Why Niacin?

Niacin (aka Vitamin B3) is crucial to health and immunity. This site aggregates and summarizes research on niacin, its receptor GPR109A and related substances like NAD+, glutamine, melatonin and butyrate.

Studies on Niacin and Related Substances

Dietary nicotinic acid supplementation improves hepatic zinc uptake and offers hepatoprotection against oxidative damage

In rats, supplementing with high levels of nicotinic acid in diet before experiencing cell damage (induced by tert-butyl hydroperoxide injections) helped protect the liver, preserving its normal structure and improving its ability to absorb zinc, a beneficial element. This effect was less pronounced if the NA was increased after the cell damage had occurred. Rats with a deficiency of nicotinic acid in their diet exhibited the highest level of liver damage.

Iron deficiency reduces the efficacy of tryptophan as a niacin precursor

Iron deficiency impairs body converting tryptophan to niacin. Chicks fed the iron-deficient diets had markedly lower hemoglobin concentrations than those fed the iron-adequate diets. Regardless of iron level, chicks had linear growth responses to either nicotinic acid or tryptophan supplementation. Low bio-available iron contributes to niacin deficiency in populations.

Niacin ameliorates ulcerative colitis via prostaglandin D2‐mediated D prostanoid receptor 1 activation

Out of 26 patients with moderate ulcerative colitis (inflammation of the colon) who were unresponsive to conventional treatments, 92.3% responded positively and 88.5% went into remission after receiving a daily niacin enema treatment for 6 weeks. The had no serious side effects, showed notable improvements in intestinal healing, reduced symptoms like rectal bleeding and stool frequency. Niacin is a promising, well-tolerated alternative for inducing clinical remission of ulcerative colitis.

Studies on Tryptophan-Niacin Metabolism in Streptozotocin Diabetic Rats

Rats where split into 2 groups, one group was injected with a single does of streptozotocin at a dose of 60 mg/kg body weight, which is a chemical that is used to induce diabetes. After 12 weeks it was found that the diabetes group was only able to convert half as much tryptophan to niacins as the control group. The rats in the diabetic group had twice the excretion of xanthurenic acid in their urine. Xanthurenic acid is a waste product that is produced when tryptophan is not converted into niacin.

Effects of Niacin and Vitamin C on Blood Sugar

Rats in group 1 received no treatment. Rats in group 2 received daily 100 mg/kg body weight niacin injections. Rats in group 3 received daily 50 mg/kg body weight vitamin C injections. Rats in group 4 received both niacin and vitamin C injections. Blood sugar levels were measured before and after treatment. The results showed that niacin and vitamin C both lowered blood sugar levels in normal rats. Niacin was more effective than vitamin C in lowering blood sugar levels in diabetic rats. The combination of niacin and vitamin C was the most effective in lowering blood sugar levels in diabetic rats.

Intravenous Niacin Acutely Improves the Efficiency of Dietary Fat Storage in Lean and Obese Humans

24 healthy men and women with a mean age of 35 years, where injected Intravenously w/ 1g of niacin or placebo for 2 weeks. The niacin group ended up with acutely lower levels of FFAs (free fatty acids, fats floating around in the bloodstream) and significantly higher levels of triglyceride stored in visceral adipose tissue. This may help to reduce the amount of fat that is stored in the liver and other organs, which can help to improve insulin sensitivity and reduce the risk of metabolic complications. IE niacin may help people with diabetes and obesity to lose weight and improve their health.

Supplementation of nicotinic acid and its derivatives up-regulates cellular NAD+ level rather than nicotinamide derivatives in cultured normal human epidermal keratinocytes

In cultured skin cells, nicotinic acid supplementation 1.3-fold up-regulated intracellular NAD+ level significantly and its metabolites nicotinic acid mono nucleotide also increased NAD+ level by 1.5-fold with 100 μM application. Surprisingly, NAM and its derivatives could not up-regulate cellular NAD+ levels in keratinocytes.

Acne Vulgaris Is a Special Clinical Type of Pellagra

People with acne often have abnormal lipid profiles and elevated oily secretion on their skin. Foam cells are an important pathological change in acne lesions. Acne is not a skin disease induced by infection, because no bacteria, fungi or parasites can be seen in early phase of acne lesion. The foam cells in acne lesions are white blood cells that have ingested large amounts of lipids. Niacin is the only vitamin that promotes the ability of HDL to scoop up cholesterol particles from plaques in the heart's blood vessels and move those particles to the liver for disposal, which prevents foam cell formation. Foam cells in acne lesions suggest that patients with acne are deficient in niacin and that acne can be considered a type of pellagra (niacin deficiency).

