Vitamin B12, like all other vitamins, is a necessary part of any diet and a deficiency in vitamin B12 can lead to a number of symptoms such as pernicious anemia, paleness, weakness, fatigue, nerve damage, delirium, paranoia and impaired mental function. Vitamin B12 deficiency is normally associated with the elderly, people who follow a strict vegetarian diet as well as various illnesses.
A deficiency of vitamin B12 has also been linked to high levels of homocysteine which are partly responsible for heart disease and may also be linked to chronic fatigue syndrome and fibromyalgia.
The Jack Miller Center for Peripheral Neuropathy at the University of Chicago says the following on their website, "Vitamin B12 deficiency is common in the United States, especially among the elderly. It is estimated that between 10% and 25% of the people over 80 years of age may have a B12 deficiency. A strict vegetarian diet may promote a B12 deficiency because animal based foods such as red meat, dairy products, fish, poultry and eggs are the only recognized source of dietary B12." (http://millercenter.uchicago.edu/learnaboutpn/typesofpn/systemic/nutrition.shtml)
Vitamin B12 deficiency has also been linked to mental disorders such as Alzheimer's and depression as well as HIV. The Alzheimer's and depression are related to high homocysteine levels and the lack of B12 to help keep these levels down. Research was also done with 700 women to determine the effects of vitamin B12 deficiency on depression and it was found that those suffering from B12 deficiency "were 2.05 times as likely to be severely depressed as were non-deficient subjects." (http://ajp.psychiatryonline.org/cgi/reprint/157/5/715)
If you are suffering from any symptoms of vitamin B12 deficiency you should try to include food rich in vitamin B12 in your diet including fish, dairy, organ meats, eggs, beef and pork as well as taking a good multi-vitamin with vitamin B complex and perhaps reinforcing this with vitamin B12 injections.
Vitamin B12 is vital for physical and mental wellbeing and a deficiency in vitamin B12 can lead to pernicious anemia and contribute to chronic fatigue, fibromyalgia, heart disease, Alzheimer's and depression due to the high levels of homocysteine related to B12 deficiency. In order to get the necessary vitamin B12 you should ensure that your diet includes fish, dairy, organ meats, eggs, beef and pork and you should consider taking a good multi-vitamin and vitamin B complex injections.
Glossary:
Homocysteine: amino acid in the blood which can lead to heart disease and various other ailments when levels are too high.