Vitamin B3 — Niacin


Vitamin B3 (Niacin) is used commonly to refer to two different compounds, nicotinic acid and niacinamide. B3 was first isolated during oxidation ofnicotine from tobacco and was thus given the name nicotinic acid vitamin, shortened to
niacin. It is not, however, the same as or even closely related to the molecule nicotine. Niacin, as nicotinic acid or niacinamide, is converted in the body to the active forms, nicotinamide adenine dinucleotide (NAD) and a phosphorylated form (NADP).

Niacin is one of the most stable of the B vitamins. It is resistant to the effects of heat, light, air, acid, and alkali. A white crystalline substance that is soluble in both water and alcohol, niacin and niacinamide are both readily absorbed from the small intestine. Small amounts may be stored in the liver, but most of the excess is excreted in the urine.

Another important fact about vitamin B3 is that it can be manufactured from the amino acid tryptophan, which is essential (needed in the diet). So niacin is not truly essential in the diet when enough protein, containing adequate tryptophan, and other nutrients are consumed. When niacin is not present in sufficient amounts, extra protein is needed. Also, when we are deficient in such nutrients as vitamins B1, B2, and B6, vitamin C, and iron, we cannot easily convert tryptophan to niacin. Many foods that are low in tryptophan are also low in niacin or, as in corn, the niacin is not readily available. Corn is low in tryptophan and its niacin is bound, so it must receive special treatment. Native Americans knew this and would soak corn in ash water before or after grinding to release the niacin. Even when they subsisted almost solely on corn, they did not experience the serious niacin deficiency
disease called pellagra. In the time around the American Civil War, in the South poor white farm workers subsisted on “quick cornmeal,” the poorly prepared white people’s version, and pellagra was epidemic until the discovery that it was a dietary deficiency disease. Pellagra, the disease of the “three Ds”–diarrhea, dermatitis, and dementia–historically
has been a problem of corn-eaters, whereas beriberi has been a disease most correlated with rice-eating cultures.

Sources: Only small to moderate amounts of vitamin B3 occur in foods as pure niacin;
other niacin is converted from the amino acid tryptophan, as just discussed. The best sources of vitamin B3 are liver and other organ meats, poultry, fish, and peanuts, all of which have both niacin and tryptophan. Yeast, dried beans and peas, wheat germ, whole grains, avocados, dates, figs, and prunes are pretty good sources of niacin. Milk and eggs are good because of their levels of tryptophan. Though B3 is stable, the milling and processing of whole grains can remove up to 90 percent of the niacin. Thus, manufacturers will often “enrich” their products by adding niacin.

Functions: Niacin acts as part of two coenzymes, nicotinamide adenine dinucleotide (NAD)
and nicotinamide adenine dinucleotide phosphate (NADP), that are involved in more than 50 different metabolic reactions in the human species. They play a key role in glycolysis (that is, extracting energy from carbohydrate and glucose), are important in fatty acid synthesis and in the deamination (nitrogen removal) of amino acids, are needed in the formation of red blood cells and steroids, and are helpful in the metabolism of some drugs and toxicants. Thus, niacin is a vital precursor for the coenzymes that supply energy to body cells.

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.

Niacin has been an important boon to the field of orthomolecular psychiatry for its use in a variety of mental disorders. It was initially well demonstrated to be helpful for the neuroses and psychoses described as the “dementia of pellagra,” the niacin deficiency disease. Since then, it has been used in high amounts, well over 100 mg. per day and often over 1,000
mg. per day (up to 6,000 mg.), to treat a wide variety of psychological symptoms, including senility, alcoholism, drug problems, depression, and schizophrenia. Niacin has been helpful in reversing the hallucinatory experience, delusional thinking or wide mood
and energy shifts of some psychological disturbances. Though this therapy has its skeptics, as does all application of nutritional medicine, some studies show promising results in treatment of schizophrenia with niacin and other supplements. Other studies show little or no effect. More research is definitely needed on niacin’s effect in mental disorders.

People on high blood pressure medicines and those who have ulcers, gout, or diabetes should be very careful taking higher-dose supplements of niacin because of its effect of lowering blood pressure, its acidity, its liver toxicity, its potential to raise uric acid levels, and its effect in raising blood sugar–though recently niacin has been shown to have a positive effect on glucose tolerance (it is part of glucose tolerance factor) and, thereby, on diabetes as well. Exercise and niacin are helpful for people with adult diabetes through their positive effects on blood sugar and cholesterol.

