What Vitamin is B3? Everything You Need to Know About Niacin

November 15, 2025 •

4 min read

According to the National Institutes of Health, vitamin B3 is also known by its generic name, niacin, and is essential for converting food into energy. It is a water-soluble vitamin required by every part of your body to function properly, especially the nervous system, digestive system, and skin.

Quick Summary

Vitamin B3, known as niacin, is a water-soluble vitamin vital for metabolism, converting food into energy. It exists in multiple forms, including nicotinic acid and niacinamide, each with different uses and effects. A deficiency can lead to pellagra, while sufficient intake supports the nervous system, skin, and digestion through food and supplements.

Key Points

Identity: Vitamin B3 is also known as niacin, a water-soluble vitamin essential for converting food into energy and maintaining cell health.
Forms: Niacin exists in several forms, including nicotinic acid and niacinamide, which have distinct uses and effects.
Functions: It supports the nervous and digestive systems, promotes brain function, and benefits skin health by protecting against sun damage.
Deficiency: Severe deficiency leads to pellagra, characterized by dermatitis, diarrhea, and dementia.
Supplements: High-dose nicotinic acid is used to treat high cholesterol but can cause uncomfortable flushing, unlike niacinamide.
Side Effects: Excessive intake from supplements can cause serious side effects, including liver damage, gastrointestinal problems, and increased blood sugar.
Food Sources: Niacin is found naturally in many foods, including poultry, fish, meat, nuts, legumes, and fortified grains.

Understanding the Basics: The Role of Niacin

Vitamin B3, or niacin, is not just a single compound but a generic name for nicotinic acid, niacinamide (nicotinamide), and related derivatives. All tissues in the body convert absorbed niacin into the metabolically active coenzyme nicotinamide adenine dinucleotide (NAD) and its counterpart, NADP, which are critical for over 400 biochemical reactions. These coenzymes are essential for converting the energy in food into a usable form for the body, as well as for vital cellular functions like DNA repair and cell communication.

The Health Benefits of Vitamin B3

Maintaining adequate levels of niacin is crucial for overall health. Its wide-ranging functions provide several key benefits, which vary depending on whether the intake is from diet or high-dose supplements.

Brain Function: Niacin plays a direct role in boosting brain function, with deficiency being linked to brain fog and psychiatric symptoms. Some research even suggests a potential protective effect against age-related cognitive decline and Alzheimer's disease.
Skin Health: This vitamin helps protect skin cells from sun damage, and when applied topically or taken orally in the form of niacinamide, it can help treat acne, reduce redness, and manage other inflammatory skin conditions.
Improved Cholesterol Levels: Therapeutic doses of nicotinic acid have been shown to reduce LDL (bad) cholesterol and triglycerides while raising HDL (good) cholesterol. However, this is primarily a medical treatment for dyslipidemia, not a general health benefit from dietary intake.
Aids Digestion: Niacin is fundamental to the metabolic process that breaks down carbohydrates and fats, supporting the health of the digestive system.
Lowered Blood Pressure: Niacin can help widen blood vessels, which may improve blood flow and contribute to lower blood pressure.

Deficiency and Toxicity: Finding the Right Balance

While obtaining sufficient niacin from a balanced diet is relatively easy in developed countries, deficiencies and excesses from supplements can occur. A severe niacin deficiency causes pellagra, a disease characterized by the "4 Ds": dermatitis (a rough, red rash), diarrhea, dementia, and if left untreated, death. Symptoms of a less severe deficiency can include fatigue, depression, headaches, and indigestion.

Conversely, high doses of supplemental niacin, especially nicotinic acid, can lead to unpleasant or even harmful side effects. The most common is the "niacin flush," a temporary reddening and tingling of the skin. Very high doses over time can cause liver damage, gastrointestinal issues, and changes in blood sugar levels.

Food Sources of Niacin

An excellent way to get your daily requirement of niacin is through your diet. A wide variety of foods, from both plant and animal sources, contain this vital nutrient.

Animal Sources: Lean meats such as poultry (chicken breast), beef, and pork are rich in niacin. Liver and fish, including salmon, tuna, and anchovies, are also excellent sources.
Plant Sources: Legumes, nuts, seeds, and brown rice provide niacin. Certain plant-based options like peanuts, mushrooms, and fortified cereals and breads are also great contributors.

Niacin vs. Niacinamide: Different Forms, Different Functions

It's important to differentiate between the forms of vitamin B3, as they have different effects on the body and potential side effects.


Feature	Nicotinic Acid (Niacin)	Nicotinamide (Niacinamide)
Effect on Cholesterol	Used in therapeutic doses to lower LDL and raise HDL cholesterol.	No significant effect on cholesterol levels.
Flushing	Commonly causes the "niacin flush"—a tingling, itching, and reddening of the skin due to vasodilation.	Does not cause the flushing reaction.
Primary Use (Supplement)	Prescribed for dyslipidemia under medical supervision.	Used more widely in general dietary supplements, skin care, and to prevent deficiency.
Side Effects (High Dose)	Can cause severe flushing, gastrointestinal issues, liver toxicity, and hyperglycemia.	Safer at higher doses with fewer side effects, but still has a Tolerable Upper Intake Level.

Conclusion: Meeting Your Niacin Needs Safely

In summary, what vitamin is B3? It is niacin, an indispensable, water-soluble nutrient vital for numerous bodily functions, from energy metabolism to nervous system health. The average person can get more than enough niacin through a balanced diet rich in meat, fish, and fortified grains, making deficiency a rarity in industrialized nations. However, certain health conditions or very limited diets can increase risk. When considering supplementation, especially for conditions like high cholesterol, it is critical to consult a healthcare provider. The form of B3, whether nicotinic acid or niacinamide, dictates its effects and potential side effects, with high doses of nicotinic acid carrying significant risks. By understanding the distinction between dietary and supplemental intake and consulting with a professional, you can ensure your body receives the niacin it needs safely and effectively.

Authoritative Resource on Vitamin B3

For in-depth information and dietary reference intakes for health professionals, the National Institutes of Health provides a comprehensive Fact Sheet on Niacin.

Frequently Asked Questions

The main difference is that niacin (nicotinic acid) can cause an uncomfortable flushing sensation at high doses and is used to treat high cholesterol under a doctor's supervision, while niacinamide does not cause flushing and is more commonly used in dietary supplements and skincare.

Vitamin B3 is crucial for converting food into energy, supporting the health of the nervous and digestive systems, maintaining healthy skin, and promoting proper brain function.

Yes, most people in developed countries get sufficient niacin from a balanced diet, as it's present in a wide range of foods, including meat, fish, fortified cereals, and legumes.

A severe Vitamin B3 deficiency results in a condition called pellagra, which is characterized by dermatitis (a red, scaly rash), diarrhea, and dementia.

For most healthy individuals who consume a varied diet, supplementation is not necessary. It is primarily used medically for specific conditions like dyslipidemia and severe deficiency, always under professional guidance.

Excellent food sources of Vitamin B3 include animal products like poultry, beef, and fish (e.g., salmon and tuna), as well as plant-based options such as nuts, legumes, brown rice, and fortified breads and cereals.

Yes, taking very high doses of Vitamin B3 supplements, especially nicotinic acid, can cause adverse effects like liver damage, elevated blood sugar, and severe skin flushing. It is crucial to use high-dose supplements only under medical supervision.