Function: Synthesis of DNA, red blood cells; nerve development
Sources: Gut bacteria synthesis, organ meats, clams, oysters, soy, milk products, cheese, chlorella, spirulina
Optimal Intake: 50-200 micrograms (mcg)
Deficiency Signs: Macrocytic anemia; glossitis; spinal cord degeneration; digestive upset; fatigue; mental abnormalities, including irritability, depression
Toxicity: None reported