Vitamin B3

Figure 1. The chemical structure of Nicotinamide, a form of Vitamin B3.

Vitamin B3 or Niacin is a micronutrient and one of eight essential B vitamins. Vitamin B3 is a water soluble vitamin and refers to a group of compounds that include nicotinamide (or niacinamide), niacin (nicotinic acid), and nicotinamide riboside. All three forms of Vitamin B3 are converted to the coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which is needed by more than 400 enzymes for various reactions. Vitamin B3 also helps convert nutrients into energy, creates cholesterol and fats, creates and repairs DNA, and exerts antioxidant effects.

Food Sources

Vitamin B3 can be found in many foods. Examples include:

• Red meat: beef, beef liver, pork
• Poultry
• Fish
• Brown rice
• Fortified cereals and breads
• Nuts, seeds
• Legumes
• Bananas 

Taken as a Dietary Supplement

As a dietary supplement, Vitamin B3 is used to treat Vitamin B3 deficiency conditions. While rare, Vitamin B3 deficiency can occur in high-risk groups such as people who are malnourished, suffer from chronic alcoholism, and afflicted with certain diseases and cancers (e.g. carcinoid syndrome). Symptoms of Vitamin B3 deficiency include:

• Depression
• Headache
• Fatigue
• Memory loss
• Hallucinations

Vitamin B3 is also commonly promoted as a supplement to help with improving blood fat levels, reducing blood pressure, lowering risk of type 1 diabetes, boosting brain function, and improving skin health.

The Recommended Dietary Allowance for Vitamin B3 for adults 19+ years is 16mg for men and 14mg for women. For pregnant and lactating women, it is 18mg and 17mg daily, respectively. The Tolerable Upper Intake Level for Vitamin B3 for all adults 19+ years is 35mg.

Vitamin B3 toxicity can occur from long-term use of high-dose supplements in the form of nicotinic acid. A reddened skin flush with itchiness or tingling on the face, arms, and chest is a common sign. Other symptoms of toxicity include dizziness, low blood pressure, fatigue, headache, upset stomach, nausea, blurred vision, impaired glucose tolerance, and inflammation of liver (in severe cases).

Background

Vitamin B3 (Nicotinamide) is listed in the World Health Organization's List of Essential Medicines.