One of the essential B vitamins, B12 has many functions in human health. It helps form red blood cells and converts carbohydrates into glucose, promoting energy. B12 also promotes the health of the nervous system.
Vitamin B12 is found naturally in foods like red meat, egg yolks, liver and dairy products. Deficiencies in B12 can occur in people over the age of 40 from decreased ability of the intestines to absorb it from food.