Oh I just watched a documentary about this! Niacin is suppose to be the best for treating depression. The doctor was talking about vitamin therapy, etc. and this was one of the topics he discussed; he mentioned that he had known of a woman that was treated with large doses of Niacin and was cured of her depression! Then the traditional "doctor" stepped in and said you shouldn't be taking all that Niacin, so she did and her depression took over again. Taking large doses of any vitamins are not bad for you, and what your body doesn't need it will excrete naturally; plus in the past 20 years, I think is what he said, there have only been 7 alleged deaths from vitamins as compared to everything else that is jaw-dropping!
What the doctor was trying to clear up was that vitamins can be used to heal our bodies in a natural way. Most doctors aren't even taught of these sorts of methods while they are in school, you have to seek out this sort of information for yourself. He even went on to mention the use of vitamins for curing cancer, it was all rather fascinating and you cannot deny the truth that is just staring you in the face by the end of it.
For those interested, it is called Food Matters.
You will never see food and medicine in the same light ever again. This opened the floodgates for me to start doing research and completely altering the way me and my family eats on a daily basis.