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Macro/Micro Nutrient

midterm review

What are the Fat Soluble vitamins? Vit A,D,E,and K
How many forms of vitamin A and carotenoids? There are three forms of vitamin A and at least 600 carotenoids identified. There are 4 we must know: retinol, retinal, retinoic acid, and beta-carotene.
List food sources of vitamin A Vit A from animals: liver, cod-liver oil, dairy products and fish. Carotenoids: yellow, orange, and green plants.
List food sources of carotenoids (alpha, beta, gamma, lycopene, and lutein) alpha-carotene: carrots and pumpkin. Lycopene: tomato, pink grapefruit, guava, and watermelon. Lutein: green leafy vegetables, broccoli, brussel sprouts, celery, leeks, and green peas.
Explain the digestion process of vitamin A Retinol is bound to fatty acid esters and undergoes hydrolysis by pepsin in the stomach and other pancreatic enzymes in the SI. After hydrolysis, retinol is taken up by the enterocytes.
Explain the absorption process of vitamin A Absorption requires bile salts that form a micelle. Some retinal may be irreversibly oxidized into retinoic acid.
How is Vit A delivered to the blood (what forms) ? Retinoic acid is picked up by the portal vein and transported in plasma bound to albumin. Retinol is esterified to palmitic acid and delivered to the blood via chylomicrons.
How is Vit A taken up from the blood? The liver uptakes chylomicron remnants; thus delivering retinol to the liver for storage as a lipid ester within lipocytes. Retinol is delivered to other tissues by retinol binding protein (RBP).
Explain the absorption process of carotenoids (enzyme involved?) Ingested beta-carotene is cleaved in the enterocyte by beta-carotene dioxygenase to produce retinal which in turn is reduced to retinol by retinaldehyde reductase, an NADPH requiring enzyme in the intestines.
How are carotenoids stored and how do they reach that organ? Carotenoids that reach the liver may be incorporated into VLDL synthesized in the liver and released as part of the VLDL for circulation to various tissues of the body and some are stored in the liver.
How much of the vitamin A and carotenoids is absorbed? About 70 to 90% of retinol from the diet is absorbed as long as the meal contains adequate fat. Carotenoids vary in absorption from about 5 to 50%.
List and explain the factors that may affect the absorption of vitamin A. Cooking (isomerization, > cis),Type (>xanthophylls <carotenes), Concentration (<),with meals (milk, fat increases absorption), Homogenation (>), Fiber (<), Fat malabsoption (<, from illnesses, intestinal parasites)
List and explain the factors that may affect the absorption of carotenoids. Concentration (<), with meals, Dissolved in oils (100% B carotene), Homogenation, fiber (<), fat, fat malabsoprtion (<, Illnesses, intestinal parasites).
List functions of vitamin A. Vitamin A helps with vision, cell differentiation, immunity, growth and development, red blood cell production and reproduction.
List functions of carotenoids. Carotenoids have antioxidant activity.
Explain the visual cycle. Retinol stored in retinal pigment epithelial cells, hydrolyzed and oxidized to 11-cis-retinal, shuttled to rod cell, binds protein opsin, forms, rhodopsin. Photon,cascade of events, signal to optic nerve. conveyed to brain, interpreted as vision.
Explain the interaction of vitamin A and carotenoids with zinc. Zinc, needed to mobilize Vit. A from the liver. Retinol to retinal requires zinc.
Explain the interaction of vitamin A and carotenoids with def of zinc. Zinc deficiency results in decreased synthesis of RBP, transports retinol in the blood to tissues; a decrease in the enzyme retinol dehydrogenase which releases retinol from its storage form in the liver.
Explain the interaction of vitamin A and carotenoids with iron. The combination of Vit. A and iron seems to reduce anemia more effectively than either iron or Vit. A alone.
Explain the interaction of vitamin A and carotenoids with vitamin E Vit. E is needed to make retinol from beta-carotene. Vit. E can prevent autooxidation of carotenoids and may slightly lower plasma carotenoids concentrations.
Explain the interaction of vitamin A and carotenoids with other factors. Chronic alcohol consumption depletes liver stores of Vit. A. and increases the liver toxicity of Vit. A.
List the signs and symptoms of vitamin A deficiency failure to grow, eye dz, loss of cilia of respiratory epithelium (thus respiratory infections), failure to reproduce, loss of normal taste, lowered resistance to infections, follicular hyperkeratosis (skin condition).
