Since it mentioned use of this Robuvit in CFS, I went looking and found this paper of a pilot study: https://www.ncbi.nlm.nih.gov/pubmed/24231834 Improved management of primary chronic fatigue syndrome with the supplement French oak wood extract (Robuvit®): a pilot, registry evaluation, by Belcaro et al. 2014.
just looks like a company wanting to create a bigger market for its product by throwing in some pseudo science not exactly a new thing in marketing ideas.
There seems to be a lot of waffle about changes in measures of ME symptoms in the paper I listed above - with only mood being highlighted as improved. That makes me suspicious that the patients ME didn't really improve. And there's no mention of double blinding. They also say oxidative stress improved in the treated group. I don't know how this is tested, but if the treatment is a natural antioxidant, that may be all that's being measured - give an antioxidant and you get an antioxidant effect. The website for the product makes huge claims to benefit energy and detox. I suspect most of it is hype. https://www.robuvit.com/home/