Robin generates a lot of clever ideas. That's awesome. I've heard him retract before, but it is tempting to make the minimum feasible patch to your stated ideas when someone exposes some shallowness or flaw in your analysis.

I'm interested in a large single prospective on vitamin supplementation. I can't believe any good will come at looking retrospectively at correlations (I'm too lazy right now to see if that's actually a problem with any of the studies used in the meta-analysis) - people with more health problems (and especially older people) tend to take more vitamins.