11-Vitamin Structure and Function Lecture UCU.pdf
- 1. Vitamins
- 2. • To recognize vitamins by name • To understand their distribution in various food sources • To understand the signs and symptoms of diseases resulting from deficiencies • To understand their role in metabolism Objectives:
- 3. A group of organic nutrients required in small quantities for a variety of biochemical functions and which , generally , cannot be synthesized by body and must therefore be supplied in the diet. Vitamins Vitamins are essential for several enzymatic functions in human metabolism
- 4. ? They are categorized on basis of their solubility - Fat soluble (Vitamin A,D,E and K) are soluble in fats, bile salts increases their absorption and they are fairly resistant to heating - water soluble( Vitamin B and C) Vitamin B complex are essential for normal cell metabolism Easily destroyed by cooking or food processing. Vitamins
- 5. Dietary vitamin deficiency may be caused by • Inadequate dietary intake • Inadequate intestinal absorption • Inadequate utilization • Increased requirements of vitamins by the body • Drug induced deficiency
- 6. Fat soluble vitamins Vitamin A- is present in the diet as retinol or as β-carotene • Found in fish, liver, eggs, butter, yellow & green vegetables, fruits • Needed for healthy skin, eyes, bones, teeth. • Function: Vitamin A(retinol) is the precursor of retinel, the light-sensitive group in rhodopsin and other visual pigments. • Deficiency causes night blindness, skin disorders, kidney stones
- 8. ? Found in liver, fish, eggs, milk, sunlight ? Needed for growth, metabolism of calcium & phosphorus ? It promotes synthesis of osteocalcin which is needed for bone mineralization. ? Deficiency causes rickets, poor teeth and bones. Vitamin D ❑ Metabolic activity of Vitamin D
- 10. VITAMIN D ❑ Vitamin D comprises a group of sterols; the most important of which are cholecalciferol (vitamin D3) & ergosterol (vitamin D2). ❑ Humans & animal utilize only vitamin D3 & they can produce it inside their bodies from cholesterol. ❑ Cholesterol is converted to 7-dehydro-cholesterol (7DC), which is a precursor of vitamin D3.
- 11. VITAMIN D ❑ Exposure to the ultraviolet rays in the sunlight convert 7-dehydro-cholesterol (7DC) to cholecalciferol. ❑ Vitamin D3 is metabolically inactive until it is hydroxylated in the kidney & the liver to the active form 1,25 Dihydroxycholecalciferol.
- 12. VITAMIN E ❑The term vitamin E describes a family of 8 antioxidants, 4 tocopherols (α,β, γ, & δ) and 4 tocotrienols. ❑α-tocopherol is the active form of vitamin E in the human body.
- 14. FUNCTIONS • The main function of vitamin E is anti oxidant. It intercepts free radicals & prevents destruction of cell membrane. • It protects the fat in LDL from oxidation. • It inhibits platelets aggregation. • It enhances vasodilatation. • It inhibits the activity of protein kinase C.
- 15. Vitamin E Dietary Sources ❑ Vegetable oils ❑ Almonds & peanuts ❑ Avocado ❑ Spinach ❑ Carrots (least)
- 16. Vitamin E deficiency •Severe vitamin E deficiency causes: Neurological symptoms (impaired coordination) & muscle weakness. Increased risk of cardiovascular diseases Hemolytic anemia in children
- 17. THERAPEUTIC USES ❑ Prevention of cardiovascular diseases ❑ Diabetes Mellitus ❑ Cancer prevention ❑ Boost immunity ❑ Dementia
- 18. TOXICITY Excess vitamin E may cause: ✔ Impaired blood clotting leading to increased risk of bleeding in some persons. ✔It is recommended that vitamin E supplements to be stopped one month before elective surgery.
- 19. ? Found in whole grains, leafy vegetables, milk, butter, vegetable oils ? Needed for healthy cell membranes, red blood cells ? Converts free radicals to inactive forms that are excreted in bile thus prevent hemolysis of RBCs ? Deficiency causes red cell rupture, muscle disorders Vitamin E
- 20. VITAMIN K • The K is derived from the German word Koagulation. • There are 2 naturally occurring forms of vitamin K. Plants synthesize phylloquinone (vitamin K1) & bacteria synthesize menaquinone-3 (vit K2). • Menaquinone-4 is produced in animals from vit K1, but its function is yet to be discovered.
