Common Vitamin Pill Doses Increase Death Rate 7%

Robin Hanson cited a survey of studies on vitamin supplementation. Their conclusion is that the dosages people take in multivitamins are harmful overall (except for selenium). Phil Goetz pointed out a huge flaw in the survey (it doesn’t have the possibility of identifying lower doses that are helpful, if larger doses in some studies were harmful).

However, there exists a single, high quality study of vitamin C and E supplementation in old men, which uses high but reasonable doses (commonly taken by many people and present in some multivitamins). They looked at cancer and heart attack, but also total mortality.

The old men are dying off 7% more often if they have the (thought to be reasonable at the beginning of the study) dose of vit C or E (compared to placebo). Redo the study and you’ll probably get something like 4-10% instead of 7%. I think this is pretty good evidence for Robin’s claim.

This sort of binary treatment-variable study can always be criticized for overly high doseage, as Phil Goetz pointed out. The 400 IU vit E every 2 days is well under the dose already commonly accepted to cause long-term problems (400 IU daily). The 500mg vit. C daily is well above the highest dietary recommendation of 100mg/day, but it’s well below the amount some people take.

I already knew that supplementing vitamin E was a bad idea. It turns out that even though it’s not fat soluble (so megadoses get excreted out quickly), supplementing past the accepted-useful amount of vitamin C (100mg/day) is harmful.

In general, supplementing fat-soluble vitamins is dangerous, because the levels build up slowly (daily consumption is not needed). You should really get your blood levels checked, and supplement only if needed. On days when I don’t get much sun (less than 10 minutes), I take 2000 IU of vitamin D. I should check if this is too much.