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Vitamin A and Carotenoids Ancient Egyptians recognized that night blindness could be treated by consumption of liver. In the late 1920’s through the efforts of a Swiss scientist named Karrer and his colleagues, the fat-soluble compound in liver was isolated and termed vitamin A. Vitamin A is Fat-soluble alcohol, most abundant in fatty fish and especially in fish-liver oils. It is not found in plants, but many vegetables and fruits contain β-carotene which is readily converted in the body to vitamin A (Provitamin). 7 5 CH2OH 4 6 3 all-trans-Retinol 8 CH3 7 4 6 3 1 2 8 CH3 11 9 10 12 14 CH3 11 15 13 CHO all-trans- Retinal CH3 5 15 13 CH3 1 2 Vit.A1: 11 9 CH2OH 10 12 14 CH3 Vit. A2: All - trans- 3-DehydroRetinol CH3 H3C CH3 CHO 11-cis-Retinal Light cause isomerization of 11-cis to all-trans isomer resulting in activation of the photoreceptor molecule. Sources Vitamin A1: A yellow crystalline compound found in: Egg yolks, Milk, and Cod-liver oil. Vitamin A2 : A golden yellow oil Found in: Livers of fresh water fish (40 % of the biological activity of vitamin A1). Carotenoids They are known as Provitamin A as they converted in the body to vitamin A. They are mostly found in plants. Plant Carotenoids are found in: Carrots, Apricots, Asparagus, Broccoli, and Green leafy vegetables. Special strain of rice “Golden Rice are rich in b-carotene. Role of Vit. A Vision: Vitamin A is the chromophore of rhodopsin (vertebrate photoreceptor molecule) used in low light levels. Rhodopsin is a complex of Vit. A and Opsin protein present in the retina. Epithelial Cells: Vitamin A is essential for the epithelial cells. In Vitamin A deficiency, mucus-secreting cells are replaced by keratin producing cells, leading to xerosis. Glycoprotein synthesis: Glycoprotein synthesis requires Vitamin A. In severe Vitamin A deficiency, lack of glycoproteins may lead to corneal ulcers or liquefaction. Immune System: Vitamin A is essential to maintain intact epithelial tissues as a physical barrier to infection, maintaining a number of immune cell types. These include the lymphocytes (B-cells, T-cells, and natural killer cells), as well as many myelocytes (neutrophils, macrophages, and myeloid dendritic cells). Formation of red blood cells: Vitamin A may be needed for normal haematopoiesis; deficiency causes abnormalities in iron metabolism. Growth: Vitamin A affects the production of human growth hormone (GH). Recommended Daily Amount (RDA) 900 micrograms/day, or 3,000 IU for a 25year old male. 1 IU of retinol is equivalent to 0.3 μg. Deficiency Night blindness: Is one of the first signs of vitamin A deficiency. Vitamin A deficiency contributes to blindness by making the cornea very dry and damaging the retina and cornea. Impaired Immunity: Vitamin A deficiency also diminishes the ability to fight infections causing frequent infections (especially respiratory). In countries where children are not immunized, infectious disease like measles have relatively higher fatality rates. Symptoms of deficiency may include, loss of appetite, hair loss, rashes, dry skin and eyes, poor growth, and fatigue. Uses Treatment of Night blindness. Skin Diseases: Psoriasis acne vulgaris Keratosis pilaris Cosmetics: vitamin A derivatives are used as so-called antiaging chemicalsvitamin A is absorbed through the skin and increases the rate of skin turnover, and gives a temporary increase in collagen giving a more youthful appearance. promote development of bones and soft tissues and sperm production. protects against bladder cancer, lung cancer (aerosol form ). Products Tretinoin : Retinoic acid: Retin-A: Retinoic acid Isotretinoin: Accutane Etretinate: Tegison Risk Factors for Deficiency Under certain circumstances some individuals may require higher doses of vitamin A as following: 1- Those who consume alcoholic beverages may be more liable to vitamin A deficiency. 2- People taking some medications, including birth control pills, methotrexate, cholestyramine, colestipol, and drugs that act to sequester bile acids. 3- Those who are chronically ill, recovering from surgery or other injuries. 