There are various forms of niacin out there, a few are nicotinic acid (NA), nicotinamide/niacinamide (NAM), nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR). Nicotinic acid has a few side effects, such as flushing, nausea, fainting and can even cause insulin resistance and liver toxicity and exacerbate peptic ulcer disease, which NAM doesn’t have. (1, 2) B3 are a precursor to nicotinamide adenine dinucleotide (NAD), which is important in the catabolism of fat, carbohydrate, protein, and alcohol, as well as cell signaling and DNA repair, and NADP mostly in anabolism reactions such as fatty acid and cholesterol synthesis. High energy requirements (brain) or high turnover rate (gut, skin) organs are usually the most susceptible to their deficiency. 

NAD is involved in many oxidative reactions, antioxidant protection, DNA metabolism and repair, anti-inflammatory, (3, 4) improves insulin sensitivity, reduce adipocyte size (5).

The flush comes from the generation of prostaglandins from arachidonic acid, which is released from cell membranes after NA ingestion. (6) This flush can be countered by taking an aspirin before taking NA, or by taking NA with a meal or taking NA with omega 3 fish oils. I personally would not take the flush version as it also increases serotonin, and taking a serotonin antagonist, such as cyproheptadine, blocks that effect. (7)

Although NA is very effective at treating hyperlipidemias, high cholesterol and triglycerides, with NAM only being able to lower LDL and increase HDL, without affecting TG.  (8)

So why would a natural bodybuilder be interested in such a substance?

Niacinamide Improves metabolic efficiency & thyroid function

Niacin (all forms) increases cellular NAD+ which used for oxidative metabolism in producing energy.  A deficiency in NAD+ results in a slow metabolism, low energy, cold intolerance, low androgen production, etc…

NAD+ is a cofactor in various enzymes in the Kreb cycle as well as during glycolysis and beta-oxidation. Without it your body cannot convert nutrients to energy and oxidative phosphorylation is slowed significantly. And without B3, your body can’t even make new mitochondria, leaving you to cope with old, damaged mitochondria and low energy. (9)

Niacinamide decreases parathyroid hormone (PTH) and thus increases metabolism by increasing thyroid. (10) High prolactin can increase serum calcium, and high prolactin can be the cause of elevated TSH and also low ATP production.

Niacinamide boosts exercise-induced Growth hormone release

The same increase in GH and decrease in exercise performance is found when taking B3 before repeated sprints. (13)

A mixture of glycine, glutamine, and niacin increase growth hormone by 70% in the elderly at rest (14). All three these ingredients are known to increase GH, so we do not know to what extent niacin contributed.

However, this anti-lipolysis of niacin and can prevent fat loss when not coupled with exercise (15). During fat-loss, it’s rather advised to take 50-100mg a few times a day, and preferably stay under 500mg daily. However, some people are really sensitive to this effect and need to eliminate all niacin supplementation for fat-loss to happen.

Niacinamide lowers cortisol

NAM is a perfect anti-cortisol compound since it may be capable of inhibiting 11b-HSD1 and enhancing 11b-HSD2, which inhibits cortisol synthesis and enhances its de-activation, respectively. (16)

Also, only NAM lowers cortisol whereas NA can actually increase it. (17).

Niacinamide Boosts brain capacity

NAM has tranquilizing and nootropic properties. A B3 deficiency delays brain development (18, 19) and supplementation thereof has been found to increase brain-derived neurotrophic factor (BDNF). (20) Niacinamide is also a very powerful neuroprotectant, and protects dopaminergic neurons from neurotoxicity, thus preventing a drop in dopamine levels.

Due to it’s tranquilizing property, NAM is anxiolytic (probably to lowering serotonin) effect, and also increases aggressive reaction threshold. (21) This will just help you to stay cool-headed, and it will not make you a submissive person.

The inhibition of MAO (a enzyme that breaks down monoamines) and COMT (degrades catecholamines, such as adrenaline and noradrenaline) will enable you to stay focused and motivated on a task for a longer period of time. However this can have its downfall as well. That ‘task’ can be a depressive thought, which can make you dwell on it for longer than you should. Low COMT activity could ‘enhance’ any activity/thought you are doing/having which could be both good and bad. However, chronic undermethylation could make you crash after a while. For e.g. concentrating/focusing on one task for long can be very draining.

Also, this undermethylated state of neurotransmitters can also lead to elevated serotonin (if you are serotonin dominant) and histamine.

However, in this study, they found that niacinamide (and not any other form) was able to inhibit serotonin. 93mg/kg is needed to completely inhibit it and 57mg/kg is used for moderate inhibition. (31)

Niacinamide is used to treat arthritis & joint problems

Orally in amounts from 900 to 4000 mg per day in divided doses, it improved joint function (increasing joint mobility and decreasing joint stiffness, swelling, deformity and pain (23).

Nicotinic acid shares with salicylates and benzoates the ability to combine with glycine, however (23) NAM can doesn’t.

A daily dosage of about 1g per 50 lb. body weight is necessary. Any trial should run for at least one month. (23)

Niacinamide lowers estrogen and boosts DHT

Niacinamide is anti-estrogenic by decreasing estrogen receptors by blocking SIRT1, (24) and by the same mechanism increases androgen receptor expression and enhances DHTs’ function (25).

NADPH (of which B3 is a precursor) is also a co-factor in various androgenic enzymes, such as the conversion of testosterone to DHT via 5 alpha reductase.

Niacinamide increases vasodilation and improves circulation

NAD is also a co-factor in the enzymes dihydrofolate reductase in the folate/tetrahydrobiopterin cycles, which aid in the production of BH4. BH4 is then used in the synthesis of catecholamines, such as dopamine and serotonin.

BH4 is also involved in the synthesis of NO with arginine, which is vitamin B2 and B3 dependent. Increase nitric oxide synthesis leads to vasodilation.

Take note

Niacin (all forms) deplete methyl donors, such as SAM. This leads to low methionine, a build-up of homocysteine (if B6 is deficient), fatty liver, DNA single-strand breaks, and depressed creatine synthesis. Although niacin depletes methyl donors, niacin is still used in methylation, by converting S-adenosylhomocysteine hydrolase (SAH) to homocysteine in the methionine cycle and also in the conversion of folate to its tetrahydrofolate (THF) derivative in the folate cycle (26).

One way to overcome this when using high dose niacin, would be to use a lipotropic (to prevent fatty liver) and a methyl donor or other nutrient to prevent homocysteine build-up.

Choline, amino acids (methionine, threonine, cysteine, etc) and inositol are all good lipotropics.

It would be better to use betaine as a methyl donor, rather than choline itself, as the enzyme activity that converts choline to betaine, choline oxidase, is very low. (1) However, choline is a better lipotropic than betaine, by 30%. I advise using at least a ratio of 1:1 of betaine to niacinamide.

Vitamin B6 can prevent homocysteine build-up by activating enzymes to convert it to cysteine, taurine, and glutathione.

Important Extras

a) Topical niacinamide reduces fine lines and wrinkles, hyperpigmented spots, red blotchiness, and skin sallowness (yellowing). In addition, it increases elasticity (as measured via cytometry) (27) and reduces skin sebum. (28)

b) It’s quite good at reducing/preventing migraines at doses of 500mg. (29)

c) A slightly better NAD booster than niacinamide is niacinamide riboside, which is more potent than niacinamide or nicotinic acid itself. NR also causes flushing, inhibits of lipolysis and has anti-atherosclerosis activity. (30) However, it doesn’t share the same anti-estrogen and anti-cortisol benefits of NAM.

d) NR supplementation increases SIRT1, which increase anti-oxidant enzymes such as Catalase, Sod1 and Sod2, which quench up free radicals. (31, 30) This probably happens because SIRT1 inhibits uncoupling, and now the body has to increase other pathways to eliminate oxidants.

e) SIRT1 is negatively associated with UCP2, thus blocking SIRT1 would increase thermogenesis through uncoupling, at which NAM is very effective at doing. (30)

f) NR increases energy expenditure and thermogenesis, but increasing mitochondrial enzymes that metabolize fuel, thus increasing mitochondrial efficiency. (30)

g)  Niacinamide function as an antioxidant, which consists of both scavenging of lipid peroxides and NAD biosynthesis that leads to activation and normalization of altered energy and lipid metabolism. (32)

Conclusion & supplements

Niacin is very much needed by the body and its requirements are increased for active individuals. B vitamins, in general, are very much needed to utilize and burn fat/energy.

I suggest starting at 50-100mg a few times daily with meals, in the form of a good B-complex. If you want to use NR, you can use a smaller dose and stick to 50mg daily, however, up to 1g plus daily is also well tolerated.

For improving blood lipids, try 1g+ daily with inositol and good quality protein.

For increased growth hormone release during a workout, take 100-500mg pre-workout.

I personally prefer to use niacinamide for my B3, as niacinamide is the only form that inhibits SIRT1, lowers estrogen, increases androgen receptors and also to lowers cortisol.

• IdealabsDC Energin – 100mg niacinamide per serving, 30 servings. Contains only 99.9% purity ingredients and no other ingredient than listed. Also contains 50mg B1 (Thiamine HCL), 15mg B2 (R5P), 6mg B6 (P5P), 1mg Biotin. Absorption is 89-90% when applied topically
• Thorne Niacinamide – 500mg per serving, 180 servings