Niacin: the vitamin that became a heart drug and then failed the trials

Niacin is needed by more enzymes than any other vitamin, and deficiency in the form of pellagra is one of the most dramatic in nutrition. It is also the vitamin with the clearest example of a supplement that looked right on paper and did nothing in large trials.

What it does in the body

• More than 400 enzymes require NAD to catalyse reactions in the body, more than for any other vitamin-derived coenzyme. — general adults Evidence E source

How much you need

• The RDA for niacin is 16 mg NE a day for adult men and 14 mg NE for adult women aged 19 and over. — general adults Evidence E source
• The body makes its own niacin out of tryptophan at roughly 60 to 1, but that rate is not a constant: it falls when tryptophan is short, when a gene stops tryptophan being absorbed, and when iron, riboflavin or B6 are missing. — general healthy population, plus named conditions that change the conversion Evidence E source
• A palm-sized portion of turkey breast is worth about 3 mg of niacin through tryptophan alone, before any of the niacin in the meat itself is counted - though how much a given person actually converts varies a lot. — general population Evidence E source
• In Nordic countries adults already eat two to three times the recommended niacin without trying, and ordinary dietary protein alone accounts for most of the recommended amount. — adults over 18 in the Nordic countries Evidence E source

How well your body absorbs it

• People short of riboflavin, vitamin B6 or iron convert less tryptophan to niacin, because the enzymes in that pathway depend on those nutrients. — general adults Evidence E source
• How much niacin a food actually delivers depends on where it came from. Animal foods carry 5-10 mg per serving in a form the body takes up easily. Grains carry 2-5 mg, of which only about 30 per cent is available at all. Fortified flour carries the free form, which is fully available. — general population, US food supply Evidence E source
• The niacin in cereal grains is chemically tied up and poorly available, and the one kitchen step known to free it is alkaline treatment - the traditional lime-soaking of maize, not boiling or baking. — general healthy population Evidence E source
• Nobody has yet worked out how niacin actually crosses the gut wall: the transporters that carry it out of the intestine have not been identified. — general healthy population Evidence E source

What too little does

• Severe niacin deficiency causes pellagra, whose first visible sign is a pigmented rash on skin exposed to sunlight. — people with severe niacin deficiency Evidence E source
• Across 1,212 confirmed modern cases, skin changes appeared in almost every one, while the gut and nerve signs of the classic triad appeared in only a little over half. — people with confirmed pellagra worldwide, reported in 133 of 918 screened studies Evidence C source
• When pellagra is treated with vitamin B3, symptoms take about four weeks to clear completely, not days. — treated pellagra cases in the same 133 studies Evidence C source
• It takes about two months of a corn-based, niacin-poor diet before deficiency symptoms appear, because the body keeps almost no reserve of niacin. — general population; the estimate comes from the classical depletion literature Evidence E source

Who is most likely to fall short

• Undernourished people, including those with alcohol use disorder, AIDS, inflammatory bowel disease or liver cirrhosis, often take in too little niacin. — undernourished adults Evidence E source
• Pellagra today is still mostly a disease of not having enough food, but one case in seven is caused by the tuberculosis drug isoniazid. — the same 1,212 confirmed cases, classified by reported cause Evidence C source

