Vitamins B complex

B vitamins are a class of water-soluble vitamins that play important roles in cell metabolism. Though these vitamins share similar names, research shows that they are chemically distinct vitamins that often coexist in the same foods. In general, supplements containing all eight are referred to as a vitamin B complex. Individual B vitamin supplements are referred to by the specific name of each vitamin (e.g., B1, B2, B3 etc.).

1. Aamir Ali Khan M.Phil Biochemistry Head of Pathology Department Northwest Institute of Health sciences

2. Vitamins Classification Chart

3. Vitamins Water-soluble Thiamine Riboflavin Niacin Pyridoxine Biotin Folic acid Cobalamin Ascorbic acid Pantothenic acid Fat-soluble Vitamin A Vitamin D Vitamin K Vitamin E

4. Thiamine B1 Vitamin B 1 Biologically active form thiamine pyrophosphate (TPP) Also can have TTP Function cofactor in oxidative decarboxylation of a- keto acids (TCA, AA degradation) RC(O)COOH to RC(O)OH + CO 2 Other coenzymes also involved in process Sources pork, whole grains, legumes, tuna, soy milk RDA 0.5 mg/1000 Cal intake or min 1 mg/day Deficiency decreased ATP production impaired cellular function Beriberi

5. Riboflavin B2 Vitamin B 2 ; vit G? Biologically active forms Flavin mononucleotide (FMN) Flavin adenine dinucleotide (FAD) Function Electron transfer FMNH 2 , FADH 2 Redox reactions (TCA, glycolysis, etc.) Needed for good vision and healthy skin Sources Milk, mushrooms, tomatoes, liver, green leafy vegetables RDA 1.1-1.3 mg/day Deficiency Growth retardation Ariboflavinosis Glossitis ( Glossitis can mean soreness of the tongue). Stomatitis ( Stomatitis is inflammation of the mouth and lips)

6. Niacin B3 Biologically active forms NAD + , Nicotinamide adenine dinucleotide NADP + Nicotinamide (readily deaminated, also in diet) Function Coenzymes in redox reactions (TCA, FA synthesis, gluconeogenesis, etc.) DNA repair Sources Unrefined grains, fortified cereal, meat, fish, tomatoes, mushrooms, milk, liver, rice Metabolism of tryptophan when AA is abundant (needs riboflavin and B6) RDA 14-16 NE/day (NE = niacin equivalents = 1 mg niacin or 60 mg tryptophan) Deficiency Pellagra = “rough skin” Toxicity Skin inflammation, heartburn, nausea, liver damage

7. Pyridoxine B6 Vitamin B 6 , pyridoxal, pyridoxamine Biologically active form pyridoxal phosphate (PLP) Function Coenzyme for transamination reactions, esp. AAs (neurotransmitters) Decarboxylation of carboxylic acids Sources Wheat, corn, egg yolk, liver, potato, banana, fish, chickpeas RDA 1.3-1.7 mg Deficiency Induced by TB drug isoniazid (supplement given) Dermatitis, fatigue Depression, confusion Convulsions, seizures Microcytic hypochromic anemia Epidemic in 1950s Toxicity Neurological disorders at > 2 g /day

8. Biotin B7 Biologically active form Binds to lysine residue of enzyme Function Cofactor in carboxylation reactions, carrier of CO 2 (acetyl-CoA to malonyl-CoA, synthesis of fatty acids) Regulation of gene expression Sources Almost all food, esp. milk, egg yolk, tomato, almond, peanuts, avocado, mushroom Also synthesized by intestinal bacteria RDA At least 30 mg/day Deficiency Deficiency does not occur naturally unless eat 20 raw egg whites per day (protein avidin binds biotin irreversibly and excreted)

9. Folic acid Biologically active form Tetrahydrofolate (THF) Function Stimulates digestive acids; appetite Receive one carbon fragments from donors and transfer them in AA synthesis and nucleotide synthesis Sources Green leafy veggies (“foliage”), organ meats, legumes, okra, whole grain cereals RDA 400 mg/day, more during pregnancy and lactation Deficiency Megaloblastic /macrocytic anemia and growth failure Once, most common vitamin deficiency in US; now fortified cereals Absorption inhibited by many medicines, so a problem with the elderly

10. Cobalamin 12 Vitamin B 12 Corrin ring system with Co in center ( Corrin is an heterocyclic compound. It is the parent macrocycle related to substituted derivative that is found in vitamin B 12 . Its name reflects that it is the "core" of vitamin B 12 ) Function Synthesis of Met Methylmalonyl-CoA to succinyl-CoA Degradation of odd-chain FA, enter TCA Transfer of methyl groups Produce red blood cells Sources Liver, whole milk, cottage cheese, oysters, salmon, clams, eggs, shrimp, pork, chicken (animal sources) RDA 2.4 mg/day Deficiency Caused by pernicious anemia Methylmalonic acidemia (MMA)