Foodchem - vitamins

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Foodchem - vitamins
2012-12-16 21:44:13
Foodchem vitamins

Foodchem - vitamins
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  1. What are Vitamins & Minerals?
    Organic substances required in the diet in small quantities for normal growth and development
  2. Which vitamin groups are water soluble?
    B complex, C
  3. Which vitamin groups are fat soluble?
    A, D, E, K
  4. What are 2 synonyms for vitamin A?
    • retinol
    • axerophthol
  5. What is retinol?
    pre-formed vitamin A found in animal sources
  6. what are the pro-vitamin A sources?
    Carotenoids: beta-carotene, alpha-carotene, beta-cryptoxanthin
  7. What are the plant food sources of vitamin A?
    • vegetable oils (particularly palm oil)
    • green leafy vegetables (like spinach)
    • peppers
    • tomatoes
    • carrots
    • fruits like melon, mango, cantaloupe, papaya, pumpkin
  8. where is vitamin A stored in the body?
    in the liver since it is fat soluble
  9. how much vitamin A can a healthy adult store in the body?
    enough to meet needs for up to a 2 years supply
  10. what are the animal sources of vitamin A?
    • liver
    • fish oil
    • fatty fish (salmon, trout, mackerel, tuna, sardines)
    • egg yolk
    • cheese whole milk
    • butter
  11. what food products is vitamin A usually added to?
    • margarine
    • fruit drinks
    • salad dressing
    • cake mixes
    • ice cream
  12. why is vitamin A addeds to foods?
    • for its vitamin A activity 
    • as a food colorant
  13. in which form is vitamin A found in the eye?
    in the all-cis-retinal form
  14. what is the first step of using vitamin A in vision?
    convert all-cis-retinal form to the all-trans-isomer
  15. in the 2nd step of using vitamin A in vision, the all-trans form binds to what to form what?
    binds with opsin (protein in the eye) to form rhodopsin
  16. what happens when light impinges on the retina in the eye in the 3rd step of using vitamin A for vision?
    • the rhodopsin is split to regenerate the opsin and the trans-form of retinal
    • this splitting process results in impulses or signals being transmitted to the brain where it is interpreted into "light" and "dark"
  17. what is the last step to using vitamin A in vision?
    the trans-retinal is converted back into the all-cis form to continue the cycle
  18. why is vitamin A considered an antioxidant?
    antioxidant activity is due to the highly unsaturated nature of the vitamin which enables it to scavenge free radicals and prevents them from causing oxidative damage to biological molecules and tissues (like biological membranes)
  19. how does vitamin A help in growth?
    vitamin A maintains appetite for food for normal growth
  20. what areas does vitamin A help protect as an antioxidant?
    surface linings of the eyes, respiratory tract, urinal tract, intestinal tract
  21. how does vitamin A help blood cells?
    helps maintain the integrity of blood cells to make them able to defend the body against invasion by foreign bodies
  22. how does vitamin A play a role in gene transcription?
    retinol as retinoic acid binds to the receptors in the nucleus known as retinoic acid receptors (RARs) to regulate gene transcription
  23. how does deficiency of vitamin A arise?
    • lipid maladsorption conditions
    • eating too little fat in the diet
  24. what decreases liver reserves of vitamin A?
    • use of oral contraceptives
    • diseases and infections
    • chronic heavy intake of alcohol
  25. what does deficiency of vitamin A cause?
    impaired vision
  26. which processing conditions destabilize vitamin A?
    air/oxygen, light, heat, acidic conditions
  27. vitamin A is moderately stable under which conditions?
    neutral to slightly alkaline conditions
  28. what is the toxicity of vitamin A?
    high levels can lead to accumulation of H2O in the brain, called HYDROCEPHALIA
  29. what do toxic levels of vitamin A manifest as?
    headaches, confusion, blurred vision
  30. what are the 2 most common forms of vitamin D?
    • ergocalciferol (D2)
    • cholecalciferol (D3)
  31. what does the term vitamin D refer to?
    a group of steroids with vitamin D activity
  32. what are the plant sources of vitamin D?
    in plant materials, but only as D2
  33. what are the animal sources of vitamin D?
    • fish (sardines, tuna, salmon)
    • fish liver oils
    • eggs
  34. which products are fortified with vitamin D?
    margarine, milk, butter, cheese
  35. what are the microbial sources of vitamin D?