What the evidence does and does not show

• Across 23 randomised trials in 39,195 people, nicotinic acid did not reduce deaths, heart attacks or strokes. — adults at cardiovascular risk, 23 RCTs, 39,195 participants Evidence A source
• A meta-analysis of 35,760 people with heart disease or high cholesterol found no protective effect of niacin on cardiovascular outcomes. — patients with a history of cardiovascular disease or dyslipidaemia, 17 trials reporting outcomes Evidence A source
• Mothers who ate too little niacin around conception were 13 per cent more likely to have a baby with a birth defect, on case-control evidence only. — women in 14 case-control studies, ten in the United States, three in the Netherlands and one in South Africa Evidence C source
• The one place vitamin B3 has ever moved a hard outcome in a randomised trial is skin: 500 mg of nicotinamide twice a day cut new non-melanoma skin cancers by 23 per cent in people who had already had two. — adults who had had at least two non-melanoma skin cancers in the previous five years Evidence B source
• Extended-release nicotinic acid lowers lipoprotein(a) by about 23 per cent, and trials using under 2,000 mg a day got much the same drop. — adults in 14 randomised placebo-controlled trials, 17 treatment arms Evidence A source
• Before statins were standard care, pooled trials really did show niacin cutting major coronary events by a quarter, which is why the reputation outlived the evidence. — mostly secondary-prevention patients on 1 to 3 g of nicotinic acid a day, in trials conducted before statin therapy became standard Evidence A source
• Niacin widens arteries measurably, improving flow-mediated dilation by about two percentage points, and that improvement had nothing to do with how much it raised HDL. — adults in seven randomised trials, in both primary and secondary prevention Evidence A source
• Feeding older adults a full month of NAD-building blocks measurably changed their niacin metabolism and changed nothing about their muscles. — community-dwelling older adults with impaired physical function, mean age 72.9 years, BMI 25.2 Evidence B source
• Pooling every randomised trial of NMN, the fashionable NAD booster, it looks safe over weeks to months and does essentially nothing to weight, blood sugar, blood fats or blood pressure. — adults taking oral nicotinamide mononucleotide or NMN-related preparations against placebo or control Evidence A source
• "No-flush niacin" lives up to its name in the least useful way: in a randomised trial the inositol hexanicotinate form produced no flush, no change in blood fats, and no sign that it was absorbed at all. — adults with mild-to-moderate dyslipidaemia, LDL 130-190 Evidence B source
• Breast milk runs low on vitamin B3 as lactation goes on - nearly a third of unsupplemented mothers were below the reference limit by month five - and giving the mothers nicotinamide raised the milk level threefold without changing anything measurable in the child. — lactating women and their infants in rural Haydom, Tanzania, enrolled at infant age under 2 weeks Evidence B source
• The study that linked breakdown products of excess niacin to heart attacks and strokes deliberately left out everyone taking niacin as a drug - so what it is pointing at is ordinary niacin from food and fortified flour. — stable patients undergoing elective diagnostic cardiac evaluation; US validation cohort from GeneBank at the Cleveland Clinic, European validation cohort from LipidCardio Evidence C source
• No food or supplement sold in the United States may legally claim that niacin prevents or treats anything. FDA has authorised no health claim for it at all. — усі харчові продукти й добавки на ринку США Evidence E source
• A decade of niacin research went into drug-sized doses, and the body that sets the Nordic norms says plainly that none of it helps work out how much a healthy person needs. — здорові популяції, для яких встановлюється норма Evidence E source

What too much does

• The Tolerable Upper Intake Level for niacin is 35 mg a day for adults aged 19 and over, set on the basis of flushing from nicotinic acid. — general adults Evidence E source
• Pooling 47 studies in 11,741 people, serious side effects of nicotinic acid in otherwise healthy adults started below 1,000 mg a day, far above the 35 mg upper limit set in the United States. — healthy adults and people with dyslipidaemia across 47 studies Evidence A source
• In people with type 2 diabetes niacin raises HDL and lowers triglycerides, and over the long term it also pushes fasting glucose up. — patients with type 2 diabetes mellitus taking niacin alone or in combination Evidence A source
• No one has ever documented harm from the niacin that is naturally in food. Every reported adverse effect comes from supplements, fortification or medicines. — general healthy population Evidence E source
• Europe sets two different safe ceilings for the same vitamin - 10 mg a day for one form of niacin and 900 mg for the other - which is why a supplement label is unreadable until you know which form is in it. — adults, European Union Evidence E source
• The American 35 mg ceiling for niacin is not a limit on food and not a toxicity threshold: it is the dose at which supplemental niacin makes skin flush, applied to both forms even though only one of them causes the flush. — healthy infants, children and adults in the United States Evidence E source
• Across fourteen reviews of niacin side effects, the nicotinamide form comes out easier on the body than nicotinic acid, and how well either is tolerated depends on what else is wrong with the person taking it. — humans taking oral nicotinamide or niacin, reviewed in an ophthalmology context because of glaucoma supplement use Evidence E source

Medicines it interacts with

• The tuberculosis drugs isoniazid and pyrazinamide block the body from making niacin out of tryptophan. — people treated for tuberculosis Evidence E source
• Statin labels approved by the FDA name niacin by dose: above a gram a day taken with a statin, cases of muscle breakdown have been seen. — people taking atorvastatin together with lipid-modifying doses of niacin Evidence E source

What to do with this

Food covers niacin easily, and the body can also make it from tryptophan in protein. That second route explains an odd detail worth knowing: if you are short of riboflavin, vitamin B6 or iron, the conversion works less well, so a niacin problem can really be a different problem.

