The over the counter supplement is TruNiagen. It reduced recovery time by about 30% vs placebo. It also ensured that recovered patients had better liver function (i.e. they were truly recovered). TruNiagen is relatively cheap, available over the counter as an anti ageing supplement, and it doesn't seem to have serious adverse side effects.
Submitted title (..reduces Covid recovery) has opposite meaning to the original (..Reduces Recovery Time..) which mean "increases recovery"..