List the signs and symptoms of vitamin A toxicity nausea, violent HA, dizziness, slowness, and desquamation of the skin. Chronic: dryness, fissures, itching of skin, hair loss, fatigue, bone and joint pain, muscle stiffness, anorexia, HA, hepatomegaly and liver damage.
What factors induce vitamin A deficiency? Inadequate food preparation, lack of intake, alcoholism, GI dz (malabsorption), not enough fat intake, liver dz
List and explain some of the therapeutic uses of vitamin A. Retinoic acid: acne, wrinkles (teratogenic). Retinol topically: dry eyes. enhance immunity; wound healing, psoriasis and menorrhagia, decrease risk: cervical dysplasia and night blindness.
List and explain some of the therapeutic uses of carotenoids. Carotenoids may protect the respiratory and digestive tracts from cancer. May also protect against heart dz and stroke. Lutein may protect the macula of the eye form damage from blue light.
List how many forms of vitamin D exist? There are 4 different forms of Vit. D: 24, 25 (OH)2 Cholecalciferol, Cholecalciferol (Calciol), 25 (OH) Cholecalciferol (Calcidiol), and 1, 25 (OH)2 Cholecalciferol (Calcitriol)
What is the most active form of Vit D? 1, 25 (OH)2 Cholecalciferol (Calcitriol) is the most active form of Vit D
What is the most circulated form of Vit D? 25 (OH) Cholecalciferol (Calcidiol) is the most circulated form of Vit. D
List the sources of vitamin D (sunlight and foods). Vit. D is found in fatty fish: herring, salmon, sardines, fish liver oils, and eggs (form hens that were fed Vit. D). fortified foods like milk, cereals, and breads in the USA. The highest source is sunlight and cod liver oil.
One microgram of vitamin D = how many IUs? 1 microgram Vit D = 40 IU of Vit D
Discuss the formation of vitamin D in skin. Cholesterol is converted to 7-dehydrocholesterol in sebaceous glands, absorbed into skin, converted from sunlight into previtamin D (precalciferol). Precalciferol naturally isomerizes in 2 to 3 days to Cholecalciferol (Vit D3).
How does vit D get from the skin to the blood? Cholecalciferol diffuses from the skin into the blood with the help of vitamin D-binding protein (DBP), which is synthesized in the liver).
Where is vitamin D deposited in the body? Much of the vitamin is deposited in muscle and adipose tissue prior to hepatic uptake.
Discuss the formation of vitamin D from dietary sources. Dietary vitamin D is absorbed from a micelle, in association with fat and with the aid of bile salts, by passive diffusion into the enterocytes.
How much Vit D gets absorbed from dietary sources? Fifty percent gets absorbed.
Discuss the absorption of vitamin D from dietary sources. rapidly absorbed in the duodenum, the largest amount absorbed in the distal SI. In the enterocyte, incorporated into chylomicrons, enter the lymphatic system and general circulation. It is returned to the liver on chylomicron remnants.
Indicate the locations of different forms of Vit D. The blood is the largest storage site of Calcidiol (half-life of 3 weeks) and is a useful indicator of Vit D nutritional status. When Calcidiol is depleted stores get released from the skin, muscle, and adipose tissues.
What is the converting enzyme involved in different forms of vit D? Calcidiol is converted to the active form of Calcitriol in the kidneys by a hydroxylation rxn and is catalyzed by 1-hydroxylase. Calcitriol is the active form.
Where can Vit D be activated? The kidney and placenta are the two organs that can activate Vit D.
What is the general role of Vit D and what is it known for? Vit D is a hormone involved in mineral metabolism and bone growth. Its best known function is in control of blood calcium concentrations along with PTH.
Discuss the role of Calcitriol and its role in resotring blood calcium levels in SI, kidney, and bone. In SI increases intestinal absorption of Ca and P. kidney increases renal reabsorption of Ca and P. bone mobilizes Ca and P from bone into the circulation, and increases extracellular fluid concentrations of Ca.
How does Vit D restore blood calcium levels? This process is mediated by Calcitriol- induced cell differentiation of hemopoietic cells to osteoclasts.
What is the role of PTH? parathyroid glands sense blood calcium level, secrete PTH if low. stimulates the activity of the 1-hydroxylase in the kidney, produce more Calcitriol. PTH required to increase bone calcium mobilization and calcium reabsorption by the kidneys.
What happens normally with decreased calcium in the blood? When serum calcium decreases, we get release of Calcitriol and PTH which leads to increased calcium absorption in the SI, decreased excretion from the kidney, and release of calcium from bone.
