Vitamin B3 (Niacin)
Also known as: Nicotinic Acid, Niacinamide, Nicotinamide
Niacin is a precursor to nicotinamide adenine dinucleotide (NAD+) and nicotinamide adenine dinucleotide phosphate (NADP+), two critical coenzymes involved in over 400 enzymatic reactions in the body. These reactions are central to energy metabolism, DNA repair, and antioxidant defense. Pharmacological doses of nicotinic acid have a well-established role in lowering LDL cholesterol and triglycerides and raising HDL cholesterol, primarily through inhibiting hepatic VLDL synthesis and reducing fatty acid mobilization. Nicotinamide, while also a source of NAD+, does not exert the same hypolipidemic effects but is crucial for various cellular processes and has shown promise in certain dermatological conditions and neurological contexts at higher doses.
Last reviewed: 2026-04-22 · 4 indexed studies
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Overview
Vitamin B3, or niacin, is a water-soluble vitamin essential for metabolism and cell function. It exists in several forms, primarily nicotinic acid and nicotinamide. Nicotinic acid is well-known for its potent lipid-modifying effects at pharmacological doses, while nicotinamide is more commonly used in general nutrition and has fewer vasodilatory side effects.
Mechanism & Function
Niacin (nicotinic acid) · C₆H₅NO₂ — source: PubChem CID 938
White crystalline B-vitamin. Causes flush at >50 mg via prostaglandin release.
- Capsule
- Tablet
- Powder
Tablet is generally preferred for bioavailability or efficacy.
Mechanism of Action
Niacin acts as a precursor for NAD+ and NADP+, which are vital coenzymes in redox reactions. Nicotinic acid specifically targets the niacin receptor 1 (NIACR1, also known as GPR109A) in adipocytes and immune cells. Activation of GPR109A inhibits adenylate cyclase, leading to reduced lipolysis and decreased free fatty acid release from adipocytes, which in turn reduces hepatic triglyceride and VLDL synthesis. Additionally, nicotinic acid can increase reverse cholesterol transport and HDL-C levels. Nicotinamide, as a non-flush form, primarily functions as a direct precursor to NAD+ without significant GPR109A activation, thus avoiding the vasodilatory effects seen with nicotinic acid.
Physiological Role
Niacin's primary physiological role is to serve as a precursor for NAD+ and NADP+. These coenzymes are indispensable for cellular energy production (glycolysis, citric acid cycle, oxidative phosphorylation), fatty acid synthesis and breakdown, cholesterol synthesis, and the metabolism of carbohydrates and amino acids. NAD+ is also a substrate for enzymes involved in DNA repair (PARPs) and cell signaling (sirtuins), highlighting its broad importance in maintaining genomic integrity and regulating cellular stress responses. Deficiency leads to pellagra, characterized by dermatitis, diarrhea, and dementia.
Primary Pathways
Performance / Health Relevance
For general performance, adequate niacin intake is crucial for maintaining efficient energy metabolism, as NAD+ and NADP+ are central to ATP production. Deficiency can impair exercise capacity due to compromised metabolic flux. While pharmacological doses of nicotinic acid are used in cardiology, they are not typically used to enhance athletic performance and can sometimes cause undesirable side effects like flushing. Nicotinamide may play a role in supporting cellular resilience and recovery but direct performance enhancement in already replete individuals is unproven.
Evidence Review
Compare Vitamin B3 (Niacin) Forms
Full comparison5 vitamin b3 (niacin) forms are indexed. Bioavailability, clinical evidence, and best-use cases differ meaningfully between them.
