Vitamin B12, also known as cobalamin, is one of eight water-soluble vitamins collectively known as the B-complex. As an essential nutrient, B12 must be consumed since your body does not make it. If you struggle with fatigue or are down in the dumps, you might wonder whether they are symptoms of vitamin B12 deficiency. Recent research indicates that B12 deficiency is more common than previously thought — up to 40 percent of the U.S. population. Vitamin B12 is structurally one of the largest and most complex of all the vitamins […]