    • yeast
    • mushrooms
  36. how is vitamin D synthesized?
    • in the presence of sunlight
    • in the liver and kidney
  37. which forms of vitamin D are synthesized in the liver and kidney?
    hydroxylated into the mono- and di- hydroxylated forms that have more potent biological activity
  38. which forms of vitamin D are synthesized from exposure to sunlight?
    enables synthesis from precursor molecules: egostreol and 7-dehydrocholesterol
  39. what does vitamin D regulate the uptake of?
    Calcium and phosphorous from the intestines into skeletal tissues for their building and maintenance
  40. Since both D2 and D3 have little biological activity, what are they converted into?
    converted to the active hormonal forms in the liver (25-hydroxycholecalciferol) and in the kidney (1,25-dihydroxycholecalciferol)
  41. What does vitamin D deficiency result in?
    • poor bone and teeth development
    • in children, as bent or crooked limbs (RICKETS)
    • in adults, as thinning of bones (OSTEOMALACIA)
  42. what is the difference between osteomalacia and osteoporosis?
    Osteomalacia results from a defect in the bone-building process, while osteoporosis develops due to a weakening of previously constructed bone.
  43. how does vitamin D deficiency arise?
    • genetic defects in the vitamin D receptors
    • severe liver or kidney disease
    • insufficient exposure to sunlight
  44. what is one of the most stable vitamins?
    • vitamin D
    • it is not destroyed by processing/storage procedures like pasteurization, boiling, freezing, etc
  45. what is vitamin D unstable to?
    • light
    • air/oxygen
  46. what are the symptoms of vitamin D toxicity?
    • weakness, tiredness, headaches
    • nausea and vomiting
    • loss of appetite
    • slow growth
    • excessive thirst and urination
    • protein presence in the urine
    • kidney failure
  47. what is the term vitamin E used to describe?
    • 8 closely related compounds:
    • 4 are tocopherols
    • 4 are tocotrienols
    • each category has an alpha, beta, gamma and delta name to distinguish it
  48. where is the name tocopherol derived from?
    from the Greek words related to fertility and childbirth
  49. which form of vitamin E is the most potent?
  50. are mammals capable of synthesizing vitamin E?
    no, they must obtain it from external sources?
  51. where do mammals store vitamin E?
    mainly in fatty tissues, as well as liver and muscle tissues
  52. what are the microbial food sources of vitamin E?
    • yeasts
    • mushrooms
  53. what are the vegetable food sources of vitamin E?
    • wheat germ
    • vegetables (broccoli, kale, collard greens, leafy greens, cabbage)
    • vegetable oils (sunflower seeds and oil)
    • fruits (pumpkin, avocado, kiwi)
  54. what are the animal food sources of vitamin E?
    • fatty fish oils
    • liver
    • dairy products
  55. does vitamin E have antioxidant power?
    yes, protects body tissues from oxidative damage from normal metabolism or toxic agents
  56. vitamin E works synergistically with which compounds?
    vitamin C, beta-carotene, selenium
  57. what does vitamin E inhibit the oxidation of?
  58. what is the result of vitamin E inhibitting LDL oxidation?
    prevents platelet aggregation (anticoagulant)
  59. which enzymes does vitamin E regulate?
    the enzymes that participate in the hydroxylation of vitamin D
  60. Is deficiency of vitamin E common?
    no, deficiency is rare because it is widespread in foods
  61. which people get vitamin E deficiencies?
    • people who cannot absorb dietay fat due to inability to secrete bile salts
    • people with genetic abnormalities in their alpha-tocopherol transfer protein
    • premature, very low birth-weight infants
  62. what can vitamin E deficiency lead to?
    • impaired coagulation
    • hemolysis
    • anemia
    • skin and nerve disorders
    • impaired immune disorders
  63. what are symptoms of vitamin E toxicity?
    • generally non-toxic
    • high levels may interfere with utilization of the other fat soluble vitamins (A, D, K)
    • stomach upset, diarrhea, dizziness
  64. what are the effects of processing on vitamin E?
    One of the most unstable vitamins and activity is hindered by several processing conditions (exposure to oxygen and light, as well as from reactions with hydroperoxides) except under neutral and slightly acidic conditions
  65. what are the 2 natural forms of vitamin K?
    • phylloquinone
    • metaquinone
  66. what is the synthetic form of vitamin K?
