[majkinetor]

Yeah, that is already done in animals few times and even in human cells in vitro, see here:

https://en.wikipedia.org/wiki/L-gulonolactone_oxidase#Animal...

> There were number of successful attempts to activate lost enzymatic function in different animal species

This is not trival change however given the amount of time that passed and that some level of adaptation to loss ocured. It would however probably be milestone in human achievements.

Even if GULO is activated it might not be enough: The process of evolution does not necessarily result in the normal provision of optimum molecular concentrations:

http://www.cellmedsoc.org/research_archive/NHC/studien_pdf/o...

Found a paper on primate micronutrient patterns too:

http://www.sciencedirect.com/science/article/pii/S1095643303...