Vitamin B complex sources and deficiencies

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.


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.

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