- 22. FUNCTIONS •Vitamin K is needed for production of vitamin K-dependent coagulation factors in the liver. •Other functions include: ✔Assist in bone mineralization. The mineral binding capacity of osteocalcin requires vit K. ✔Gas6 is vit K-dependent protein identified in 1993. It is important for neuronal function.
- 23. SOURCES OF VITAMIN K Bacteria in large intestine produce vit K2 and supply 40-50% of human requirement. Vegetable oils Almonds & peanuts Avocado & Broccoli Spinach, Lettuce, parsley (raw)
- 24. ? Found in leafy vegetables, soybeans, made by intestinal bacteria ? Needed for normal blood clotting ? Deficiency causes slow clotting, hemorrhaging. Vitamin K ❑ This vitamin is the only acting coenzyme among fat soluble vitamins
- 25. Water soluble vitamins – B1 (Thiamine) – B2 (Riboflavin) – B3 (Niacin) – B5 (Pantothenic Acid) – B6 (Pyridoxine) – B7 (Biotin) – B9 (Folic Acid) – B12 (Cobalamin) ❑ C (Ascorbic acid) ❑ Vitamin B Complex
- 26. ? Found in organ meats, whole grains, vegetables ? Needed for proper functioning of heart, nervous system, digestion ? Deficiency causes beriberi, cardiovascular disorders. Vitamin B1 (Thiamine)
- 27. Most vitamins act as coenzymes Thiamin e Pyrophosphate (Pi) from ATP Thiamine pyrophosphate (TPP) This TPP molecule is a coenzyme for all Decarboxylation of alpha keto acids like pyruvate
- 28. ? Found in liver, poultry, milk, eggs, cheese, fish, green vegetables, whole grain ? Needed for metabolism of protein, carbohydrates, and fats ? Used to make FAD for metabolism ? Deficiency causes dime vision, premature aging, sore mouth Vitamin B2 (Riboflavin)
- 29. ? Riboflavin is a component of the flavin coenzymes such as the FAD and FMN. ? It is mainly used in the energy metabolism of Sugars and Lipids. The activation of FMN and FAD is an ATP-dependent.
- 30. ? Food sources and distribution: Fish, meat, poultry, cereal, nuts, ? Signs and symptoms of deficiency - Pellagra (pella agra: rough skin) characterized by inflammation of mucous membranes - dermatitis( red itchy skin), diarrhea, red swollen tongue observed in chronic alcoholics ? Needed for metabolism, digestion, nerves, skin B3 (Niacin)
- 31. ? Niacin when activated it forms NAD+ which when phosphorylated forms NADP+ which are used as cofactors for many dehydrogenases. Niacin molecule
- 32. ? Food sources and distribution: Ubiquitous Easily destroyed by heating ? Signs and symptoms of deficiency Very rare Neuromuscular degeneration B5 (Pantothenic acid)
- 33. ? Found in meats, liver, whole grains, vegetables ? Needed for sodium and phosphorus balance ? Deficiency causes anemia, nausea, loss of appetite, nervousness Vitamin B6 (Pyridoxine)
- 34. Vitamin B6 exists in 3 forms and their corresponding phosphates Pyridoxal phosphate (PLP) acts as a cofactor by participating in transamination and decarboxylation reactions
- 35. ? Food sources and distribution: Can be synthesized by intestinal bacteria Found in most foods ? Signs and symptoms of deficiency Very rare, include dermatitis, muscle pain B7 (Biotin)
- 36. • Biotin is a coenzyme commonly associated with enzymes performing carboxylation reactions eg BIOTIN - Acetyl CoA carboxylase Acetyl-CoA + ATP + HCO3- <=> Malonyl-CoA + ADP + Pi + H+ - Pyruvate carboxylase involved in gluconeogenesis. Pyruvate + HCO3- + ATP <=> Oxaloacetate + ADP + Pi + H+
- 37. ? Found in green vegetables, liver, whole grains, legumes ? Needed for manufacture of proteins and red blood cells, needed for cell division, helps prevent spina bifida ? Deficiency causes inflamed tongue, diarrhea, B12 deficiency. ? Its active form is tetrahydropholate (THF) B9 (Folic Acid)
- 38. FOLIC ACID ❑ Folic acid is obtained from yeasts and leafy vegetables as well as animal liver. Animals can’t synthesize folate, thus, it must come from diet. ❑ Folate is needed for synthesis of nucleic acids ❑ Deficiency causes megaloblastic anemia & neural tube defects in utero. ❑ Used for treatment of chronic hemolytic anemia.
