Niacin was the first vitamin for which there was evidence that taking large doses could benefit people with coronary heart disease. It does all the right things with blood lipids: it lowers total cholesterol, raises HDL cholesterol, and lowers trigylcerides. It has also been proven to reduce the chances of having a heart attack. If you have high blood pressure and high cholesterol that you can't lower by diet alone, niacin may help you.

You need to take a total of about 1500 mgs per day. It comes in two forms: the regular short-acting preparation which has to be taken three times a day, and slow-release preparations, which only need be taken once a day. The biggest problem with niacin is its side effects, of which the most prominent are flushing and itching in the face. This can largely be overcome by using only the slow- or time-release preparations and by building up the dose gradually. An aspirin a day also helps to reduce the flushing. Other side effects include abnormal liver function tests, increased uric acid (the cause of gout), increased blood sugar (which means that diabetics should not take it), and stomach ulcers.

So if you have diabetes, a stomach ulcer, liver disease, gout, or if you are taking diuretics for your blood pressure, it is not a good idea to take niacin. Check with your doctor.