Abstract

Vitamin B12 (cobalamin) is a water-soluble vitamin. It is a crucial vitamin for the health of humans, contributing immensely to numerous biological processes. This study aims to highlight the importance of vitamin B12 in nourishing hair growth and the nervous system and how its malabsorption might trigger various problems in the body. Major absorption of vitamin B12 takes place in the small intestine from several foods like milk, eggs, fish, liver, meat, and yoghurt. Several factors can cause malabsorption of vitamin B12, including atrophy of the gastric mucosa, disease of the terminal ileum in the body, and cigarette smoking. These factors can lead to the demyelination of large nerve fibers in the spinal cord, a variation in the fraction of S-adenosylmethionine to S-adenosylhomocysteine, and an alteration in TNF and epidermal growth factor (EGF) levels, which can cause optic neuropathy and hair loss. Maintaining a proper diet and leading a healthy lifestyle are crucial for maintaining vitamin B12 levels in the body, as the body can store this vitamin for up to 3–6 years. Mainly, the level of vitamin B12 in the healthy human body is 160 to 950 picogrammes per millilitre In conclusion, the factors leading to malabsorption of vitamin B12 and their consequent deficiencies were examined. The body's numerous crucial functional pathways are influenced by vitamin B12.

Keywords: Vitamin B12, malabsorption, cigarette smoking, deficiency, nervous system defects, hair loss.