Vitamin B3: Benefits, functions & foods

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 to keep your 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 meat, such as:^3,4

1. Liver
2. Beef
3. Chicken
4. Turkey
5. Oily fish

Vegetarian sources include:

6. Eggs
7. Milk and dairy products
8. Bread
9. Fortified breakfast cereals
10. Broccoli
11. Asparagus
12. Peanuts
13. Mushrooms
14. Green peas
15. Sunflower seeds
16. Avocado

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

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.

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.⁶

The four main functions of niacin include:^7,8

1. Promoting skin health
2. Supporting the nervous system
3. Helping keep normal, psychological function
4. Reducing tiredness and fatigue

How much niacin do I need?

How much niacin vitamin B3 you need is dependent on your age and gender.

The reference nutrient intake (RNI) for vitamin B3 is:⁹

• 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.¹⁰

Do children need niacin?

The guidelines for children are as follows:¹¹

Vitamin B3 foods

Wondering how you can make sure you get your daily dose of B3? Read on to find out. 

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.

But how much is in each food? The below table should give a clearer picture of how much niacin is in each:^12,13,14

What are the symptoms of a niacin deficiency?

A niacin deficiency is very rare in most Western countries. Symptoms include those related to the skin, nervous system and digestive system - in severe cases this can include:

1. Thick, scaly pigmented rash on skin exposed to sunlight
2. Headache
3. Memory loss
4. Dry skin
5. Nausea / vomiting
6. Irritability
7. Disorientation
8. Fatigue
9. Feeling lethargic

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?

It’s not possible to overdose on niacin through your diet, but you can if you take too many supplements, for example taking a multivitamin and a separate B-complex.

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, but talk to your GP if you’re interested in taking it.¹⁸

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, with niacin in particular warding off cognitive decline and the development of Alzheimer’s Disease.^20,21

A number of studies have found that certain B vitamins may benefit people with osteoarthritis.²²

It’s not fully understood how, but niacinamide can improve joint mobility and reduced inflammation in those with OA.²³