Niacin

Niacin, also known as vitamin B3, is a water-soluble vitamin. Water-soluble vitamins are stored in the body in very limited amounts and are excreted through the urine. Therefore, it is a good idea to have them in your daily diet. In addition to getting niacin from dietary sources, the body can synthesize a form of niacin from the amino acid tryptophan.

Functions

Niacin’s functions include:

• Aiding in the catabolism (breakdown) of carbohydrate, fat, protein, and alcohol to produce energy
• Supplying energy to all body cells
• Assisting in fatty acid and cholesterol synthesis
• Helping the formation of red blood cells
• Assisting in the metabolism of several drugs and toxins
• Maintaining the integrity of all body cells

Recommended Intake:

Niacin Deficiency

A niacin deficiency is called pellagra. The most common symptoms affect the skin, the digestive system, and the nervous system. Symptoms of niacin deficiency include:

• Thick, dark, scaly pigmented rash on skin areas exposed to sunlight, heat, or mild trauma
• Bright red tongue
• Vomiting
• Diarrhea
• Irritability
• Headache
• Insomnia
• Memory loss
• Depression
• Fatigue
• Disorientation

If left untreated, pellagra can lead to death.

Niacin Toxicity

For adults, the tolerable upper intake level (UL) for niacin from dietary sources and supplements combined is 35 mg. Niacin toxicity does not seem to occur when its only source is foods which have not been fortified with niacin. Symptoms of niacin toxicity have been reported in people using niacin supplements.

Symptoms of toxicity include:

• Flushing of the skin, primarily on the face, arms, and chest
  *This side effect may occur at doses as low as 30 mg/day
• Itching
• Nausea
• Vomiting
• Skin rash
• Dry skin
• Headache
• Signs of liver toxicity, including jaundice and elevated liver enzymes

Major Food Sources

Health Implications

The following populations may be at risk for niacin deficiency or have an increased need for niacin and may require a supplement:

• People who consume excessive amounts of alcohol
• People taking the antituberculosis drug isoniazid
• People with Hartnup's disease

Several well-designed clinical studies have shown that niacin can lower LDL-cholesterol and triglycerides (high blood levels of LDL-cholesterol and triglycerides are considered unhealthy); studies have also shown that niacin can raise HDL-cholesterol (higher blood levels of HDL-cholesterol are considered healthy). However, the studies that found positive results used pharmacologic doses of niacin. These doses are much larger than the current recommended dietary allowances (RDA) and should only be used under the supervision of a qualified healthcare provider.

Tips For Increasing Your Niacin Intake:

To help increase your intake of niacin:

• Use mashed avocado in place of cream cheese, butter, or margarine on your morning bagel, or mayonnaise on your lunchtime sandwich.
• For lunch, have a few slices of lean turkey with lettuce and tomato on wheat bread.
• Grill salmon, halibut, or trout for dinner. Crack a bit of pepper, sprinkle some salt, squeeze a touch of lemon, and finish off with a splash of olive oil.
• Munch on a handful of peanuts as an afternoon snack.
• Bake a potato and top with black beans, salsa, and cheese or steamed broccoli, carrots, and a spoonful or 2 of low-fat sour cream.
• If you take a vitamin supplement, make sure it contains niacin (but no more than 100% of the RDA).

Revision Information

• Reviewer: Michael Woods, MD
• Review Date: 05/2016
• Update Date: 06/05/2014