Vitamin B3/Niacin is a water-soluble vitamin belonging to the vitamin B family, which occurs in many animal and plant tissues, with antihyperlipidemic activity. Niacin is converted to its active form niacinamide, which is a component of the coenzymes nicotinamide adenine dinucleotide (NAD) and its phosphate form, NADP. These coenzymes play an important role in tissue respiration and in glycogen, lipid, amino acid, protein, and purine metabolism. Although the exact mechanism of action by which niacin lowers cholesterol is not fully understood, it may act by inhibiting the synthesis of very-low-density lipoproteins (VLDL), inhibiting the release of free fatty acids from adipose tissue, increasing lipoprotein lipase activity, and reducing the hepatic synthesis of VLDL-C and LDL-C.
Niacinamide is the active form of vitamin B3 and a component of the coenzyme nicotinamide adenine dinucleotide (NAD). Niacinamide acts as a chemo- and radio-sensitizing agent by enhancing tumor blood flow, thereby reducing tumor hypoxia. This agent also inhibits poly(ADP-ribose) polymerases, enzymes involved in the rejoining of DNA strand breaks induced by radiation or chemotherapy.
Vitamin B3 also referred to as niacin, is the generic term for nicotinic acid, its amide (nicotinamide or niacinamide), and their biologically active derivatives. It is also found in the form of the pyridine nucleotide coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADPH). These are essential in all cells for energy production, metabolism, and DNA repair. Severe deficiency results in pellagra, which is a combined deficiency of both niacin and its precursor, tryptophan. The symptoms of deficiency are primarily dermatitis, diarrhea, and dementia. Death results if the condition is untreated.
Deficiency Symptoms of Vitamin B3 / Niacin
- Symmetrical lesions on both sides of the body. The lesions are most visible at pressure points and on areas of the skin exposed to the sun. Some people develop lesions that cover their entire hands or feet.
- Butterfly-shaped lesions on the face, or a “necklace” of lesions around the neck that develops after spending time in the sun.
- Pain, swelling, and irritation of the mouth or other mucous membranes, such as the vagina or the urethra. Severe deficiency can cause the tongue to turn red or swell. Some people develop sores under the tongue or on their lips.
- Pain and burning in the throat, chest, or stomach.
- Digestive pain, such as swelling, vomiting, nausea, diarrhea, and constipation. Some people develop ulcers in their bowels that cause bloody diarrhea.
- Changes in personality and mental health, including losing contact with reality (psychosis), confusion, memory problems, depression, and paranoia. Sometimes, these symptoms may be incorrectly diagnosed as mental illness.
- irritated or red skin
- headaches
- fatigue
- unexplained digestive problems
- mood issues, such as anxiety or depression
- changes in thinking or the ability to concentrate
- dizziness
- poor circulation
Food Source of Vitamin B3 / Niacin
Niacin is found in a variety of whole and processed foods, including fortified packaged foods, meat from various animal sources, kinds of seafood, and spices.
Among whole food sources with the highest niacin content per 100 grams
Meats
- cooked skipjack tuna, 18.8 mg
- cooked light meat turkey, 11.8 mg
- cooked, lean ground pork, 11.1 mg
- cooked venison, 10.8 mg
- cooked, lean veal, 8.0 mg
Plant foods and spices
- sesame seed flour, 12.5 mg
- ground ginger, 9.6 mg
- dried tarragon, 9.0 mg
- dried, green sweet peppers, 7.4 mg
- grilled portobello mushrooms, 6.2 mg
- roasted sunflower seeds, 4.1 mg
- dehydrated apricots, 3.6 mg
- baked potato, 3.1 mg
Fortified breakfast cereals have among the highest niacin contents (more than 20 mg per 100 grams). Whole grain flours, such as from wheat, rice, barley or corn, and pasta have niacin contents in a range of 3–10 mg per 100 grams.
