Vitamin B6 can be helpful for hypothyroidism when triggered by abnormal liver functions, however the body seems to eventually adapt to whatever amounts are supplemented, so in order to maintain normal thyroid activity with Vitamin B6, ever-increasing amounts would have to be taken. This of course becomes self-limiting, since magnesium levels, and Vitamin B6 itself would become unreasonably high in the long run, and there is a potential risk of Vitamin B6 overdose-related toxic effects... Full Text