The B vitamins 

There are many different types of vitamin B and they all have important functions.

This section has information on:

Thiamin (vitamin B1)

Thiamin is also known as vitamin B1. It has several important functions, including:

  • working with other B-group vitamins to help break down and release energy from food
  • keeping nerves and muscle tissue healthy

Good sources of thiamin

Thiamin is found in most types of food. Good sources include:

  • vegetables
  • peas
  • fresh and dried fruit
  • eggs
  • wholegrain breads
  • some fortified breakfast cereals
  • liver

How much thiamin do I need?

The amount of thiamin you need is:

  • 1mg a day for men
  • 0.8mg a day for women

You should be able to get all the thiamin you need from your daily diet.

Thiamin cannot be stored in the body, so you need it in your diet every day.

What happens if I take too much thiamin?

There is not enough evidence to know what the effects might be of taking high doses of thiamin supplements each day.

What does the Department of Health advise?

You should be able to get all the thiamin you need by eating a varied and balanced diet. If you take supplements, do not take too much because this might be harmful.

Taking 100mg or less a day of thiamin supplements is unlikely to cause any harm.

Riboflavin (vitamin B2)

Riboflavin is also known as vitamin B2. Its functions include:

  • keeping skin, eyes and the nervous system healthy
  • helping the body release energy from carbohydrate

Good sources of riboflavin

Good sources of riboflavin include:

  • milk
  • eggs
  • fortified breakfast cereals
  • rice

UV light can destroy riboflavin, so ideally these foods should be kept out of direct sunlight.

How much riboflavin do I need?

The amount of riboflavin you need is about:

  • 1.3mg a day for men
  • 1.1mg a day for women

Riboflavin cannot be stored in the body, so you need it in your diet every day.

You should be able to get all the riboflavin you need from your daily diet.

What happens if I take too much riboflavin?

There is not enough evidence to know what the effects might be of taking high doses of riboflavin supplements each day.

What does the Department of Health advise?

You should be able to get all the riboflavin you need by eating a varied and balanced diet. If you take supplements, do not take too much because this might be harmful.

Taking 40mg or less a day of riboflavin supplements is unlikely to cause any harm.

Niacin (vitamin B3)

Niacin is also known as vitamin B3. It has several important functions, including:

  • helping produce energy from the foods we eat
  • helping keep the nervous and digestive systems healthy

Good sources of niacin

There are two forms of niacin nicotinic acid and nicotinamide  both of which are found in food.

Good sources of niacin include:

  • meat
  • fish
  • wheat flour
  • maize flour
  • eggs
  • milk

How much niacin do I need?

The amount of niacin you need is about:

  • 17mg a day for men
  • 13mg a day for women

You should be able to get all the niacin you need from your daily diet.

There are two forms of niacin  nicotinic acid and nicotinamide  both of which are found in food. Niacin cannot be stored in the body, so you need it in your diet every day.

What happens if I take too much niacin?

Taking high doses of nicotinic acid supplements can cause skin flushes. Taking high doses for a long time could lead to liver damage.

There is not enough evidence to know what the effects might be of taking high daily doses of nicotinamide supplements.

What does the Department of Health advise?

You should be able to get the amount of niacin you need by eating a varied and balanced diet. If you take niacin supplements, do not take too much because this might be harmful.

Taking 17mg or less of nicotinic acid supplements a day or 500mg or less of nicotinamide supplements a day is unlikely to cause any harm.

Pantothenic acid

Pantothenic acid has several functions, such as helping release energy from the food we eat.

Good sources of pantothenic acid

Pantothenic acid is found in virtually all meat and vegetable foods. Good sources include:

  • chicken
  • beef
  • potatoes
  • porridge
  • tomatoes
  • kidney
  • eggs
  • broccoli
  • wholegrains, such as brown rice and wholemeal bread

Breakfast cereals are also a good source if they have been fortified with pantothenic acid.

How much pantothenic acid do I need?

You should be able to get all the pantothenic acid you need from your daily diet.

Pantothenic acid cannot be stored in the body, so you need it in your diet every day.

What happens if I take too much pantothenic acid?

There is not enough evidence to know what the effects might be of taking high daily doses of pantothenic acid supplements.

What does the Department of Health advise?

You should be able to get all the pantothenic acid you need by eating a varied and balanced diet. If you take supplements, do not take too much as this might be harmful.

Taking 200mg or less a day of pantothenic acid in supplements is unlikely to cause any harm.

