Vitamin B3

Niacin (Vitamin B-3) is the common name for two compounds: nicotinic acid, which is easily converted to the biologically active form, and nicotinamide (or niacinamide). It should not be confused with the toxic drug, nicotine, found in tobacco and cigarettes. Niacin is a water-soluble vitamin that participates in more than 50 metabolic functions, all of which are important in the release of energy from carbohydrates. Because of its pivotal role in so many metabolic functions, niacin is vital in supplying energy to, and maintaining the integrity of, all body cells. Niacin also assists in antioxidant and detoxification functions, and the production of sex and adrenal hormones. Niacin deficiency, known as pellagra, not surprisingly affects every cell, and is characterized by dermatitis, diarrhea, and dementia.

The body is able to convert tryptophan, an amino acid, into niacin. Niacin is also available in supplemental form. Supplements appear in two forms: niacin and niacinamide. Niacin is sold as nicotinic acid or nicotinate. It is sometimes recommended as a favorable treatment for lowering blood cholesterol. Niacinamide is effective in arthritis and early onset type-1 diabetes. However, two studies warn that the sustained-release form of the vitamin is hepatoxic.1 The immediate-release form might be the preferred treatment choice for high cholesterol, according to a 1994 Virginia Commonwealth University study.2

Niacin has been found to work better than many traditional drugs to lower cholesterol. The benefits of niacin are that it lowers LDL cholesterol, lipoprotein, triglyceride, and fibrinogen levels, while raising HDL cholesterol levels. HDL, or high density lipoprotein, is considered a good kind of cholesterol. Follow-up studies point to the long-lasting effects of niacin treatment as well. In one comparative study published in 1994, the drug Lovastatin and niacin were tested.3 While Lovastatin displayed a greater ability to lower LDL levels, niacin had a more significant overall effect. Niacin initiated an increase in HDL cholesterol and lowered Lp(a) lipoprotein levels. These factors are greater indicators of heart disease. Lovastatin showed no effect for lipoproteins. A 1995 study found niacin to be more effective in renal transplant patients than Lovastatin.4 These patients had lipid problems and an increased risk for heart disease.

1 McKenny J, Proctor J, Harris S, et al., A comparison of the efficacy and toxic effects of sustained- vs immediate-release niacin in hypercholesterolemic patients. J Am Med A 1994; 271:672-677.

2 Yin S, SatoI, Yamaguchu K: Comparison of selenium level and glutathione peroxidase activity in tissues of vitamin B-6 deficient rats fed sodium selenite or DL-selonomethionine. J Nutr Bioc 1992; 3:633-643.

3 Illingworth DR, et al., Comparative effects of lovastatin and niacin in primary hypercholesterolemia. Arch Intern Med 154, 1586-1595, 1994.

4 Lal SM, et al., Effects of nicotinic acid and lovastatin in renal transplant patients: A prospective, randomized, open-labeled crossover trial. Am J Kidney Dis 25, 616-622, 1995.

Vitamin B-3: SOURCES

• Beef liver
• Brewer's yeast
• Chicken, white meat
• Halibut
• Peanuts
• Pork
• Salmon
• Sunflower seeds
• Swordfish
• Tuna
• Turkey
• Veal

Available as:

• Tablets or capsules: Take with meals or 1 to 1-1/2 hours after meals unless otherwise directed by your doctor.
• Extended-release capsules or tablets: Take with or immediately after food to decrease stomach irritation.
• Oral solution: Dilute in at least 1/2 glass water or other liquid. Take with meals or 1 to 1-1/2 hours after meals unless otherwise directed by your doctor.
• Injectable forms are administered by doctor or nurse.
• A constituent of many multivitamin/mineral preparations.
• Niacin is available in two forms: Niacin and niacinamide. Niacin is available as nicotinic acid, nicotinate, and inositol hexanicotinate (hexaniacin).
• Niacinamide is available as nicotinamide.
• Timed-release supplemental niacin is not recommended because they are toxic to the liver.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN B-3: PROVEN BENEFITS

• Maintains normal function of skin, nerves, digestive system.
• Reduces cholesterol and triglycerides in blood.
• Corrects niacin deficiency.
• Dilates blood vessels.
• Treats vertigo (dizziness) and ringing in ears.
• Prevents premenstrual headache.
• Treats pellagra.
• Niacin lowers total blood cholesterol and raises HDL cholesterol.
• Niacinamide is used in the treatment of arthritis and early onset diabetes.

What this vitamin does:

• Aids in release of energy from foods.
• Helps synthesize DNA.
• Becomes component of two co-enzymes (NAD and NADP), which are both necessary for utilization of fats, tissue respiration and production of sugars.
• Involved in the manufacture of sex and adrenal hormones.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN B-3: UNPROVED SPECULATED BENEFITS

• Prevents heart attacks.
• Treats or prevents motion sickness.
• Alleviates mental illness, notably schizophrenia.
• Cures depression.
• Prevents migraine headaches.
• Improves poor digestion.
• Protects against pollutants and toxins.
• Treats leprosy.
• Stimulates sex drive.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN B-3: SPECIAL CONSIDERATIONS

• Anyone with inadequate caloric or nutritional dietary intake or increased nutritional requirements.
• Older people (over 55 years).
• Pregnant or breast-feeding women.
• Those who abuse alcohol or other drugs.
• People with a chronic wasting illness including malignancies, pancreatic insufficiency, cirrhosis of the liver, sprue.
• Anyone who experiences excess stress for long periods or who have recently undergone surgery.
• Athletes and workers who participate in vigorous physical activities.
• Those with a portion of the gastrointestinal tract surgically removed.
• People with recent severe burns or injuries.
• Those with diabetes.
• Infants born with errors of metabolism (congenital disorders due to chromosome abnormalities).
• Anyone with hyperthyroidism.