Discuss functions of vitamin D. Vit D is important for bone remodeling, sythesis of osteocalcin, some transcriptional effects (calcium transport, osteoblasts, enzymes in kidneys), Cell proliferation, differentiation and growth, immunity.
How does Vit D affect osteocalcin? Vit D is important for bone remodeling. Calcitriol is important in the synthesis of osteocalcin (protein found in bone and dentine). Osteocalcin is associated with new bone formation.
How does Vit D, affect DNA transcrition? forms a heterodimer VDRE, change in the rate of transcription. , Vit D-dependent calcium transporters in the SI, osteoblasts in bone, and the 1-hydroxylase enzyme in the kidneys.
Why is Vit D useful for psoriasis? Vit D analogs have been used to treat severe cases of psoriasis because of its effect on cell proliferation, differentiation and growth.
What is the role of Vit D in the immune response? Vit D receptors have been identified in T-lymphocytes. Immune responses that are mediated by T-cells, inhibited by large doses of Calcitriol. deficiency of Vit D interferes with T-cell mediated immunity.
What are the risk factors for vitamin D deficiency? Infants and elderly with min. sun exposure, darkly pigmented skin, covering all exposed skin, fat malabsorption syndromes, kidney failure, genetic dz, anti-convulsant medications, and cholestyramines medications (used to lower cholesterol).
List the signs and symptoms of vitamin D deficiency A deficiency can lead to hypocalemia low blood calcium levels thus leading to severe bone dz, such as rickets and osteomalacia (adult rickets).
List the signs and symptoms of vitamin D toxicity Toxicity can cause the deposition of Ca in soft tissues (KI, HT, lung, BV), hypercalemia, hypercalciuria, kidney stones, and irreversible kidney damage.
List and explain some of the therapeutic use of vitamin D. Naturopaths use Vit D to treat rickets, fx in elderly, osteoporosis, and as a cancer prophylaxis for colorectal cancer and breast cancer, seasonal affective disorder, and is used to treat psoriasis.
List how many forms of vitamin E exist (synthetic and natural forms). There are 8 forms of Vit E. There are 4 tocopherols and 4 tocotrienols ( alpha, beta, gamma, and delta). The natural form of Vit E is d-alpha-tocopherol. The synthetic form is dl-alpha-tocopherol and is less biologically active.
What is the RDA for vitamin E? 15 mg of a-tocopherol per a day for adult men and women ages 19 and older
Currently, most food compositions and tables uses what unit of vitamin E? Mg but used to be IU (international unit)
List food sources of vitamin E. Highest to lowest = almonds, sunflower oil, hazelnuts, sunflower oil, avocado, peanuts, canola oil, wheat bran, and green leafy vegetables.
List the factors that may affect the absorption of vitamin E. Pancreatic secretions, bile acids(liver/GB dx), GI dx, surgical removal of intestines, chylomicron syn, defective intestinal lymphatic channels.
List functions of vitamin E. Antioxidant, maintains integrity of cell membranes, prevents LDL oxidation, reacts with peroxyl free radicals to prevent formation of lipid peroxides, protects against heavy metals, hepatotoxins; immune fxn, dev of neuromuscular sys, retina.
What form(s) of vitamin E can lower serum cholesterol (by inhibiting synthesis), as well as suppress tumor growth and cell proliferation? Tocotrienols
What vitamin can inhibit platelet aggregation by increasing prostacyclin production? Vitamin E.
Which form of vitamin E is preferentially secreted by the liver? alpha-tocopherol.
What organ and what protein discriminates between tocopherols? The liver. alpha-tocopherol transport protein (alpha-TTP) transports the RRR only.
What are the different forms of Vitamin K? There are 3 forms of Vit K. The two natural forms are known as Vitamin K1 (phylloquinone) and Vitamin K2 (menaquinone). The synthetic form is menadione.
List the sources of vitamin K. Phylloquinone (K1) is obtained via green leafy vegetables such as kale, cabbage, and some vegetable oils. Large intestinal bacteria synthesize menaquinones, but not enough for all needs of their host human.
How are the different forms of vitamin K absorbed? K1 is absorbed in the SI by a satiable energy-dependent process. The other two forms are absorbed by passive diffusion in the distal SI and colon.
Where is vitamin K stored? The lung, adrenal gland, bone marrow, and the kidney store Vit K. Turnover in the liver is rapid and is rapidly depleted when dietary intake is restricted.
List the functions of vitamin K. Carboxylation, coagulation, synthesis of protein Z,C, and S, bone mineralization.
