Vitamins and supplements are a waste of money

Welcome to Impact Factor, your weekly dose of comments on a new medical study. I am Dr. F. Perry Wilson.

Thirty billion dollars. That's how much Americans spend each year on vitamins and supplements. And according to the most comprehensive analysis of their effects, most of this money is wasted.

The umbrella magazine in the Annals of Internal Medicine,^[1] is a comprehensive report on randomized trials of vitamins and supplements examining their effects on cardiovascular disease and overall mortality.

Including only randomized trials was an excellent choice. Observational studies on the use of vitamins and supplements are hindered by what is called the "healthy user bias": people who choose to take vitamins adopt often other healthy behaviors. Time and time 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 about vitamins and supplements in one place, which allows me to say the following: There is no high quality evidence that a vitamin or supplement would have a beneficial effect on the body. overall mortality.

But okay, I'll give you the details.

The analysis included studies of 24 different interventions – I listed most of them here – including 277 randomized trials and close to one million patients. And, basically, the bupkis.

The only intervention for which average quality data on protection against all-cause mortality was available was the reduction in salt intake, which frankly does not seem to me to be a vitamin or a supplement.

To give a good result to the other findings, there was low-quality evidence that omega-3 fatty acids could protect against myocardial infarction and heart disease, and that folic acid could protect against stroke. There was evidence of moderate quality that a combination of calcium and vitamin D from our great friend increased the risk of stroke.

But all these effects were rather weak.

Why? Well, remember that vitamins were usually identified through their deficiency syndromes. We know that vitamin C is vital for life because without it, scurvy is a disease. But nothing has ever explained why excessive intake of any of these chemicals would be extremely beneficial to health.

To be fair, it is only mortality and cardiovascular consequences. It remains possible that vitamins and supplements improve subjective quality of life. But you know what else improves the quality of life? Money. And based on this study, you may want to save yours as you go through the vitamin aisle.