Niacin, also known as vitamin B-3, provides numerous health benefits when obtained from dietary sources such as peanuts, salmon, eggs, chicken and beets. It improves the health of your skin, eyes and hair; helps you convert carbohydrates to glucose for energyl and helps you metabolize fats and proteins. Dietary niacin also helps improve liver function, but taking niacin in prescription or over-the-counter formulas may damage your liver.
Most people don't need to take niacin supplements to obtain their recommended daily allowance of 14 mg to 16 mg. A 1-oz. serving of peanuts -- about a handful -- provides 3.4 mg of niacin. A 3 1/2-oz. serving of skinless roasted chicken contains 11.8 mg. Fortified breakfast cereals can also help you obtain enough niacin to promote healthy liver function. A single serving of some commercial brands of cereal provides more than a full day's supply of niacin.
Vitamin B-3 supplements come in three types: niacin, available only by prescription; niacinamide, the type of vitamin B-3 most commonly found in over-the-counter niacin formulas; and inositol hexanicotinate, another form of vitamin B-3 found in some niacin supplements available in drugstores and health food stores. If you take high amounts of niacin or niacinamide, you may incur liver damage. Side effects of inositol hexanicotinate remain largely unstudied. Doctors may prescribe niacin in amounts of up to 3,000 mg to treat cholesterol. Niacinamide and inositol supplements come in doses as high as 500 mg. You may incur side effects, including liver damage, if you take more than 100 mg a day.
Generally, liver damage becomes more likely the longer you take niacin. If you take niacin in any form, you should get your liver checked periodically. If you take very high doses of niacin, you may incur liver damage after brief use. An article in the November 2007 issue of "Annals of Emergency Medicine" reported that a patient required a liver transplant after taking 5,000 mg of niacin for a few days in an attempt to pass a drug screening test.
Niacin, prescribed for more than 50 years, proves effective in treating cholesterol, but over-the-counter formulas demonstrate no ability to improve cholesterol or prevent heart disease. Niacinamide supplements may treat niacin deficiencies, but talk to your doctor before taking niacin supplements for any reason. If you take niacin or niacinamide, side effects in addition to liver damage include nausea, diarrhea, headaches, vomiting, gout, stomach ulcers and vision loss. If you have kidney disease or diabetes, niacin may worsen these conditions.
- University of Maryland Medical Center: Vitamin B3 (Niacin)
- MedlinePlus: Niacin and Niacinamide (Vitamin B3)
- “Annals of Emergency Medicine”; Toxicity From the Use of Niacin to Beat Urine Drug Screening; Majoj Mittal, et al.; November 2007
- EurekAlert!; Misusing Vitamin to Foil Drug Test May Be Toxic; Plus, It Doesn’t Work; April 2007
- USDA National Nutrient Database