Daily Requirement of Vitamin B3 / Niacin
Intake recommendations for vitamin B3 or niacin and other nutrients are provided in the Dietary Reference Intakes (DRIs) developed by the Food and Nutrition Board (FNB) at the Institute of Medicine of the National Academies. DRI is the general term for a set of reference values used for planning and assessing nutrient intakes of healthy people. These values, which vary by age and sex, include:
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| Australia and New Zealand | ||
| Age group | RDI for niacin (mg NE/day) | Upper level of intake |
|---|---|---|
| Infants 0–6 months | 2 mg/d performed niacin* | ND |
| Infants 7–12 months | 4 mg/d NE* | |
| 1–3 | 6 | 10 |
| 4–8 | 8 | 15 |
| 9–13 | 12 | 20 |
| 14–18 | – | 30 |
| 19+ | – | 35 |
| Females 14+ | 14 | – |
| Males 14+ | 16 | |
| Pregnant females 14–50 | 18 | – |
| Pregnant females 14–18 | – | 30 |
| Pregnant females 19–50 | – | 35 |
| Lactating females 14–50 | 17 | – |
| Lactating females 14–18 | – | 30 |
| Lactating females 19–50 | – | 35 |
| * Adequate Intake for infants | ||
| Canada | ||
| Age group (years) | RDA of niacin (mg NE/d) | Tolerable upper intake level |
| 0–6 months | 2 mg/d preformed niacin* | ND |
| 7–12 months | 4 mg/d NE* | |
| 1–3 | 6 | 10 |
| 4–8 | 8 | 15 |
| 9–13 | 12 | 20 |
| Females 14–18 | 14 | 30 |
| Males 14–18 | 16 | |
| Females 19+ | 14 | 35 |
| Males 19+ | 16 | |
| Pregnant females <18 | 18 | 30 |
| Pregnant females 18–50 | 18 | 35 |
| Lactating females <18 | 17 | 30 |
| Lactating females 18–50 | 17 | 35 |
| European Food Safety Authority | ||
| Gender | Adequate Intake (mg NE/MJ) | |
| Females | 1.3 | |
| Males | 1.6 | |
| Age (years) | Tolerable upper limit of Nicotinic acid (mg/day) | Tolerable upper limit of Nicotinamide (mg/day) |
| 1–3 | 2 | 150 |
| 4–6 | 3 | 220 |
| 7–10 | 4 | 350 |
| 11–14 | 6 | 500 |
| 15–17 | 8 | 700 |
| United States | ||
| Age group | RDA for niacin (mg NE/day) | Tolerable upper intake level |
| Infants 0–6 months | 2* | ND** |
| Infants 6–12 months | 4* | |
| 1–3 years | 6 | 10 |
| 4–8 years | 8 | 15 |
| 9–13 years | 12 | 20 |
| Females 14–18 years | 14 | 30 |
| Males 14–18 years | 16 | 30 |
| Females 19+ years | 14 | 35 |
| Males 19+ years | 16 | 35 |
| Pregnant females 14–18 years | 18 | 30 |
| Pregnant females 19–50 years | 18 | 35 |
| Lactating females 14–18 years | 17 | 30 |
| Lactating females 19–50 years | 17 | 35 |
| * Adequate intake for infants, as an RDA has yet to be established ** Not possible to establish; source of intake should be formula and food only |
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Health Benefit of Vitamin B3 / Niacin
Vitamin B3 (niacin) is important for the body because it helps to:
- Niacinamide is the active form of vitamin B3 and a component of the coenzyme nicotinamide adenine dinucleotide (NAD). Niacinamide acts as a chemo- and radio-sensitizing agent by enhancing tumor blood flow, thereby reducing tumor hypoxia. This agent also inhibits poly(ADP-ribose) polymerases, enzymes involved in the rejoining of DNA strand breaks induced by radiation or chemotherapy.
- Niacin is prescribed pharmacologically to lower LDL fats and triglycerides by preventing the breakdown of fats into these individual components. Niacin consumed at such high levels can cause rashes, headaches, nausea, and diarrhea. Consult your doctor before taking niacin supplements in high doses.
- Studies suggest that vitamin B3 (niacin) can help decrease insulin sensitivity, however, other studies find no difference. Niacin has also been shown to help alleviate some of the destructive autoimmune reactions of type I diabetes, and further studies are being conducted to asses its effectiveness.5
- Studies show that niacin reduces cancer risk via ensuring DNA integrity and maintenance, and through proper regulation of the tumor suppressor gene: p53.
- An observational study has reported slowing the progression of AIDS and increasing survival with high doses of niacin.
- The body’s immune system creates a specific cytokine, interferon-gamma, which breaks down tryptophan, a precursor of niacin. Studies show that HIV patients who take increased levels of niacin slow the progression of AIDS.
- Bran, which is high in vitamin b3, is typically removed during any refining process. Anyone who eats high amounts of white bread, white rice, corn syrup, or other refined products will not receive adequate amounts of niacin. Even though most of these foods are now fortified, it is still best to eat unrefined food products.
- Convert food into glucose, used to produce energy
- Produce macromolecules, including fatty acids and cholesterol
- Facilitate DNA repair and stress responses.
- Normal energy-yielding metabolism
- The normal function of the nervous system
- The maintenance of normal skin and mucous membranes
- Normal psychological functions
- The reduction of tiredness and fatigue.
Niacin and niacinamide are indicated for the prevention and treatment of vitamin B3 deficiency states. Vitamin B3 (Niacin) also acts to reduce LDL cholesterol, triglycerides, and HDL cholesterol. The magnitude of individual lipid and lipoprotein responses may be influenced by the severity and type of underlying lipid abnormality. The increase in total HDL is associated with a shift in the distribution of HDL subfractions (as defined by ultra-centrifugation) with an increase in the HDL2: HDL3 ratio and an increase in apolipoprotein A-I content. Vitamin B3 (Niacin) treatment also decreases the serum levels of apolipoprotein B-100 (apo B), the major protein component of the VLDL (very low-density lipoprotein) and LDL fractions, and of lipoprotein-a, a variant form of LDL independently associated with coronary risk.