| Form | Evidence |
|---|---|
Vitamin B3 (Niacin)This page Both nicotinic acid and nicotinamide are well absorbed orally. Nicotinic acid has varying pharmacokinetic profiles depending on the formulation (immediate-release vs. sustained-release). | 80/100 |
| Vitamin B3 (Niacinamide) Highly bioavailable orally, with absorption rates typically exceeding 90%. | 65/100 |
| Nicotinamide Riboside Oral NR increases circulating NAD+ and, in at least one trial, brain NAD+; magnitude of change is variable between individuals. | 61/100 |
| NMN Oral NMN raises plasma NAD+; sublingual delivery may improve bypass of gut conversion. | 54/100 |
| Nicotinamide Mononucleotide Rapidly absorbed and converted to NAD+ within 30 minutes. Some degradation by CD73 ectoenzyme in the GI tract — sublingual delivery may improve yield. | 50/100 |
Practical Use & Dosage
- Minimum Effective Dose
- 15 mg/day (RDA)
- Optimal Range
- 15-20 mg/day (for general health); 500-2000 mg/day (pharmacological for lipids, under medical supervision)
- Upper / Caution Level
- 35 mg/day (UL for general population from supplements); Higher doses (1000+ mg/day) require medical monitoring dueed to potential liver toxicity and other side effects.
- Timing
- Can be taken with meals to reduce gastrointestinal upset, especially nicotinic acid. Sustained-release forms might be taken once daily.
- Best Format
- Nicotinamide for general supplementation; Nicotinic acid (immediate or sustained release) for lipid management, under medical supervision.
- Bioavailability
- Both nicotinic acid and nicotinamide are well absorbed orally. Nicotinic acid has varying pharmacokinetic profiles depending on the formulation (immediate-release vs. sustained-release).
- Absorption Considerations
- Generally good absorption. High doses of nicotinic acid can cause flushing, which can be mitigated by taking with food or using sustained-release forms. Absorption is not significantly impacted by food or other nutrients at typical doses.
Safety & Interactions
Side Effects
- •Flushing (vasodilation, redness, itching, tingling, warmth - common with nicotinic acid, especially immediate-release)
- •Gastrointestinal upset (nausea, vomiting, diarrhea)
- •Hepatotoxicity (liver damage, especially at high doses of sustained-release nicotinic acid)
- •Hyperglycemia
- •Hyperuricemia (gout)
- •Pruritus
- •Hypotension
Contraindications
- Active liver disease
- Severe hypotension
- Arterial hemorrhage
- Active peptic ulcer disease
Drug Interactions
- •Statins (increased risk of myopathy, rhabdomyolysis)
- •Antihypertensive drugs (additive hypotensive effects)
- •Anticoagulants (increased bleeding risk at very high doses)
- •Aspirin (can exacerbate flushing)
- •Oral hypoglycemic agents (can alter blood glucose control)
Who Should Avoid
- •Individuals with active liver disease
- •People with peptic ulcers
- •Those with severe low blood pressure
- •Individuals with uncontrolled diabetes without medical supervision
- •People with gout (may worsen hyperuricemia)
Monitoring
For pharmacological doses of nicotinic acid, regular monitoring of liver enzymes (ALT, AST), blood glucose, and uric acid is essential. Lipid panels should also be monitored to assess efficacy. Patients should be educated on managing flushing.
Frequently Asked Questions
Auto-generated from indexed evidence — dosage, safety, interactions, and more.
When is Vitamin B3 (Niacin) typically used or indicated?
Vitamin B3 (Niacin) is most commonly used for: Cholesterol management, Pellagra prevention, Cardiovascular health. Niacin's primary physiological role is to serve as a precursor for NAD+ and NADP+. These coenzymes are indispensable for cellular energy production (glycolysis, citric acid cycle, oxidative phosphorylation), fatty acid synthesis and breakdown, cholesterol synthesis, and the metabolism of carbohydrates and amino acids. NAD+ is also a substrate for enzymes involved in DNA repair (PARPs) and cell signaling (sirtuins), highlighting its broad importance in maintaining genomic integrity and regulating cellular stress responses. Deficiency leads to pellagra, characterized by dermatitis, diarrhea, and dementia.
How does Vitamin B3 (Niacin) work?
Niacin acts as a precursor for NAD+ and NADP+, which are vital coenzymes in redox reactions. Nicotinic acid specifically targets the niacin receptor 1 (NIACR1, also known as GPR109A) in adipocytes and immune cells. Activation of GPR109A inhibits adenylate cyclase, leading to reduced lipolysis and decreased free fatty acid release from adipocytes, which in turn reduces hepatic triglyceride and VLDL synthesis. Additionally, nicotinic acid can increase reverse cholesterol transport and HDL-C levels. Nicotinamide, as a non-flush form, primarily functions as a direct precursor to NAD+ without significant GPR109A activation, thus avoiding the vasodilatory effects seen with nicotinic acid.