Miscellaneous information:

• The body manufactures niacin from tryptophan, an amino acid.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN B-3: DEFICIENCY SYMPTOMS

Early Symptoms:

• Muscle weakness
• General fatigue
• Loss of appetite
• Headaches
• Swollen, red tongue
• Skin lesions, including rashes, dry scaly skin, wrinkles, coarse skin texture
• Nausea and vomiting
• Dermatitis
• Diarrhea
• Irritability
• Dizziness

Late Symptoms of severe deficiency called pellagra:

• Dementia
• Death1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN B-3: UNPROVED SPECULATED SYMPTOMS

• Acne
• Poor circulation
• Mental problems1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

LAB TESTS TO DETECT DEFICIENCY

• Urinary 1 N-methyl nicotinamide.
• Urinary 2Ñpyrindone/N-1 methylnicotinamide. Test results not always conclusive.
• Abnormal liver-function studies.
• Lymphocytic growth response1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN B-3: OPTIMAL LEVELS

20-100 mg.

VITAMIN B-3: MINIMUM DOSAGE

Recommended Dietary Allowance (RDA):

Estimate of adequate daily intake by the Food and Nutrition Board of the National Research Council, 1989.

Age -- RDA

0-6 months 5mg

6-12 months 6mg

1-3 years 9mg

4-6 years 12mg

7-10 years 13mg

MALES

11-14 years 17mg

15-18 years 20mg

19-50 years 19mg

51+ years 15mg

FEMALES

11-50 years 15mg

51+ years 13mg

Pregnant 17mg

Lactating 20mg

VITAMIN B-3: WARNINGS AND PRECAUTIONS

• Niacin may produce a temporary flushing or itching.
• Don't take if you:
• Are allergic to niacin or any niacin-containing vitamin mixtures.
• Have impaired liver function.
• Have an active peptic ulcer.
• Consult your doctor if you have:
• Diabetes.
• Gout.
• Gallbladder or liver disease.

Over age 55:

• Consult your doctor if you have any questions.

Pregnancy:

• Don't take megadoses unless recommended by a doctor.

Breast-feeding:

• Studies are inconclusive. Consult doctor about supplements.
• Don't take megadoses.

Effect on lab tests:

• Urinary catecholamine concentration may falsely elevate results.
• Urine glucose (using Benedict's reagent) may produce false-positive reactions.
• Falsely elevates blood sugar.
• Falsely increases growth-hormone level in blood.
• Falsely elevates blood uric acid with large daily doses.

Storage:

• Store in cool, dry place away from direct light, but don't freeze.
• Store safely out of reach of children.
• Don't store in bathroom medicine cabinet. Heat and moisture may change action of vitamin.

Others:

• High dosages over long periods may cause liver damage or aggravate a stomach ulcer.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN B-3: OVERDOSE/TOXICITY

Signs and symptoms:

Body flush, nausea, vomiting, abdominal cramps, diarrhea, weakness, lightheadedness, headache, fainting, sweating, high blood sugar, high uric acid, heart rhythm disturbances, jaundice.

Niacin may cause flushing of the skin twenty to thirty minutes after taking. It may also cause gastric irritation, nausea, and liver damage. Inositol hexanicotinate does not produce these effects.

What to do:

For symptoms of overdosage: Discontinue vitamin, and consult doctor. Also see ADVERSE REACTIONS OR SIDE EFFECTS.

For accidental overdosage (such as child taking entire bottle): Call emergency services, the telephone.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN B-3: ADVERSE REACTIONS OR SIDE EFFECTS

Reaction or effect What to do

Abdominal pain Discontinue. Call doctor immediately.

Diarrhea Discontinue. Call doctor when convenient.

Faintness Discontinue. Call doctor immediately.

Headache Discontinue. Call doctor when convenient.

"Hot" feeling, with skin Nothing.

flushed in blush zone (always)

Jaundice (yellow skin and eyes) Discontinue. Call doctor immediately.

Nausea or vomiting Discontinue. Call doctor immediately.

Skin dryness Discontinue. Call doctor when convenient.

Vomiting Discontinue. Call doctor immediately.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

VITAMIN B-3: INTERACTION WITH OTHER SUBSTANCES

• Anti-diabetics decrease anti-diabetic effect.
• Beta-adrenergic blockers lower blood pressure to extremely low level.
• Chenodiol decreases chenodiol effect.
• Guanethidine increases guanethidine effect.
• Isoniazid decreases niacin effect.
• Mecamylamine lowers blood pressure to extremely low level.
• Pargyline lowers blood pressure to extremely low level.
• Tobacco decreases absorption. Smokers may require supplemental niacin.
• Alcohol may cause extremely low blood pressure. Use caution.
• Niacin can impair glucose tolerance.1

1 From Griffith HW, Vitamins, Minerals, and Supplements.

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