Forming red blood cells

Perhaps the most well-known function of B12 involves its role in the development of red blood cells. As red blood cells mature, they require information provided by molecules of DNA. (DNA, or deoxyribose nucleic acid, is the substance in the nucleus of our cells which contains genetic information.) Without B12, synthesis of DNA becomes defective, and so does the information needed for red blood cell formation. The cells become oversized and poorly shaped, and begin to function ineffectively, a condition called pernicious anemia. More often than not, pernicious anemia isn't caused by a lack of B12 itself, but by a lack of intrinsic factor -- the stomach-made protein required for the absorption of B12.