The other really important point is that often our bodies ignore or are unable to process many vitamins if they occur on their own (as in supplement capsules) versus when then appear in particular combinations in real food. This very often will "unlock" the body's ability to digest and absorb the nutrients. We have evolved to eat food, not nutrients.
All this said, you can go a long time without any food at all, and almost indefinitely with extremely minimal food (lemon juice fasting etc) so I wouldn't worry about it while hiking very much at all. There is no particular reason to maintain a "normal" diet while hiking for a few days, even nutritionally, except psychological hurdles (diabetes and other health issues excepted). I find that if I keep active, even my energy levels remain high while fasting. When I allow myself to stop, then I crash... but that's exactly what you want when you stop for the night anyway.