Discovering everything you need to know about vitamin B12 would take months of research. For beginners, here are a few basic question and answer topics designed to give you a quick overview. The most important thing for vitamin B12 explorers to remember is that there is more to B12 than meets the eye. Clearly stated, there is more to vitamin B12 than meets the blood stream.
What exactly is Vitamin B12?
Vitamin B12 is a water-soluble organic compound essential to humans that was first isolated in 1948 by chemists Karl Folkers and Baron Alexander Todd. Vitamin B12 is a vitamin that aids in the development of red blood cells, and is unique because it contains the metallic ion cobalt. Chemically speaking, B12 occurs in forms known as cobalamins. B12 is also known as Cyanocobalamin, which is the form most commonly used in various vitamin supplements and prescription pharmaceuticals. 
What does Vitamin B12 do for the human body?
Everything you need to know about vitaminB12 and its role in the human body begins with understanding that B12 is extremely necessary for the proper production of DNA and red blood cells. Vitamin B12 is also involved in cellular metabolism and the synthesis of fatty acids that surround nerve cells.
What does a Vitamin B12 deficiency do to the human body?
The lack of vitamin B12 leads to hypocobalaminemia , which is simply defined as a low level of vitamin B12. Hypocobalaminemia can cause permanent damage to nervous tissue as a long term effect . Some patients with dementia and cognitive impairment have been treated successfully after being diagnosed with vitamin B12 deficiencies, but if the deficiency has been prolonged, reversal may be impossible.
What Foods Contain Vitamin B12?
To make sure you are getting enough vitamin B12 in your diet, choose to eat foods with significant quantities of vitamin B12. Fish, Liver, Beef, Eggs, Dairy, and fortified cereal products are all foods that contain various quantities of vitamin B12. Many energy drinks and energy “shots” also contain large quantities of vitamin B12, often several times more than the recommended daily allowance. The USDA National Data Base provides a detailed list of Selected Foods that contain VitaminB12 sorted by nutrient content . Unfortunately, there are no vegan foods that contain vitamin B12, so it is extremely important for vegans to seriously consider taking a B12 supplement or shots in order to avoid health risks.
What Supplemental Forms are available for Vitamin B12?
In over-the-counter supplements, vitamin B12 is usually present as cyanocobalamin, a form that the body readily converts to the active forms methylcobalamin and 5-deoxyadenosylcobalamin. Dietary supplements can also contain methylcobalamin and other forms of vitamin B12. In addition to oral dietary supplements, vitamin B12 is available in over-the-counter sublingual preparations as tablets, lozenges, or lollipops. These preparations are frequently marketed as having superior bio-availability.
Vitamin B12 can also be administered as a prescription medication in the form of a liquid shot that is injected either intravenously or intramuscular. Prescriptions of B12 are also available for a gel formulation that is applied through the nose, or in a transdermal patch form that adheres to the skin. 
- Encyclopædia Britannica. Vitamin B12
- Wikipedia. Vitamin B12 deficiency
- The Vitamins and Nutrition Center. Vitamin B12 Deficiency and Dementia
- USDA Agricultural Research Services. SR24 – Reports by Single Nutrients
- National Institutes of Health Office of Dietary Supplements. Dietary Supplement Fact Sheet Vitamin B12
- The great benefits of b12 shots