The B Vitamins
There are eight members of the B-Complex group of vitamins – thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folate (B9), and cyanocobalamin (B12). They have inter-related and synergistic functions, and a deficiency of one or more can often cause deficiency in the others which is why they are most often taken together in supplement form. They play a vital role in the metabolism of fats, carbohydrates and protein and are components of enzymes that utilise the energy produced to generate new cells. They are necessary for the healthy functioning of the brain and nervous system, the immune system, the production of red blood cells, and the maintenance of healthy skin, hair, eyes, intestinal muscle and the liver.
The B vitamins are water-soluble and must therefore be consumed regularly as most are not stored by the body (B12 and folate are stored in the liver). They are found in whole unprocessed foods, particularly in meat, pulses, wholegrains, brewer’s yeast and molasses. Food processing, over-cooking, malabsorption syndromes and alcohol consumption can severely reduce their availability. In many countries thiamine, riboflavin, niacin, and folic acid are reintroduced into white flour after it has been processed, and many breakfast cereals are likewise fortified with B vitamins.
Because they are water-soluble, excess B vitamins are readily excreted in the urine, so large doses of supplements are unnecessary. The elderly may need to supplement their intake of B12 and other B vitamins due to impaired absorption, while athletes require more due to their increased needs for energy production. Folate deficiency in the early development of the foetus has been linked to neural tube defects such as spina bifida, so women planning to become pregnant are encouraged to take a folic acid supplement. The B-vitamins can also become depleted in those who drink lots of alcohol or who are under prolonged stress. Common symptoms of B-vitamin deficiencies include skin disorders, anaemia, poor food digestion and absorption, diarrhoea, nervous problems and mouth sores. Deficiency in in children can lead to hyperactive behaviour.
Vitamin B1 – Thiamin
Thiamin is necessary in order to convert carbohydrates into energy and for the health of the nervous system, cardiovascular system and muscles. It is involved in the production of RNA and DNA, and offers some protection from the degenerative effects of ageing. There is, as yet, inconclusive evidence that thiamine may help boost memory in cases of Alzheimer’s disease.
The amount of thiamin adults need is 1mg a day for men and 0.8mg a day for women. Food sources include pork, liver, wholegrains, seeds, nuts, pulses, wheatgerm, eggs, brewer’s yeast and fortified breakfast cereals.
In the West, thiamin deficiency is usually a result of poor diet or excessive alcohol consumption which affects its absorption in the gut and increases its excretion. Those who drink large quantities of coffee or tea may also have depleted thiamine levels. Characteristic deficiency symptoms include muscle weakness, tingling sensations, irritability, depression, irregular heartbeat, loss of appetite, weight loss, constipation and forgetfulness.
B2 – Riboflavin
Riboflavin is involved in the release of energy from protein, fats and carbohydrates, and is required for the maintenance of healthy skin, eyes and nervous system; it also has a role in the production of thyroid hormone. It is also necessary for the conversion of Vitamins B3 and B6 into their active forms. Riboflavin may delay or prevent the development of cataracts and is believed to reduce the frequency and severity of migraines.
Daily requirements for adults are around 1.3mg a day for men and 1.1mg a day for women. Food sources include milk, yoghurt, cottage cheese, wholegrain breads and cereals, egg white, leafy green vegetables, meat, brewer’s yeast, liver and kidney. Riboflavin is destroyed by ultra-violet light so these foods should be kept out of direct sunlight.
Deficiency is rare but more common in those who consume excessive alcohol or who adopt dairy-free diets. Characteristic symptoms of riboflavin deficiency include eye disorders, light sensitivity, cracked lips, inflamed tongue, mouth sores, peeling skin, hair loss, and digestive disorders. High intakes of riboflavin may turn the urine bright yellow.
B3 – Niacin
Niacin is involved in the metabolism of glucose, fats and alcohol, and helps to control blood sugar levels. It plays a role in the formation of steroids, sex hormones and red blood cells and helps maintain healthy skin, brain and nervous system. It is involved in the production of stomach acid and other digestive secretions. There is some evidence to suggest that niacin supplementation may be of benefit to those suffering from anxiety and depression.
The best sources of niacin are high-protein foods such as meat and fish, or foods with a high tryptophan content such as eggs and dairy products. The body is able to obtain about half of its niacin requirements by converting it from tryptophan, an amino acid. Daily requirements of niacin are around 16.5mg a day for men and 13.2mg a day for women.
Most niacin supplements are sold in the form of nicotinamide. Niacin supplements in the form of nicotinic acid may cause skin flushing, itching and fainting and should therefore be taken only on the advice of a doctor.
A deficiency of niacin may lead to depression, fatigue, insomnia, muscle weakness, skin conditions, low blood sugar and poor digestion. Chronic deficiency leads to pellagra, the main symptoms of which are dementia, diarrhoea and dermatitis. People who consume excessive alcohol are particularly at risk.
High doses of niacin supplements can cause skin flushing and, if use is prolonged, could lead to liver damage.
B5 – Pantothenic acid
Pantothenic acid is necessary for the release of energy from carbohydrates, proteins, fats and alcohol. It is involved in the production of red blood cells and steroid hormones. Known as the anti-stress vitamin, it is required in greater amounts during periods of stress due to its role in the production of corticosteroid hormones which enable the body to better cope with demanding situations. It enhances stamina and is often used in the treatment of anxiety and depression. It is required for a healthy skin, brain and immune system.
