Vitamin B12 (cobalamin) plays an essential role in your metabolism. This molecule is necessary for the production of amino acids and the proper synthesis of cellular DNA. It acts synergistically with folic acid, contributing to the formation of blood cells and the preservation of nerve function (1, 2).
If your vitamin B12 levels are insufficient, DNA formation in new cells is impossible. The synthesis of myelin, a substance that surrounds nerve fibers, will also be reduced. In addition, the paralysis of enzymatic processes will lead to the deposition of molecules such as homocysteine.
If your organism cannot create new cells, you will have anemia. At a microscopic level, you can observe how the cellular precursors grow in size, preparing for a division that isn't possible due to the B12 deficiency. This is known as megaloblastic anemia, which literally means few large-size blood cells (3).
If your nervous system loses its protective lining, it will undergo degenerative changes. Nerve fibers need to be protected by the myelin sheath in order to transmit electrical impulses to the brain. A lack of B12 will cause demyelination; this affects your balance, vision, memory, and concentration, among other things (1, 4).
If a homocysteine deposit occurs, the cardiovascular risk may increase. Some studies have linked increased plasma homocysteine concentrations to a higher risk of cardiovascular events or stroke. These findings are currently under study (5, 6).
These alterations will harm your quality of life. Megaloblastic anemia will decrease your resistance to fatigue. At the same time, degeneration of the nervous system can cause you to experience brain fog, the lack of concentration that vegans worry about so much. We have listed more symptoms of vitamin B12 deficiency in the following table (3, 4, 6, 7):