I try to be cautious with vitamins. It appears that taking them in pill form might not be safe. I switched to a high-nutrient diet that focuses on getting nutrients from food wherever possible.
Some examples of cases where vitamins that are beneficial in food form might be dangerous in extracted form:
I haven't checked the others, but in the first one they seem to have given people 400 IU Vitamin E, which is equivalent to 180mg synthetic Vitamin E or 12x the RDA for Vitamin E. And they did that for 7-12 years straight. Also, the increase in cancer risk doesn't seem that significant if I'm reading the results right.
I'm not a fan of multivitamins that go crazy over the RDA unless I know the RDA number is way too low to begin with (like in Vitamin D's case). It's also an especially bad idea to go crazy over RDA with fat-soluble vitamins, because those are the ones that are stored in your body for longer periods of time. At least the water-soluble ones come out when you pee, but I think there's some new evidence that even some of those is stored or at least it may not be a good idea to "mega-dose" on them.
I recall Rhonda Patrick explaining on a podcast that they used an extremely high amount of vitamin E, all in the form of alpha-tocopherol which leads to depletion of gamma-tocopherol.
But I agree about trying to get your vitamins from your diet in general.
I wouldn't call the dose extremely high. Some over the counter supplement pills have 1000 IUs and it looks like the study was done with only 400 IUs. (It's over the current recommended daily intake though.)
I'm not a fan of multivitamins that go crazy over the RDA unless I know the RDA number is way too low to begin with (like in Vitamin D's case). It's also an especially bad idea to go crazy over RDA with fat-soluble vitamins, because those are the ones that are stored in your body for longer periods of time. At least the water-soluble ones come out when you pee, but I think there's some new evidence that even some of those is stored or at least it may not be a good idea to "mega-dose" on them.