U01.01.062 Vitamins: Water soluble

Water-soluble vitamins play essential roles in various metabolic processes. Most of these vitamins are easily excreted in urine, except for B12 and B9 (folate), which are stored in the body for varying durations.

Key Water-Soluble Vitamins

The following list includes the primary water-soluble vitamins, their active forms or coenzymes, and their key functions:

Vitamin	Active Form/Coenzyme	Function
B1 (Thiamine)	Thiamine pyrophosphate (TPP)	Involved in carbohydrate metabolism and nerve function.
B2 (Riboflavin)	Flavin mononucleotide (FMN), Flavin adenine dinucleotide (FAD)	Essential for redox reactions, involved in energy production.
B3 (Niacin)	Nicotinamide adenine dinucleotide (NAD+), NADP+	Key role in redox reactions, energy metabolism.
B5 (Pantothenic Acid)	Coenzyme A (CoA)	Important for fatty acid metabolism and synthesis of CoA.
B6 (Pyridoxine)	Pyridoxal phosphate (PLP)	Critical for amino acid metabolism and neurotransmitter synthesis.
B7 (Biotin)	Biotin	Involved in carboxylation reactions in metabolic pathways.
B9 (Folate)	Tetrahydrofolate (THF)	Important for DNA synthesis and repair, especially during cell division.
B12 (Cobalamin)	Methylcobalamin, 5′-Deoxyadenosylcobalamin	Key role in DNA synthesis, red blood cell formation, and neurological function.
C (Ascorbic Acid)	Ascorbate	Antioxidant, involved in collagen synthesis, and iron absorption.

Storage and Excretion

Excretion: All water-soluble vitamins, except for B12 and B9, are easily excreted from the body in urine.
Storage:
- B12: Stored in the liver for approximately 3–4 years.
- B9: Stored in the liver for approximately 3–4 months.

Deficiencies and Clinical Manifestations

Deficiency in B-complex vitamins can lead to several common symptoms, including:

Dermatitis: Inflammation of the skin, often seen in deficiencies of B2, B3, and B6.
Glossitis: Inflammation of the tongue, commonly associated with B-complex deficiencies.
Diarrhea: A common symptom due to impaired digestion and absorption.

Coenzyme and Precursors

Some water-soluble vitamins act as coenzymes (e.g., ascorbic acid in collagen synthesis).
Others serve as precursors to coenzymes (e.g., FAD from riboflavin, NAD+ from niacin).

Points to Remember

Water-soluble vitamins are essential for numerous metabolic processes and are typically excreted in the urine, except for B12 and B9, which are stored in the liver.
A deficiency in B-complex vitamins can lead to skin issues, tongue inflammation, and digestive problems.
B12 and B9 have long-term storage capabilities, with B12 stored for several years and B9 for several months.

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