Known as the energy vitamin, B12 aids in the formation of blood cells in bone marrow and the production of genes, and nerve tissue. Older people often use B12 as an energy boost, and to help prevent mental deterioration. The main food sources are red meat, fish, poultry, eggs, and milk. A deficiency can lead to sore tongue, weakness, fatigue, weight loss, back pain and, in extreme cases, severe anemia (a lack of oxygen in the blood).
