Summary

  • The B-group vitamins are a collection of eight water-soluble vitamins essential for various metabolic processes.
  • Most of these vitamins can’t be stored by the body and must be consumed regularly in the diet.
  • Extended cooking, food processing and excess alcohol consumption can destroy or reduce the availability of many of these vitamins.
  • It is important not to self-diagnose a vitamin deficiency, because some vitamins can be toxic if taken incorrectly and/or mask other vitamin deficiencies. See your doctor or dietitian for advice.
     

Vitamins naturally occur in food and are needed in very small amounts for various bodily functions such as energy production and making red blood cells. There are 13 vitamins that our body needs, eight of which make up the B-group (or B-complex) vitamins.

The B-group vitamins do not provide the body with fuel for energy, even though supplement advertisements often claim they do. However, it’s true though that without B-group vitamins the body lacks energy. This is because the B-group vitamins are needed to help the body to use the energy-yielding nutrients (such as carbohydrates, fat and protein) for fuel. Other B-group vitamins are needed to help cells to multiply by making new DNA.

Vitamin B in food

Even though the B-group vitamins are found in many foods, they are water soluble and are generally quite delicate. They are easily destroyed, particularly by alcohol and cooking. 

Food processing can also reduce the amount of B-group vitamins in foods – either by destroying them, or in white flours, white breads and white rice removing the parts that contain the most B-group vitamins. This is one of the reasons white flours, white breads and white rice are less nutritious than their wholegrain counterparts.

The body has a limited capacity to store most of the B-group vitamins (except B12 and folate, which are stored in the liver). A person who has a poor diet for a few months may end up with B-group vitamins deficiency. For this reason, it’s important that adequate amounts of these vitamins be eaten regularly as part of a well-balanced, nutritious diet.

Vitamin B supplements

Although vitamin supplements are readily available and it might sound like a good idea to take them just in case, it’s important to always see your doctor or a dietitian for advice before starting. The body only needs small amounts of vitamins and most of these needs can be met by eating a nutritious diet.

Taking vitamins that your body does not need can mean, at a best-case scenario, that your body gets rid of the excess in your urine (so you waste your money). But some vitamins can also be toxic if taken incorrectly, so you could also be damaging your body instead of helping it. 

Some B-group vitamins also work together in the body (for example, vitamin B12 and folate or folic acid). This means taking supplements can sometimes hide deficiencies of other vitamins, which can also lead to health problems.

Types of vitamin B

There are eight types of vitamin B:

  • thiamin (B1)
  • riboflavin (B2)
  • niacin (B3)
  • pantothenic acid (B5)
  • pyridoxine (B6)
  • biotin (B7)
  • folate or ‘folic acid’ when included in supplements (B9)
  • cyanocobalamin (B12).

Thiamin (B1)

Thiamin is also known as vitamin B1. It helps to convert glucose into energy and has a role in nerve function.

Good sources of thiamin

  • wholemeal cereal grains
  • seeds (especially sesame seeds)
  • legumes
  • wheatgerm 
  • nuts
  • yeast 
  • pork.

In Australia, it’s mandatory that white and wholemeal flour used for bread is fortified with thiamin. 

Thiamin deficiency 

Thiamin deficiency is generally found in countries where the dietary staple is white rice. Deficiencies in the Western world are generally caused by excessive alcohol intake and/or a very poor diet. Symptoms include – confusion, irritability, poor arm or leg (or both) coordination, lethargy, fatigue and muscle weakness.

Beriberi is a condition caused by thiamin deficiency and affects the cardiovascular, muscular, gastrointestinal and nervous systems. It can be classified as ‘wet’ and ‘dry’ beriberi. ‘Dry’ beriberi affects the nervous symptom while ‘wet’ beriberi affects the cardiovascular system. 

Wernicke-Korsakoff syndrome (also called ‘wet brain’) is another thiamin-deficiency disease linked to alcohol excess and a thiamin-deficient diet. Alcohol reduces thiamin absorption in the gut and increases its excretion from the kidneys. 

Riboflavin (B2)

Riboflavin is primarily involved in energy production and helps vision and skin health.

Good sources of riboflavin

  • milk
  • yoghurt
  • cottage cheese
  • wholegrain breads and cereals
  • egg white
  • leafy green vegetables
  • meat
  • yeast
  • liver
  • kidney.

Riboflavin deficiency (ariboflavinosis)


Riboflavin deficiency (or ariboflavinosis) is rare and is usually seen along with other B-group vitamin deficiencies. People at risk include those who consume excessive amounts of alcohol and those who do not consume milk or milk products. 

