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Limited evidenceHeart & metabolic

Vitamin B3 (Niacin)

Niacin reliably raises HDL and lowers triglycerides, but two large outcome trials showed no reduction in cardiovascular events on top of statins — and real harm, including new-onset diabetes, infections and bleeding. The lipid numbers move; the patients do not benefit.

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What the science says

  • Improves lipid numbers (raises HDL, lowers triglycerides and Lp(a)) Strong evidence

    Extended-release niacin at 1.5-2 g/day raises HDL-C by roughly 20-25%, lowers triglycerides by 20-30% and reduces Lp(a) by around 20%. This is consistent across dozens of trials — it is the single best-documented biochemical effect of any B vitamin.

  • Reduces cardiovascular events Limited evidence

    AIM-HIGH randomised 3,414 patients with atherosclerotic disease and low HDL on simvastatin to extended-release niacin 1.5-2 g/day and was stopped early for futility despite the expected HDL rise. HPS2-THRIVE randomised 25,673 patients to niacin plus laropiprant and found no reduction in major vascular events plus a significant excess of serious adverse events. Two large trials, both negative — this claim is effectively refuted for statin-treated patients.

  • Causes clinically meaningful harm at pharmacologic doses Strong evidence

    HPS2-THRIVE found significant excesses of new-onset diabetes, disturbances of diabetes control, serious infection and serious bleeding with niacin/laropiprant. Combined with flushing and hepatotoxicity risk, this harm profile is the main reason niacin has fallen out of guideline use.

  • Treats pellagra and niacin deficiency Strong evidence

    Niacin cures pellagra (dermatitis, diarrhoea, dementia), which is why it was discovered in the first place. Deficiency is rare in fortified-grain countries but occurs in alcohol use disorder, carcinoid syndrome, Hartnup disease and isoniazid therapy. Ordinary nutritional doses of 15-20 mg/day suffice.

Dosage & safety

Studied doseRDA is 16 mg NE/day for men and 14 mg NE/day for women — trivially met by diet. Lipid trials used 1,500-2,000 mg/day of extended-release nicotinic acid, titrated up over weeks. Nicotinamide (niacinamide) does not raise HDL and does not cause flushing; 500 mg twice daily has separate dermatology evidence for reducing non-melanoma skin cancer. Inositol hexanicotinate ('no-flush niacin') releases little free nicotinic acid and does not meaningfully alter lipids.
SafetyProstaglandin-mediated flushing (burning, itching, redness) affects most users at gram doses and is the main reason for discontinuation; taking with food or pretreating with aspirin blunts it. Dose-dependent hepatotoxicity — sustained-release formulations carry the highest risk and fulminant hepatic failure has been reported. Raises fasting glucose and precipitates new-onset diabetes; worsens glycaemic control in existing diabetes. Increases uric acid and can trigger gout. Increased serious infection and bleeding in HPS2-THRIVE. Interacts with statins (myopathy risk) and antihypertensives (additive hypotension). Prescription niacin products exist in many countries; gram-level use should be physician-supervised, and it is no longer recommended as add-on therapy to statins.

How to take it

TimingExtended-release at bedtime; immediate-release with the evening meal — both to move the flushing into sleep.
With food?Always with food — an empty stomach makes the flush considerably worse.
Worth knowingNever swap between immediate-release, sustained-release and 'no-flush' at the same milligram number: sustained-release is the most liver-toxic and inositol hexanicotinate does essentially nothing to lipids.

Interactions

With medications

  • statins

    Combining gram-dose niacin with a statin increases the risk of myopathy and rhabdomyolysis, and adds no outcome benefit in trials. niacin is no longer recommended as an add-on to statins — do not self-add it

  • insulin, metformin and other antidiabetic drugs

    Niacin raises fasting glucose and can unmask or worsen diabetes, requiring larger doses of diabetes medication. monitor glucose closely and only use gram doses under medical supervision

  • blood pressure medication and nitrates

    Niacin causes vasodilation, so hypotension and dizziness can be additive. stand up slowly when starting; discuss with your prescriber

  • allopurinol and gout treatment

    Niacin raises uric acid and can trigger gout flares, working against the drug. avoid gram doses if you have gout

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does niacin prevent heart attacks?

No — the evidence is limited and negative for statin-treated patients. Niacin raises HDL and lowers triglycerides, but the large AIM-HIGH and HPS2-THRIVE trials found no fewer cardiovascular events, and HPS2-THRIVE found more serious adverse events.

Does niacin have side effects at high doses?

Yes. Flushing affects most people taking niacin at gram doses, and niacin can damage the liver, raise blood sugar and trigger new diabetes or gout; HPS2-THRIVE also found more serious infections and bleeding. Gram doses of niacin should be physician-supervised.

Is no-flush niacin as effective as regular niacin?

No. 'No-flush' niacin (inositol hexanicotinate) releases little free nicotinic acid and does essentially nothing to lipids. Never swap niacin forms at the same milligram number, since sustained-release is the most liver-toxic.

Is niacin safe with a statin?

Adding gram-dose niacin to a statin raises the risk of muscle damage and added no outcome benefit in trials. Niacin is no longer recommended as an add-on to statins, so do not add it yourself.

Scientific references

Where to buy

Life Extension, Vitamin B3 Niacin, 500 mg, 100 Capsules

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