- 40. COBALOMIN (VIT B12) ❑ B12 functions as a cofactor for enzymes required for the catabolism of fatty acids & the conversion of homocysteine to methionine. ❑ B12 is not available in plant & deficiency may occur in strict vegetarians & in pts with GIT problems & those on prolonged antibiotic treatment. ❑ Deficiency causes megaloblastic anemia, SACDC, & high homocysteine in blood which is a risk of IHD & stroke.
- 41. ? Found in Liver, meats, eggs, cheese, dairy products ? Needed for red cell production, healthy nervous system. ? Deficiency causes pernicious anemia. Vitamin B12 (Cobalamin)
- 43. VITAMIN C ▪ Humans, unlike other mammals, are unable to make ascorbic acid & they get it from food. ▪ Rich dietary sources are citrus juices (orange, grapefruit & lime), strawberry, Guava, tomato, sweet red pepper & broccoli. ▪ Recommended daily intake is between 15-120 mg/day depending on age. Smokers & lactating
- 44. FUNCTIONS ❑ Collagen synthesis ❑ Antioxidant ❑ Synthesize of noradrenaline ❑ Carnitine synthesize ❑ Metabolism of cholesterol to bile salts
- 45. Vitamin C deficiency ❑ Severe deficiency leads to Scurvy with the following manifestations: Bleeding & bruising easily Hair & teeth loss Joint pain & swelling Fatigue & lack of concentration
- 46. THERAPEUTIC USES • Cardiovascular diseases • Cataracts • Diabetes Mellitus • Cancer prevention • Common cold • Lead toxicity
- 47. ? Found in citrus and other fruits, leafy vegetables, tomatoes, potatoes ? Needed for healthy blood vessels, resistance to infection, healing ? Deficiency causes scurvy, bleeding gums Vitamin C (Ascorbic acid)
- 49. ? Some vitamins have ability to remove free radicals from the body and thus act as antioxidants ? This activity protects the body from heart disease, cancer, alzheimer’s disease ? These vitamins include; carotenoids (vit A), vitamin C and vitamin E Antioxidants
- 50. Differences between water soluble and fat soluble vitamins
- 52. ? Discuss the two classes of vitamins, their sources and implication in disease ? What are the differences between fat soluble and water soluble vitamins ? Describe one way that vitamins are used in the metabolic process Questions
- 53. Importance of vitamins in preventing diseases
- 54. Importance of vitamins in preventing diseases
- 57. ? Calcium and phosphorous- needed for the dramatic increase in skeletal growth. ? Iron – for transporting oxygen in the blood stream and preventing anemia ? Zinc- vital for protein formation and gene expression Minerals include: Vitamins include: Vitamin A,E,C Folate Others include: Fiber for normal bowel function, Cholesterol and sodium.
- 58. Key Mineral and Vitamin Needs ? Calcium ◦ Essential for fetal development of bones and teeth ◦ Supplements might be needed in cases of poor maternal stores or pregnancies involving more than one fetus ? Iron and iodine ◦ Iron essential for increased hemoglobin synthesis as fetal development and growth requires sufficient oxygen ◦ Iodine is essential for production of more thyroxine
- 59. ? Folate ( Vitamin B) ◦ Builds mature red blood cells during pregnancy ◦ Needed during early periconceptional period ◦ Recommend daily folate intake of 600 mcg during pregnancy, 400 mcg per day for non-pregnant women during childbearing years ◦ Some women may require folate supplements Key Mineral and Vitamin Needs
- 60. Key Mineral and Vitamin Needs ? Vitamin D ◦ Is a fat soluble vitamin which ensures absorption and utilization of calcium and phosphorus for fetal bone growth ◦ Daily intake of three to four cups fortified milk ◦ Exposure to sunlight increases endogenous synthesis of vitamin D