4- Patients undergoing treatments for cancer (radiation and chemotherapy). 5- Other conditions that may impair vitamin A balance including chronic diarrhea, cystic fibrosis, and kidney or liver disease. 6- Diabetics persons are often deficient in vitamin A. Vitamin A Toxicity 1- High level of carotenoid ( β-carotene) was associated with an increase risk of lung cancer in male smokers. In nonsmokers, the opposite effect has been noted. 2- Excess vitamin A during early pregnancy has also been associated with an increase in birth defects (Terratogenic effects). No more than 5,000 IU per day. 3- Tingling and itchy feeling due storage of excessive amounts of vitamin A in fat cells. Symptoms of Vit. A toxicity include: Dry lips and skin. Bone and joint pain. Blurred or double vision. Confusion and fatigue. liver and spleen enlargement. Diarrhea, vomiting, headaches. Soft spot on the head in infants. Very high levels of vitamin A may also create deficiencies of vitamins C, E, and K. Drug Interactions Vitamin A supplements should not be taken in conjunction with any retinoid medications, due to higher risk of toxicity. Using of mineral oil impairs absorption of all the fatsoluble vitamins, including A. Aluminum-containing antacids and cholesterol-lowering drugs (cholestyramine and colestipol) may inhibit absorption vitamin A Alcohol, barbiturates, caffeine, cortisone, tobacco, and very high levels of vitamin E deplete the body of Vitamin A. Overuse of alcohol and vitamin A together may increase the possibility of liver damage. Vitamin C, vitamin E, Zinc, and Selenium optimizes absorption and use of vitamin A and carotenoids. Iron deficiency anemia is better treated with a combination of iron supplements and vitamin A than with iron alone. Vitamin D Vitamin D is a generic description of a group of compounds have equivalent activity. On of the fat soluble vitamins. Know as Sunshine vitamin as it is formed by the effect of UV rays during the midday from sterols. Forms of Vitamin D Vitamin D1: Mixture of ergocalciferol with lumisterol 1:1 Vitamin D2: ergocalciferol or calciferol (made from ergosterol) Vitamin D3: cholecalciferol (made from 7dehydrocholesterol) Vitamin D4: 22,23-dihydroergocalciferol Vitamin D5: sitocalciferol (made from 7dehydrositosterol) D2 Vitamin D2 = Ergocalciferol (Deltalin®) D3 Vitamin D3 = Cholecalciferol Sources Code liver oil Tuna Sardines Biosynthesis UV Light HO HO 7-dehydrocholesterol pre-vitamin D3 Isomerization Calcitriol OH 25-hydroxycholecalciferol (calcidiol) formed and stored in the liver The main biologically active form 1,25-dihydroxycholecalciferol (calcitriol) formed in the Kidney. HO OH HO Vitamin D3 (cholecalciferol) Role of Vit D Vitamin D has the net effect of increasing the serum calcium and phosphate concentrations by: 1- By increasing intestinal calcium and phosphate absorption and reabsorption from the kidney. 2- increasing the effect of parathyroid hormone (PTH) on bone. Controls parathyroid gland growth and production of the parathyroid hormone. Treatment of rickets and osteomalacia. It is an immunomodulator. Regulation of insulin production. It is required for female reproduction. Recommended Daily Amount (RDA) 10 mg Cholecalcifrol = 400 IU. Materno-fetal transfer of vitamin D is mostly in the form of calcidiol (25-OH vitamin D), which readily crosses the placenta. The half-life of calcidiol is approximately three to four weeks. Thus, the serum concentration of vitamin D falls rapidly after birth unless additional sources are available. Causes of deficiency Vitamin D deficiency can occur as a result of: Decreased intake or absorption, Reduced sun exposure, Increased hepatic catabolism, Decreased endogenous synthesis (via 25hydroxylation in the liver and subsequent 1hydroxylation in the kidney). End-organ resistance to vitamin D . Diseases caused by deficiency Vitamin D deficiency is known to cause several bone diseases including: Rickets: a childhood disease characterized by failure of growth and deformity of long bones. Osteoporosis: a condition characterized by fragile