Sufficient thyroid function is necessary to utilize supplemental riboflavin, as thyroid hormones convert riboflavin into its active form, FAD.

“in order for that rabbit flavin to actually be utilized by your entire enzyme you have to have sufficient thyroid function and not enough people talked about this so because if you look at the pathway planners as Paul was talking about that that I drew up from all sorts of research papers and consolidating my findings on the one diagram you know rabbits not just listed as riboflavin it's listed as FA D we're changing it back to just be - and riboflavin just for clarity's sake but your thyroid function has to be functional because your thyroid hormones convert the riboflavin that you are consuming into active riboflavin which is FA D which is FA D”