Do not take high-dose niacin for your heart on your own. Across 23 randomised trials in 39,195 people, nicotinic acid did not reduce deaths, heart attacks or strokes, and the doses used in those trials are far above anything food delivers.

If you are being treated for tuberculosis, the drugs isoniazid and pyrazinamide interfere with making niacin from tryptophan. That is a conversation for the clinician managing the treatment, not a reason to add a supplement yourself.

If you came here about pellagra, look at what the evidence under it is made of. A review screened 918 studies and everything usable was a case report or a small series, so every percentage below describes patients whom somebody chose to write up. Skin changes appeared in 98.63 per cent of 1,212 cases, gut signs in 59.4 per cent and nerve signs in 54.2 per cent. Take the rash as the sign that carries weight, and take the absence of the other two as no reassurance at all. Recovery is slow, an average of 27.42 days to full resolution, so a week of treatment with no change tells you very little.

Not having enough food is behind 85 per cent of cases, and 93 per cent of those happened where food insecurity or a humanitarian crisis had made normal eating impossible. The tuberculosis drug isoniazid accounts for 14.3 per cent, which is one published case in seven and worth raising with whoever runs that treatment.

The one high dose with a hard outcome behind it belongs to dermatology. In 386 people who had already had two non-melanoma skin cancers, 500 mg of nicotinamide twice a day cut new ones by 23 per cent over a year, and the effect stopped when the tablets stopped. A gram a day is close to thirty times the 35 mg ceiling, so that is a specialist's decision about a person with a history behind them.

Why the label number and the useful number differ

Niacin is measured in niacin equivalents, and that unit hides two separate complications.

The first is that your body makes niacin out of tryptophan, the amino acid in protein, at roughly 60 mg of tryptophan to 1 mg of niacin. A palm-sized portion of turkey breast, about 85 g, carries around 180 mg of tryptophan, so it is worth about 3 mg of niacin through that route before anyone counts the niacin in the meat itself. The conversion is not a fixed rate. It falls when tryptophan is short, in the inherited condition Hartnup disease, and when iron, riboflavin or vitamin B6 are missing. So a niacin problem is sometimes a different deficiency wearing niacin's clothes.

The second is that the niacin in grain is chemically tied up. Animal foods carry 5 to 10 mg a serving in a form the body takes up easily. Grains carry 2 to 5 mg, of which only about 30 per cent is available at all. Fortified flour carries the free form, which is fully available. The one kitchen step known to release the bound form is alkaline treatment, the traditional lime-soaking of maize. Boiling and baking do not do it, and that single piece of food chemistry is the reason pellagra followed maize into Europe while it never took hold where maize arrived with the nixtamalisation.

Against all of that, the amount most people eat is not close. Nordic adults take in 29 to 31 niacin equivalents a day as women and 39 to 41 as men, against a recommendation in the 14 to 16 range. Ordinary dietary protein on its own supplies 12 to 19 of those. Two to three times the recommendation, without anybody trying.

Reading a niacin supplement label

Not for everyone. A niacin label is unreadable until you know which of two molecules is in it. Europe sets 10 mg a day as the safe ceiling for nicotinic acid and 900 mg for nicotinamide, the same vitamin, a ninetyfold difference. The American 35 mg limit is a third answer, and it is set on skin flushing rather than on damage. It applies to supplemental niacin rather than to food, and it covers nicotinamide as well even though nicotinamide does not cause the flush it was built on. Across fourteen reviews of side effects, nicotinamide came out easier on the body than nicotinic acid, with problems depending heavily on what else was wrong with the person, kidney trouble in particular.

Nothing in that paragraph is about food. No study has ever documented harm from the niacin naturally present in food. Every reported adverse effect comes from a supplement, a fortified product or a medicine.

Myth. No-flush niacin gives you the benefits without the flushing. The inositol hexanicotinate form was tested against an extended-release niacin at the same 1,500 mg a day. The extended-release form cut total cholesterol by 11 per cent, LDL by 18 and non-HDL by 15, and raised HDL by 12. The no-flush form changed blood fats no more than placebo, and showed no sign of being absorbed at all. It lives up to its name in the least useful way.

The NAD supplements, tested

Niacin is the raw material for NAD, and NAD is the story behind an expensive category of anti-ageing supplements. Both halves of it have now been checked.

