Niacin (vitamin B3) is one of the B vitamins. It was discovered by the U.S. Public Health Service in the early twentieth century. At that time, a disease called pellagra, characterized by cracked, scaly, discolored skin, digestive problems, and overall bodily weakness was increasingly prevalent in the southern region of the United States. The Public Health Service found a connection between the disease and cornmeal-based diets. Several years later, niacin was identified as the missing nutrient in the cornmeal-based diets. Corn as a whole food contains plenty of niacin, but when corn is dried and refined into cornmeal, it needs to be prepared in a way that releases the niacin for absorption. For example, lime (the mineral, not the fruit) can help release niacin from corn and make it available for absorption. Native Americans added ash from cooking fires (“pot ash” or “potash”) to corn-based recipes, which helped make niacin available for absorption.

The term “niacin” actually refers to several different chemical forms of the vitamin. These forms include nicotinic acid, nicotinamide (also called niacinamide), and  inositol hexanicotinate. The names “niacin,” “nicotinic acid,” and “nicotinamide” are all derived from research studies on tobacco in the early 1930’s. At that time, the first laboratory isolation of vitamin B3 occurred following work on the chemical nicotine that had been obtained from tobacco leaves.

Niacin is important for the following functions:

1. Energy production: Like its fellow B-complex vitamins, niacin is important in energy production. Two forms of niacin (nicotinamide adenine dinucleotide, or NAD, and nicotinamide adenine dinucleotide phosphate, or NADP) are essential for converting your body’s proteins, fats, and carbohydrates into usable energy. Your body also uses niacin to synthesize starch that can be stored in your muscles and liver for eventual use as an energy source.
2. Metabloism of fats: Niacin plays a critical role in the processing of fats in your body. The fatty acid building blocks for fat-containing structures in the body (like cell membranes) typically require the presence of niacin for their synthesis, as do many fat-based hormones (steroids). Niacin is required for production of cholesterol by the liver.
3. Support of genetic processes: Components of deoxyribose nucleic acid (DNA), the primary genetic material in your cells, require niacin for their production, and deficiency of niacin (like deficiency of other B-complex vitamins) has been directly linked to genetic (DNA) damage. The relationship between niacin and DNA damage appears to be particularly important in relationship to cancer and its prevention.
4. Regulation of insulin activity: Niacin has repeatedly been shown to be involved in insulin metabolism and blood sugar regulation.
5. Regulation of cholesterol: Niacin lowers harmful LDL cholesterol while raising good HDL cholesterol, reducing the risk of heart disease.
6. Hormone production: Niacin helps your body make hormones in your adrenal glands and other parts of your body.
7. Reduction of anxiety and neurosis: Niacin, along with glutamate, enhances gamma amino butyric acid (GABA) activity in your brain, which in turn helps reduce anxiety and neurosis.
8. Regulation of mood: Niacin also is also a precursor to several neurotransmitters in your brain, which may have an affect on mood.
9. Improving circulation: Niacin can help improve circulation.
10. Protection against Alzheimer’s disease and age-related cognitive decline: Regular consumption of niacin-rich foods provides protection against Alzheimer’s disease and age-related cognitive decline. People aged 65 or older who get the most niacin from foods (22 mg per day) were 70% less likely to have developed Alzheimer’s disease than those consuming the least (about 13 mg daily), and their rate of age-related cognitive decline was significantly less.

You can meet all of your body’s needs for niacin through diet. It is rare for anyone in the developed world to have a niacin deficiency. In the United States, alcoholism is the main cause of naicin deficiency. Intestinal problems, including chronic diarrhea, inflammatory bowel disease, and irritable bowel disease can all trigger niacin deficiency. Because part of your body’s niacin supply comes from conversion of the amino acid tryptophan, deficiency of tryptophan can also increase risk of niacin deficiency. (Foods rich in tryptophan include crimini mushrooms, soybeans, tofu, sunflower seeds, spinach, and asparagus.) The conversion of tryptophan to niacin also requires the presence of thiamine and vitamin B6, and when thiamine or B6 are deficient, niacin can also become deficient. Niacin deficiency also appears to be related to vitamin B12 status, since even mild deficiencies in vitamin B12 can increase loss of niacin in the urine. Physical trauma, all types of stress, long-term fever, and excessive consumption of alcohol have also been associated with increased risk of niacin deficiency. Symptoms of mild deficiency include indigestion, fatigue, canker sores, vomiting, and depression. Severe deficiency can cause a condition known as pellagra. Pellagra is characterized by cracked, scaly skin, dementia, and diarrhea. It is generally treated with a nutritionally balanced diet and niacin supplements. Niacin deficiency also causes burning in the mouth and a swollen, bright red tongue.

In the amounts provided by food, no symptoms of toxicity have been reported in the scientific literature. In 1998, the Institute of Medicine at the National Academy of Sciences set a tolerable upper limit (UL) for niacin of 35 milligrams. This UL applies to men and women 19 years or older, and is limited to niacin that is obtained from supplements and/or fortified foods.  At high doses (50 milligrams or more) niacin can be toxic. You should not take doses higher than the Recommended Daily Allowance except under your doctor’s supervision. The most common side effect is called “niacin flush,” which is a burning, tingling sensation in the face and chest, and red or flushed skin. High doses of niacin may also cause stomach upset (which usually subsides within a few weeks), headache, dizziness, blurred vision, and liver damage.

Niacin is one of the more stable water-soluble vitamins and is minimally susceptible to damage by air, light, and heat.

Daily recommendations for niacin in the diet of healthy individuals are listed below.

• Infants birth – 6 months: 2 mg (adequate intake)
• Infants 7 months – 1 year: 4 mg (adequate intake)
• Children 1- 3 years: 6 mg (RDA)
• Children 4 – 8 years: 8 mg (RDA)
• Children 9 – 13 years: 12 mg (RDA)
• Boys 14 – 18 years: 16 mg (RDA)
• Girls 14 – 18 years: 14 mg (RDA)
• Men 19 years and older: 16 mg (RDA)
• Women 19 years and older: 14 mg (RDA)
• Pregnant women: 18 mg (RDA)
• Breastfeeding women: 17 mg (RDA)

The best food sources of niacin are brewer’s yeast, spelt, sunflower seeds, peanuts, shiitake mushrooms, crimini mushrooms, and asparagus.

It’s best to get your niacin from food. People with a history of liver disease, kidney disease, stomach ulcers, low blood pressure, or gout should not take niacin supplements. Those with diabetes, gallbladder disease, coronary artery disease or unstable angina should not take niacin without their doctor’s supervision. Niacin and niacinamide supplements may make allergies worse by increasing histamine.

Taking any one of the B vitamins for a long period of time can result in an imbalance of other important B vitamins. For this reason, you may want to take a B complex vitamin, which includes all the B vitamins.

If you are currently taking any medications, you should not use niacin supplements without first talking to your health care provider.