Vitamin B6

Vitamin B6 is also known as pyridoxine. It has several important functions, including:

  • allowing the body to use and store energy from protein and carbohydrates in food
  • helping form haemoglobin, the substance that carries oxygen around the body

Good sources of vitamin B6 

Vitamin B6 is found in a wide variety of foods such as:

  • pork
  • poultry (such as chicken or turkey)
  • fish
  • bread
  • whole cereals, such as oatmeal, wheat germ and rice
  • eggs
  • vegetables
  • soya beans
  • peanuts
  • milk
  • potatoes
  • some fortified breakfast cereals

How much vitamin B6 do I need?

The amount of vitamin B6 you need is about:

  • 1.4mg a day for men
  • 1.2mg a day for women

You should be able to get all the vitamin B6 you need from your daily diet. You need it in your diet every day because it cannot be stored in the body.

What happens if I take too much vitamin B6?

Taking more than 200mg a day of vitamin B6 for a long time can lead to a loss of feeling in the arms and legs, known as peripheral neuropathy.

Generally, the symptoms are reversible, so once you stop taking supplements the symptoms usually stop.

However, in a few cases when people have taken large amounts of vitamin B6, especially for more than a few months, the effect has been irreversible.

Taking doses of 10-200mg a day for short periods may not cause any harm. However, there is not enough evidence to say for how long these doses could be taken safely.

What does the Department of Health advise?

You should be able to get the vitamin B6 you need by eating a varied and balanced diet. If you take vitamin B6 supplements, do not take too much because this could be harmful.

Do not take more than 10mg of vitamin B6 a day in supplements, unless advised to by a doctor.

Folic acid

Folic acid, known as folate in its natural form, is one of the B-group vitamins.

Folic acid has several important functions. For example, it:

  • works together with vitamin B12 to form healthy red blood cells
  • helps reduce the risk of central nervous system defects such as spina bifida in unborn babies

A lack of folic acid could lead to folate deficiency anaemia.

Good sources of folic acid

Folic acid is found in small amounts in many foods. Good sources include:

  • broccoli
  • brussels sprouts
  • liver
  • spinach
  • asparagus
  • peas
  • chickpeas
  • brown rice
  • fortified breakfast cereals

How much folic acid do I need?

Adults need 0.2mg of folic acid a day.

Folic acid cannot be stored in the body, so you need it in your diet every day.

Most people should be able to get the amount they need by eating a varied and balanced diet.

However, if you are pregnant or thinking of trying to have a baby, take a 0.4mg (400 microgram) of folic acid supplement daily from the time you stop using contraception until the 12th week of pregnancy. This is to help prevent birth defects of the central nervous system, such as spina bifida, in your baby.

If you have a family history of conditions like spina bifida (known as neural tube defects), you may need to take 5mg of folic acid each day until the 12th week of pregnancy. This is available on prescription from your GP. Women with diabetes and those taking anti-epileptic medicines should speak to their GP for advice.

Read more about vitamins and minerals during pregnancy.

What happens if I take too much folic acid?

Taking doses of folic acid higher than 1mg can disguise vitamin B12 deficiency.

An early symptom of vitamin B12 deficiency is anaemia. However, taking large amounts of folic acid treats the anaemia without treating the B12 deficiency. If a vitamin B12 deficiency is not noticed, it can eventually damage the nervous system.

This is particularly a concern for older people because it becomes more difficult to absorb vitamin B12 as you get older.

What does the Department of Health advise?

The Department of Health recommends that folic acid supplements are taken by women who are pregnant or thinking of having a baby (see above).

Women who are not pregnant or planning for a baby should be able to get all the folate they need by eating a varied and balanced diet.

If you are taking folic acid supplements, it is important not to take too much because this could be harmful.

Taking 1mg or less a day of folic acid supplements is unlikely to cause any harm.

Vitamin B12

Vitamin B12 has several important functions and is involved in:

  • making red blood cells and keeping the nervous system healthy
  • releasing energy from the food we eat
  • processing folic acid

A lack of vitamin B12 could lead to vitamin B12 deficiency anaemia.

Good sources of vitamin B12

These include:

  • meat
  • salmon
  • cod
  • milk
  • cheese
  • eggs
  • some fortified breakfast cereals

How much vitamin B12 do I need?

Adults need approximately 0.0015mg a day of vitamin B12.

If you eat meat, fish or dairy foods, you should be able to get enough vitamin B12 from your diet.

However, because vitamin B12 is not found in foods such as fruit, vegetables and grains, vegans may not get enough of this vitamin. See the vegan diet for information and advice about vegan nutrition.

What happens if I take too much vitamin B12?

There is not enough evidence to show what the effects may be of taking high doses of vitamin B12 supplements each day.

What does the Department of Health advise?

You should be able to get all the vitamin B12 you need by eating a varied and balanced diet. If you take vitamin B12 supplements, do not take too much because this could be harmful.

Taking 2mg or less a day of vitamin B12 in supplements is unlikely to cause any harm.


Page last reviewed: 26/11/2012

Next review due: 26/11/2014