Deficiency of metabolite sensing receptor HCA2 impairs the salutary effect of niacin in hemorrhagic shock

Niacin improves organ function and survival following hemorrhagic shock. Rats and mice where bled 60% of their blood volume, and replaced with Ringers lactate solution to induce hemorrhagic shock ( deprive tissue of oxygen and blood ). After 10 minutes of shock the animals where split into 3 groups and injected with nicotinic acid, NMN or DMSO, at 3 levels of dosing. Niacin at 10mg/kg, which was the highest dose given, had by far the best level of survivability. Rats, given NMN even at a 5x higher dose than niacin at 50mg/kg did not achieve a survival rate to the level observed in the 10mg/kg or the even 5mg/kg treated mice. Use of GPR109A knockout mice confirmed that the niacin GPR109A receptor plays a major role in the survivability enhancing effect of niacin.

A comparison of the efficacy and toxic effects of sustained vs immediate-release niacin in hypercholesterolemic patients

The effects on cholesterol of modified "sustained release" niacin was compared to immediate release niacin (aka nicotinic acid) and showed that sustained release tends to lower LDL more, while immediate release raises HDL more at all dosage levels. The key takeway though is that 52% of the patients taking sustained release developed signs of liver toxixity, while 0% of the ones taking immediate release did.

Plasma acetylcholine and nicotinic acid are correlated with focused preference for photographed females in depressed males: an economic game study

This study showed depressed males have a narrower preference for female photographs (only preferring good looking ones) which is a marker for lower cognitive flexibility. The less nicotinic acid in their body, the narrower their preference. This indicates nicotinic acid may regulate human social decision-making (especially preference-related behaviors) by acting on the HCAR2 in microglia (the resident immune cells of the brain and spinal cord which constantly patrol the cerebral microenvironment to respond to pathogens and damage).

Politics and Pellagra: The Epidemic of Pellagra in the U.S. in the Early Twentieth Century

The 1906 to 1940 epidemic of pellagra was around 3 million cases, with 1 in 30 resulting in death. A Dr Goldberger was appointed to study the cause. Even though correctly identified the root cause as a nutritional deficiency (later to be confirmed as niacin specifically) his prognosis was rejected by politicians in affected regions since they basically didn't want to admit that a diet consisting of largely degerminated cornmeal (which was a key economic export) was not appropriate for human wellbeing. The invention of degerminating corn, which removes nutrients but prolongs shelf-life, coincided with the appearance of the disease. Goldberger would cure orphans suffering from pellagra by feeding them a more varied diet including fresh milk and meat.

Niacin reduces abdominal fat: pilot study

Participants in an open label study at Kaiser Permanente in San Francisco supplemented ~3g niacin a day. After about 1 year, 81% of patients had an by an average reduction of 27% in intra-abdominal fat. The degree of fat loss was associated with the degree of increase in HDL cholesterol and a reduced Total Cholesterol/HDL cholesterol ratio.

NAD+ homeostasis in human health and disease

In depth review of NAD+, how its made in the human body, how it becomes deficient, and how its deficiency is a causal factor of a wide range of diseases. And how boosting NAD+ via enhancing agents like niacin ( especially niacin since it is the primary, so called Preiss–Handler pathway of manufacture ) can help cure a wide range of diseases.

Treatment of Asthma by Nicotinic Acid

Relief of the asthma attacks was obtained in 21 out of 30 cases with niacin either via intravenous injection (16 out of 21 patients relieved) or orally (5 out of 9 patients relieved). A series of 50 or 100 mg doses used. Relapse was common once niacin was discontinued.

Nicotinic acid inhibits glioma invasion by facilitating Snail1 degradation

This study grafted malignant gliomas cells (which are one of the most common types of primary brain tumors) into rat brains to see if nicotinic acid administration would help regulate the implanted tumor. ~70% of the allografted rats that were continuously administered with nicotinic acid were still alive on day 58. 100% of control group died by day 24. Biopsy showed much less tumor spread in nicotinic acid rats. Their results suggest that niacin the helps prevent the invasion of other kinds of malignant cells such as melanoma ( skin cancer ) cells and that this points to a general role of nicotinic acid in regulating tumor invasion.

Antiatherothrombotic effects of nicotinic acid

Niacin reduces blood viscosity through a variety of mechanisms, thus improving blood flow and perfusion through choke points of the vasculature. Finally, niacin has cardioprotective effects that may limit ischemia–reperfusion injury. By preserving glycolysis during periods of inadequate blood supply and improving blood flow to the heart after a stroke, niacin can improve the functional recovery of the muscular tissue of the heart.

Leucine-nicotinic acid synergy stimulates AMPK/Sirt1 signaling and regulates lipid metabolism and lifespan in Caenorhabditis elegans, and hyperlipidemia and atherosclerosis in mice

Low dose niacin (50 mg/kg diet and 250 mg/kg diet) when supplemented in combination with leucine (24 g/kg diet) has a similar effect on lowering cholesterol in mice than standard therapeutic dose (1000 mg/kg diet) of niacin without leucine supplementation. Leucine amplifies niacin effect on lipid metabolism, hyperlipidemia and atherosclerosis in mice, at least in part by activation of the AMPK/Sirt1 axis.

Curcumin Nicotinate Selectively Induces Cancer Cell Apoptosis and Cycle Arrest through a P53-Mediated Mechanism

Curcumin is an anticancer agent, it has demonstrates potent anti-proliferative activity in a wide range of cancer cells, including liver, breast, lung, stomach, colon, prostate, head and neck cancers. This study modified curcumin by adding 2 niacins molecules to it to make Curcumin Nicotinate. They tested it out on some cancer cell cultures and it showed that the Curcumin Nicotinate improved the anti cancer effect of curcumin by improving its cell selectivity.

Niacin protects against UVB radiation-induced apoptosis in cultured human skin keratinocytes

Niacin pretreatment of skin cells protects against UV-induced cell death and apoptosis by enhancing the pro-survival pathways including AKT, mTOR and S6 in skin keratinocytes. Oral and external niacin is safe and appears to be a promising chemo-preventive supplement for reducing the mutagenic, immunosuppressive and cell damage effects of sunlight. This is also the first study providing a molecular mechanism to support that niacin can be utilized as a skin photo-damage protective agent.

Activation of Gpr109a, Receptor for Niacin and the Commensal Metabolite Butyrate, Suppresses Colonic Inflammation and Carcinogenesis

GPR109A expressed in immune cells as well as in colonic tissue is necessary for protection against colitis and colon carcinogenesis. Niacin suppresses colitis and colon cancer in a GPR109A-dependent manner. GPR109A is key in mediating the beneficial effects of gut microbiota and dietary fiber in colon. Niacin suppresses atherosclerosis by activating GPR109A in immune cells. GPR109A mediates butyrate effects in colon and is a critical molecular link between colonic bacteria and dietary fiber and the host.

Intestinal Flora as a Potential Strategy to Fight SARS-CoV-2 Infection

Many microbial metabolites, especially butyrate, found in the intestinal flora, are extremely important in regulating systemic and pulmonary immune and inflammatory responses and have a wide range of anti-inflammatory and immunity enhancing functions. Improving intestinal micro-ecology via like butyrate supplementation may partially mediate the effects of SARS-CoV-2 on the both local gastrointestinal response and systemic immune response of the host, and thus be a target for COVID-19 prevention and treatment.

Melatonin supplementation ameliorates myocardial connexin-43 disorders and arrhythmia risk of hypertensive and obese rats

Melatonin supplementation benefits male hypertensive and female obese rats due to suppression of metabolic disorders and lethal arrhythmia risk. Arrhythmia is a problem with the rate or rhythm of your heartbeat. Protection against arrhythmia may attributed, at least in part, to up-regulation of myocardial Cx43, which is a protein that is essential for the formation of heart structures.

The Effect of Melatonin on Thrombosis, Sepsis and Mortality Rate in COVID-19 Patients

Single-center, open-label, randomized clinical trial done on Covid patients in Iraq to study melatonin supplementation for Covid treatment. All 158 patients got standard care, 82 of those patients ate 10mg melatonin each night. Thrombosis and sepsis developed significantly less in melatonin group. 13 patients in control group died vs 1 person in the melatonin group.

Niacin Reverses Migratory Macrophage Foam Cell Arrest Mediated by oxLDL In Vitro

Oxidized Low Density Cholesterol, oxLDL induced inhibition of macrophage migration may be reversed by Niacin, which explains part of Niacin's atheroprotective effects on cardiovascular disease independent of its effects on plasma lipids. Macrophage foam cells are a type of macrophage that localize to fatty deposits on blood vessel walls. Niacin also inhibited the formation of peroxynitrite (which is a powerful oxidant exhibiting a wide array of tissue damaging effects)

TRPV4 Stimulation Induced Melatonin Secretion by Increasing Arylalkymine N-acetyltransferase (AANAT) Protein Level

The role of TRPV4 channel present in human ciliary body epithelial cells in AANAT production was studied. AANAT, Aralkylamine N-acetyltransferase seems to be the key enzyme involved in producing melatonin from serotonin. In rodents, transcriptional activation of aanat gene is the classical mechanism to induce melatonin biosynthesis. TRPV4 is present in the human ciliary body and ciliary body epithelial cells. Activating TRPV4 channel increases the expression of AANAT, which elevates the concentration of NAS and melatonin

Nicotinic Acid is a Common Regulator of Heat-Sensing TRPV1-4 Ion Channels

NA activates the capsaicin receptor TRPV1 by lowering the activation threshold for heat, causing channel activation at physiological body temperature. Conversely it inhibits TRPV4 by raising activation temp to above body temp, ~41 celsius. Overall, the effects on TRPV1 and TRPV3 are potentiating while those on TRPV2 and TRPV4 are inhibitory. Little is known about the detailed structures of TRPV2-4. The TRPV receptors play a role in the flushing response.