Myth. NMN restores your metabolism. Pooling every randomised trial of it, at 250 to 2,000 mg a day for anything from 14 days to 24 weeks, NMN looks reassuringly safe. No rise in adverse events, none in liver enzymes. It also produced no significant change in body weight, body mass index, fasting glucose, HbA1c, blood fats or systolic blood pressure. Safe and inert is the honest summary.

Established. Feeding older adults 207.5 niacin equivalents a day for a month, as tryptophan, nicotinic acid and nicotinamide together, did change their niacin metabolism. Muscle methyl-nicotinamide rose from 0.025 to 0.098. Nothing else moved. Mitochondrial respiration, maximally uncoupled respiration and exercise efficiency all came back unchanged. The biochemistry did exactly what the theory said, and the muscle did not care.

The uncomfortable one

Unsettled. A 2024 study followed the terminal breakdown products of excess niacin, called 2PY and 4PY, and found they predicted heart attacks and strokes over three years. Hazard ratios ran from 1.64 to 2.02 for 2PY and from 1.89 to 1.99 for 4PY across two validation cohorts. The detail that matters is who was excluded. The researchers deliberately left out everyone taking niacin as a drug, so what the finding points at is ordinary niacin from food and from fortified flour. That is uncomfortable, because fortification is a public health success with a long record behind it. Metabolites are not outcomes, one cohort study does not overturn that record, and nothing here is a reason to avoid bread. It is a reason to notice that the question of how much niacin a population should get is open again.

For context on how little is settled underneath, two separate gaps are worth naming. The transporters that carry niacin out of the intestine have not been identified, so how dietary niacin is absorbed is described only in outline, and nobody can yet explain why different sources deliver such different amounts.

The second gap is about the recommendation itself. The body that sets the Nordic norms says plainly that the past decade of niacin research, which went into pharmacological doses of nicotinic acid for blood fats and into NAD precursors, makes no useful contribution to working out what a healthy person needs. The requirement is estimated instead from how much nicotinamide breakdown product turns up in urine. That is a biochemical marker rather than anything that happens to a person, and the enormous recent NAD literature has not changed it.

Not for everyone. One drug pairing is named on FDA-approved statin labels. Above a gram of niacin a day taken alongside atorvastatin, cases of muscle breakdown have been seen, and the label tells prescribers to weigh that up. Lipid doses of niacin are not something to add to a statin on your own initiative.

Unsettled. One finding belongs to breastfeeding mothers. Milk vitamin B3 falls as lactation goes on, and by month five nearly a third of unsupplemented mothers were below the lower reference limit, 28.8 per cent against 9.9 per cent among those taking 250 mg of nicotinamide a day. Supplementing raised median milk B3 by about 290 per cent and pushed most mothers above the upper reference limit instead. Nothing measurable changed in the children. So there is a real dip, a dose that overshoots it, and no demonstrated consequence either way. That is a question for a doctor who knows the baby rather than a reason to buy nicotinamide.

What a niacin label is allowed to say

Established. No food or supplement sold in the United States may legally claim that niacin prevents or treats anything. A health claim is unlawful unless the regulations specifically provide for it, and the sections that do provide for one run without gaps from 101.72 to 101.83. They cover calcium and vitamin D, dietary lipids, sodium, saturated fat, fibre, fruits and vegetables, folate, sugar alcohols, soluble fibre, soy protein and plant sterols. Niacin is not among them, and there is no qualified claim for it either, which is the lower bar the regulator uses when evidence is suggestive without being conclusive.

That result is easy to turn into something it does not say, so here is the careful version. An empty register is a fact about the regulator rather than about the vitamin. It records that the evidence never reached the bar an authorised claim demands. It does not record that niacin does nothing, and this page has already set out the things it does. Two useful conclusions come out of it. Anyone printing a health promise about niacin on a package is outside the rules. And no authority has ever examined the evidence and been persuaded, which is worth weighing against any confident sentence on a bottle.