  67. what are the 2 best known forms of vitamin K?
    • the natural ones:
    • phylloquinone (K1)
    • menaquinone (K2)
  68. what species can synthesize vitamin K?
    • plants
    • intestinal bacteria in mammals
  69. which forms of vitamin K tend to be non toxic?
    the natural forms
  70. which form of vitamin K can cause toxicity, and how?
    • menadione (synthetic)
    • can cause toxicity in excess in infants via breakdown of bilirubin and red blood cells to cause jaundice and anemia 
  71. what are the plant food sources of vitamin K?
    • green leafy vegetables, oats, soy bean, potatoes, brussels sprouts, spinach, cabbage, cauliflower, coffee, green tea
    • fruits like avocado, prunes, kiwi
  72. what are the animal sources of vitamin K?
    • bacon
    • organ meats (liver, kidney, brain)
    • egg yolk
    • butter
    • cheese
  73. which food products are fortified with vitamin K?
  74. what synthesis is helped by vitamin K?
    synthesis of blood proteins (for coagulation) and bone proteins (for bone development)
  75. vitamin K functions to help conversion of what?
    glucose into glycogen for storage
  76. what is the primary function of vitamin K?
    carboxylation of protein molecules essential for blood-clotting (prothrombin, factors VII, IX & X), and bone proteins (osteocalcin) for calcification
  77. is deficiency of vitamin K common?
    rare, except in newborn infants or from excessive use of antibiotics
  78. what does vitamin K deficiency result in?
    failure of blood clotting (hemorrhages)
  79. what decomposes vitamin K?
    • oxygen
    • exposure to light
    • extreme cold (freezing)
    • alkaline conditions
  80. what conditions is vitamin K stable under?
    • heat treatment
    • soluble in acidic conditions
    • exposure to air
  81. what is the B complex?
    B1, B2, B6, B12, niacin, folic acid, pantothenic acid, biotin
  82. what is vitamin B1?
  83. what is B1 composed of?
    a pyrimidine residue and a thiozole residue
  84. B1 is an essential cofactor of what?
    TTP (thiamine pyrophosphate)
  85. what are the plant sources of vitamin B1?
    • cereals
    • whole grains
    • green leafy vegetables
  86. what are the animal sources of vitamin B1?
    meats (pork, beef, lamb, poultry)
  87. what are the microbial sources of vitamin B1?
    Brewer's yeast
  88. what is TTP (thiamine pyrophosphate)?
    • also known as co-carboxylase
    • a cofactor for several crucial enzymes in intermediary metabolism (ex pyruvatte dehydrogenase, pyruvate decarboxylase, alpha-ketoglutorate dehydrogenase, transketolase (in the pentose phosphate pathway))
  89. besides being the precursor for TTP, what is the other primary function of vitamin B1?
    aids in efficient metabolism of carbohydrates
  90. what are the symptoms of vitamin B1 deficiency?
    • low energy, tiredness
    • anorexia
    • mental depression
    • confusion
    • impaired synthesis of the crucial biomolecules
    • Beriberi
  91. which vitamin is considered one of the most susceptible to destruction by processing?
    vitamin B1
  92. what are some effects of processing on vitamin B1?
    • additives like sulfites destroy the vitamin
    • lost to cooking water
    • neutral and alkaline conditions
    • exposure to oxygen
  93. what food products is vitamin B1 generally added to?
    flour and other grain/cereal products to compensate for losses during processing
  94. Is vitamin B1 generally considered toxic? why?
    considered non toxic because it is excreted in urine and sweat
  95. what have some studies shown that high levels of B1 can cause?
    can affect insulin and thyroid production
  96. what is vitamin B2?
  97. what are the 2 components that riboflavin is comprised of?
    • 3 ringed flavin
    • 5C alcohol (ribitol)
  98. what are the 2 active forms of riboflavin?
    • FMN (flavin mononucleotide) in which the riboflavin is phosphorylated at the 5-position of ribitol
    • FAD (flavin adenosine) in which the ribitol group in riboflavin is esterified with adenosine diphosphate
  99. where is vitamin B2 produced?
    by intestinal bacteria
  100. what are the plant sources of vitamin B2?
    • green leafy vegetables
    • peas
    • tomatoes
    • whole grains
    • cereals
  101. what are the animal sources of vitamin B2?