Niacin (B3)

Niacin is essential for the body to convert carbohydrates, fat and alcohol into energy. It helps maintain skin health and supports the nervous and digestive systems. Unlike other B-group vitamins, niacin is very heat stable and little is lost in cooking.

Good sources of niacin

  • meats
  • fish
  • poultry
  • milk
  • eggs
  • wholegrain breads and cereals
  • nuts
  • mushrooms 
  • all protein-containing foods.

Niacin deficiency (pellagra)

People who drink excessive amounts of alcohol or live on a diet almost exclusively based on corn are most at risk of pellagra. Others causes are associated with digestive problems where the body does not absorb niacin efficiently.

The main symptoms of pellagra are commonly referred to as the three Ds – dementia, diarrhoea and dermatitis. This disease can lead to death if not treated.

Excessive niacin intake

Large doses of niacin produce a drug-like effect on the nervous system and on blood fats. While favourable changes in blood fats are seen, side effects include – flushing, itching, nausea and potential liver damage.

Pantothenic acid (B5)

Pantothenic acid is needed to metabolise carbohydrates, proteins, fats and alcohol as well as produce red blood cells and steroid hormones.

Good sources of pantothenic acid

Pantothenic acid is widespread and found in a range of foods, but some good sources include liver, meats, milk, kidneys, eggs, yeast, peanuts and legumes.

Pantothenic acid deficiency

Because pantothenic acid is found in such a wide variety of foods, deficiency is extremely rare. 

 

Vitamin B6 (pyridoxine)

Pyridoxine is needed for protein and carbohydrate metabolism, the formation of red blood cells and certain brain chemicals. It influences brain processes and development, immune function and steroid hormone activity.

Good sources of pyridoxine

  • cereal grains 
  • legumes
  • green and leafy vegetables
  • fish and shellfish
  • meat and poultry
  • nuts
  • liver 
  • fruit.

Pyridoxine deficiency

Pyridoxine deficiency is rare. People who drink excessive amounts of alcohol, women (especially those on the contraceptive pill), the elderly and people with thyroid disease the most at risk. 

Excessive pyridoxine intake

Pyridoxine toxicity is mostly due to supplementation and can lead to harmful levels in the body that can damage the nerves. 

Biotin (B7)

Biotin (B7) is needed for energy metabolism, fat synthesis, amino acid metabolism and glycogen synthesis. High biotin intake can contribute to raised blood cholesterol levels.

Good sources of biotin

  • liver
  • cauliflower
  • egg yolks
  • peanuts
  • chicken
  • yeast 
  • mushrooms.

Biotin deficiency

Biotin deficiency is very rare – it’s widely distributed in foods and only required in small amounts. Over-consumption of raw egg whites over periods of several months (by bodybuilders, for example) can induce deficiency because a protein in the egg white inhibits biotin absorption. 

Folate or folic acid (B9)

Folate, or folic acid (the synthetic form of folate which is used extensively in dietary supplements and food fortification) is needed to form red blood cells, which carry oxygen around the body. It helps the development of the foetal nervous system, as well as DNA synthesis and cell growth. Women of child-bearing age need a diet rich in folate for this reason. 


If planning a pregnancy or in the first trimester of pregnancy, you should visit your doctor to make sure you’re getting enough folate. This is important to reduce the risks of neural tube defects such as spina bifida in the baby. 

Good sources of folate

  • green leafy vegetables
  • legumes
  • seeds
  • liver
  • poultry
  • eggs
  • cereals
  • citrus fruits. 

Since 2009, all bread sold in Australia (except organic) has been fortified with folic acid.

Excessive folic acid intake


Although folic acid is generally considered non-toxic, excessive intakes above 1,000 mg per day over a period of time can lead to malaise, irritability and intestinal dysfunction. The main risk with excessive folate intake is that it can mask a vitamin B12 deficiency, so it’s best to consume these two vitamins within the recommended amounts.

Cyanocobalamin (B12)

Cyanocobalamin (or vitamin B12) helps to produce and maintain the myelin surrounding nerve cells, mental ability, red blood cell formation and the breaking down of some fatty acids and amino acids to produce energy. Vitamin B12 has a close relationship with folate, as both depend on the other to work properly.

Good sources of B12

  • liver
  • meat
  • milk
  • cheese
  • eggs 
  • almost anything of animal origin.

Vitamin B12 deficiency

Because vitamin B12 is only found in foods from animal sources, people following strict vegan diets, as well as breastfed babies of vegan mothers, tend to be most commonly affected. 

Absorption of B12 from the gut also tends to decrease with age, so the elderly is another group who are more at risk of deficiency. 

 

Where to get help

 

References

 

 

 

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This page has been produced in consultation with and approved by: Deakin University - School of Exercise and Nutrition Sciences

Last updated: May 2020

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