83: Niacin (part 3 of 3)

Dietary Sources:

The best dietary sources of vitamin B3 are found in beets, brewer's yeast, beef liver, beef kidney, fish, salmon, swordfish, tuna, sunflower seeds, and peanuts. Bread and cereals are usually fortified with niacin. In addition, foods that contain tryptophan, an amino acid the body coverts into niacin, include poultry, red meat, eggs, and dairy products.

Available Forms:

Vitamin B3 is available in several different supplement forms: niacinamide, niacin, and inositol hexaniacinate. Niacin is available as a tablet or capsule in both regular and timed-release forms. The timed-release tablets and capsules may have fewer side effects than regular niacin; however, the timed-release versions are more likely to cause liver damage. Regardless of which form of niacin you're using, doctors recommend periodic liver function tests when using high doses (above 100 mg per day) of niacin.

How to Take It:

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

Generally, high doses of niacin are used to control specific diseases, such as high cholesterol. Such high doses are considered "pharmacologic" and must be prescribed by a doctor, who will have you increase the amount of niacin slowly, over the course of 4 - 6 weeks, and take the medicine with meals to avoid stomach irritation.

Pediatric

• 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)
• Males 14 - 18 years: 16 mg (RDA)
• Females 14 - 18 years: 14 mg (RDA)

Adult

• Males 19 years and older: 16 mg (RDA)
• Females 19 years and older: 14 mg (RDA)
• Pregnant females: 18 mg (RDA)
• Breastfeeding females: 17 mg (RDA)

Precautions:

Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.

High doses (50 mg or more) of niacin can cause side effects. 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. Taking an aspirin 30 minutes prior to the niacin may help reduce this symptom.

At the very high doses used to lower cholesterol and treat other conditions, liver damage and stomach ulcers can occur. Your health care provider will periodically check your liver function through a blood test.

People with a history of liver disease or stomach ulcers should not take niacin supplements. Those with diabetes or gallbladder disease should do so only under the close supervision of their doctor.

Niacin should not be used if you have gout.

Taking any one of the B complex vitamins for a long period of time can result in an imbalance of other important B vitamins. For this reason, it is generally important to take a B complex vitamin with any single B vitamin.

Possible Interactions:

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

Antibiotics, Tetracycline -- Niacin should not be taken at the same time as the antibiotic tetracycline because it interferes with the absorption and effectiveness of this medication. (All vitamin B complex supplements act in this way and should therefore be taken at different times from tetracycline.)

Aspirin -- Taking aspirin before taking niacin may reduce flushing associated with this vitamin, but should only be done under your doctor's supervision.

Anticoagulants (blood thinners) -- Niacin may make the effects of these medications stronger, increasing the risk of bleeding.

Blood Pressure Medications, Alpha-blockers -- Niacin can make the effects of medications taken to lower blood pressure stronger, leading to the risk of low blood pressure.

Cholesterol-lowering Medications -- Niacin binds bile-acid sequestrants (cholesterol-lowering medications such as colestipol, colesevelam, and cholestyramine) and may decrease their effectiveness. For this reason, niacin and these medications should be taken at different times of the day.

Recent scientific evidence suggests that taking niacin with simvastatin (a drug that belongs to a class of cholesterol-lowering medications known as HMG-CoA reductase inhibitors, or statins), appears to slow down the progression of heart disease. However, the combination may also increase the likelihood for serious side effects, such as muscle inflammation or liver damage.

Diabetes Medications -- Niacin may increase blood glucose (sugar) levels. People taking insulin, metformin, glyburide, glipizide, or other medications used to treat high blood sugar levels should monitor their blood sugar levels closely when taking niacin supplements.

Isoniazid (INH) -- INH, a medication used to treat tuberculosis, may lower levels of niacin in the body and cause a deficiency.

Nicotine Patches -- Using nicotine patches with niacin may worsen or increase the risk of flushing associated with niacin.

Alternative Names:

Inositol hexaniacinate; Niacin; Niacinamide; Nicotinamide; Nicotinic acid

* Information source: http://www.umm.edu/altmed/articles/vitamin-b3-000335.htm

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