In this randomized, double blind, placebo-controlled trial – the gold standard for determining cause and effect – older adults who took 200 mg vitamin E had more severe respiratory infections.
Among persons experiencing an infection, those individuals who received vitamin E instead had longer total illness duration, more symptoms, and a higher frequency of fever and restriction of activity.
If our results are confirmed and vitamin E exacerbates respiratory tract infections, elderly people, especially those who are already well-nourished, should be cautious about taking vitamin E supplements.
The authors speculated high-dose vitamin E may become a prooxidant in the body (as opposed to the desirable antioxidant). They may have been on to something: The Pro-Oxidant Activity Of High-Dose Vitamin E Supplements In Vivo.
The RDA for vitamin E is 15 mg. The upper limit is 1000 mg. People think 200 mg is no big deal, that “it’s no harm and could be helping.” It’s more like “it’s no help and could be harming.”
An old chart I made: