Find out all about vitamin B3 (niacin), including what it does, how much you need, where to find it and who might need to supplement their diet
Written by Nic Hopkirk on December 5, 2018
Reviewed by Dr Sarah Schenker on December 18, 2018
What is vitamin B3 and what does it do?
Vitamin B3 – also known as niacin – is one of the eight essential B vitamins. It helps to release energy from the food we eat, supports normal nervous system function, fights fatigue and also helps keep skin healthy.1
Niacin is water-soluble, so we need to find it in our daily diet. Our bodies do make a small amount of niacin, but we get most of it from our food.2 B3 is found in:3,4
- red meat
- oily fish
- milk and dairy products
- fortified breakfast cereals
A niacin deficiency is rare in the UK, but a severe lack of vitamin B3 can lead to a condition called pellagra. Symptoms include dry, itchy skin (dermatitis) and diarrhoea.5
Function of niacin
What does niacin do in the body?
Like all the B vitamins, niacin helps to break down fats and protein, converting our food into energy. It helps keep the skin and nervous system healthy, and contributes to normal psychological function, too. Niacin also plays a role in reducing tiredness and fatigue.6,7
There are two main forms of niacin: nicotinic acid and niacinamide (or nicotinamide). Nicotinic acid has been shown to help reduce LDL or ‘bad’ cholesterol and increase levels of HDL or ‘good’ cholesterol.8
How much niacin do I need?
The reference nutrient intake (RNI) for vitamin B39 is:
- 2mg a day for women
- 5mg a day for men
Our body can make small amounts of niacin from the amino acid tryptophan,10 but you still need to get enough from your diet every day.
Do children need niacin?
- Age 1 – boys; 5mg, girls; 4.7mg a day
- 2-3 – boys; 7.2mg, girls; 6.6mg a day
- 4-6 – boys; 9.8mg, girls; 9.1mg a day
- 7-10 – boys; 12mg, girls; 11.2mg a day
- 11-18 – boys; 16.5mg, girls; 13.2mg a day11
Vitamin B3 foods
Which foods are the best sources of niacin?
The richest sources of niacin are animal-based foods but if you’re vegetarian or vegan, you can find all the vitamin B3 you need in a wide variety of plant foods.
The best food sources of niacin12 include:
- meat, especially red meat and liver
- oily fish, such as mackerel or salmon
- milk and dairy products
The best plant sources of niacin13 include:
- wheat and maize flour
- fortified food such as cereals or plant milks
What are the symptoms of a niacin deficiency?
A niacin deficiency is very rare in most Western countries, but early symptoms can include:14
- memory problems
- dry skin
If left untreated, a niacin deficiency can develop into pellagra that produces sore or ‘raw’ skin, similar to sunburn. It can also lead to dementia and could even be fatal.15
What happens if I consume too much niacin?
Too much nicotinic acid can cause itching or flushing skin, and, over time, may lead to liver damage. There’s not enough research to show what happens if you take too much nicotinamide.16
The NHS says taking less than 17mg of nicotinic acid, or less than 500mg of nicotinamide, a day is not likely to cause any harm.17
When should I take a niacin supplement?
If you eat a balanced diet with a wide range of foods, you should get all the niacin you need. Niacin is sometimes prescribed by health professionals to help with high cholesterol,18 but talk to your GP if you’re interested in taking it.
Should children take a niacin supplement?
Children should be able to get all the niacin they need from their daily diet.
Should women take a niacin supplement during pregnancy?
If you are deficient in vitamin B3 – ask your doctor for a blood test – a niacin supplement may have the potential to help prevent miscarriage or developmental problems. But the NHS doesn’t recommend that pregnant women in general take vitamin B3.19
What are the potential benefits of taking a niacin supplement?
B vitamins have been shown to help brain function,20 with niacin in particular warding off cognitive decline and the development of Alzheimer’s Disease.21
A number of studies have found that certain B vitamins may benefit people with osteoarthritis.22 It’s not fully understood how, but niacinaminde can improve joint mobility and reduced inflammation in those with OA.23
Advice is for information only and should not replace medical care. Please check with your GP before trying any remedies.
1. NHS. B vitamins and folic acid
2. Kerri-Ann Jennings. Healthline. 9 Science-Based Benefits of Niacin (Vitamin B3)
3. As Source 1
4. Christian Nordqvist. Medical News Today. Why do we need vitamin B-3, or niacin?
5. BMJ Best Practice. Vitamin B3 deficiency
6. As Source 1
7. European Food Safety Authority. Scientific Opinion on the substantiation of health claims related to niacin and reduction of tiredness and fatigue (ID 47), contribution to normal energy‐yielding metabolism (ID 51), contribution to normal psychological functions (ID 55), maintenance of normal blood flow (ID 211), and maintenance of normal skin and mucous membranes (ID 4700) pursuant to Article 13(1) of Regulation (EC) No 1924/2006
8. Brown WV. Niacin for lipid disorders
9. As Source 1
10. British Nutrition Foundation. Vitamins – niacin (nicotinic acid)
11. Public Health England. Government Dietary Recommendations
12. Erica Julson. Healthline. 16 Foods That Are High in Niacin (Vitamin B3)
13. As above, and Source 10
14. The Health and Food Supplements Information Service. Vitamin B3 (Niacin)
15. As Source 10
16. As Source 1
17. As Source 1
18. As Source 4
19. NHS. Vitamin B3, found in Marmite, unproven to prevent miscarriage
20. Kennedy DO. B Vitamins and the Brain: Mechanisms, Dose and Efficacy – A Review
21. Morris MC, et al. Dietary niacin and the risk of incident Alzheimer’s disease and of cognitive decline
22. VersusArthritis. Vitamins B complex
23. Jonas WB, Rapoza CP, Blair WF. The effect of niacinamide on osteoarthritis: a pilot study