Vitamin B

Vitamins are organic compounds in food that are needed in very small amounts for various metabolic processes and other functions. There are 13 vitamins that our body requires, eight of which make up the B-group (or B-complex) vitamins. B-group vitamins are essential for metabolic processes such as energy production and red blood cell synthesis.

Despite supplement advertisements that claim otherwise, the B-group vitamins do not provide the body with fuel for energy. It is true, though, that without B-group vitamins the body would lack energy. The energy-yielding nutrients – carbohydrate, fat, and protein – are used for fuel, while the B-group vitamins help the body to use that fuel. Other B-group vitamins play other indispensable roles in metabolism such as helping cells to multiply by making new DNA.

Although present in many foods, the B-group vitamins are water soluble and delicate. They are easily destroyed, particularly by alcohol and cooking. Food processing can also reduce the amount of B-group vitamins in foods, making white flours, breads and rice 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). Deficiencies of some of the B-group vitamins can be seen after only a few months of eating a poor diet. For this reason, adequate amounts of these vitamins should be consumed regularly as part of a well-balanced, nutritious diet.

Taking B-group vitamin supplements can sometimes mask deficiencies of other vitamins. It is also important not to self-diagnose a vitamin deficiency because some vitamins can be toxic if taken incorrectly. See your doctor or dietitian for advice.

The B-group vitamins

The eight B-group vitamins are:

• Thiamin
• Riboflavin
• Niacin
• Pantothenic acid
• Biotin
• Vitamin B6 (pyridoxine)
• Folate (called folic acid when included in supplements)
• Vitamin B12 (cyanocobalamin).

Thiamin

Thiamin helps to convert glucose into energy and has a role in nerve function. More information about thiamin:

• Good sources of thiamin – these include wholemeal cereal grains, seeds (especially sesame seeds), legumes, wheatgerm, nuts, yeast and pork. In Australia, white flour is also fortified with thiamin.
• 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 a very poor diet. Symptoms include confusion and irritability, poor arm or leg (or both) coordination, lethargy, fatigue and muscle weakness.
• ‘Wet’ and ‘dry’ beriberi – this is caused by thiamin deficiency and affects the cardiovascular, muscular, gastrointestinal and nervous systems. As well as the above symptoms, a person with ‘dry’ beriberi may have nerve degeneration, nervous tingling throughout the body, poor arm and leg coordination, and deep pain in the calf muscles. Symptoms of ‘wet’ beriberi include an enlarged heart, heart failure and severe oedema (swelling).
• Wernicke-Korsakoff syndrome – this syndrome is a thiamin-deficiency disease associated with alcohol excess and a thiamin-deficient diet. Alcohol reduces thiamin absorption in the gut and increases its excretion from the kidneys. The disease is characterised by involuntary movement of the eyeball, paralysis of the eye muscle, staggering and mental confusion.

Riboflavin

Riboflavin is primarily involved in energy metabolism and supports vision and skin health. More information about riboflavin:

• Good sources of riboflavin – these include milk, yoghurt, cottage cheese, wholegrain breads and cereals, egg white, leafy green vegetables, meat, yeast, liver and kidney.
• Riboflavin deficiency – people at risk of deficiency include those who consume excessive amounts of alcohol and those who do not consume milk or milk products. Riboflavin deficiency is rare and is usually seen along with other B-group vitamin deficiencies. Symptoms include an inflamed tongue (painful, smooth, purple-red tongue), cracks and redness in the tongue and corners of the mouth, anxiety, inflamed eyelids and sensitivity to light, hair loss, reddening of the cornea and skin rash.

Niacin

Niacin is essential for the body to metabolise carbohydrates, fat and alcohol to produce 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. More information about niacin:

• Good sources of niacin – these include meats, fish, poultry, milk, eggs, wholegrain breads and cereals, nuts, mushrooms and all protein-containing foods.
• Excessive intake – large doses of niacin in the form of nicotinic acid produce a drug-like effect on the nervous system and on blood lipids. While favourable changes in blood lipids are seen, side effects include flushing, itching, nausea and potential liver damage.
• Niacin deficiency – the name given to the disease of niacin deficiency is pellagra. People who drink excessive amounts of alcohol or live on a diet almost exclusively based on corn are at risk of pellagra. The main symptoms of pellagra are commonly referred to as the three Ds – dementia, diarrhoea and dermatitis. Other symptoms include an inflamed and swollen tongue, irritability, loss of appetite, mental confusion, weakness and dizziness. This disease can lead to death if not treated.

