Niacin (vitamin B3) helps convert food into energy and keeps skin, nerves and the digestive system healthy. Most people get enough from food, but high-dose supplements can cause side effects.
Here are the NIH figures, food sources and safety points.
Daily niacin requirement
Average daily recommended amount in mg NE (niacin equivalents, which count niacin plus what the body makes from tryptophan):
- Children 1 to 3 years: 6 mg NE
- Children 4 to 8 years: 8 mg NE
- Children 9 to 13 years: 12 mg NE
- Teen boys 14 to 18: 16 mg NE, teen girls: 14 mg NE
- Adult men: 16 mg NE, adult women: 14 mg NE
- Pregnant women: 18 mg NE, breastfeeding women: 17 mg NE
Upper limit from supplements and fortified foods (mg per day): children 1 to 3: 10, 4 to 8: 15, 9 to 13: 20, teens: 30, adults: 35. Niacin from food is considered safe.
Best food sources of niacin
Good sources include:
- Poultry, beef, pork and fish
- Some nuts, legumes and grains
- Enriched and fortified breads and cereals
Niacin deficiency and pellagra
Severe deficiency is called pellagra. Signs include rough skin that reddens or browns in the sun, a bright red tongue, vomiting, diarrhea or constipation, depression, headaches and extreme tiredness. It is very rare in the US.
Higher risk: people with alcohol use disorder, anorexia, inflammatory bowel disease or liver cirrhosis, and those whose diets lack iron, riboflavin or vitamin B6.
Too much niacin: flushing and other effects
Supplements with 30 mg or more of nicotinic acid can cause flushing, burning, tingling and itching of the face, arms and chest, plus headaches and rashes. Very high doses of nicotinic acid medicine (1,000 mg a day or more) can cause low blood pressure, high blood sugar, nausea and, with long-term use, liver problems. Nicotinamide at 500 mg a day or more can cause diarrhea and easy bruising.
Medicine interactions
The tuberculosis drugs isoniazid and pyrazinamide can lower niacin levels. High-dose nicotinic acid (1,500 mg a day or more) can raise blood sugar and interfere with diabetes medicines. High-dose niacin is a prescription cholesterol medicine, so use it only under a doctor’s supervision.
Frequently Asked Questions
How much niacin do adults need?
Adult men need 16 mg NE and adult women 14 mg NE per day.
What causes niacin flush?
Supplements with 30 mg or more of nicotinic acid can cause flushing, burning and itching of the face, arms and chest.
What is the upper limit for niacin?
For adults, 35 mg per day from supplements and fortified foods. Food niacin is considered safe.
Which foods are rich in niacin?
Poultry, beef, pork, fish, some nuts, legumes and fortified grains.
Can niacin affect blood sugar?
High-dose nicotinic acid, 1,500 mg a day or more, can raise blood sugar and interfere with diabetes medicines.
Related reading: Vitamin B6 daily needs | Vitamin B2 (riboflavin) daily needs | Choline daily needs
Sources
Medical disclaimer: this article is for general information and does not replace advice from a qualified doctor. Do not start, stop or change any supplement or medicine without medical advice.