zinc can be quite bad for you if taken for prolonged periods of time i have heard. Apparently can significantly reduce the amount of copper in your blood, which is bad.
Ask a health food shop person.
i also take vitamins-nu hair and multi vitamins-both bottles say that there info has not been studied by the fda but i still believe in them shou wu root i heard is good for the hair-it is know to make white hairs turn black?
i called nu hair and they have been in buisness for over 7 years-scams usually dont last that long.