What is the recommended dose of Vitamin B3 (Niacin)?
The optimal range is 15-20 mg/day (for general health); 500-2000 mg/day (pharmacological for lipids, under medical supervision). with a minimum effective dose of 15 mg/day (RDA). Best taken: Can be taken with meals to reduce gastrointestinal upset, especially nicotinic acid. Sustained-release forms might be taken once daily.. Upper / caution level: 35 mg/day (UL for general population from supplements); Higher doses (1000+ mg/day) require medical monitoring dueed to potential liver toxicity and other side effects..
What are the side effects of Vitamin B3 (Niacin)?
Reported side effects include: Flushing (vasodilation, redness, itching, tingling, warmth - common with nicotinic acid, especially immediate-release); Gastrointestinal upset (nausea, vomiting, diarrhea); Hepatotoxicity (liver damage, especially at high doses of sustained-release nicotinic acid); Hyperglycemia; Hyperuricemia (gout); Pruritus; and Hypotension. Monitoring: For pharmacological doses of nicotinic acid, regular monitoring of liver enzymes (ALT, AST), blood glucose, and uric acid is essential. Lipid panels should also be monitored to assess efficacy. Patients should be educated on managing flushing.
Does Vitamin B3 (Niacin) interact with medications?
Known or theoretical interactions: Statins (increased risk of myopathy, rhabdomyolysis); Antihypertensive drugs (additive hypotensive effects); Anticoagulants (increased bleeding risk at very high doses); Aspirin (can exacerbate flushing); and Oral hypoglycemic agents (can alter blood glucose control). Always check with a clinician before combining with prescription medication.
Who should avoid Vitamin B3 (Niacin)?
Vitamin B3 (Niacin) is generally not recommended for: Individuals with active liver disease; People with peptic ulcers; Those with severe low blood pressure; Individuals with uncontrolled diabetes without medical supervision; People with gout (may worsen hyperuricemia); Active liver disease; Severe hypotension; Arterial hemorrhage; and Active peptic ulcer disease.
How strong is the evidence for Vitamin B3 (Niacin)?
Evidence level: Strong (overall score 80/100), based on 4 indexed studies on SuppIndex.
Research & References (4)
Meta-analysis of niacin and risk of incident cardiovascular events.
This meta-analysis synthesized data from multiple randomized controlled trials to evaluate the effect of niacin on cardiovascular events.
Effect of sustained-release niacin on serum lipids, lipoproteins, and lipoprotein(a).
This randomized, placebo-controlled trial investigated the lipid-modifying effects of sustained-release niacin in patients with dyslipidemia.
Nicotinamide for skin cancer chemoprevention.
A randomized, double-blind, placebo-controlled trial examining the effect of oral nicotinamide on the rate of new non-melanoma skin cancers and actinic keratoses.
The effect of niacin on glycemic control in patients with type 2 diabetes and dyslipidemia: a systematic review and meta-analysis of randomized controlled trials.
This systematic review and meta-analysis evaluated the impact of niacin on glycemic parameters in individuals with type 2 diabetes and dyslipidemia.
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Research Overview
Strong EvidenceCite this ingredient
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Stable URL
https://thesuppindex.com/ingredients/vitamin-b3-niacin
SuppIndex. (2026). Vitamin B3 (Niacin): Evidence summary, dosage and clinical studies. Retrieved October 23, 2026, from https://thesuppindex.com/ingredients/vitamin-b3-niacin
Based on 4 indexed studies · Evidence level: Strong.
Goal Ratings
Stack Compatibility
Generally safe with most vitamins and minerals at recommended daily allowances. For high-dose nicotinic acid, careful consideration of drug interactions and potential side effects is paramount, especially with other lipid-lowering agents or drugs affecting liver function.