Basically, the coenzymes of niacin help break down and utilize proteins, fats, and carbohydrates. Vitamin B3 also stimulates circulation, reduces cholesterol levels in the blood of some people, and is important to healthy activity of the nervous system and normal brain function. Niacin supports the health of skin, tongue, and digestive tract tissues. Also, this important vitamin is needed for the synthesis of the sex hormones, such as estrogen, progesterone, and testosterone, as well as other corticosteroids.

Niacin, taken orally as nicotinic acid, can produce redness, warmth, and itching over areas of the skin; this "niacin flush" usually occurs when doses of 50 mg. or more are taken and is a result of the release of histamine by the cells, which causes vasodilation. This reaction is harmless; it may even be helpful by enhancing blood flow to the "flushed" areas, and it lasts only 10-20 minutes. When these larger doses of niacin are taken regularly, this reaction no longer occurs because stores of histamine are reduced. Many people feel benefit from this "flush," but if it is not enjoyable, supplements that contain vitamin B3 in the form of niacinamide or nicotinamide can be used, as they will not produce this reaction. (Note: When vitamin B3 is used to lower cholesterol levels, the nicotinic acid form must be used; the niacinamide form does not work for this purpose.)

Uses: Niacin is used to support a variety of metabolic functions and to treat a number of conditions. Many niacin deficiency symptoms can be treated by adjusting the diet and by supplementing B3 tablets along with other B complex vitamins. Many uses of niacin are based primarily on positive clinical experience and are not as well supported by medical research, although more studies are being done.

Niacin helps increase energy through improving food utilization and has been used beneficially for treating fatigue, irritability, and digestive disorders, such as diarrhea, constipation, and indigestion. It may also stimulate extra hydrochloric acid production. Niacin, mainly as nicotinic acid, helps in the regulation of blood sugar (as part of glucose tolerance factor) in people with hypoglycemia problems and gives all of us a greater ability to handle stress. It is helpful in treating anxiety and possibly depression. B3 has been used for various skin reactions and acne, as well as for problems of the teeth and gums. Niacin has many other common uses. It is sometimes helpful in the treatment of migraine-type headaches or arthritis, probably in both cases through stimulation of blood flow in the capillaries. This vitamin has also been used to stimulate the sex drive and enhance sexual experience, to help detoxify the body, and to protect it from certain toxins and pollutants. For most of these problems and the cardiovascular-related ones mentioned below, the preference is to take the "flushing" form of niacin, or nicotinic acid, not niacinamide.

Nicotinic acid works rapidly, particularly in its beneficial effects on the cardiovascular system. It stimulates circulation and for this reason may be helpful in treating leg cramps caused by circulatory deficiency; headaches, especially the migraine type; and Meniere's syndrome, associated with hearing loss and vertigo. Nicotinic acid also helps reduce blood pressure and, very importantly, acts as an agent to lower serum cholesterol. Treatment with about 2 grams a day of nicotinic acid has produced significant reductions in both blood cholesterol and triglyceride levels. To lower the LDL component and raise the good HDL cholesterol, people usually take 50-100 mg. twice daily and then increase the amount slowly over two or three weeks to 1500-2500 mg. Generally, for those with high cholesterol levels it has been used to help reduce the risk for atherosclerosis. Because of its vascular stimulation and effects of lowering cholesterol and blood pressure, vitamin B3 has been used preventively for such serious secondary problems of cardiovascular disease as myocardial infarctions (heart attacks) and strokes. Also, some neurologic problems, such as Bell's palsy and trigeminal neuralgia, have been helped by niacin supplementation. In osteoarthritis, to help reduce joint pain and improve mobility, niacinamide has been used in amounts beginning at 500 mg. twice daily up to 1,000 mg. three times a day along with 100 mg. daily of B complex.