Name the drug that is a vitamin K antagonist. Warfarin, aka coumarin or Coumadin
List reasons that may lead to a vitamin K deficiency. 1)Faulty absorption due to a lack of bile and fat 2) Malabsorption syndrome due to diarrhea, ulcerative colitis, sprue, and celiac dz 3) use of abx for prolonged period of time which reduce intestinal synthesis.
Indicate why newborn that are exclusively breastfed are at increased risk of vitamin K deficiency. Human milk is low in K vs formula. The neonatal gut is sterile during the first few days, no bact menaquinones. The K cycle may not be fully functional in newborns. The placenta transmits K poorly, the neonatal liver has immature prothrombin synth.
Discuss the hemorrhage disease of the newborn. Vit K deficiency in newborns may result in a bleeding disorder called hemorrhagic dz of the newborn also known as Vit K deficiency bleeding (VKDB).
List and explain some of the therapeutic use of vitamin K. Blood clotting disorders due to Vit k def, osteoporosis (Vit K induces an inc in serum osteocalcin and a dec in urinary Ca excretion). Used to treat nausea and vomiting in preg, to treat fx, RA, and prevention of calcium oxalate kidney stone.
Which vitamins contain sulfur in its structure? Biotin and thiamin (B1), CoaSH (B5, pantothenic acid) (lipoic acid?)
What are the coenzyme forms for B1? Thiamine pyrophosphate (TPP) and thiamine diphosphate (TDP)
List food sources for B1? Whole grain cereals, legumes, nuts, lean pork, and yeast are rich sources of thiamin
What are the factors which may increase the requirements of the vitamin B1? Age (children), Activity (high physical activity), and Physiologic state (pregnancy and lactation)
Explain the digestion process of B1? It is dephosphorylated prior to absorption. Free form in plants but occurs as TDP or TPP in animals.
Explain the absorption process of B1? Active transport mainly in upper jejunum. Bound to albumin or found as thiamin monophosphate (TMP) in blood. Free thiamin is taken up by the liver and phosphorylated.
Where is thiamine stored in the body? Not much storage, skeletal muscle, heart liver, kidney, and brain. Excess is excreted in urine.
What is the decarboxylation reaction (thiamin)? Pyruvate to acetyl CoA (oxidative decarboxylation), and alpha-ketoglutarate to succinyl CoA (oxidative decarboxylation). TPP is required for alphaketoacid dehydrogenases.
What are the functions of B1, including the rxns? Energy production in the krebs cycle and the pentose phosphate pathway. Neurological fxn, not known, vital role in nerve fx.
Explain the energy production of vitamins (how many vitamins are involved in the energy production, reactions). It is part of a large enzyme complex, pyruvate dehydrogenase involving lipoic acid, FAD, NAD, and Coenzyme CA (panthothenic acid).
What vitamin is involved in HMPS? ?
What are the toxicity symptoms for B1? No known toxic effects. Sx can include HA, irritability, weakness, flushing, and itching. Def results in beri beri.
What are the deficiency symptoms for B1? It is characterized by anorexia, weight loss, enlarged heart, nueromuscular sx such s paresthesia, muscle weakness, lassitude, and foot and wrist drop.
What is Wernicke's and Korsakoff's Syndrome? Dz affects alcoholics, due to poor diets, high carbs (>demand for thiamine), ETOH inhibits absorption (intestinal ATPase),
What are the signs of Wernicke's and Korsakoff's Syndrome? the signs include CN VI nerve damage (opthamoplegia and dystagmus), physchosis, confabulation, and impaired retentive memory and cognitive fxn, coma (severe).
How many forms of beri beri do we have? There are five forms of beri beri: Dry, Wet, Infantile, Shoshin, and Aphonic.
What are the symptoms of wet beriberi? Substantial cardiac involvement especially tachycardia in addition to peripheral neuropathy. Edema progresses from the feet upward to the heart and results in CHF in severe cases.
What are the symptoms of dry beriberi? Mainly affects the peripheral nerves and is characterized by atrophy (wasting) and peripheral neuritis of the legs and paraplegia.
What are the symptoms of infantile beriberi? results in anorectic babies who can't keep milk down and can cause heart failure in a matter of hours.
