Does anyone know what the time-line is on vitamin deficiencies? I mean might this be like cigarettes - increases your risk of something going wrong massively but only becomes apparent years down the line when you're already screwed.
That wouldn't be consistent with studies showing very strong and consistent effects on children. Source: the section in this blog post from Yvain, the section on Multivitamins.
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.