bones. Osteomalacia: a bone-thinning disorder in adults that is characterised by proximal muscle weakness and bone fragility. Osteomalacia can only occur in a mature skeleton. Vitamin D malnutrition may be linked to chronic diseases such as cancer (breast, ovarian, colon, prostate, lung and skin cancer), chronic pain, several autoimmune diseases, high blood pressure, depression, and seasonal affective disorder Rickets Rickets is a softening of the bones in children potentially leading to fractures and deformity. Rickets is among the most frequent childhood diseases in many developing countries. The predominant cause is a vitamin D deficiency, but lack of adequate calcium in the diet may also lead to rickets. Osteoporosis Osteoporosis is a disease in which bones become fragile and more likely to break. If not prevented or if left untreated, osteoporosis can progress painlessly until a bone breaks. These broken bones, also known as fractures, occur typically in the hip, spine, and wrist Osteomalacia Osteomalacia is a softening of the bones, resulting from defective bone mineralization. It may show signs as pain, weakness, and fragility of the bones. This is caused from the lack of Vitamin D in adults, or Rickets in children Groups at greater risk Older people (age 50 and over) have a higher risk of developing vitamin D deficiency because: a- The ability of skin to convert 7-dehydrocholesterol to pre-vitamin D3 is decreased in older individuals. b- The kidneys, which help convert calcidiol to its active form, sometimes do not work well. Newborn infants who are exclusively breastfed require vitamin D supplements. Breast milk does not contain significant levels of the vitamin. Infant formula is generally fortified with vitamin D. so this requirement only applies to breastfed infants. Those who avoid or are not exposed to summer midday sunshine may also require vitamin D supplements. Dark-skinned individuals may require extra vitamin D because melanin acts like a sun-block, prolonging the time required to generate vitamin D. Obese people have lower levels of the circulating form of vitamin D, probably because it is deposited in body fat compartments and is less bioavailable. Patients with chronic liver disease or intestinal malabsorption , parathyroid glands removed General Use of Vitamin D 1- Prevent and treat osteoporosis as a result of calcium depletion. Treatment require taking both calcium and vitamin D. fractures. 2- Osteomalacia and rickets are also effectively prevented and treated through adequate vitamin D supplementation. 3- Vitamin D also has a role in cancer prevention (colon cancer, breast and prostate cancer). The action of Tamoxifen (Chemotherapeutic agent) appears to be improved with small added doses of vitamin D. 4- Treatment of hearing loss resulted from vitamin D deficiency that affect the function of small bones in the ear responsible sound transmition. 5- In combination with phosphate to treat some metabolic diseases as Fanconi syndrome and familial hypophosphatemia. Fanconi syndrome: is a disorder in which the proximal tubular function of the kidney is impaired, resulting in decreased reabsorption of electrolytes and nutrients back into the bloodstream. Compounds involved include glucose, amino acids, uric acid, phosphate and bicarbonate. Familial hypophosphatemia: is a rare inherited disorder characterized by impaired transport of phosphate and altered vitamin-D metabolism in the kidneys. In addition, calcium and phosphate are not absorbed properly in the intestines, which can lead to softening of bones. 6- A topical form of vitamin D can be helpful in the treatment of plaque-type psoriasis (Oral doses of vitamin D are not effective). Side Effects Minor side effects are poor appetite, constipation, dry mouth, increased thirst, metallic taste, or fatigue. Other reactions are headache, nausea, vomiting, diarrhea, or confusion. Interactions 1- The absorption of vitamin D is improved by calcium, choline, fats, phosphorus, and vitamins A and C. 2- Rifampin, H2 blockers, barbiturates, heparin, isoniazid, colestipol, cholestyramine, carbamazepine, phenytoin, fosphenytoin, and phenobarbital reduce serum levels of vitamin D and increase its metabolism. 