How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Niacin (vitamin B3)
Niacin (vitamin B3): at high doses, it improves cholesterol, but two major trials in statin-treated patients find no benefit for the heart, and it increases the risk of diabetes. Nicotinamide reduced skin cancers in at-risk individuals.
Benefits
- Skin cancers: in 386 people who had already had at least two non-melanoma skin cancers, 500 mg of nicotinamide twice a day for 12 months reduced new cancers by 23%, and actinic keratoses by 11% starting at 3 months.
- Cholesterol: in 468 patients with diseased leg arteries, up to 3,000 mg of niacin per day increased HDL by 29%, and decreased triglycerides by 23 to 28% and LDL by 8 to 9%, with or without diabetes.
- LDL: in 201 people with high LDL, 1,500 and 2,000 mg per day of extended-release niacin decreased LDL by 19.3% and 26%.
- Lipoprotein(a): across 14 trials and 9,013 people, extended-release niacin lowers lipoprotein(a) by an average of 22.9%.
- Arteries: in 71 statin-treated patients with low HDL, 2 g per day for 12 months reduced the carotid wall by 1.64 mm² compared to placebo.
- Glaucoma: in 57 patients, 6 weeks at 1.5 g then 6 weeks at 3 g of nicotinamide per day improved retinal function by 14.8 %, compared to 5.2 % with placebo.
- Heart, before statins: out of 11 old trials conducted before statins became the standard treatment, niacin reduced major coronary events by 25% and all cardiovascular events combined by 27%.
Precautions
Flushing: in 33 healthy adults, a single dose of 500 mg of immediate-release niacin on an empty stomach caused 100% of them to flush, after an average of 18.2 minutes and lasting for 75 minutes; this was accompanied by chills (51.5%), itching (75%), digestive disorders (30%), and tingling (30%). Six could not tolerate it and three needed medical care. Diabetes: across 11 trials and 26,340 non-diabetic people, niacin makes diabetes 1.34 times more frequent, meaning one extra case for every 43 people treated for 5 years. Antidiabetics: in diabetics, niacin slightly raises blood glucose (8.7 mg/dl) and, at 1,500 mg per day, glycated hemoglobin (from 7.2% to 7.5%); if you are taking antidiabetic drugs, talk to your doctor. Statins: in 25,673 statin-treated patients, 2 g of extended-release niacin (with laropiprant) increased serious adverse effects: worsening of diabetes (3.7 points more), new-onset diabetes (1.3), digestive disorders (1.0), muscular disorders (0.7), infections (1.4), and bleeding (0.7); if you are taking a statin, talk to your doctor. Dose: trials use 500 to 3,000 mg per day, well above the European limit of 10 mg per day for nicotinic acid; in a review of 47 studies in healthy people, major adverse effects appeared under 1,000 mg per day. Limits: heart, with a statin: in 3,414 patients, the AIM-HIGH trial was stopped after 3 years due to a lack of efficacy (16.4% of events with niacin vs. 16.2% with placebo), despite a higher HDL; in 25,673 patients followed for 3.9 years, nothing significant either (13.2% vs. 13.7%). Meta-analyses: out of 117,411 patients, niacin does not change mortality, coronary mortality, or strokes; out of 35,760 patients, no preventive effect in those who already have cardiovascular disease, with favorable results coming mainly from two old trials in patients without statins. Old results: a 2013 meta-analysis (11 trials, 9,959 people) found even fewer cardiovascular events, prior to the publication of the trial on 25,673 patients; in 8,341 men after a myocardial infarction, in a trial conducted from 1966 to 1975, niacin had not reduced mortality during the trial. Arteries: in 107 coronary patients, 1,000 mg per day for 12 weeks did not improve artery dilation, except in a subgroup with low HDL. Type 1 diabetes: in 552 high-risk relatives of diabetics, 5 years of nicotinamide neither prevented nor delayed the onset of diabetes.
Recommended dosage
Trials: 1,000 to 3,000 mg of niacin per day, or 500 mg of nicotinamide twice a day. European limit for nicotinic acid: 10 mg per day.
How to take it
- Who is it for: the trials involve patients (heart or artery disease, high cholesterol, diabetes, glaucoma, repeated skin cancers); none involve sports.
- Two forms: niacin (nicotinic acid) is used in cholesterol and heart trials; nicotinamide is used in skin, glaucoma, and type 1 diabetes trials.
- Extended-release: recent cholesterol trials use extended-release niacin, once daily (1,000 or 1,500 mg in 148 diabetics, for 16 weeks).
- Skin: 500 mg of nicotinamide twice a day for 12 months; no benefit remained after discontinuation.
- Glaucoma: 1.5 g of nicotinamide per day for 6 weeks, then 3 g per day for 6 weeks.
- With a meal or on an empty stomach: the flushing trial gave 500 mg of immediate-release niacin on an empty stomach; no study in this file compares taking it with a meal versus without.
Did you know?
In a trial conducted from 1966 to 1975 on 8,341 men after a heart attack, niacin had not reduced mortality. But 15 years later, nearly 9 years after stopping treatment, mortality was 11% lower in the niacin group (52.0% vs 58.2%).
What the studies say
This systematic review and meta-analysis of 17 clinical trials, totaling 35,760 patients, evaluated the role of niacin in the prevention of cardiovascular disease. Cumulative analysis found no preventive association of niacin with cardiovascular events in secondary prevention. However, stratified analysis suggested that niacin monotherapy might reduce certain cardiovascular events (acute coronary syndrome, stroke, revascularization) in patients without statin therapy, with these results coming primarily from older studies.
D'Andrea E, Hey SP, Ramirez CL, Kesselheim AS. — JAMA network open (2019) — View the source study
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more