Vitamins Vitamins are essential for life Vitamins are needed in small amounts Vitamins do not provide energy Vitamins have to be supplied by foods History Purified diets of carbohydrate, protein, fat, minerals and water were not capable of normal growth “Accessory growth factors” Casimir Funk, a Polish biochemist, isolated an antiberberi substance from rice polishings Named it vitamine An amine Vital for life

Classification of Vitamins Classified according to solubility — Determines site in body were they function Body tissues: watery or fatty (oily) — Fluids outside/inside body cells = waterbased — Cell membranes (layers)/nerve tissues = fatty substances Vitamins that function in the watery areas = water-soluble vitamins Vitamins that function in fatty tissues = fat-soluble vitamins

Fat versus water soluble vitamins Fat-soluble vitamins Dissolve in fat Need fat: for absorption & transport Can be stored in body: liver, adipose tissue Water-soluble vitamins Dissolve in water Are easily absorbed and excreted (via urine) Are not easily stored

Fat soluble vitamins Vitamin A = retinol Vitamin D3 = cholecalciferol Vitamin E = α- tocopherol Vitamin K1 = phylloquinone d Water soluble vitamins B-group — B1 = thiamin — B2 = riboflavin — Niacin = nicotinamide = nicotinic acid = B3 — Pantothenic acid = B5 — B6 = pyridoxine — Biotin = vitamin B8 = vitamin H — Folic acid = folate = B11 — B12 = cobalamin ِ Vitamin C = ascorbic acid

Function Essential for many processes in body Vitamins play a role in digestion & utilization of — Protein — Fat — Carbohydrates Vitamins are components of enzymes Some vitamins can be synthesised by body itself vitamin A β-carotene — β-carotene = pro-vitamin A = vitamin A precursor (fore-runner) From cholesterol vitamin D — In skin under influence of sunlight — Daily: 5-10 minutes Bacterial flora in GI-tract vitamin K

Vitamin A Growth & repair of body tissues Bone formation Normal vision Immune function Deficiency: eye diseases leading to blindness

Function of Vitamin D

Vitamin A deficiency. 1. Impaired night vision (night blindness). 2. Dried skin, and mucous membranes fail to secrete mucus, causing: a)Drying and hardening of the cornea. 2) Severe – keratomalacia (total blindness) b) Drying and hardening of salivary glands, susceptible to infection, loss of appetite. c) Changes in GI tract lining, causing diarrhea. β-carotene is an antioxidant, which may decrease the risk of CVD and lung cancer.

Vitamin D Ca & P absorption / utilization: building bone mass & preventing bone loss Skeletal integrity Deficiency: rickets (malformation of bones) Vitamin D raises the blood concentration of Ca by: 1.Stimulating absorption of Ca and P from intestine (synthesis of calcium binding protein). 2.Withdrawing Ca from bones into blood for use in other parts of the body. 3.Stimulating Ca retention by kidneys.

Vitamin D Deficiency Rickets (in children) Teeth: Slow eruption, not well formed, tendency to decay. Blood: Decreased Ca and/or P Bone: Poor calcification and retarded growth, deformities of ribs, enlargement of ends of long bones,,. Osteomalacia (in adults) Bone:Softening of bones, bone fracture, deformities of spine Blood: Decreased Ca and/or P levels,

Vitamin K Vitamin K is essential for synthesis of several proteins needed for blood coagulation or clotting. Deficiency is rare: could be caused by conditions that interfere with absorption of fat or liver and gall bladder disease. Deficiency results in “Hemorrhagic Disease”. Vitamin K sources: – Made by intestinal bacteria – Food sources: green leafy vegetables, cabbage, milk, liver. Prolonged use of Sulfa drugs and antibiotic use may cause vitamin K deficiency. 2-methyl-1,4-naphthoquinone structure phylloquinone (vitamin K 1 ) and menaquinones (vitamin K 2 ) Menadione, formerly known as vitamin K 3

Vitamin K,II,VII,X,XII

Vitamin E The most active form of vitamin E, a-tocopherol, is a 6- hydroxychroman derivative.

Vitamin E Vitamin E acts as an “antioxidant”. It protects vitamin A and polyunsaturated fatty acids from oxidation. Antioxidant: compound that protects others from oxidation by being oxidize itself. – One of the most important organs where vitamin E exerts its antioxidant effect in lungs, where exposure to O2 is maximal, protects RBC and cells of lungs itself. – Vitamin E is also protective against strong oxidizing agents like ozone and nitrogen dioxide – air pollutants. These cause peroxidation of cell membrane lipids.

Regulation of Vitamin C in the Body Absorption in small intestine via active transport Uses glucose transport protein High intakes Absorbed by simple diffusion in stomach & small intestine Circulates to liver via blood Excess excreted in urine Functions of Vitamin C Antioxidant Accepts & donates electrons Involved in a variety of redox reactions