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Water -Soluble Vitamins

Water -Soluble Vitamins. Thiamin. Thiamin consists of a central carbon to which is attached a six-member nitrogen containing ring and a five-member sulfur-containing ring. The name comes from thio , meaning "sulfur,"

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Water -Soluble Vitamins

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  1. Water-Soluble Vitamins Dr. May Hamdan

  2. Thiamin • Thiamin consists of a central carbon to which is attached a six-member nitrogen containing ring and a five-member sulfur-containing ring. • The name comes from thio, meaning "sulfur," and amine, referring to the nitrogen groups in the molecule. • participates in carbohydratemetabolism. Dr. May Hamdan

  3. The chemicalbond between each ring and the central carbon in thiamin is easily broken by prolonged exposure to heat, thus destroying the functions of the vitamin. • This destruction also occurs if food is cooked in alkaline solutions (pH> 8.0 ). Sometimes bakingsoda is added to the water in which fresh green beans are cooked to retain their bright green color; this practice is not recommended. Dr. May Hamdan

  4. Absorption, Transport, Storage, and Excretion of Thiamin • Thiamin is absorbed mainly in the small intestine by active absorption process. • It is transported in the blood by red blood cells. • Storage is poor; only a small reserve is found in muscles and the liver. • Any excess intake is promptly excreted in the urine. Dr. May Hamdan

  5. Functions of Thiamin • in the metabolism of carbohydrates and of branched-chainamino acids(leucine, isoleucine, ,and valine ) . • Itspecificallyparticipates in the action of the enzynmetransketolase, Transketolaseistheenzymeresponsible for the formation of the five-carbon sugar components of RNA and DNA from the six-carbon glucose using a series of reactions called the pentose phosphate pathway. 3. also plays a role in nerve function. It may aid in the synthesis of neurotransmitters and participate in the conduction of nerve impulses. Dr. May Hamdan

  6. Thiamin in Foods • Thiamin is found in a wide variety of foods, although generally in a small amount. Foods rich in thiamin are • pork products, • sunflower seeds, • legumes, • wheat germ, • And watermelon. • whole grains and enriched grains, • green beans, • asparagus, • Organ meats (such as liver ), • peanuts and other seeds, • and mushrooms. Dr. May Hamdan

  7. ThiaminNeeds • The RDA for thiamin for adult men and women is approximately 1.2 mg/day and 1.1mg/day, respectively. Dr. May Hamdan

  8. Thiamin-DeficiencyDiseases • The classic thiamin-deficiency disease beriberi has afflicted polished rice-eating populations forcenturies. • thediseasedevelops because thiamin is so important to energy metabolism and because all cells needenergy. Dr. May Hamdan

  9. three parts of the body are especially at risk to a deficiency of thiamin: • Onepartisthenervous system because nerve cells use a lot of energy compared to most cells. • In addition, the skin and GI tract are very sensitive to deficiencies of thiamin. The reason is that skin and GI tract cells are replaced frequently, which requires much energy input . Dr. May Hamdan

  10. The clinical signs of thiamin deficiency include: • anorexia, • weight loss, • apathy, • loss of short-termmemory, • confusion , • GI tractdistress, • irritability, • and muscleweakness. Dr. May Hamdan

  11. Niacin • The B vitaminniacinactuallyexists in twoforms- • nicotinicacid (niacin) • and nicotinamide(niacinamide). • The two coenzyme forms of niacin are : • nicotinamide adenine dinucleotide (NAD+) and • nicotinamideadeninedinucleotidephosphate (NADP+) . Both forms participate in numerous chemical reactions in the body. Dr. May Hamdan

  12. Absorption, Transport, Storage, and Excretion of Niacin • Nicotinic acid and nicotinamide are readily absorbed from the stomach and the intestine by: active transport and passive diffusion, so that almost all niacin consumed is absorbed. • Niacin is transported from the liver to all tissues, where it is converted to its coenzyme forms, NAD+ and NADP+, • Niacin coenzymes are stored in the liver • and excess niacin intake is excreted as a variety of metabolic products in the urine Dr. May Hamdan

