6. Vitamins Lecture 4

Classification of vitamins

Vitamin C- Ascorbic Acid The active form of vitamin C is ascorbate. Function Formation of collagen. Helps form connective tissue that hold bones, muscles, and tissues together. Wound healing; maintaining blood vessels facilitates the absorption of iron, calcium. Protects the body from free radicals (antioxidant) Vitamin C reduce the risk of heart attack & slow down the progression of atherosclerosis, because it is protect arteries against damage. Source Citrus fruits, broccoli, strawberries, melon, green pepper, tomatoes, dark green vegetables, potatoes.

Vitamin C -Ascorbic Acid Deficiency Weight loss , fatigue and joint pain & reduced resistance to colds and infections Scurvy, a disease characterized by sore, spongy gums loose teeth fragile blood vessels swollen joints anaemia.

Vitamin A Fat soluble vitamin Family of molecules found in the body in 3 forms: Retinol, Retinal, Retinoic acid. collectively known as Retinoid. Beta-Carotene plant foods contain β-carotene, which can be oxidatively cleaved in the intestine to yield two molecules of retinal. Retinol A primary alcohol containing a β-ionone ring with an unsaturated side chain. Named because of its concern with retina of eye & only found in animal foods.

Functions Helps to form skin and mucous membranes and keep them healthy, thus increasing resistance to infections; essential for night vision; promotes bones and tooth development. Beta carotene is an antioxidant and may protect against cancer. Sources Retinol liver oil, Liver Dairy products, Egg yolk. Beta-Carotene Dark green leafy vegetables, Broccoli, Carrots, Deep orange fruits and vegetables

Deficiency Mild: Night blindness, diarrhea, intestinal infections, impaired vision. Severe: leads to dryness of the conjunctiva, cornea &inflammation of eyes, If untreated result blindness . Keratinization of skin and eyes. Over 500,000 children worldwide are blinded each year caused by insufficient vitamin A in the diet. Conjunctiva: the mucous membrane that covers the front of the eye and lines the inside of the eyelids.

Vitamin D the most important compounds of vitamin D are vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol). The D vitamins are a group of sterols that have a hormone-like function. Only a few foods contain vitamin D. The major natural source of the vitamin is synthesis of cholecalciferol in the skin from cholesterol through a chemical reaction that is dependent on sun exposure (specifically UVB radiation).

Vitamin D-fortified dairy products. Fish liver oils Dairy products Function Regulate the plasma levels of calcium and phosphorus. Increasing uptake of calcium by the intestine. Minimizing loss of calcium by the kidney. Stimulating re-sorption of bone. Sources Sunlight conversion Vitamin D-fortified dairy products. Fish liver oils Dairy products Oily fish Margarine

Deficiency Demineralization of bone, resulting in rickets in children and osteomalacia in adults.

Vitamin E -Tocopherols The vitamin E consist of eight naturally occurring tocopherols, of which α-tocopherol is the most active. Functions Powerful antioxidant in prevention of non-enzymic oxidation of cell components (such as polyunsaturated fatty acids) by molecular oxygen and free radicals. Improves absorption of vitamin A. prevents damage to cell membranes.

Sources Vegetable oils, margarine, butter. Liver and Eggs whole grain products Leafy greens Deficiency: sensitivity of erythrocytes to peroxide, and the appearance of abnormal cellular membranes. Vitamin E requirement increases as the intake of polyunsaturated fatty acid increases.  

Vitamin K Vitamin K exists in several forms: in plants as phylloquinone (vitamin K1) in intestinal bacterial flora convert vitamin K1 to vitamin K2 (menaquinone). Menadione as synthetic derivative of vitamin K, is available for therapy purpose. Functions Constituent of prothrombin which is necessary in blood clotting. Prothrombin: a protein present in blood plasma that is converted into active thrombin during coagulation.

Cabbage, Cauliflower, Spinach, Egg yolk & Liver Source Cabbage, Cauliflower, Spinach, Egg yolk & Liver Synthesis by the bacteria in the gut. Toxicity of vitamin K Prolonged administration of large doses of vitamin K can produce Hemolytic anemia Jaundice in the infant due to toxic effects on the membrane of red blood cells. There is no RDA for vitamin K, but 70 to 140 mg/day is recommended as an adequate level.

How vitamins help each other Vitamin E keeps Vitamin A from being destroyed in the intestines. Vitamin D enables the body to absorb calcium and phosphorous. Vitamin C helps folate build proteins. Vitamin K is important in making sure that the calcium you get from foods or supplements is used in your bones. Vitamin D and vitamin K work together to strengthen your bones and to help them develop properly