Where to get it from food

The bottom line

You need 16 mg a day as a man and 14 as a woman, and an ordinary diet with meat, fish, nuts or fortified grain covers it. The upper limit of 35 mg exists because of flushing, not organ damage, and it applies to supplements rather than food. The part worth remembering is the trial result. Across 23 randomised trials in 39,195 people, nicotinic acid did not reduce deaths, heart attacks or strokes, and a separate meta-analysis of 35,760 patients found no protective effect in people who already had heart disease. Deficiency today is a marker of undernutrition rather than of a poor food supply. Two more things are worth carrying away. Niacin moves markers well and outcomes not at all. It lowers lipoprotein(a) by about 23 per cent across 14 trials, and it improves how well arteries widen by about two percentage points across seven. That vessel effect turned out to have no relation to how much HDL cholesterol changed, and HDL was the entire story the drug was sold on. Before statins existed, 11 trials did show a 25 per cent cut in major coronary events, and that history is why the reputation outlived the evidence. The one high dose with a hard result behind it is in skin rather than in hearts: in people who had already had two non-melanoma skin cancers, nicotinamide cut new ones by 23 per cent, and the benefit stopped with the tablets. Three things about the numbers on this page are worth adding. The 35 mg ceiling is built on skin flushing rather than on organ damage, it covers supplements rather than food, and Europe splits the same vitamin into two limits, 10 mg a day for nicotinic acid and 900 mg for nicotinamide. No harm has ever been documented from the niacin naturally present in food. Meanwhile the newer supplements sold on the NAD story have been tested: pooling every randomised trial of NMN, it looks safe over weeks to months and changed nothing about weight, blood sugar, blood fats or blood pressure.