Pantothenic acid

Pantothenic acid is needed to metabolise carbohydrates, proteins, fats and alcohol. More information about pantothenic acid:

• Good sources of pantothenic acid – this is widespread in a range of foods, but some good sources include liver, milk, kidneys, eggs, meats, yeast, peanuts and legumes.
• Pantothenic acid deficiency – this is extremely rare. Symptoms include loss of appetite, tiredness, fatigue and insomnia, constipation, vomiting and intestinal distress.

Biotin

This vitamin is needed for energy metabolism, fat synthesis, amino acid metabolism and glycogen synthesis. High biotin intake can contribute to raised blood cholesterol levels. More information about biotin:

• Good sources of biotin – these include cauliflower, egg yolks, peanuts, liver, chicken, yeast and mushrooms.
• Biotin deficiency – biotin is widely distributed in foods and is only required in small amounts, so deficiency is very rare. Symptoms include pale or grey skin, cracked sore tongue, depression, hallucination, abnormal heart actions, loss of appetite, nausea, dry skin and scaly dermatitis, hair loss, muscle pain, and weakness and fatigue.

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. More information about pyridoxine:

• Good sources of pyridoxine – these include cereal grains and legumes, green and leafy vegetables, fish and shellfish, meat and poultry, nuts, liver and fruit.
• Excessive intake – this can lead to harmful levels in the body that can damage nerves. Symptoms include walking difficulties and numbness in the hands and feet. Large doses of B6 taken over a long period can lead to irreversible nerve damage.
• PMS and carpal tunnel syndrome – there is some evidence that vitamin B6 may be useful in the treatment of carpal tunnel syndrome and premenstrual syndrome. Seek advice from a doctor before using large doses of this supplement (above 100mg per day) because of the danger of overdose and nerve damage.
• Pyridoxine deficiency – people with excessive alcohol intake, women (especially those on the contraceptive pill), the elderly and people with thyroid disease are at particular risk of deficiency. Symptoms include insomnia, depression, anaemia, smooth tongue and cracked corners of the mouth, irritability, muscle twitching, convulsions, confusion and dermatitis.

Folate

Folate 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. 

If planning a pregnancy, you should consider taking supplements or eating fortified foods. This is important to reduce the risk of neural tube defects such as spina bifida in the baby. Folic acid is the synthetic form of folate and is used extensively in dietary supplements and food fortification. 

More information about folate:

• Good sources of folate – these include green leafy vegetables, legumes, seeds, liver, poultry, eggs, cereals and citrus fruits. From September 2009, all flour used in bread making (except for flour to be used in breads listed as ‘organic’) has been fortified with folic acid.
• Excessive intake – folate is generally considered non-toxic, although excessive intakes above 1,000µg 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 is best to consume these two vitamins within the recommended amounts.
• Folate deficiency – the symptoms include weight loss, tiredness, fatigue and weakness, folate-deficiency anaemia (megaloblastic anaemia) and (during pregnancy) an increased risk of a neural tube defects such as spina bifida for the baby.

Vitamin B12 (cyanocobalamin)

Vitamin B12 is involved in the production and maintenance of 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. More information about vitamin B12:

• Good sources of B12 – these include liver, meat, milk, cheese and eggs – almost anything of animal origin.
• Vitamin B12 deficiency – this is most common in the elderly, vegans (vitamin B12 is only found in foods of animal origin) and breastfed babies of vegan mothers and is called pernicious anaemia. Symptoms include tiredness and fatigue, lack of appetite and weight loss, apathy and depression, anaemia, smooth tongue and degeneration of peripheral nerves progressing to paralysis.

Where to get help

• Your doctor
• An accredited practising dietitian, contact the Dietitians Association of Australia.

Things to remember

• The B-group vitamins are a collection of eight vitamins that are essential for various metabolic processes.
• Most of these vitamins can’t be stored by the body and have to be consumed regularly in the diet.
• Extended cooking, food processing and alcohol 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. See your doctor or dietitian for advice.