Chemistry · Ch 14 — Biomolecules
Classification of Vitamins
Classification of Vitamins
Vitamins are classified into two groups based on their solubility, either in water or in fat.
Fat-soluble vitamins are best absorbed when taken together with fatty food, and because they do not dissolve in water they are instead stored in fatty tissues and in the liver. Vitamins A, D, E and K are the fat-soluble vitamins.
Water-soluble vitamins -- the B vitamins (B1, B2, B3, B5, B6, B7, B9 and B12) and vitamin C -- are, by contrast, readily soluble in water. Unlike the fat-soluble vitamins, these cannot be stored in the body: any excess is simply excreted through the urine, so water-soluble vitamins must be supplied to the body regularly through the diet. The gaps in the B-vitamin numbering (there is no B4, B8, B10 or B11 in current use) exist because those numbers were originally assigned to substances once thought to be vitamins but later found not to qualify; the numbers were simply never reassigned, leaving permanent gaps in the seq …
| Vitamin | Sources | Functions | Deficiency Disease |
|---|---|---|---|
| Vitamin A (Retinol) | Liver oil, fish, carrot, milk, spinach and fruits such as papaya and mango | Vision and growth | Night blindness, xerophthalmia, keratinisation of skin |
| Vitamin B1 (Thiamine) | Yeast, milk, cereals, green vegetables, liver, pork | Co-enzyme in the form of thiamine pyrophosphate (TPP) in glycolysis | Beri-beri (peripheral nerve damage) |
| Vitamin B2 (Riboflavin) | Soybean, green vegetables, yeast, egg white, milk, liver, kidney | Coenzyme in the form of FMN (flavin mononucleotide) and FAD (flavin adenine dinucleotide) in redox reactions | Cheilosis (lesions of the corner of the mouth, lips and tongue) |
| Vitamin B3 (Niacin) | Cereals, green leafy vegetables, liver, kidney | Coenzyme in the form of NAD⁺ and NADP⁺ in redox reactions | Pellagra (photosensitive dermatitis) |
| Vitamin B5 (Pantothenic acid) | Mushroom, avocado, egg yolk, sunflower oil | Part of coenzyme A in carbohydrate, protein and fat metabolism | Inadequate growth |
| Vitamin B6 (Pyridoxine) | Meat, cereals, milk, whole grains, egg | Coenzyme in amino acid metabolism, formation of heme in haemoglobin | Convulsions |
| Vitamin B7 (Biotin) | Liver, kidney, milk, egg yolk, vegetables, grains | Coenzyme in fatty acid biosynthesis | Depression, hair loss, muscle pain |
| Vitamin B9 (Folic acid) | Egg, meat, beetroot, leafy vegetables, cereals, yeast | Nucleic acid synthesis, maturation of red blood cells | Megaloblastic anaemia |
| Vitamin B12 (Cobalamin) | Egg, meat, fish | Coenzyme in amino acid metabolism, red blood cell maturation | Pernicious anaemia |
| Vitamin C (Ascorbic acid) | Citrus fruits (orange, lemon etc.), tomato, amla, leafy vegetables | Coenzyme, antioxidant, building of collagen | Scurvy (bleeding gums) |