Sources

1. nia-01 · Position of an expert body · expert body statement
   More than 400 enzymes require NAD to catalyze reactions in the body, which is more than for any other vitamin-derived coenzyme.
   NIH Office of Dietary Supplements, Niacin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
2. nia-02 · Position of an expert body · expert body statement
   19+ years: 16 mg NE male; 14 mg NE female (value from the source's table, not a sentence)
   NIH Office of Dietary Supplements, Niacin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
3. nia-c-03 · Position of an expert body · scoping review
   In general, it is assumed that 60 mg of tryptophan is needed for de novo synthesis of 1 mg of NAD. The conversion efficiency depends on tryptophan status rather than on niacin status...Thus, low tryptophan intake, deficient tryptophan transport (e.g. Hartnup´s disease) or conditions associated with increased tryptophan metabolism decrease the conversion and increase the need for preformed niacin. Furthermore, adequate intakes of the micronutrients needed as cofactors in the de novo pathway (iron, riboflavin, vitamin B6) are needed.
   Aakre & Meltzer, Food & Nutrition Research, 2023 (Nordic Nutrition Recommendations 2023) · checked 2026-09-21 · independently re-checked
4. nia-c-04 · Position of an expert body · agency fact sheet
   Turkey is an example of a food high in tryptophan; a 3-oz portion of turkey breast meat provides about 180 mg tryptophan, which could be equivalent to 3 mg niacin [9]. However, the efficiency of the conversion of tryptophan to NAD varies considerably in different people [3].
   Niacin, Fact Sheet for Health Professionals, NIH Office of Dietary Supplements (оновлено 2022-11-18) · checked 2026-09-21 · independently re-checked
5. nia-c-05 · Position of an expert body · scoping review of national dietary surveys
   The diet among adults (>18 years) in the Nordic countries provides 29–31 and 39–41 mg NE for women and men, respectively...The average protein intake in the Nordic countries of 92–112 and 72–81 g/day for men and women, respectively, and this would provide 12–19 mg NE/day (33).
   Aakre & Meltzer, Food & Nutrition Research, 2023 (Nordic Nutrition Recommendations 2023) · checked 2026-09-21 · independently re-checked
6. nia-04 · Position of an expert body · expert body statement
   People who do not consume enough riboflavin (vitamin B2), pyridoxine (vitamin B6), or iron convert less tryptophan to niacin because enzymes in the metabolic pathway for this conversion depend on these nutrients to function.
   NIH Office of Dietary Supplements, Niacin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
7. nia-c-01 · Position of an expert body · agency fact sheet
   Many animal-based foods—including poultry, beef, and fish—provide about 5–10 mg niacin per serving, primarily in the highly bioavailable forms of NAD and NADP [3]. Plant-based foods, such as nuts, legumes, and grains, provide about 2–5 mg niacin per serving, mainly as nicotinic acid. In some grain products, however, naturally present niacin is largely bound to polysaccharides and glycopeptides that make it only about 30% bioavailable [3,4].
   Niacin, Fact Sheet for Health Professionals, NIH Office of Dietary Supplements (оновлено 2022-11-18) · checked 2026-09-21 · independently re-checked
8. nia-c-02 · Position of an expert body · scoping review
   In plant products, especially in cereal grains, niacin is found mainly as nicotinic acid that is often bound to proteins, glycopeptides, or polysaccharides and is poorly available (20). Food processing (alkaline treatment) may increase the bioavailability of the nicotinic acid in cereals.
   Aakre & Meltzer, Food & Nutrition Research, 2023 (Nordic Nutrition Recommendations 2023) · checked 2026-09-21 · independently re-checked
9. nia-c-17 · Position of an expert body · scoping review
   The intestinal niacin transporters have not yet been fully clarified.
   Aakre & Meltzer, Food & Nutrition Research, 2023 (Nordic Nutrition Recommendations 2023) · checked 2026-09-21 · independently re-checked
10. nia-05 · Position of an expert body · expert body statement
    Severe niacin deficiency leads to pellagra, a disease characterized by a pigmented rash or brown discoloration on skin exposed to sunlight; the skin also develops a roughened, sunburned-like appearance
    NIH Office of Dietary Supplements, Niacin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
11. nia-t3 · Observational data · systematic review of case reports and case series
    The search identified 918 studies, of which 133 met the inclusion criteria, comprising 1212 pellagra cases. Cutaneous manifestations were the most common (98.63%), followed by gastrointestinal (59.4%) and neurological (54.2%) signs.
    Int J Dermatol, 2026 · checked 2026-09-17 · independently re-checked
12. nia-t4 · Observational data · systematic review of case reports and case series
    Complete symptom resolution occurred on average within 27.42 days of vitamin B3 supplementation.
    Int J Dermatol, 2026 · checked 2026-09-17 · independently re-checked
13. nia-c-08 · Position of an expert body · scoping review
    The body has a limited capacity for storing niacin nucleotides and deficiency symptoms can occur after 50–60 days of consuming a low-niacin, corn-based diet (26).
    Aakre & Meltzer, Food & Nutrition Research, 2023 (Nordic Nutrition Recommendations 2023) · checked 2026-09-21 · independently re-checked
14. nia-06 · Position of an expert body · expert body statement
    People who are undernourished because they live in poverty or have anorexia, alcohol use disorder, AIDS, inflammatory bowel disease, or liver cirrhosis often have inadequate intakes of niacin and other nutrients
