Abstract
There are a number of large-scale clinical studies which were implemented for elucidating efficacy of vitamins. In them, however we can find quite a few studies which are inappropriate for using as trustable evidence. Actually, in these studies endpoints were not set suitably for participants' pathophysiological aspects intervened by vitamins supplementation. Furthermore, setting of vitamin intervention strategy according to participants' metabolic feature in which vitamins exert an effect as a coenzyme seems unfavouralbe. Thus, clinical practitioners (a user of the evidence) need to understand various issues which the mentioned large-scale studies should involve. It is expected that research methods using vitamins are making progress in the future.
