I don't think there is a limit on consumption as it is not a supplement but a food/ plant. However, like with anything, don't go overboard! :) There are different ways to eat it and incorporate it into your diet, which might be fun to research. Yes, you can use it on your scalp and your strands, whatever works best for you. To be safe, always do a patch test! Just be sure when eating it/ using it on your hair that you prepare it properly. The correct method and reason for it are outlined in the Beginners Guide to Making Hair Care at Home!