3- Overuse of mineral oil and stimulant laxatives may deplete vitamin D. 4- Osteoporosis and hypocalcemia can result from prolonged use of corticosteroids. It is necessary to take of calcium and vitamin D together with corticosteroid drugs. 5- The use of thiazide diuretics with vitamin D can cause hypercalcemia in individuals with hypoparathyroidism. 6- Concomitant use of digoxin or other cardiac glycosides with vitamin D may lead to hypercalcemia and heart irregularities. Vitamin E A group of compounds (α, β, γ, and δ-tocopherols) with a chromanol ring and phytyl side chain. They have the activity equivalent to d-a-tocopherol. CH3 H3C O CH3 CH3 CH3 CH3 CH3 HO 6 CH3 Phytyl side chain Chromanol group Sources Natural sources: Natural vitamin E (RRR-a-tocopherol) present in plants only mainly the leaves of green vegetables. Vegetable oils (wheat germ, sunflower, cottonseed, safflower, soybean, and corn oil) . Unprocessed grains, nuts. Synthetic sources all racemic-tochopherol. Gastrointestinal absorption of all forms of vitamin E is equivalent. the subsequent physiological steps are sharply in favor of the RRR form. The cellular liver transfer protein that maintains the plasma level is specific for the RRR form of α -tocopherol. It selectively choosing the RRR form and bind it into plasma lipoproteins for distribution of the vitamin to every tissue and organ in the body. Recommended Daily Amount (RDA) d-a-tocopherol Equivalent (TE): 1 TE = 1 mg = 1.5 IU 30 IU commercial products, however it is safe so larger doses are allowed. Role of Vitamin E Vitamin E has a very important role in normal cells metabolism. It protects with other nutrient (Vitamin C and Selenium) against he damaging free radicals formed during metabolism of fatty acids. Causes of deficiency Insufficient dietary intake. Impaired absorption. Other factors: Deficiency of Riboflavin and cystein. Deficiency of minerals like Cu, Zn and Mg. Uses Cancer prevention and treatment: Vitamin E is a known antioxidant reduces risk of Cancer. High doses of dietary antioxidants may increase the efficacy of the radiation treatment and protects healthy cells against damage. Immune system stimulation: Especially in elderly patients, boosts immune system function. It also slow disease progression in HIV-positive patients. Eye disease prevention: Reduces the risk for cataracts and for macular degeneration, particularly among women. Macular degeneration: is a medical condition predominantly found in elderly adults in which the center of the inner lining of the eye, known as the macula area of the retina, suffers thinning, atrophy, and in some cases bleeding. A cataract is a condition of clouding lens of the eye. A patient who is blind from cataracts might have white not clear corneas. Lens clarity was better in regular users and higher blood levels of vitamin E. Memory loss prevention. Alzheimer's disease (AD) treatment: Alzheimer's patients who took daily vitamin E maintained normal functioning longer than patients who took a placebo. High dietary intake of vitamin E lowers the risk of developing AD. Diabetes treatment: Vitamin E reduces the symptoms of diabetic neuropathy and to improve the speed of transmission of nerve impulses. Pain relief: Vitamin E acts as both an anti-inflammatory and analgesic. It may be useful in arthritis pain in some individuals. Vitamin E may protect the liver against disease. Parkinson's disease prevention: High doses of vitamin E lowered risk of developing Parkinson's disease. Heart disease prevention:Vitamin E may prevent heart disease by lowering total blood cholesterol levels and preventing oxidation of LDL cholesterol. Skin care: Vitamin E is thought to increase an individual's tolerance to UV rays when taken with vitamin C and to promote faster healing of wounds. Side Effects Vitamin E is well-tolerated, and side effects are rare. However, in some individuals who are vitamin K deficient, vitamin E may increase the risk for hemorrhage or bleeding. Vitamin E