What are the symptoms of Shoshin beriberi? affects the heart and lungs
What are the symptoms of Aphonic beriberi? results in changes in the child's voice
What is the differential diagnosis between different forms of beriberi? Dry- nerves, Wet- (congestion) lungs, heart, Infantile- vomiting, Shoshin- heart and lungs, Aphonic- voice
What are the factors that may increase B1 deficiency? Intake, increased req., excessive loss, consumption of antithiamin factors (ATFs) found in coffee and tea, blueberries, black currant, brussels sprouts and red cabbage.
What is ATF? Anti-Thiamin factor which is a polyhydroxyphenol suc as tannic acid and caffeic acid.
What is vitamin B2 called? Riboflavin
What are the co-enzyme forms for B2? FAD and FMN.
List food sources for B2 most plant and animal derived foods. Fortified cereals, and organs meats: liver, kidney, fish and leafy veggies, roots, and fruits.
What factors will affect vitamin B2 content in food? exposure to light. Just two hours of exposure will reduce riboflavin in milk by 50%.
What factors increase the requirements for B2? growth, convalescence after severe trauma, lactation, burns or surgery, increased protein intake.
Explain the digestion process of B2 riboflavin is found free or protein bound, and as FMN and FAD in foods. Cleaved from protein. Animal sources are better absorbed than plants. (70% / 15%)
Explain the absorption process of B2 In the enterocyte riboflavin is phosphorylated into FMN. It is then dephosphylated to riboflavin and enters the portal system, carried to liver and converted to FMN and FAD. Transported by variety of proteins.
What factors inhibit the absorption of B2? Divalent metals (Cu, Zn, Mn) inhibit absorption of it.
Where does absorption of B2 take place? Free riboflavin is absorbed by active transport in the SI. Small amount in the LI.
Where are the greatest concentrations of B2 found? Liver, kidney, and heart. Excess is excreted in the urine about 2 hours later and is fluorescent yellow in color.
What is the role of the flavokinase enzyme? converts riboflavin to FMN and requires Zn.
What are the functions of B2? oxidation-reduction rxns (FAD and FMN). Metabolism of carbs, fats, and proteins (flavins). FA oxidation, catabolism of Vit B6, glutathione redox xyxle, synthesis of niacin containing coenzymes (tyrptophan), acitvation of folate
What are the rxns invloving B2? Oxidative decarboxylation of pyruvate and alpha-ketoglutarate, Interconversion and catabolism of Vit B6 (PLP req FMN), Glutathione redox cycle, sythesis of the active form of folate
What are the deficiency symptoms of B2? Sore throat, redness and swelling of the lining of the mouth and throat, cracks or sores on the outside of the lips and the corners of the mouth, inflammation and redness of the tongue, moist and scaly skin inflmaation, and vascularization of the cornea.
What are the deficiency symptoms of B2? Pharangitis, angular stomatitis, magenta tongue, dermatitis, keratitis
What are the toxicity symptoms of B2? no known toxicity, no UL set.
What is magenta tongue? red and inflamed tongue
What is glositis? inflammation and redness of the lining of the mouth and throat
What is angular stomatitis? cracks and sores at the corner of the mouth
What are factors the may increase B2 deficiency? < dietary intake, < absorption (lactose intolerance, surgical removal of SI, diarrhea, infection), destruction (phytotherapy), drugs < incorporation into FAD and FMN (antipsychotic, antidepressants, and anti malarial meds), activity level
What is Vitamin B3 called? Niacin
What are the coenzyme forms for B3? Nicotine adenine dinucleotide (NAD) and nicotine adenine dinucleotide phosphate (NADP)
List food sources for B3 yeast, poultry, fish with red meat (tuna, salmon, beef, chicken, turkey) , cereals, legumes, and seeds. Milk, green leafy vegetables, coffee, and tea.
List the RDA levels for B3 Adult men-16 mg/day, Adult women-14mg/day
Explain the digestion process of B3 NAD and NADP are hydrolyzed, dephosphorylated within the intestinal tract by glycohydrolase to free nicotinamide. Nicotinamide and nicotinic acid are absorbed in the stomach/SI by active transport.
Explain the absorption process of B3 Nicotinic acid is converted to nicotinamide in enterocyte, in blood, cross membranes by diffusion. Nicotinic acid transport, kidneys/RBCs active tranport.
What are the fxn of B3? about 200 enzymes req NAD or NADP as cofactors. NADP is involved in energy production, and is an important reducing agent.
What rxns is B3 (coenzyme forms) involved in? Glycolysis, oxidative decarboxylation of pyruvate, Beta oxidation, and ethanol metabolism. Synthesis of fatty acids, cholesterol and steroid hormones, and for DNA.
