Vitamin B-12, also called cobalamin, is one of eight B vitamins that are vital for good mood. Vitamin B-12 is involved in the formation of neurotransmitters or chemicals that help relay signals from one area of the brain to another. Serotonin and dopamine are examples of neurotransmitters that are necessary for balanced mood and happy emotions.
B-12 and Neurotransmitters
The production of many neurotransmitters is critically dependent on a type of biochemical reactions known as methylation, which involves the passing of a methyl group -- one carbon and three hydrogen atoms -- from one molecule to another. Vitamin B-12 participates in methylation by helping a compound called S-adensosyl methionine, commonly known as SAM or SAM-e, pass a methyl group to an amino acid to make neurotransmitters. If vitamin B-12 is deficient, SAM-e cannot do its job, and the production of the feel-good chemicals suffers.
Toxic Brain
If your body does not produce enough vitamin B-12, a toxic chemical known as homocysteine builds up in your brain, which may increase depression. A study published by Oxford University Press in 2011 found that high levels of homocysteine can worsen depression and that lowering levels of the toxic chemical reduces depression. Vitamin B-12 is important because it helps convert homocysteine into SAM-e, boosting neurotransmitter production. Homocysteine also damages brain cells and interferes with the coordination of brain function.
Sources
Vitamin B-12 is an essential nutrient, which means that your body cannot synthesize or make it in adequate amounts. That's why it is necessary to supplement. Vitamin B-12 is commonly found in animal sources and fortified foods such as fish, shellfish, meat, eggs, dairy products and fortified cereals. Vitamin B-12 is also found in many vitamin B-complex formulations. When buying vitamin B-12, choose methylcobalamin or methyl B-12 over cyanocobalamin because the former exists biologically in your body whereas the latter does not.
B-12 Deficiency
According to a Tufts University study, 39 percent of people between the ages of 26 and 83 have plasma B-12 levels in the low-normal range, 16 percent are at "near deficiency" and 8 percent are deficient in the vitamin.
Many factors contribute to vitamin B-12 deficiency. Some of these risk factors are vegetarian and vegan diets, malabsorption conditions such as celiac and Crohn's disease, alcohol consumption and the use of common pharmaceutical drugs such as oral contraceptives, acid blockers and some diabetes drugs. Elderly people are especially at risk because stomach-acid production decreases with increasing age and stomach acid is necessary to release vitamin B-12 from food.