Vitamin B3

Vitamin B3, also known as niacin, is an essential water-soluble vitamin that plays a crucial role in various metabolic processes in the human body. Niacin is part of the B-vitamin family.


Niacin was first discovered in the 1930s by Conrad Elvehjem, an American biochemist. He identified the active component in liver extracts that could cure pellagra, a disease caused by niacin deficiency, which was prevalent in the early 20th century. 

Niacin exists in two primary forms: nicotinic acid and nicotinamide (also called niacinamide). Both forms can be converted into the active coenzymes nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP), which play a vital role in cellular energy production and metabolism.

Functions of Vitamin B3

  • Energy production: Niacin is a key component of two important coenzymes, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP). These coenzymes participate in numerous cellular processes, such as glycolysis, the citric acid cycle, and the electron transport chain, which are responsible for the production of adenosine triphosphate (ATP), the primary source of energy for cells.
  • Metabolism: Vitamin B3 plays an essential role in the metabolism of carbohydrates, fats, and proteins. It is involved in breaking down these nutrients into smaller molecules, which can then be used as building blocks for other molecules or as an energy source.
  • DNA repair and synthesis: Niacin is crucial for the maintenance, repair, and synthesis of DNA. It is involved in DNA replication and repair, contributing to overall genetic stability and preventing mutations that may lead to various diseases, including cancer.
  • Antioxidant activity: NAD, one of the coenzymes derived from niacin, has antioxidant properties that help neutralise harmful free radicals in the body. Free radicals are molecules that can cause oxidative stress and damage cells, leading to aging and various diseases.
  • Cholesterol regulation: Nicotinic acid, one form of niacin, can help lower LDL (“bad”) cholesterol and triglyceride levels and increase HDL (“good”) cholesterol levels when taken in high doses under medical supervision. This can contribute to a reduced risk of cardiovascular diseases, such as heart disease and stroke.
  • Nervous system function: Vitamin B3 plays a role in maintaining the proper function of the nervous system, as it is involved in the synthesis of various neurotransmitters that are essential for cognitive function and mood regulation.

Good Sources Of Vitamin B3

Vitamin B3, or niacin, can be found in a variety of both animal and plant-based foods. Good dietary sources of vitamin B3 include:

  • Meat and poultry: Lean meats such as beef, chicken, and turkey are rich sources of niacin. Organ meats like liver are particularly high in vitamin B3 content.
  • Fish: Fish, especially oily fish like tuna, salmon, and mackerel, are good sources of niacin, as well as omega-3 fatty acids and other essential nutrients.
  • Dairy products: Milk, yogurt, and cheese provide some niacin, along with other important nutrients like calcium, protein, and vitamin D.
  • Eggs: Eggs are a source of niacin, as well as protein, healthy fats, and other essential nutrients.
  • Legumes: Beans, lentils, and peas are good plant-based sources of niacin, as well as protein, fiber, and various minerals.
  • Nuts and seeds: Almonds, peanuts, sunflower seeds, and other nuts and seeds provide niacin, along with healthy fats, protein, and other essential nutrients.
  • Whole grains: Whole grain products like whole wheat bread, brown rice, quinoa, and barley contain niacin and other B vitamins, fiber, and various minerals.
  • Fortified cereals: Some breakfast cereals are fortified with niacin and other B vitamins, providing an easy way to increase your vitamin B3 intake.
  • Vegetables: Certain vegetables, like mushrooms, potatoes, avocados, and leafy greens, contain small amounts of niacin.

How Much Vitamin B3 Do We Need?