ointments, oils, or creams may trigger an allergic reaction known as contact dermatitis. Interactions Vitamin E can alter the efficacy of anticoagulant or anticonvulsant drugs. Vitamin E increase bleeding time in patient taking herbal preparations as Feverfew or Gingko Biloba. Inorganic iron supplements destroy vitamin E, so individuals taking iron supplements should space out their doses (e.g., iron in the morning and vitamin E in the evening). Large doses of vitamin A can decrease the absorption of vitamin E. Alcohol and mineral oil can also reduce vitamin E absorption, and these substances should be avoided in vitamin E deficient individuals. Vitamin K (Antihemorrhagic factor) A group of compounds derived from 2-methyl-1,4naphthoquinone that prevent bleeding in mammals and birds. Forms of Vitamin K: Vitamin K1 (Phylloquinones, Phytonadione) is produced by green plants. Vitamin K2 (Menaquinones, MK) is produced by intestinal bacteria. Vitamin K3 (Menadione) is a synthetic compound. Sources Rich Food in Vitamin K: Kale, Spinach, Turnip, Parsley and Mustard. Food Moderate in Vitamin k: Lettuce and Broccoli. O 1 [ 4 O ] n Vitamin K1 = Phytonadione O 1 2 [ 4 O Vitamin K2(30) = Menaquinone-6 Vitamin K2(35) = Menaquinone-7 O 1 4 O Menadione ] n n=4 n=5 Role of Vitamin K Vitamin K (hydroquinone , the active form) is involved as a cofactor in the carboxylation of certain glutamate residues in proteins to form γ-carboxyglutamate residues (Gla-residues). Gla-residues are usually involved in binding calcium. The Gla-residues are essential for the biological activity of : Blood coagulation: (factors II (prothrombin), IX, X , VII anticoagulant proteins C and S, and the thrombin-targeting protein Z ) must be convered to γ-carboxyglutamate and bind to Ca to form clot. This is the most important role of Vitamin K. Bone metabolism: Bone Gla-protein Osteocalcin: Regulate incorporation of Calcium Phosphate into bones. Matrix Gla protein (MGP)]: Clearance of extracellular Calcium to protect against soft tissue calcification. Vascular biology. Recommended Daily Amount (RDA) Male: 80 mg/day Female: 65 mg/day New Born: 500- 1000 mg/day (Sterile intestine) 0- 6 Months: 5 mg/day 6- 12 Months: 15 mg/day Commercial infant formula contain 50- 125 mg/day Absorption Vitamin K1 is absorbed through Active transport mechanism. Vitamins K2 and K3 are absorbed through passive diffusion. Metabolism 70% of Vit K3 excreted in urine in 24 hr in the form of sulphate, phosphate and glucuronic acid conjugate. Small % excreted in faces as glucuronic acid conjugate. Vit K2 and K3 undergo slower metabolism to shorten the side chain to 5- 7 carbons carboxylate. Causes of Deficiency Disturbed intestinal uptake (a bile duct obstruction). Therapeutic or accidental intake of vitamin Kantagonists. Nutritional vitamin K-deficiency. Deficiency Uncontrolled internal bleeding. Cartilage calcification developing bone. Deposition of insoluble calcium salts in the arterial vessel walls. and malformation of Structure Activity Relationship (SAR) O A 1 CH3 B 4 O Increase activity: Ring A : a- Aromatic or hydro- aromatic. Ring B is aromatic or hydro- aromatic. b- Not substituted. Decrease Activity: Alkyl group larger than Methyl at C-2. Hydroxyl group at C-3 or hydroxtlation of the side chain. O A 1 CH3 B 4 O Activity not affected if positions 1 and 4 are: OH O-Ac OCH3 OC2H5 C=O Toxicity Vitamins K1 and K2 are non-toxic in large doses. Vitamin K3 is toxic in doses tree time more than the usual dose. Toxicity cause: Hyperbilirubinemia. Sever Jaundice. Anemia. Interaction Some interactions may increase the need for vitamin K: Antibiotics: Prevent absorption and kill normal bacterial folra. Anticonvulsants: Affect the body ability to use Vit K. Bile Acid Sequestrants (Cholestyramine) and Aspirin: Affect absorption. Mineral oil laxatives: Affect absorption. Weight Loss Products (Orlistat and olestra): Affect absorption as they prevent absorption of fats. X-rays and Radiation: Deplete vitamin K levels and raise vitamin K requirements. Avoid high doses of vitamin K and food rich in vitamin K when anticoagulants are used.