Almost all meats and vegetables contain pantothenic acid, particularly liver, kidney, eggs, brewer’s yeast and pulses, so pantothenic acid deficiency is extremely rare in those with a varied and balanced diet. Characteristic symptoms include appetite loss, fatigue, nausea and insomnia, tingling in the hands, constipation and vomiting.
B6 – Pyridoxine
Pyridoxine is involved in a huge range of bodily functions. It plays a vital role in the release and utilisation of energy, the formation of red blood cells, protein and fat metabolism and the activation of enzyme systems. It helps maintain the health of the cardiovascular and immune systems, the brain and nervous system, and is involved in the synthesis of DNA and RNA.
Pyridoxine is a popular supplement for premenstrual women as it supports the endocrine system and production of prostaglandins and is believed to reduce the effects of high oestrogen levels, a factor in premenstrual syndrome. Many asthma sufferers find that a pyridoxine supplement reduces the intensity and frequency of attacks. It is also frequently used in the treatment of carpal tunnel syndrome.
The daily pyridoxine requirement for adults is around 1.4mg a day for men and 1.2mg a day for women. Food sources include wholegrains, pulses, eggs, milk, leafy green vegetables, fish, meat, nuts, bananas and fortified breakfast cereals.
Characteristic symptoms of pyridoxine deficiency include mouth sores, skin disorders, insomnia, irritability, depression, fatigue, headaches, impaired growth, pink eye, neurological symptoms such as twitching muscles convulsions and confusion. Those most at risk are heavy drinkers, women who take the contraceptive pill, the elderly, and people with thyroid disorders.
Excessive supplementation cause peripheral neuropathy, a numbness in the hands and feet, which will improve when supplements are withdrawn but which may lead to permanent, irreversible nerve damage if large doses of the vitamin are taken over a prolonged period.
B7 – Biotin
Very small amounts of biotin are required by the body so deficiency is rare. It plays a role in fat, protein and carbohydrate metabolism and is necessary for the normal growth and development of healthy bone marrow, nerve, muscle, skin and nail cells. It may help improve the quality of brittle fingernails.
Biotin is found at low levels in foods such as egg yolk, nuts, brewer’s yeast, mushrooms, chicken and cauliflower. It is also produced by our intestinal bacteria so it is essential to maintain a healthy gut flora. Antibiotic use destroys those bacteria, so it is worth taking a course of probiotics following antibiotic therapy.
A varied diet and healthy gut flora should provide sufficient biotin for the body’s needs.
Deficiency does not typically cause symptoms in adults but can include skin disorders, hair loss, depression and a sore tongue. Biotin deficiency in infants may lead to impaired growth and neurological disorders.
A very high intake of biotin may contribute to elevated blood cholesterol levels.
B9 – Folate
Folic acid, known as folate in its natural form, is required for the formation of red blood cells. It is vital for the development of the foetal nervous system, and is necessary for the synthesis of DNA and RNA and for cell growth. It helps maintain normal cholesterol levels and supports the immune system by playing a role in the formation and functioning of white blood cells. Recent research shows that folic acid may also offer protection against health problems later in life.
Food sources include leafy green vegetables, broccoli, brussels sprouts, liver, poultry, eggs, pulses, seeds, fortified breakfast cereals. It is not stored in the body, so must be included in the diet every day.
Adults require 200 µg of folate/folic acid a day. The Department of Health advises that 400 µg folic acid be supplemented by all women planning a pregnancy up until the end of the first trimester. Research has shown that itis essential for the normal development of the baby’s neural tube, a vital part of the nervous system, reducing the risks of defects like spina bifida.
Folate can become depleted in those who smoke, drink lots of alcohol, suffer from malabsorption diseases or who are extremely stressed. Characteristic deficiency signs and symptoms include a sore, red tongue, anaemia, fatigue, digestive disorders, memory loss and laboured breathing. Severe deficiency can result in megaloblastic anaemia.
Excessive intake of folic acid supplements can mask the symptoms of Vitamin B12 deficiency which can lead to damage to the nervous system and intestinal dysfunction if left untreated. This is of particular concern in the elderly as it becomes increasingly difficult to absorb Vitamin B12 with advancing age. Too much folate can be a risk for people with hormone-related cancers such as breast or prostate cancer.
B12 – Cyanocobalamin
An adequate intake of Vitamin B12, along with iron and folate, is essential for red blood cell production. It is required for the formation and maintenance of the myelin sheath covering and protecting nerve cells. It plays a role in the digestion and absorption of food, protein synthesis and the metabolism of carbohydrates and fatty acids. It is also required for the synthesis of DNA and RNA.
Food sources include liver, meat, fish, milk, cheese and eggs. Adults require about 1.5µg a day of vitamin B12, which is stored in the liver. It improves the immune response, particularly in the elderly.
Vitamin B12 deficiency is most commonly found in the elderly who often suffer from malabsorption syndromes or the autoimmune disease pernicious anaemia, people with digestive disorders such as Crohn’s disease, and in those who follow a vegan diet. Characteristic symptoms are fatigue, loss of appetite and other digestive disorders, palpitations, shortness of breath, disturbed vision, depression and memory loss. Prolonged deficiency leads to anaemia. Sufferers of Alzheimer’s disease appear to have low levels of B12 but it is unclear as yet whether this is a cause of effect of the disease.
Excess Vitamin B12 is excreted in the urine.