The National Institutes of Health (NIH) recommends the following daily intake of vitamin B3 for different age groups:

  • Infants 0-6 months*: 2 mg/day (milligram)
  • Infants 7-12 months*: 4 mg/day
  • Children 1-3 years: 6 mg/day
  • Children 4-8 years: 8 mg/day
  • Children 9-13 years: 12 mg/day
  • teens 14-18 years (males): 16 mg/day
  • Teens 14-18 years (females): 14 mg/day
  • Adults 19 years and older (males): 16 mg/day
  • Adults 19 years and older (females) 14 mg/day
  • Pregnant women: 18 mg/day
  • Breastfeeding women: 17 mg/day

* Adequate intake (AI)

It is essential to note that these values are for general informational purposes and may not be suitable for everyone. Individual nutrient needs can vary based on factors such as age, sex, body size, genetics, health status, and specific dietary requirements. Always consult with a healthcare professional for personalised recommendations based on your individual needs and circumstances.

Reference: National Institutes of Health, Office of Dietary Supplements. (2021). Niacin: Fact Sheet for Health Professionals. Retrieved from

What Are The Signs of Vitamin B3 Deficiency?

Deficiency in vitamin B3 can lead to a variety of symptoms and, in severe cases, result in a condition called pellagra. Some of the signs and symptoms of vitamin B3 deficiency include:

  • Fatigue and weakness: A lack of vitamin B3 can cause feelings of fatigue, weakness, and overall exhaustion, as it is essential for energy production in the body.
  • Skin issues: Vitamin B3 deficiency can lead to dermatitis, which is characterised by inflamed, dry, and scaly skin, particularly in areas exposed to sunlight.
  • Digestive problems: Niacin is important for maintaining a healthy digestive system. A deficiency in vitamin B3 can result in symptoms such as indigestion, nausea, vomiting, and diarrhoea.
  • Mood disorders: Vitamin B3 plays a role in maintaining brain function and mental health. Deficiency can lead to mood disorders, irritability, anxiety, and even depression.
  • Cognitive decline: Inadequate levels of vitamin B3 can affect cognitive function, leading to memory loss, confusion, and mental fog.
  • Swollen and cracked tongue: A condition called glossitis, characterized by a swollen, red, and painful tongue, can occur due to vitamin B3 deficiency.

What Happens If I Take Too Much Vitamin B3?

Taking excessive amounts of vitamin B3 (niacin) can cause side effects, especially when consumed in the form of supplements. The tolerable upper intake level (UL) for niacin varies by age and is set to help prevent the risk of adverse effects. Potential side effects of consuming too much vitamin B3 include:

  • Niacin flush: High doses of niacin, particularly in the form of nicotinic acid, can cause “niacin flush,” which is characterised by redness, warmth, itching, and tingling of the skin. This reaction typically occurs within 30 minutes to an hour after taking the supplement and can last for several hours. Although generally harmless, it can be uncomfortable.
  • Gastrointestinal issues: Overconsumption of niacin can lead to gastrointestinal symptoms such as nausea, vomiting, diarrhoea, and stomach cramps.
  • Liver toxicity: Prolonged use of high doses of niacin can cause liver damage, resulting in elevated liver enzymes and, in severe cases, liver failure. It is essential to monitor liver function if taking niacin supplements at high doses for an extended period.
  • Dizziness and low blood pressure: High doses of niacin can cause dizziness, light-headedness, and low blood pressure, particularly when standing up quickly.
  • Impaired glucose tolerance: High doses of niacin can impair glucose tolerance, potentially leading to increased blood sugar levels and worsening symptoms in individuals with diabetes or pre-diabetes.
  • Gout: High levels of niacin can lead to elevated levels of uric acid in the blood, increasing the risk of developing gout in susceptible individuals.
  • Vision problems: In rare cases, excessive niacin intake may cause blurred or impaired vision and other eye-related issues.

It is important to note that most of these side effects are associated with high-dose niacin supplements, rather than obtaining niacin through dietary sources. To reduce the risk of adverse effects, it is generally advised to meet your vitamin B3 requirements through a balanced diet that includes a variety of niacin-rich foods.

If you are considering taking niacin supplements or have concerns about your niacin intake, consult with a healthcare professional or registered dietitian for personalised advice and recommendations.