In his TED talk, Weller gives a potential alternate benefit source in nitric oxide production which leads to potential cardiovascular benefits. So, the short an

In his TED talk, Weller gives a potential alternate benefit source in nitric oxide production which leads to potential cardiovascular benefits. So, the short answer is it may not be (just) vitamin-d. The bigger point though is that there are a lot of very complex things that happen when you go outside and benefits could come from many of them. We want an easy 'this one thing happens so we can replicate just that' but maybe it is actually a combination of many things so there may be no easy one pill replacement.