Historically, the B vitamins were once thought to be a single vitamin, referred to as vitamin B (much like how people refer to vitamin C or vitamin D). The vitamin B family consists of 8 chemically distinct B vitamins that often coexist in the same foods. B Vitamins help us use energy. B vitamins are all required for different stages of the process whereby energy is released from the food we eat every day. The vitamins that make up the B Family are Thiamin (B1), Riboflavin (B2), Niacin (B3), Pantothenic Acid (B5), Pyridoxine (B6), Biotin (B7), Folic Acid (B9), Cyanocobalamin (B12).

All B vitamins are water soluble, and are dispersed throughout the body. Most of the B vitamins must be replenished daily, since any excess is excreted in the urine. All of the B vitamins are important, but people will often use specific B vitamins for their unique properties. For example, vitamin B12 (the focus of this article) can benefit vegetarians who may be deficient in this nutrient.

Vitamin B12 is also known as the "red vitamin" and its primary functions are in the formation of red blood cells and the maintenence of a healthy nervous system. Vitamin B12 is necessary for the rapid synthesis of DNA during cell division. This is especially important in tissues where cells are dividing rapidly, particularly the bone marrow tissues responsible for red blood cell formation. If vitamin B12 deficiency occurs, DNA production is disrupted and abnormal cells called megaloblasts occur and can result in anaemia.

Symptoms include excessive tiredness, breathlessness, listlessness, pallor, and poor resistance to infection. Other symptoms can include a smooth, sore tongue and menstrual disorders. Anaemia may also be due to folic acid deficiency, folic acid also being necessary for DNA synthesis. Vitamin B12 is also important in maintaining the nervous system and plays an important role in concentration, balance and memory.. Nerves are surrounded by an insulating fatty sheath comprised of a complex protein called myelin. Vitamin B12 plays a vital role in the metabolism of fatty acids essential for the maintainence of myelin. Prolonged vitamin B12 deficiency can lead to nerve degeneration and irreversible neurological damage.

Vitamin B12 is hard to digest so we need to ingest much higher amounts than the RDA in order to absorb enough. Vitamin B12 is found only in animal foods, so a supplement may be needed to aquire the RDA. Because vitamin B12 is stored in the liver, kidneys and other body tissues. Most people, apart from vegans, have a three to five year supply in their bodies. For this reason it may take years of a vitamin B12 deprived diet to show signs of vitamin B12.

Initial symptoms of vitamin B12 deficiency can include dizziness and shortness of breath, fatigue, mild depression, irritability and confusion. If left untreated Vitamin B12 deficiency can cause progressive damage to the nervous system, especially the nerves outside the brain and spinal cord. When the spinal cord is involved, the first symptoms include difficulty in feeling vibrations in the feet, loss of position sense, and loss of muscle co-ordination (ataxia). As a general rule, most individuals who develop a vitamin B12 deficiency have an underlying stomach or intestinal disorder that limits the absorption of vitamin B12 [10]. Sometimes the only symptom of these intestinal disorders is subtly reduced cognitive function resulting from early vitamin B12 deficiency.

It is important to note that vitamin B12 supplements can be destroyed if taken within an hour of large amounts of vitamin C. Absorption can also be impaired by deficiencies in folic acid, iron or vitamin While adverse effects resulting from taking vitamin B12 supplements are extremely rare, side effects may include swelling, itching, and shock. Very high doses of vitamin B12 may sometimes cause acne. Other uncommon side effects include skin rash, hot flushes, nausea, dizziness and cardiac arrhythmias.

Use of nicotine or excessive alcohol can also deplete vitamin B12. Improved absorption of vitamin B12 occurs when it is taken with other B vitamins or calcium. Some medications may also cause an increased use or decreased absorption of vitamin B12 (eg corticosteroids, oral contraceptives, colchicine, proton pump inhibitors).