Vitamin B12 and Folic Acid: Biochemistry, and Burden of Disease in India

Vitamin B12 (B12) and folic acid (FA) are two key, interdependent, B-group vitamins that are essential for carrying out several cellular reactions essential for vital systemic functions in humans. While it is important to understand the available natural sources of both B12 and FA, their modes of absorption, the factors that influence these, and subsequent biochemical reactions to diagnose clinically overt deficiency syndromes, the subclinical deficiency states can easily be missed in routine practice, with potential clinical ramifications. While FA deficiency states are relatively uncommon, thanks to the already existing food fortification policies in India, the B12 deficiency syndrome continues to remain as just a “tip of the iceberg” phenomenon, both at the community and hospital setting at large. This chapter aims to present a comprehensive overview of these two micronutrients, from their biochemistry to the burden of clinical/subclinical disease out of their deficiency in the Indian scenario.