  13. Niacin in Foods • Niacin can be found in foods as the vitamin itself or as the amino acid tryptophan, which can be synthesized into niacin by the body. Rich sources of niacin are • mushrooms, • wheat bran , • tuna (as well as other fish), • chicken, • turkey, • asparagus, • and peanuts. • Animal proteins which are especially rich in tryptophan. Unlike some other water-soluble vitamins, niacin is very heat stable, and little is lost in cooking. Dr. May Hamdan

  14. NiacinNeeds For adult men the RDA for niacin is 16 mg/day, and for adult women it is 14 mg/day • Function: participate in numerous cellular metabolic pathway. Dr. May Hamdan

  15. Niacindeficiencydiseases • In the early 1900s, the niacin deficiency disease pellagra was epidemic in the southeastern United States. • Pellagra was prevalent because the diet among the poor people consisted of cornmeal which is a poor sources of niacin. • Pellagracauses symptoms that are remembered as the three Ds: • dermatitis, • diarrhea, • and dementia. If untreated, a fourth “D” results—death. Dr. May Hamdan

  16. Excess of niacin • megadoses of niacinmayhave adverse effects, including: • flushing of the skin (the initial adverse effect ). • itching, • GI tract upsets (such as nausea and vomiting), • and liver damage. Dr. May Hamdan

  17. PantothenicAcid • Pantothenic acid is part of coenzyme A (CoA), which plays a vital role in energy metabolism. Absorption, Transport, Storage, and Excretion of PantothenicAcid • It is released during digestion in the small intestine, then absorbed there. • Storage is minimal and is as the coenzyme form in the liver. • Excretion of pantothenic acid is via the urine. Dr. May Hamdan

  18. Functions of PantothenicAcid Coenzyme A is essential for the formation of ATP from the breakdown of carbohydrate, protein, alcohol, and fat. • PantothenicAcid in Foods • The Greek word pantothen, meaning " from every side," reflects the ample supply of pantothenic acid in foods, Rich sources of pantothenic acid are • mushrooms, • liver, • peanuts, Dr. May Hamdan

  19. eggs, • broccoli, • milk. • meat, • And many vegetables . Dr. May Hamdan

  20. PantothenicAcidNeeds • For adults, the Adequate Intake set for pantothenic acid is 5mg/day. PantothenicAcidDeficiencyDiseases • A deficiency of pantothenic acid might occur in cases of alcoholism in which a vary nutrient deficientdietisconsumed. symptoms of Deficiency: • headache, • fatigue, • impaired muscle coordination , • and GI tract disturbances. Dr. May Hamdan

  21. Riboflavin • Riboflavin contains three linked six-memberedrings, with a sugar alcohol attached to the middle ring. • The name comes from its yellow color (flavin means "yellow" in Latin ). • Riboflavin is a component of two coenzmes that play key roles in energy metabolism: • flavinmononucleotide (FMN) • and flavinadeninedinucleotide (FAD) Dr. May Hamdan

  22. Absorption, Transport, Storage, and Excretion of Riboflavin • In the stomach, HCIreleases riboflavin from its bound forms. • Absorption is primarily via: • active transport • or facilitated diffusion in the small intestine. • In the blood, riboflavin is transported by protein carriers. Dr. May Hamdan

  23. Riboflavin is converted to its coenzyme forms, FMN and FAD, in most tissues, but mainly in: • the small intestine, • liver, • heart , • and kidney. • A small amount of riboflavin is stored in: • the liver, • kidneys, • and heart . Dr. May Hamdan

  24. Any excess intake is excreted in the urine. • For people who take excessive amounts in supplement form, riboflavin imparts a bright yellow color to the urine. Dr. May Hamdan

  25. Functions of Riboflavin • Riboflavin coenzymes are involved in many enzyme reactions, a number of which are critical to energy metabolism. • participates in the breakdown of fatty acids • synthesize the amino acid tryptophan into the B vitamin niacin, • and participate in folatemetabolism Dr. May Hamdan

