Someone who does experiments on single substances shows a want of understanding. A network is the only suitable object of study.
If I am right in believing that in the body, every important substance is a member of multiple networks of important substances and each important substance has a small role to play. In short, the network is everything and the individual components are little nothings. Only in each of the many networks of which they are members do the little nothings have importance and value. By belonging to multiple networks, the little nothings acquire significance on their own.
If this is true, and if one is studying the antioxidant network, e.g., and one preloads all people to have measurably adequate levels of all known components (this experiment has to be repeated with each new validated member) of this network except vitamin C, which is left at its natural, unmodified level, (with the complication that the preloading likely shifted these values), and then studies the effects of normalizing vitamin C to its adequate level in all individuals capable of achieving this, one might find the hypothesis is indeed true. Beyond that, one could test the effects of Pauling type doses – one may not be able to find any effect other than more soluble urine specimens and shorter, less arduous duration of illnesses. Or for the first time, one may be poised to find the effect of therapeutic doses of vitamin C, given a body that is prepared to work with higher doses.
A complication – vitamin C is a member of other networks, including immune networks, connective tissue networks, other networks where its hydroxylation is useful, ADME networks in which vitamin C is a member, etc. The putative therapeutic effect may be in one or more of these networks.
How complicated nature is!
Yes, nature could not work – life would not be possible – without complication. Multitasking is not something we invented, but something we discovered at work in nature.