How many percent of glucose and HDL are often changed with supplement of biotin?

Question

How is it effective in preventing gray hair?

Answer 1

There's no good evidence that biotin supplements change any of these things. Under current law, supplements do not have to show evidence of effectiveness to be sold in the way that drugs do, so all sorts of wild and unsubstantiated claims float around. When challenged, the hucksters usually trot out some conspiracy theory about the medical community. To show the absurdity of that concept, one only has to look at the use of aspirin in cardiovascular disease. It's been incorporated into standard practice because it works, and nobody's getting rich off aspirin.