  26. Riboflavin in Foods • The richest source of riboflavin is milk and milk products. • Rioboflavin intake typically comes from: • white bread, • rolls , enriched • and crackers • eggs • and meat. Dr. May Hamdan

  27. Foods rich in riboflavin are: • liver, • mushrooms, • spinach • and other green leafy vegetables, • broccoli, • asparagus, Dr. May Hamdan

  28. Exposure to lightcauses riboflavin to break down rapidly. To prevent this light-induced breakdown, paper cartons-not glass- should be used in packaging riboflavin-rich foods such as milk, milk products, and cereals. • RiboflavinNeeds • The RDA for riboflavin is 1.1 to 1.3 mg/day for adults. Dr. May Hamdan

  29. Riboflavin-DeficiencyDiseases The signs and symptoms associated with riboflavin deficieny (technically called ariboflavinosis) include: • inflammation of the tongue, • cracking of tissue around the corners of the mouth (cheilosis), • inflammation of the mouth and throat , • Various eye and nervous system disorders, • confusion • and headaches Dr. May Hamdan

  30. Biotin • Biotin is commonly found in two forms in foods: • the free vitamin • and the protein-bound coenzyme form, called biocytin. In the formation of biocytin, biotin forms a bond with the amino acidlysine in a protein. Dr. May Hamdan

  31. Absorption, Transport, Storage, and Excretion of Biotin • Biotin is absorbed from the small intestine , whereas the biocytinform is not absorbed until the enzyme biotinidase, which is present in the small intestine, cleaves the bond linking biotin to a protein, releasing the free vitamin. • Biotin is stored in small amounts in: • the muscles, • liver, • And brain. • Biotin excretion is mostly via the urine Dr. May Hamdan

  32. Functions of Biotin • biotin is involved in important metabolic pathways, • fatty acid synthesis, • and amino acid catabolism Dr. May Hamdan

  33. Sources of Biotin Sources of biotinincluded: • Wholegrains, • Eggs, • nuts, • and legumes A protein called avidin in raw egg whites binds biotin and inhibits its absorption. cooking denatures avidin in such a way that it can no longer bind biotin and becomeavailable for absorption. Dr. May Hamdan

  34. BiotinNeeds • The Adequate Intake for biotin for adults of 30 μg/day. Biotin-DeficiencyDiseases • Overall a biotin deficiency is rare. Signs and symptoms of deficiency: • a skin rash • hair loss. • neurological disorders, • and impaired growth. Dr. May Hamdan

  35. Vitamin B-6 • The generic name for the vitamin is B-6 or pyridoxine. • Vitamin B-6 is actually a family of three compounds: • pyridoxal, • pyridoxine, • and pyridoxamine All three forms can be phosphorylated to the active vitamin B-6 coenzymes, • the primary one being pyridoxal phosphate (PLP). The coenzymes participate in numerous metabolic reactions. Dr. May Hamdan

  36. Absorption, Transport, Storage, and Excretion of Vitamin B-6 • The free forms of vitamin B-6 can be absorbed bypassive means. • Vitamin B-6 as such is transported to the liver via the blood. where ultimately the three forms of the vitamin are phosphorylated. • The coenzyme forms is absorbed by passive diffusion. Dr. May Hamdan

  37. The main storage of vitamin B-6 in the body takes place in muscle tissue. • Excess vitamin B-6 is generally excreted in the urine Dr. May Hamdan

  38. Functions of Vitamin B-6 • Vitamin B-6 as PLP plays a coenzyme role in more than 100 enzymatic reactions, almost all of which involve nitrogen-containing compounds. Forexample: • Amino AcidMetabolism • A major role of PLP is to participate in amino acid metabolism. For example PLP participates in reactions to form nonessential amino acids via transamination. (If we didn't have the services of PLP, every amino acid would be essential because it would have to be supplied by the diet). PLP acts to loosen the bond between the nitrogen group ( NH2) and the central carbon on the amino acid, allowing it to be removed and to give a new amino acid. Dr. May Hamdan

