Vitamins B6, Folic Acid and B12: Molecular Functions and Prevalence of Deficiency in India

Abstract

Vitamin B6 (B6), folate, and vitamin B12 (B12) are essential right from the inception of life as important players in numerous biochemical and molecular functions. They are interdependent, and deficiency of one of them is likely to influence the metabolism of the other. B6 is involved in numerous reactions such as synthesis of neurotransmitters, histamines, and haemoglobin; and transamination, and decarboxylation reactions. Recent studies have revealed the role of B6 in various non-enzymatic reactions as an antioxidant, carbonyl scavenger, metal chelator, and antiglycating agent. Folate plays a pivotal role due to its involvement in the synthesis of precursors of DNA and RNA, methylation reactions and metabolism of some amino acids. B6 along with folate and B12 play a crucial role in the network of one-carbon metabolism, which governs a myriad of functions in the body. Suboptimal B6 status is associated with various diseases. Impaired folate status is implicated in various chronic diseases including megaloblastic anaemia, neural tube defects, cardiovascular diseases, cancer and neurological problems. Low intake of B12 results in methylmalonic aciduria leading to neurological problems and also megaloblastic anaemia. Reports on the prevalence of B6 deficiency are scarce in India. The majority of the studies on folate and B12 deficiencies are focused on categories of the population such as elderly people, pregnant women, and children. In other cases, studies on folate and B12 were carried out in connection with some disease conditions such as cognitive dysfunction, anaemia, low birth weight and maternal nutrition. The molecular functions of these vitamins and studies on the prevalence of deficiency of these vitamins in India have been summarized in this review.