What vitamins and mineral are required for the conversion of trytophan to Niacin? 60 molecules of tryptophan are needed to make one molecule of Niacin (60mg=1mg). Other vitamins: Thiamin (B2), Biotin , and Pyridoxine (B6)
Explain the role of B3 in dz tx (high cholesterol and CHD, HIV/ AIDS) reduce blood cholesterol, blocks HMG coReductase to block synthesis of VLDL. HIV increases risk of niacin def.
What is Pellagra? 4 D's, def of niacin or tryptophan, dermatitis (casal necklace), Diarrhea, Dementia, Death
What are the factors that may increase B3 deficiency? intake, Hartnup's dz (typtophan absorption), carcinoid syndrome (increased serotonin instead of niacin), antituberculosis drugs.
Discuss the toxicity issues related to B3? flushing and itching, GI disturbances, hepatotoxicity, hypotension and HA. Impaired glucose tolerance, > uric acid, blurred vision and other eye problems. Nicotinamide better tolerated
List the B3/drugs interactions lovastatin (rhabdomyolysis), Isoniazid (niacin antagonist), oral contraceptives (decreased synthesis)
What is the difference between the structure of pantothenic acid and its coenzyme form structure? Beta-alanine + Pantoic acid joined by a peptide bond. The co-enzyme form is CoASH.
What is pantethine? derivative of pantothenic acid. Pantethine is two molecules of pantetheine joined by a disulfide bond, synthetic pathway of CoA
Explain the digestion process of pantothenic acid CoA is hydrolyzed in SI to pantotheine, then to pantothenic acid. Free PA absorbed by active transport.
Explain the absorption process of pantothenic acid 40-69% of PA is absorbed (< if high concentration), metabolized to CoA.
What is CoA used for? Synthesis of ACP (Acyl carrier protein) of the fatty synthase enzyme (FA synthesis), storage: liver, adrenals, kidneys, brain, heart, and testis. Excreted in urine (Pantothenic acid).
What are the functions of CoA? energy metabolism, oxidative decarboxylation of pyruvate and alpha-ketoglutarate, as carrier of acyl groups for energy production. Synthesis of cholesterol, ketone bodies, CoQ10, acetyl choline, phospholipids, and sphingomyelin.
What are the functions of ACP? energy metabolism, oxidative decarboxylation of pyruvate and alpha-ketoglutarate, as carrier of acyl groups for energy production
Discuss the deficiencies for pantothenic acid Not normal, Severe malnutrition: alcoholics, DM, inflammatory bowel dz. Skin sensations of feet and lower legs, > warmth, <cold
What is thiopanic acid? a pantothenic acid antagonist, sx fatigue, CV def, GI tract disturbances, numbness and tingling of the extremeties (burning feet syndrome), depression, URTI's.
Discuss the toxicities for pantothenic acid no known toxicity, large amounts lead to diarrhea (10-20g's)
Does Vitamin B5 lower cholesterol? Pantethine lowers total cholesterol and TG levels in blood, Pantothenic acid does NOT lower lipids.
How many forms exist for Biotin? There are 8 different forms of biotin. Only one of them D-Biotin occurs naturally and has full vitamin activity.
What is avidin? glycoprotein found in egg white, binds biotin and prevents its absorption. Cooking eggs denatures avidin.
List the sources for biotin egg yolk, liver, soybeans, and yeast. Corn, avacados, raspberries, cooked artichoke, cheese, and raw cauliflower.
Can we get enough biotin from intestinal flora? No, we cannot get enough to stave off a deficiency, just to supplement (pantothenic acid and Vit K, as well)
Discuss the absorption of biotin bound to proteins, released in SI by protein hydrolysis and biotinidase. Absorped in upper SI, active transport and slow diffusion. Reg carrier inverse to [biotin]. Also in colon.
Discuss the transport of biotin. Distributed to all tissues, liver and retinal tissues main storage sites. Metabolites excreted in urine (non active).
What are the 4 carboxylases considered biotin-dependent? 1) Acetyle-CoA carboxylase, 2) Pyruvate carboxylase, 3) methylcrotonyl-CoA carboxylase, 4) Proppionyl-CoA carboxylase 1) FA synthesis, 2) gluconeogenesis, 3) leucine metabolism, 4) AA, cholesterols, and odd chain FA metabolism
Discuss the deficiency symptoms of biotin very rare, hair loss, scaly red rash around the eyes, nose, mouth, and genital areas. Depression, lethargy, hallucination, numbness and tingling extremities. Characteristic facial rash, fat distribution= "biotin def. face"
Discuss the mechanism that may explain the glucose lowering effect of biotin Biotin plays a special role by enabling the body to use blood glucose as major source of energy for body fluids.
