Niacin Requirements and Dietary Sources

Niacin is a member of the water-soluble family of B-complex vitamins. Also known as vitamin B3, niacin works as a coenzyme in the body and is required for many different reactions, including normal digestive function, converting the food you eat into energy and for healthy skin and nervous system function. It's also helpful for blood circulation, and your adrenal glands need niacin to make hormones such as cortisol, testosterone, and estrogen.

Niacin deficiency is rare in modern Western diets—it usually occurs as a consequence of alcoholism. Symptoms of a mild niacin deficiency include digestive upset, fatigue, canker sores, vomiting, and depression. Pellagra is caused by a full-blown niacin deficiency. Symptoms include dementia, diarrhea, sores on the skin, and may lead to death.

The Health and Medicine Division of National Academies of Sciences, Engineering, and Medicine sets the daily dietary reference intakes (DRI) for vitamins and minerals. The DRI for niacin is determined by age and sex. Women who are pregnant or breastfeeding need the largest amounts.

The DRIs are based on what an average healthy person needs—if you have any health conditions you should speak with your healthcare provider about your niacin requirements.

Dietary Reference Intakes

Niacin is found in a variety of foods including poultry, fish, lean meats, nuts, legumes, eggs, and vitamin-fortified foods. Since it's easily obtained from many different foods, most people don't need to take supplements to ensure adequate intake.

Niacin Supplements and Cholesterol

When taken in large doses, niacin supplements may be used to reduce elevated triglycerides and LDL cholesterol levels in the blood and to increase levels of HDL cholesterol (generally considered healthy cholesterol).

Although it's available as an over-the-counter supplement, taking extra niacin may cause problems: Ingesting large amounts of supplemental niacin may result in liver damage, can interact with some types of medications, and might increase glucose levels in people with diabetes. Speak to your doctor if you're thinking about taking niacin for cholesterol support.

Taking niacin in large amounts may also cause an uncomfortable reaction called the niacin flush, which includes a burning and itching sensation of the face and joints. It's not dangerous, but it can be frightening if it happens.

Due to these reactions and safety concerns, the Institute of Medicine established 35 milligrams per day as the upper tolerable intake level of niacin for adults. No matter what form of niacin is used, large doses should only be used under the supervision of a physician.