    NIH Office of Dietary Supplements, Niacin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
15. nia-t5 · Observational data · systematic review of case reports and case series
    Dietary deficiency remained the predominant cause of pellagra (85%), and it was particularly common in populations affected by food insecurity or humanitarian crises, accounting for 93% of cases. Alcohol misuse was reported in 9.6% of cases. Isoniazid was the leading drug-related cause (14.3%).
    Int J Dermatol, 2026 · checked 2026-09-17 · independently re-checked
16. nia-08 · Meta-analysis or systematic review · review of trials cited by expert body
    Overall, use of nicotinic acid did not reduce overall mortality or cardiovascular mortality rates or the number of fatal or nonfatal myocardial infarctions or strokes
    NIH Office of Dietary Supplements, Niacin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
17. nia-t1 · Meta-analysis or systematic review · systematic review and meta-analysis of randomised trials
    The meta-analysis included 35 760 patients with histories of cardiovascular disease or dyslipidemia. Cumulative evidence found no preventive association of niacin with cardiovascular outcomes in secondary prevention.
    Schandelmaier et al., JAMA Network Open, 2019 · checked 2026-09-16 · independently re-checked
18. nia-t6 · Observational data · systematic review and meta-analysis of case-control studies
    The meta-analysis showed that expectant mothers with an insufficient niacin intake were significantly more likely to have babies with congenital abnormalities (odds ratio 1.13, 95% confidence interval 1.02-1.24) compared to mothers with adequate niacin intake. A similar association between niacin deficiency and congenital anomalies was observed (OR 1.15, 95% CI 1.03-1.26) when sensitivity analysis was conducted by quality of the included studies.
    Eur J Nutr, 2022 · checked 2026-09-17 · independently re-checked
19. nia-r5-1 · Randomised controlled trial(s) · randomised controlled trial
    At 12 months, the rate of new nonmelanoma skin cancers was lower by 23% (95% confidence interval [CI], 4 to 38) in the nicotinamide group than in the placebo group (P=0.02). Similar differences were found between the nicotinamide group and the placebo group with respect to new basal-cell carcinomas (20% [95% CI, -6 to 39] lower rate with nicotinamide, P=0.12) and new squamous-cell carcinomas (30% [95% CI, 0 to 51] lower rate, P=0.05).
    Chen et al., New England Journal of Medicine, 2015 · checked 2026-09-17 · independently re-checked
20. nia-r5-3 · Meta-analysis or systematic review · meta-analysis of randomised controlled trials
    Meta-analysis suggested a significant reduction of Lp(a) levels following ER niacin treatment (weighted mean difference - WMD: -22.90%, 95% CI: -27.32, -18.48, p<0.001)...When the studies were categorized according to the administered dose, there was a comparable effect between the subsets of studies with administered doses of <2000mg/day (WMD: -21.85%, 95% CI: -30.61, -13.10, p<0.001)
    Sahebkar et al., Metabolism, 2016 · checked 2026-09-17 · independently re-checked
21. nia-r5-4 · Meta-analysis or systematic review · meta-analysis of randomised controlled trials
    In primary analysis, niacin significantly reduced major coronary events (relative odds reduction=25%, 95% CI 13, 35), stroke (26%, 95% CI=8, 41) and any cardiovascular events (27%, 95% CI=15, 37). Except for stroke, the pooled between-group difference remained significant in sensitivity analysis excluding the largest trial.
    Bruckert et al., Atherosclerosis, 2010 · checked 2026-09-17 · independently re-checked
22. nia-r5-5 · Meta-analysis or systematic review · meta-analysis of randomised controlled trials
    Niacin therapy significantly improved FMD (WMD: 1.98%; 95% CI: 0.91-3.05%; p = 0.0003) and this effect was robust in the sensitivity analysis...Meta-regression indicated no association between niacin-induced changes in FMD and changes in plasma HDL-cholesterol, low-density lipoprotein-cholesterol or triglycerides.
    Sahebkar, Vascular Medicine, 2014 · checked 2026-09-17 · independently re-checked
23. nia-c-06 · Randomised controlled trial(s) · randomised controlled trial
    Conversely, neither ADP-stimulated [INT, 82.1 ± 19.0 compared with CON, 84.0 ± 19.2; P = 0.716] nor maximally uncoupled mitochondrial respiration [INT, 103.4 ± 30.7 compared with CON, 108.7 ± 33.4; P = 0.495] improved under NAD+-precursor supplementation, nor did net exercise efficiency during the submaximal cycling test [INT, 20.2 ± 2.77 compared with CON, 20.8 ± 2.88; P = 0.342].
    Remie et al., The Journal of Nutrition, 2021 · checked 2026-09-21 · independently re-checked
24. nia-c-07 · Meta-analysis or systematic review · meta-analysis of randomised controlled trials
    Fifteen trials were included, with 10 contributing to safety analyses. NMN doses ranged from 250-2000 mg/day, and durations ranged from 14 days to 24 weeks. NMN did not increase overall, serious, withdrawal-related, or system-specific adverse events, nor did it significantly elevate ALT or AST. No significant effects were observed on body weight, BMI, fasting glucose, HbA1c, lipid profiles, or systolic blood pressure.
    Nutrients, 2026 · checked 2026-09-21 · independently re-checked
25. nia-c-14 · Randomised controlled trial(s) · randomised controlled trial
    Pharmacokinetics demonstrated an intermediate release and absorption rate for WMER over 6 hours and IHN showed no evidence of bioavailability.
    Keenan, Journal of Clinical Lipidology, 2013 · checked 2026-09-21 · independently re-checked
26. nia-c-15 · Randomised controlled trial(s) · randomised controlled trial (secondary analysis)