What are the forms of Vitamin B6? Pyridoxal (PL), pyridoxamine (PM) and pyridoxine (PN)
What forms of Vit B6 are found in animal food sources? What about plant food sources? Animal: PLP and PMP. Plant: PN (esp PN glucoside)
Vit B6 is absorbed and transported in the ________ form, and upon entering the cell, is ______. unphosphorylated, phosphorylated.
Absorption of PN, PL, and PM occur by ____ ____ in the jejunum. passive diffusion.
What is the major form of Vit B6 in blood and cells? PLP.
What other vitamin is needed with an oxidase to turn PNP or PMP to PLP? B2 (FMN)
Where in the body is PLP found the most? the muscle
What is needed in the reaction to convert PL to pyridoxic acid (PIC) along with an aldehyde dehydrogenase? NAD
What is needed to in the reaction to convert PL to PIC along with an aldehyde oxidase? FAD
List food sources for B-6. Whole grains, bananas, legumes, nuts, potato, chicken, liver, beef, fruits, vegetables, egg yolk, fish, milk, cabbage.
List some functions of B-6. transamination, deamination, trans- and de-sulfhydration, cleavage, racemization, decarboxylation in the synth of serotonin, RBC formation and fxn, coenzyme in the synth of heme.
PLP is a coenzyme for a critical reaction in the synth of _____ from tryptophan. niacin
What is the relationship b/w B-6 and hormones? PLP binds to steroid receptors in a way that inhibits the binding of steroid hormones, decreasing their effects. The B-6 status of an individual may have implications for diseases affected by steroid hormones, such as breast cancer and prostate cancer.
What is the relationship b/w B-6 and nucleic acid synthesis? PLP serves as a coenzyme for a key enzyme involved in the mobilization of single-carbon functional groups (one-carbon metabolism). Such reactions are involved in the synthesis of nucleic acids (DNA and RNA).
What are the deficiency symptoms of B-6? seizures, abnormal EKG, irritability, depression, and confusion, inflam of the tongue, sores or ulcers of the mouth (glossitis), ulcers of the corners of mouth, peripheral neuritis, dermatitis (skin inflam), depression, confusion, and convulsions, anemia.
What are the toxicity symptoms of B-6? painful neurological symptoms, sensory neuropathy, pain and numbness of the extremities, difficulty walking.
List food sources that contain Vitamin C: Plant sources: citrus, peppers, melons, berries, tomatoes, parsley, green fresh veggies, turnips. Animal sources: milk Many supplement forms
True or False: V-C is easily destroyed with light, oxygen, heat. True
Main functions of V-C: Collagen, Carnitine, & Tyrosine synthesis: hydroxylation reactions (keeps Fe in reduced form)
Main functions of V-C: Tyrosine catabolism (alkaptonuria & homogentisic acid)
Main functions of V-C Neurotransmitter synthesis, Antioxidant, Vitamin activation, Antihistamine
List sns/sxs of V-C deficiency: Scurvy: bleeding/bruising anemia, gum disease, swelling, tenderness, gingivitis, redness, ulceration; Hair/tooth loss, joint pain/swelling, slow wound healing, defects in bone calcification
True/False: Mostly collagen related issues are due to V-C deficiency. True
List conditions that are induced by toxic levels of V-C intake: genetic mutations, birth defects, cancer, atherosclerosis, kidney stones, oxidative stress, excess iron absorption, B12 deficiency, erosion of dental enamel
List Some Special Considerations for V-C: Oral contraceptives & aspirin may lower Vit C levels in plasma/WBCs. Vit C may decrease effectiveness of anticoagulant medications.
What is Gulonolactone Oxidase? An enzyme involved in the synthesis of V-C. In man and primates, the enzyme Gulonolactone Oxidase is missing, thus they are unable to synthesize V-C.
List the RDA levels for vitamin C Non smoking adult men ages 19 and older: 90 mg of vitamin C/day Non smoking adult women ages 19 and older: 75 mg/day Adult men who smoke: 125 mg/day. Adult women who smoke: 110 mg/day
What forms of vitamin C are found in supplements Examples: Sodium ascorbate, Calcium ascorbate, Potassium ascorbate, Magnesium ascorbate, Zinc ascorbate, Molybdenum ascorbate, Chromium ascorbate, Manganese ascorbate, Ester-Cᅡᆴ, Vitamin C with bioflavonoids, and Ascorbyl palmitate.
