Vitamin B12, also known as cobalamin, is an essential water-soluble vitamin. It must be taken in through the diet; it is naturally present in some foods, added to others and is available as a dietary supplement and prescription medication. It is required in the body for the normal formation of red blood cells, nerve health and function, as well as DNA synthesis.
When vitamin B12 exists naturally in food it is bound to protein and needs to be released, this occurs through the activity of hydrochloric acid and enzymes in the stomach. In foods that are fortified with vitamin B12 and dietary supplements it is already in free form and does not need to be released. Free vitamin B12 combines with a substance in the stomach called intrinsic factor, the resulting complex can then be absorbed in the small intestine. Intrinsic factor is required to enable absorption of vitamin B12.
Vitamin B12 deficiency is characterised by megaloblastic anemia, fatigue, weakness, constipation, loss of appetite and weight loss. Numbness and tingling in the hands and feet can also occur. Further symptoms of vitamin B12 deficiency include difficulty maintaining balance, depression, confusion, dementia, poor memory and soreness of the mouth or tongue. Many of these symptoms are general and can result from a variety of medical conditions other than vitamin B12 deficiency.
The best sources of vitamin B12 are listed below:
It is important to understand the reasons for vitamin B12 deficiency in order to increase levels. For some dietary change may improve vitamin B12 status however for others supplementation or injections by the GP may be required.
I achieved a First-Class Honours degree in BSc Nutritional Science, Nutrition Sciences from the University of Reading and now have over 35 years experience in all types of cuisine, dietary plans, recipe development, health and nutrition. I have been writing for over 10 years for magazines and websites as well as ghostwriting for ebooks, Kindle and fully published books. I’m also a proud member of the Guild of Food writers.