Niacin is one of several B vitamins that are water-soluble. In old nutrition textbooks, niacin is called vitamin PP. There are three forms of vitamin-B3: niacinamide, nicotinic acid and niacinamide. In the body, niacin is convered to nicotinamide and eventually to NAD, NADH, NADPH and NADP, used in thousands of reactions in every cell and organ.
Like other B vitamins, vitamin-B3 assists enzymes that break down and utilize fat, protein and carbohydrates as a coenzyme. Niacin is also essential for the creation of sex hormones, DNA repair, and the creation of healthy skin in the body.
Niacin improves circulation and creates a red flushing reaction in the body called a niacin flush; however the nicotinamide and niacinamide forms do not do this. Another form of the vitamin, inositol hexanicotinate, is called no-flush niacin.
The advantage of the flush is that as circulation is increased, the cholesterol level is reduced in the blood. Simultaneously, this B vitamin increases the level of good cholesterol, the HDL-cholesterol. A niacin flush may be accompanied by tingling and itching sensations. The head may throb as well. Generally a niacin flush passes in about 20 minutes and indicates that parts of the body affected by the flush are receiving circulation.
Niacin may help those who are trying to lose weight because it raises blood sugar levels and is beneficial for those with low blood sugar.
High doses have been helpful for schizophrenics because niacin relieved paranoia and hallucinations.
Peanuts and lean meats, fish and poultry are good sources of niacin. Superfoods such as wheat germ, dessicated liver and brewer's yeast are also high in niacin. Other foods are extremely low in the B vitamin.
When niacin amount is calculated in food, two types are used: pure niacin and the amount of tryptophan that can be converted into niacin in the body. The latter type is called niacin equivalents.
It's impossible to get too much niacin, or an amount to cause toxicity from foods high in niacin. However, synthetic forms are another matter. Liver damage can result from niacinamide if levels are close to 3000 mg a day. That's why physicians prescribing synthetic niacin for heart disease and to lower cholesterol levels monitor their patients with a blood test every month or so. Large doses should not be taken on an empty stomach because of the ability of vitamin B3 to produce hydrochloric acid.
High doses of niacin may elevate the blood sugar level and by doing this, worsen diabetes mellitus. Some reports say that extremely high doses may thicken the macula and result in blurred vision and blindness. Be careful and keep a watchful eye if you use this vitamin as a drug.
An easy way to remember what happens during a niacin deficiency is to think of the four D's: dermatitis, dementia, diarrhea, and death. In the early stages, the person with a niacin deficiency is fatigued and weak, loses his or her appetite, has bad breath, small canker sores and is irritable. Skin especially around the elbows is rough and inflamed. This is called pellagra. The person also has tremors and an upset stomach. Diarrhea can occur during this phase. Often he cannot sleep at night. He may have episodes of vomiting, tender gums, and feels a lot of strain and tension. The person is deeply depressed. Death can result if the condition progresses.
The cure is simply to take niacin supplements. In about two days, the diarrhea is gone, the production of hydrochloric acid in the stomach is increased and helps improve digestion, and clears up the skin (this may take longer).
Small amounts of 20 mg are needed per day for adults. Whenever there is trauma to the tissues, growth, pregnancy or breastfeeding, the a requirement for niacin increases. Specific amounts for expectant moms and breast-feeding moms are 18 mg/day. Since niacin is a B vitamin, increasing the other B vitamins is important when supplementing with high doses of niacin.
1. Dunne, Lavon. Nutrition Almanac, McGraw-Hill Publishing, 2002.