Vitamin B are a class of water-soluble vitamins that play important roles in cell metabolism. Though these vitamins share similar names, they are chemically distinct compounds that often coexist in the same foods. In general, dietary supplements containing all eight are referred to as a vitamin B complex. All B Vitamins with their food sources and deficiencies are mentioned below :
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 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)
In Australia, it’s mandatory that white and wholemeal flour used for bread is 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/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 is primarily involved in energy production and helps vision and skin health.
Good sources of riboflavin
- cottage cheese
- wholegrain breads and cereals
- egg white
- leafy green vegetables
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 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
- wholegrain breads and cereals
- 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
- green and leafy vegetables
- fish and shellfish
- meat and poultry
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) 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
- egg yolks
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
- 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 (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
- 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.
To find the dietary recommendations of. Vitamin B click here.