    • organ meats
    • lean meats
    • eggs
    • fish
    • milk and dairy products
  102. why are FMN and FAD important in the body?
    electron carriers in the electron transport chain and oxidative phosphorylation (both can accept H to form the reduced forms)
  103. what is vitamin B2 essential for the efficient utilization of?
    major biological molecules (fats, carbs, proteins, nucleic acids) for energy production
  104. what are some other biological functions that vitamin B2 helps with?
    proper circulation and proper skin formation
  105. what is vitamin B2 necessary for?
    • protein use
    • growth
    • pregnancy
    • lactation
    • wound healing
  106. what processing techniques degrade vitamin B2?
    • lost to cooking water
    • light
    • heat
    • alkaline conditions
  107. what processing techniques is vitamin B2 stable to?
    • acids
    • oxygen
    • dry heat
  108. what are the symptoms of vitamin B2 deficiency?
    • skin disorders
    • hardening of the cornea
    • destruction of red blood cells, leading to anemia
    • nervous disorders
  109. how does deficiency of vitamin B2 arise?
    • excess alcohol and antibiotic use can kill off the intestinal bacteria and cause deficiency
    • but deficiency is rare, since it's produced by intestinal bacteria
  110. what are the symptoms of vitamin B2 toxicity?
    • numbness in extremeties
    • yellow pigmented skin and veins
    • discolored urine (very yellow in color)
  111. what is vitamin B3?
  112. what is niacin made up of?
    • nicotinic acid
    • nicotinamide
  113. niacin is a component of which 2 cofactors?
    • NAD and NADP
    • these both act as hydrogen acceptors in metabolism to form the reduced equivalent
    • NADH2 is used to generate energy via transfer to FMN of FAD and the ETC
    • NADPH2 is used for the synthesis of biological molecules like nucleic acids, fats, hormones, amino acids/proteins
  114. what are the plant sources for vitamin B3?
    • cereals
    • peas
    • nuts
    • green leafy vegetables
    • whole grains
  115. what are the animal sources for vitamin B3?
    • fish
    • poultry
    • organ meats (liver, kidney)
    • lean meats
    • seafood (salmon, tuna)
    • cheese
    • eggs
    • milk
  116. what are the microbial sources for vitamin B3?
  117. what are NAD and NADP important for?
    • dehydrogenation reactions
    • ETC and oxidative phosphorylation
    • synthesis of biomolecules (like fatty acids)
  118. what are the symptoms of vitamin B3 deficiency?
    • skin disorders (dermatitis)
    • diarrhea
    • dementia (pellagra)
    • death
  119. is vitamin B3 deficiency common?
    no, very rare
  120. what is considered one of the most stable vitamins?
    • vitamin B3
    • only lost to cooking water because it is water soluble
  121. what is vitamin B5?
    pantothenic acid
  122. what are the other 2 names for vitamin B5?
    • coenzyme A
    • pantothenate
  123. what are the 2 compounds with vitamin B5 activity?
    • pantothenic aid
    • panthenol
  124. what are the plant sources for vitamin B5?
    • whole grains, cereals and seeds
    • green leafy vegetables
    • nuts
  125. what are the animal sources for vitamin B5?
    • shellfish
    • eggs
    • cheese
    • meats
    • milk
    • liver
    • kidney
  126. what are the microbial sources for vitamin B5?
    • Brewer's yeast
    • intestinal microflora
  127. what are the 2 key cofactors that vitamin B5 is a cofactor for?
    • CoASH (coenzyme A)
    • Acyl carrier protein (ACP)
  128. what are CoASH (coenzyme A)and Acyl carrier protein (ACP) important for, biologically?
    • participate in several steps in carb, lipid, and protein metabolism
    • several enzymes (more than 70) require these cofactors for activity
    • required for synthesis of nerve regulating substances, like acetylcholinesterase
  129. what are the symptoms of vitamin B5 deficiency?
    • impaired growth
    • anemia
    • skin disorders
  130. how does vitamin B5 deficiency arise?
    • rare since we consume it widely in foods and also synthesized by intestinal bacteria
    • prolonged use of alcohol and antibiotics kills off intestinal bacteria which can cause deficiency
  131. is vitamin B5 toxic?
    generally considered as non toxic
  132. what are the processing conditions that vitamin B5 is stable to?
