Niacin -- one of my favorite nutrients.
Read here about the "niacin flush" and how beneficial it is.
There is a "niacin summary page" you can visit for lots more data.
Read here the history of Niacin:
Consequences of Eugenics The Contested Etiology of Pellagra -- Niacin The Cure
The most important role niacin can play in your life is to help get rid of toxins.
It does this by causing the small blood vessels, after taking niacin, to increase in size. When this happens you will "flush." That is, many of those small blood vessels (capillaries) are near the surfact of the body, in the skin. So, when they enlarge in size, more blood moves through them (causing the cleansing action) and the skin will typically get red (flush) and often itchy.
This is a very beneficial action for the body, but many ignorant scientists mistake this action for a "toxic" reaction from niacin and wrongly warn people to avoid using niacin.
The quantity of niacin which will cause this flush varies. If you have not been taking niacin at all, then usually 100 mg to 200 mg, in one dose, will do the job. It would be foolish, at that time, to take more. After a day or so on the same dosage, you'll find that that dosage no longer causes the flush and you have to increase the dosage -- perhaps to 300 mg.
Then, with the slightly larger dose you can get the flush again. Each time it will wear off and you will have to increase the dosage.
Years ago I went through a cleansing action, using niacin, and eventually got up to 5,000 mg per day -- with no flush.
Those scientists who start a person off with 3,000 mg of niacin are foolish. Then, when they repeat that dosage every day for weeks, they don't observe that the flush discontinues after several days -- no matter how much niacin you get, for these purposes it is only the flush that is useful and the flush requires constantly increasing dosages.
Niacin, when used this way, must be accompanied by all the other "regular" vitamins in proper balance.
Niacin, alone, brings down cholesterol levels and blood pressure. It is far safer and of course much cheaper than the drug company's "solutions," such as Mevacor and others. These drugs can cost $500 or more per year and have adverse side effects they don't tell you about.
Niacin is a very safe vitamin to use. Yes, it causes a flush, but the flush is exactly the effect you want.