The B-group vitamins do not provide the body with fuel for energy, but they are needed to help the body to use the energy-yielding nutrients (such as carbohydrates, fat and protein) for fuel. They also help cells to multiply by making new DNA.
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.
There are 8 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).
| Vitamins | DVs for adults and children ages 4+ | DVs if pregnant or breastfeeding |
| thiamin (B-1) | 1.2 mg | 1.4 mg |
| riboflavin (B-2) | 1.3 mg | 1.6 mg |
| niacin (B-3) | 16 mg or equivalent | 18 mg or equivalent |
| pantothenic acid (B-5) | 5 mg | 7 mg |
| vitamin B-6 | 1.7 mg | 2 mg |
| biotin (B-7) | 30 mcg | 35 mcg |
| folate (B-9) | 400 mcg or equivalent | 600 mcg or equivalent |
| vitamin B-12 | 2.4 mcg | 2.8 mcg |
1. 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, such as black beans and soy beans
- wheatgerm
- nuts
- yeast
- pork
- trout
- mussels
- acorn squash
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.
Wernicke-Korsakoff syndrome (also called ‘wet brain’) is another thiamin-deficiency disease linked to alcohol excess and a thiamin-deficient diet. It results in tingling and numbness un the hands and feet, memory loss and confusion. Alcohol reduces thiamin absorption in the gut and increases its excretion from the kidneys.
2. Riboflavin (B2)
Riboflavin is primarily involved in energy production and helps vision and skin health. It helps the body break down fats, drugs, and steroid hormones, converting tryptophan into niacin (vitamin B-3), converting vitamin B-6 into a coenzyme that the body needs.
Good sources of riboflavin:
Riboflavin deficiency (or ariboflavinosis) is rare and is usually seen along with other B-group vitamin deficiencies. However, having a severe riboflavin deficiency can lead to anemia and cataracts. Being riboflavin deficient during pregnancy can create a higher risk certain birth defects.
People at highest risk of riboflavin deficiency include:
- those following a vegan diet or who do not consume dairy products
- athletes who do not eat meat, especially those who also do not eat dairy or other animal products
- women who are pregnant or lactating, especially those who do not consume meat or dairy products
- skin disorders
- sores at the corners of the mouth
- swelling of the mouth and throat
- swollen, cracked lips
- hair loss
- red, itchy eyes
3. Niacin (B3)
The body converts niacin into a coenzyme called nicotinamide adenine dinucleotide (NAD). NAD is a necessary part of more than 400 different enzyme reactions in the body, the highest of all vitamin-derived coenzymes. These enzymes help with:
- changing the energy in carbohydrates, fats, and proteins into a form the body can use
- metabolic processes in the body’s cells
- communication among cells
- expression of DNA in cells
In short, 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:
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 3 Ds – dementia, diarrhoea and dermatitis. This disease can lead to death if not treated.
- brown discoloration on skin exposed to sunlight
- patches of skin with a rough appearance
- a bright red tongue
- vomiting, diarrhea, or constipation
- headache
- fatigue
- depression
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.
4. Pantothenic acid (B5)
Pantothenic acid is needed to metabolise carbohydrates, proteins, fats and alcohol as well as produce red blood cells and steroid hormones.
Pantothenic acid is widespread and found in a range of foods, but some good sources include:
- beef liver
- shiitake mushrooms
- sunflower seeds
- meats
- tuna
- avocados
- milk
- kidneys
- eggs
- yeast
- peanuts
- legumes.
Because pantothenic acid is found in such a wide variety of foods, deficiency is extremely rare.
5. 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
- potatoes
- chickpeas
- fish and shellfish
- meat and poultry
- nuts
- liver
- fruit.
Pyridoxine deficiency is rare. People at risk of a vitamin B-6 deficiency include those who have:
- renal (kidney) disease
- had a kidney transplant
- celiac disease
- Crohn’s disease
- ulcerative colitis
- autoimmune disorders such as rheumatoid arthritis
- alcohol dependence
Pyridoxine toxicity is mostly due to supplementation and can lead to harmful levels in the body that can damage the nerves.
6. 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 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.
7. 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:
- dark green leafy vegetables
- beef liver
- avocado
- papaya
- beans
- nuts
- seeds
- liver
- poultry
- eggs
- cereals
- orange juice
- citrus fruits.
Since 2009, all bread sold in Australia (except organic) has been fortified with folic acid.
Although folic acid is generally considered non-toxic, excessive intakes above 1,000mcg 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 2 vitamins within the recommended amounts.
8. 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:
- beef liver
- meat
- clams
- salmon
- milk
- yogurt
- cheese
- eggs
- almost anything of animal origin.
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.
People can treat and prevent B vitamin deficiencies by increasing their dietary intake of high-vitamin foods or taking vitamin supplements.
Source:
https://www.betterhealth.vic.gov.au/health/healthyliving/vitamin-b
https://www.medicalnewstoday.com/articles/325292#supplements
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