Anti-inflammatory effects of nicotinic acid

Niacin has multi-faceted anti inflammatory properties that act in both localized and systemic ways. A major area of its activity is in tissue related to fat storage via the GPR109A receptor. Dosing cells with TNF-alpha ( an inflammatory substance ) showed that niacin treated cells increased the atheroprotective hormone adiponectin and reduced macrophage chemotaxis

Oral niacin prevents photocarcinogenesis and photoimmunosuppression in mice

Mice subjected to high dose ultraviolet light for about 6 months while fed a diet supplemented with 0%, 0.1%, 0.5%, or 1.0% (by dry weight of feed) of niacin showed 68%, 60%, 48%, and 28% rates of skin cancer respectively, indicating a protective effect. Elevated levels of NAD found in niacin supplemented mice. NAD modulates the function of DNA strand scission surveillance proteins p53 and poly(ADP-ribose) polymerase, two proteins critical in cellular responses to UV-induced DNA damage.

Melatonin: Regulation of Biomolecular Condensates in Neurodegenerative Disorders

Melatonin plays a key role in intracellular membrane integrity, especially when a cell is in under stress. Melatonin plays role in maintaining a high ATP:ADP ratio, which suppresses glycolysis. Supplemental melatonin shown to accumulate in all cells, accumulates 10x in membrane compared to mitochondria. Plays unique role in fat/water interfaces, as it can combine with both. Biomolecular condensates play a big role in brain disorders and are shaped by complex relationships between membraneless organelles, membranes/lipid rafts, ATP, RNA, and most of all, stress. Melatonin’s intimate association with each of these decisive influencers may position it as an important mediator of sorting out of these condensates in health and disease via ATP-dependent mechanisms.

Physiological and Anti-obesity Effects of Melatonin and Niacin Supplements in Rat Models

Rats where given unlimited access to food and a controlled amount of exercise. Those taking niacin + melatonin lost statistically significantly more weight, compared to control, niacin only and melatonin only groups. Suggests a synergy between niacin & melatonin supplementation for anti-obesity. It's noted that mice lacking the niacin receptor GPR109A had progressive weight gain and liver fat accumulation.

The COVID-19 Burden or Tryptophan Syndrome: Autoimmunity, Immunoparalysis and Tolerance in a Tumorigenic Environment

Long covid is due to changes in the metabolism of tryptophan and the lack of niacin (NAD/NADH+). Tryptophan has its metabolism altered by the lack of intestinal absorption due to internalization of ACE-2 and hypoxemia and inflammation, diverting its products to the formation of toxic Kynurenine metabolites. The longer time under hypoxemia, the less niacin and the more tryptophan will deviate to Kynurenine in an inflamed environment

Melatonin in Mitochondria: Mitigating Clear and Present Dangers

It's inferred that the majority of melatonin is created inside the mitochondria, independent of the pineal daylight associated melatonin. Melatonin has a 3 billion year history of use inside cells as a highly efficient anti-oxidant. It functions as an anti-oxidant for both plants and animals. It stimulates synthesis of other antioxidants like glutathione. It's the "swiss army knife" of anti-oxidants and uniquely positioned as the "fox in the hen house" inside the mitochondria where many free radicals originate. Melatonin reverses the Warburg effect and aids in arresting cancer cell growth.

Niacin requirements for genomic stability

Niacin involved with over 400 NAD+ dependent reactions. Essentially all cancer patients are deficient in niacin. Exposing mice to high levels of UVB radiation to induce skin cancer showed that mice on the highest doses of niacin had the lowest rate of skin cancer at 28% compared to 68% in the control group.

Melatonin alleviates titanium nanoparticles induced osteolysis via activation of butyrate/GPR109A signaling pathway

Supplementing mice with melatonin increases butyrate production in their gut via bacteria, conversely antibiotics severely impair this butyrate production. When mice are poisoned with titanium nanoparticles to induce bone deterioration, butyrate has a protective effect against bone loss. This protective effect is specifically dependent on the GPR109A receptor that seems to be activated by the butyrate enriched gut microbiota.

A novel treatment target for Parkinson's disease

The GPR109A receptor and its agonists (niacin and butyrate) have anti-inflammatory actions in the skin, gut and retina. For Parkinson's disease, niacin supplementation may have 3 benefits: lower inflammation via GPR109A-related mechanisms, increase dopamine production in the brain by supplying NADPH and boosting mitochondrial functions by increasing the NAD/NADH ratio.