Deficiency and toxicity: As with the other B vitamins, there are really no toxic effects from
even the high doses of niacin, though the “niacin flush” previously described may be uncomfortable for some. However, with the use of high-dose niacin in recent years, the occasional person experiences some minor problems, such as irritation of the
gastrointestinal tract and/or the liver, both of which subside with decreased intake of niacin. In addition, some people taking niacin experience sedation rather than stimulation.

Deficiency problems have been much more common than toxicity, and for a long period of history, the niacin deficiency disease, pellagra, was a very serious and fatal problem. Characterized as the disease of the “three Ds,” pellagra causes its victims to experience dermatitis, diarrhea, and dementia. The fourth D was death.

As described previously, the classic B3 deficiency occurs mainly in cultures whose diets rely heavily on corn and where the corn is not prepared in a way that releases its niacin. One of the first signs of pellagra, or niacin deficiency, is the skin’s sensitivity to light, and the skin becomes rough, thick, and dry (pellagra means “skin that is rough” in Italian). The skin then becomes darkly pigmented, especially in areas of the body prone to be hot and sweaty or those exposed to sun. The first stage of this condition is extreme redness and sensitivity of those exposed areas, and it was from this symptom that the term “redneck,” describing the bright red necks of eighteenth- and nineteenth-century niacin-deficient fieldworkers, came into being.

In general, niacin deficiency affects every cell, especially in those systems with rapid turnover, such as the skin, gastrointestinal tract, and nervous system. Other than photosensitivity, the first signs of niacin deficiency are noted as decreased energy
production and problems with maintaining healthy functioning of the skin and intestines. These symptoms include weakness and general fatigue, anorexia, indigestion, and skin eruptions. These can progress to other problems, such as a sore, red tongue, canker sores, nausea, vomiting, tender gums, bad breath, and diarrhea. The neurological symptoms may begin with irritability, insomnia, and headaches and then progress to tremors, extreme anxiety, depressionÑall the way to full-blown psychosis. The skin will worsen, as will the diarrhea and inflammation of the mouth and intestinal tract. There will be a lack of stomach acid production (achlorhydria) and a decrease in fat digestion and, thus, lower availability from food absorption of the fat-soluble vitamins, such as A, D, and E. Death could occur, usually from convulsions, if the niacin deficiency is not corrected.

Niacin deficiency symptoms can be seen in diets with niacin intake below 7.5 mg. per day, but often this is not the only deficiency; vitamin B1, vitamin B2, and other B vitamins, as well as protein and iron may be low. To treat pellagra and niacin deficiency disorders, vitamin B3 supplements should be taken along with good protein intake to obtain adequate levels of the amino acid tryptophan. As described earlier, about 50 percent of daily niacin comes from the conversion in our livers of tryptophan to niacin with the help of pyridoxine (vitamin B6).

Requirements: Many food charts list only sources that actually contain niacin and do not
take into account tryptophan conversion into niacin. Approximately 60 mg. of tryptophan can generate 1 mg. of niacin. But tryptophan is available for conversion only when there are more than sufficient quantities in the diet to synthesize the necessary proteins as tryptophan is used in our body with the other essential amino acids to produce protein.

Niacin needs are based on caloric intake. We need about 6.6 mg. per 1,000 calories, and no less than 13 mg. per day. Women need at least 13 mg. and men at least 18 mg. per day. The RDA for children ranges from 9-16 mg.

Niacin needs are increased during pregnancy, lactation, and growth periods, as well as after physical exercise. Athletes require more B3 than less active people. Stress, illness, and tissue injury also increase the body’s need for niacin. People who eat much sugar or refined, processed foods require more niacin as well.

Realistically, 25-50 mg. per day is adequate intake of niacin if minimum protein requirements are met. On the average, many supplements provide at least 50-100 mg. per day of niacin or niacinamide, which is a good insurance level. For treatment of the variety of conditions described previously, higher amounts of niacin may be needed to really be helpful, and levels up to 2-3 grams per day are not uncommon as a therapeutic dose. The other B vitamins should also be supplied so as to not create an imbalanced metabolic condition.

Elson M. Haas MD Written by Elson M. Haas MD

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