Discuss the absorption of vitamin C In men and guinea pigs: AA absorbed in SI (ileum) by active transport mechanism (Na+-dependent, energy requiring, carrier mediated transport system) Losses up to 20% occur during absorption (destroyed in GI tract)
Discuss the transport of V-C: Ascorbic acid is transported as a free anion (with albumin).
What happens to excess metabolites of Vit C? Metabolites in excess are excreted in the kidneys.
Discuss the metabolism of V-C: The kidneys reabsorb Vitamin C in an effort to maintain a 1500 mg body pool, If body pool is > 1500 mg, then metabolites appear in the urine. If < 1500 mg, little or no ascorbic acid appears in urine.
What tissues contain highest concentration of vitamin C: Highest concentrations: Adrenal cortex, pituitary gland and retina
What tissues intermediary concentration of vitamin C: ntermediary concentrations: liver, lungs, pancreas, kidneys, spleen, heart, WBCs.
what tissues low concentration of vitamin C: Low concentrations: RBC's, and muscle
What are some of the reactions V-C is involved in? Best known is role in collagen synthesis - proline and lysine in procollagen need to be hydroxylated by proline and lysine hydroxylase (also called dioxygenase to form collagen).
What are some of the reactions V-C is involved in? Need vitamin C to keep Fe in reduced form for reactions catalyzed by proline hydroxylase and lysine hydroxylase.
What are some of the reactions V-C is involved in? During the hydroxylation rxn, the Fe cofactor in the enzyme is oxidized, converted from a ferrous (+2) to a ferric (+3) state. Ascorbate needed to function as reductant, thereby reducing Fe back to its ferrous state (+2) in the prolyl & lysyl hydroxylases
What is the most important sign of biotin deficiency for this class? biotin deficient face= a scaly red rash around the eyes, nose, and mouth as well as an unusual facial fat distribution
V-C and carnitine synthesis: Ascorbic Acid needed for two steps in carnitine synthesis (hydroxylations involving Fe)
Causes of V-C deficiency: nadequate dietary intake, High alcohol consumption, Smoking, Stress, Elderly, Achlorhydria, Rheumatic fever, Rheumatoid arthritis, Institutionalized, and Surgical and cancer patients
True/False Severe vitamin C deficiency has been known for many centuries as the potentially fatal disease, scurvy. True
Symptoms of Scurvy a V-C deficiency include: Bleeding and bruising easily Anemia (Microcytic, hypochromic). Gums disease, swelling, tenderness, gingivitis, redness, ulceration
Symptoms of Scurvy a V-C deficiency include: Hair and tooth loss Joint pain and swelling Defects in the bone calcification Slow wound healing
True/False: Scurvy symptoms appear to be related to the weakening of blood vessels, connective tissue, and bone, which contain collagen.
What are early sns/sxs of Scurvy? What could these early sns/sxs be a result of: Early symptoms of scurvy such as fatigue may result from diminished levels of carnitine, needed to derive energy from fat, or decreased synthesis of the neurotransmitter norepinephrine.
True/False: None of the in vitro studies on adverse health effects caused by toxic levels of V-C have been confirmed. True
V-C can interfere with a number of tests (False positive or negative laboratory test) for: Fecal occult blood (false negative) Occult blood in urine (false negative) Urinary glucose in diabetes (False positive e.g. fecal blood)
V-C INTERACTIONS - How is V-C related to estrogen? Estrogen-containing contraceptives are known to lower vitamin C levels in plasma and white blood cells.
V-C INTERACTIONS - What pain medication can affect V-C levels? Aspirin can lower vitamin C levels if taken frequently. For example, two aspirin tablets taken every six hours for a week has been reported to lower white blood cell vitamin C by 50%, primarily by increasing urinary excretion of vitamin C.
Besides Vit k, what other vitamin could possibly interact with blood thinners? (this is controversial) There is some evidence, though controversial, that vitamin C interacts with anticoagulant medications (blood thinners) such as warfarin (coumarin).
V-C INTERACTIONS - What does V-C convert into its active form? Facilitates conversion of inactive folic acid to active dihydro- and tetrahydro- folic acid. (folicine -> THFA)
SUGGESTED THERAPEUTIC AND PREVENTIVE USES OF V-C: Cardiovascular diseases, Vitamin C and stroke, Diabetes mellitus, Cancer, Common cold, Vitamin C and gallbladder disease, Cataracts
Created by: AaronsWorld