    The proportion of human-milk total vitamin B-3 concentrations below the lower reference limit increased over time in both those without and with nicotinamide supplementation (2.9% compared with 0.5% ≤0.720 mg/L at 1 mo; 28.8% compared with 9.9% ≤0.549 mg/L at 5 mo)...No associations were observed between human-milk total vitamin B-3 or vitamer concentrations and child weight, height, or head circumference ≤18 mo or with MDAT scores at 18 mo.
    American Journal of Clinical Nutrition, 2026 · checked 2026-09-21 · independently re-checked
27. nia-c-16 · Observational data · prospective cohort study with metabolomics and mendelian analyses
    For the present studies, in the US Validation Cohort, subjects with evidence of (prescriptive) niacin use at time of enrollment or within the preceding 30 days were excluded.
    Ferrell et al., Nature Medicine, 2024 · checked 2026-09-21 · independently re-checked
28. nia-c-18 · Position of an expert body · federal regulation
    No expressed or implied health claim may be made on the label or in labeling for a food, regardless of whether the food is in conventional food form or dietary supplement form, unless:
    21 CFR 101.14, Health claims: general requirements, пункт (e) Prohibited health claims · checked 2026-09-21 · independently re-checked
29. nia-c-19 · Position of an expert body · scoping review
    The focus of interest for niacin over the last decade has primarily been on pharmacological doses of nicotinic acid as a lipid-lowering agent and other NAD precursors as potential enhancers of cellular NAD+ concentrations. None of these studies, however, makes a useful contribution to understanding dietary requirements in healthy populations.
    Aakre & Meltzer, Food & Nutrition Research, 2023 (Nordic Nutrition Recommendations 2023) · checked 2026-09-21 · independently re-checked
30. nia-03 · Position of an expert body · expert body statement
    35 mg for adults age 19+ years. The FNB acknowledges that although excess nicotinamide does not cause flushing, a UL for nicotinic acid based on flushing can prevent the potential adverse effects of nicotinamide.
    NIH Office of Dietary Supplements, Niacin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
31. nia-t2 · Meta-analysis or systematic review · systematic review and meta-analysis
    In healthy individuals treated with nicotinic acid alone, major adverse effects occurred at doses below 1000 mg/d.
    Guyton et al., Nutrition Reviews, 2017 · checked 2026-09-16 · independently re-checked
32. nia-r5-2 · Meta-analysis or systematic review · meta-analysis of randomised controlled trials
    The estimated pooled mean changes (95% confidence interval) with niacin were 0.27 (95% CI: 0.24 to 0.30; P < 0.001) mmol/L for HDL-c, -0.250 (95% CI: -0.47 to -0.03; P < 0.05) mmol/L for LDL-c and -0.39 (95% CI: -0.43 to -0.34; P < 0.001) mmol/L for TG compared with controls...Subgroup analyses revealed a significant increase in FPG 0.085 (95% CI: 0.029 to 0.141; P < 0.05) mmol/L compared with controls in patients with long term treatment.
    Ding et al., Clinical Nutrition, 2015 · checked 2026-09-17 · independently re-checked
33. nia-c-09 · Position of an expert body · scoping review
    There are no studies indicating adverse effects of consumption of naturally occurring niacin in foods. However, adverse effects may result from excess intakes from dietary supplements, fortified foods, and pharmacological agents. Intakes of nicotinic acid, but not nicotinamide, as a supplement or fortificant in the range of 30 mg/d to 1000 mg/d can result in mild symptoms such as flushing.
    Aakre & Meltzer, Food & Nutrition Research, 2023 (Nordic Nutrition Recommendations 2023) · checked 2026-09-21 · independently re-checked
34. nia-c-10 · Position of an expert body · agency position reported in a scoping review
    The EU Scientific Committee for Food (28) has set an upper limit for nicotinic acid of 10 mg/d and for nicotinamide of 900 mg/d for adults.
    Aakre & Meltzer, Food & Nutrition Research, 2023 (Nordic Nutrition Recommendations 2023) · checked 2026-09-21 · independently re-checked
35. nia-c-11 · Position of an expert body · agency fact sheet
    The FNB has established ULs for niacin that apply only to supplemental niacin for healthy infants, children, and adults [2]. These ULs are based on the levels associated with skin flushing.
    Niacin, Fact Sheet for Health Professionals, NIH Office of Dietary Supplements (оновлено 2022-11-18) · checked 2026-09-21 · independently re-checked
36. nia-c-12 · Position of an expert body · overview of systematic reviews
    (2) Oral NAM is associated with a lower incidence of AEs than niacin. (3) AEs are more common with higher doses of oral NAM/niacin, and limits tolerability depending on co-morbid status (e.g.: renal dysfunction).
    Eye (London), 2025 · checked 2026-09-21 · independently re-checked
37. nia-07 · Position of an expert body · expert body statement
    Isoniazid and pyrazinamide (together in Rifater), used to treat tuberculosis, are structural analogs of niacin and interrupt the production of niacin from tryptophan by competing with a vitamin B6-dependent enzyme required for this process
    NIH Office of Dietary Supplements, Niacin - Health Professional Fact Sheet · checked 2026-09-16 · extracted
38. nia-c-13 · Position of an expert body · approved drug label
    Niacin Clinical Impact: Cases of myopathy and rhabdomyolysis have been observed with concomitant use of lipid modifying dosages of niacin ( > 1 gram/day niacin) with atorvastatin.
    Atorvastatin calcium, затверджена інструкція FDA, розділ Drug Interactions, чинна з 2025-08-28 · checked 2026-09-21 · independently re-checked