I tried the food version: 10 units of fruits /veggies daily, plus alot of amla, acerola etc as supplements. One and a half year, because I believed in the hype of "real" vit C vs "syntetic"
It did not work at all: one of the biggest mistakes I did according my health.
4-5 grams of vit c / ascorbic acid daily is the best aid in health progress, IMO.