contentious subject to write about. You might think that it’s just a vitamin which humans naturally make when exposed to sunlight, and therefore people who don’t get much sun should probably supplement, but you’d be wrong. Vitamin D works in many body systems, and low levels of the substance have been associated with everything from an increased risk of cancer to more heart attacks. This has spawned a massive, billion-dollar industry selling vitamin D pills to people, as well as a large body of research.
The thing about vitamin D supplementation is that it has two major things going for it:
Very cheap
Largely harmless
While no medical intervention is entirely cost- or harm-free, vitamin D is one of the closest. Each pill costs cents to manufacture, and there is very little evidence that taking even quite high doses of vitamin D is actively harmful. It’s possible that very high doses for a long period of time might cause some ill health, but that’s true of pretty much anything that you can put into your body anyway.
There have been studies looking at whether vitamin D prevents diabetes, makes adults less likely to get a cold, helps to manage asthma, improves outcomes for newborn babies, improves blood pressure and fitness for older adults, or even whether vitamin D reduces the risk of cancer and heart disease. And, with few exceptions, vitamin D supplementation has resoundingly failed to live up to the hype. It doesn’t seem to improve heart health. There’s no evidence that taking a vitamin D pill daily will prevent diabetes, even if you have very low levels in your blood to start with. Just look through the references above - these are a few examples of massive trials or large systematic reviews that have failed to find any benefits for taking vitamin D on a whole range of diseases.
And it’s happened again. Another newly-released paper, looking at a huge sample of people, has found that taking vitamin D supplements is unlikely to benefit your health. It’s one of the least surprising findings of the last 50 years.
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