Possible Interactions
Because of its impact on the liver, vitamin B3 can interact with several medications. If you are currently taking medications, or regularly drink alcohol, you should not use niacin without talking to your health care provider first. Below is a partial list of medications that may interact with vitamin B3.
Antibiotics, tetracycline: Niacin should not be taken at the same time as the antibiotic tetracycline because it interferes with the absorption and effectiveness of this medication. All vitamin B complex supplements act in this way and should be taken at different times from tetracycline.
Aspirin: Taking aspirin before taking niacin may reduce flushing from niacin. But take it only under your doctor’s supervision.
Anti-seizure medications: Phenytoin (Dilantin) and valproic acid (Depakote) may cause niacin deficiency in some people. Taking niacin with carbamazepine (Tegretol) or mysoline (Primidone) may increase levels of these medications in the body.
Anticoagulants (blood thinners): Niacin may make the effects of these medications stronger, increasing the risk of bleeding.
Blood pressure medications, alpha-blockers: Niacin can make the effects of medications taken to lower blood pressure stronger, leading to the risk of low blood pressure.
Cholesterol-lowering medications: Niacin binds the cholesterol-lowering medications known as bile-acid sequestrants and may make them less effective. For this reason, niacin and these medications should be taken at different times of the day. Bile-acid sequestrants include colestipol (Colestid), colesevelam (Welchol), and cholestyramine (Questran).
Statins: Some scientific evidence suggests that taking niacin with simvastatin (Zocor) appears to slow the progression of heart disease. However, the combination may also increase the likelihood for serious side effects, such as muscle inflammation or liver damage.
Diabetes medications: Niacin may increase blood sugar levels. People taking insulin, metformin (Glucophage), glyburide (Dibeta, Micronase), glipizide (Glucotrol), or other medications used to treat high blood glucose levels should monitor their blood sugar levels closely when taking niacin supplements.
Isoniazid (INH): INH, a medication used to treat tuberculosis, may cause a niacin deficiency.
Nicotine patches: Using nicotine patches with niacin may worsen or increase the risk of flushing associated with niacin.
These medications may lower levels of niacin in the body:
- Azathioprine (Imuran)
- Chloramphenicol (Chloromycetin)
- Cycloserine (Seromycin)
- Fluorouracil
- Levodopa and carbidopa
- Mercaptopurine (Purinethol)
Precautions
Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider. Side effects may include diarrhea, headache, stomach discomfort, and bloating.
High doses (50 mg or more) of niacin can cause side effects. The most common side effect is called “niacin flush,” which is a burning, tingling sensation in the face and chest, and red or flushed skin. Taking an aspirin 30 minutes prior to the niacin may help reduce this symptom.
At very high doses, used to lower cholesterol and treat other conditions, liver damage and stomach ulcers can occur. Your doctor will regularly check your liver function through a blood test.
People with a history of liver disease, kidney disease, or stomach ulcers should not take niacin supplements. Those with diabetes or gallbladder disease should do so only under the close supervision of their doctors.
Stop taking niacin or niacinamide at least 2 weeks before a scheduled surgery.
Niacin and niacinamide may make allergies worse by increasing histamine.
People with low blood pressure should not take niacin or niacinamide because they may cause a dangerous drop in blood pressure. DO NOT take niacin if you have a history of gout.
People with coronary artery disease or unstable angina should not take niacin without their doctor’s supervision, as large doses can raise the risk of heart rhythm problems.
Taking any one of the B vitamins for a long period of time can result in an imbalance of other important B vitamins. For this reason, you may want to take a B-complex vitamin, which includes all the B vitamins.
References
Dr. Md. Harun Ar Rashid, MPH, MD, PhD, is a highly respected medical specialist celebrated for his exceptional clinical expertise and unwavering commitment to patient care. With advanced qualifications including MPH, MD, and PhD, he integrates cutting-edge research with a compassionate approach to medicine, ensuring that every patient receives personalized and effective treatment. His extensive training and hands-on experience enable him to diagnose complex conditions accurately and develop innovative treatment strategies tailored to individual needs. In addition to his clinical practice, Dr. Harun Ar Rashid is dedicated to medical education and research, writing and inventory creative thinking, innovative idea, critical care managementing make in his community to outreach, often participating in initiatives that promote health awareness and advance medical knowledge. His career is a testament to the high standards represented by his credentials, and he continues to contribute significantly to his field, driving improvements in both patient outcomes and healthcare practices.