  39. 2. CarbohydrateMetabolism • PLP is part of the enzyme that releases glucose from glycogen during glycogen breakdown. • Therefore, vitamin B-6 helpsmaintainbloodglucoseconcentrations. ((Thisactionis an exception to the rule that vitamin B-6 works with nitrogen-containing compounds)) Dr. May Hamdan

  40. 3. NeurotransmitterSynthesis • Not only are amino acids used to build proteins, but they are also used to make nonprotein nitrogen compounds. • Many of these compounds are neurotransmitters, which are important for brain function. • PLP plays in the synthesis of the neurotransmitters, like: • serotoninfromtryptophan, • dopamine (DOPA) fromtyrosine, Dr. May Hamdan

  41. 4. VitaminFormation • PLP participates in the conversion of the amino acid tryptophan to the B-vitamin niacin. Vitamin B-6 in Foods Vitamin B-6 is stored in the muscle tissues of animals, and thus: • meat, • fish, • and poultry are some of the best sources of this vitamin B-6 Dr. May Hamdan

  42. whole grains also are good sources of vitamin B-6. • Most fruits and vegetables are not good vitamin B-6 sources, but there are some exceptions: • carrots, • potatoes, • spinach, • bananas, • and avocados. Dr. May Hamdan

  43. Vitamin B-6 Needs The adult RDA for vitamin B-6 is 1.3 to 1.7 mg/day. Vitamin B-6-Deficiency Diseases The symptoms of vitamin B-6 deficiency include • dermatitis, • Convulsions, • depression, • and confusion. Dr. May Hamdan

  44. Folate • The word folate derives from the Latin word for leaf (folium) because dark green, leafy vegetables are ,among the best sources of this vitamin. • What we call folate today was known earlier as either folic acid or Folacin. • Today, the term folate is a generic name for the vitamin and also refers to the various forms of the vitamin found naturally in foods. • Folic acid refers specifically to the form of the vitamin found in supplements and fortified foods. Dr. May Hamdan

  45. Folate consists of three parts: • pteridine, • para-amino benzoic acid (PABA), • and one or more molecules of the amino acid glutamic acid (glutamate). If only one glutamate molecule is present, it is called folatemonoglutamate. In food about 90% of the folate molecules have three or more glutamates attached and are known as folatepolygltuamates . Dr. May Hamdan

  46. Absorption, Transport, Storage, and Excretion of Folate • To be absorbed, folatepolyglutamates must be broken down (hydrolyzed) to the monoglutamate form in the GI tract. • Themonoglutamateform is then actively transported across the intestinal wall by passive diffusion. • is transported to the liver via the blood, where ultimately is stored. • and excessfolatintake is excreted as a variety of metabolic products in the urine Dr. May Hamdan

  47. Functions of Folate • Needed for the synthesis of DNA • and the metabolism of various amino acids • Another key function of folate is the formation of neurotransmitters in the brain, • Meeting folate needs can improve the depressed state seen in some Cases of mental illness. Dr. May Hamdan

  48. Becausefolate is needed for DNA synthesis, folate deficiency may be induced during a common form of cancer therapy. One example is the cancer drugmethotrexate. It inhibits folate metabolism. When the drug is taken in high doses, it reducesDNA synthesis throughout the body by interfering with folate metabolism. This reduction in DNAsynthesis can stop the growth of cancer cells, but it also affects other rapidly growingcells, such as intestinal cells and red blood cells. Dr. May Hamdan

  49. Folate in Foods • Thebestsources, from the standpoint of amount and availability, are: • legumes, • dark green leafy vegetables in general. • liver, • fortified ready to eat breakfast cereals and other grain products, Dr. May Hamdan

  50. Other, less rich sources of folate include: • eggs, • dried beans, • And oranges. Folate Needs • The RDA for folate for adults is 400μg/day. Dr. May Hamdan

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