You should check out the research cited on Vitamin D in the first link: "vitamin D supplementation decreases all-cause mortality in adults and older people"
While it certainly is possible to "get vitamin D" by going outside, that doesn't mean it's enough.
The leading theory as to the advantage of having white skin is that it assists in providing more vitamin D in latitudes without as much direct sunlight. This means the amount you get by "going outside once in a while" is not sufficient (otherwise we wouldn't need the advantage of getting as much as possible)
Likewise, drinking coffee removes calcium and vitamin d from your body, so it is wise to replace them, especially if you drink a lot of coffee.
Also, while I might not "need" to supplement them because I am getting "enough" that doesn't mean I won't benefit by taking more. Indeed, we're talking about Nootropics here, not just staying alive.
While it certainly is possible to "get vitamin D" by going outside, that doesn't mean it's enough.
The leading theory as to the advantage of having white skin is that it assists in providing more vitamin D in latitudes without as much direct sunlight. This means the amount you get by "going outside once in a while" is not sufficient (otherwise we wouldn't need the advantage of getting as much as possible)
Likewise, drinking coffee removes calcium and vitamin d from your body, so it is wise to replace them, especially if you drink a lot of coffee.
Also, while I might not "need" to supplement them because I am getting "enough" that doesn't mean I won't benefit by taking more. Indeed, we're talking about Nootropics here, not just staying alive.