    • air
    • slightly acidic to neutral pH (5-7)
  133. what are the processing conditions that dsegrade vitamin B5?
    • extreme pH conditions
    • dry heat
  134. what is vitamin B6?
  135. what are the 3 compounds with vitamin B6 activity?
    • pyridoxol
    • pyridoxine
    • pyridoxamine
  136. for more pronounced vitamin B6 activity, the 3 forms must be phosphorylated into what?
    • PALP (pyridoxal phosphate)
    • PALP is phosphorylated by pyridoxal kinase
  137. can humans synthesize B6?
    no they are incapable
  138. what are the plant sources of vitamin B6?
    • carrots
    • whole grains
    • seeds, nuts
    • peas
    • bananas
    • grapes
    • potatoes
  139. what are the animal sources of vitamin B6?
    • fish (salmonids, tuna, halibut, herring, mackerel)
    • liver
    • lean meats (beef, pork, lamb, poultry)
    • eggs
    • cheese
  140. where is vitamin B6 stored in the body?
    brain, liver, muscle
  141. what are the microbial sources of vitamin B6?
    Brewer's yeast
  142. what is vitamin B6 a cofactor for?
    transaminases and deaminases that catalyze transamination and deamination reactions in amino acid metabolism
  143. what does vitamin B6 assist in the synthesis of?
    • purine nucleotides
    • certain amino acids (glycine, serine, methionine, and choline)
  144. why is vitamin B6 deficiency rare?
    it is widespread in the foods we consume
  145. how can vitamin B6 deficiency arise?
    • when certain drugs bind PALP and prevent its availability for their normal functions
    • examples of these drugs include:
    • isoniazid (used for treatment of tuberculosis)
    • hydrallazine (anti-hypertensive drug)
    • cycloserine (antibiotic)
  146. how does vitamin B6 deficiency manifest?
    • skin disorders - lesions on skin and mucosa
    • loss of appetite
    • tiredness
    • anemia
    • convulsions
  147. under which processing conditions is vitamin B6 stable?
    acidic and neutral pH
  148. under which processing conditions is vitamin B6 unstable?
    • light
    • air
    • heat
    • alkaline pH
  149. what is the toxicity of vitamin B6?
    considered non-toxic
  150. what is vitamin B7?
  151. what is biotin made up of?
    2 fused rings
  152. what are the plant sources of vitamin B7?
    • fruits
    • vegetables
    • seeds
  153. what are the animal sources of vitamin B7?
    • organ meats (liver, kidney, heart, brain)
    • lean meats
    • fish
    • eggs
    • milk
  154. what are the microbial sources of vitamin B7?
    • Brewer's yeast
    • synthesized by intestinal bacteria
  155. what is the vitamin B7 a cofactor for?
    • carboxylases and decarboxylases
    • these are essential CO2 carriers for carboxylation (like in fatty acid synthesis) and decarboxylation (like in catabolism of carbs and proteins) reactions
  156. what are some examples of enzymes requiring vitamin B7?
    • Acetyl CoA carboxylase
    • pyruvate carboxylase
  157. what is the mechanism by which vitamin B7 participates in carboxylation and decarboxylation reactions?
    biotin binds reversibly with CO2 to form carboxybiotin (biotin +CO2 --> carboxybiotin) 
  158. how common is vitamin B7 deficiency?
  159. how does vitamin B7 deficiency arise?
    excessive consumption of raw eggs (avidin found in egg white is an antagonist of biotin) and prolonged use of antibiotics can cause deficiency of the vitamin
  160. how does vitamin B7 deficiency manifest?
    • dermatitis
    • anorexia
    • nausea
    • muscular pain
    • skin disorders
    • loss of appetite
    • anemia
  161. what processing conditions degrade vitamin B7?
    lost to cooking water, otherwise one of the most stable vitamins
  162. what processing conditions is vitamin B7 stable to?
    • air
    • acid
    • neutral pH
  163. what is the toxicity of vitamin B7?
  164. what is vitamin B9?
    folic acid
  165. which 3 compounds are bound together to form vitamin B9?
    • pyridine
    • p-amino benzoic acid (PABA)
    • glutamic acid
  166. what else is vitamin B9 known as besides folic acid?
    folacin, folate, vitamin Be, vitamin BM
  167. what are the plant sources of vitamin B9?
    • pulses
    • grains
    • green leafy vegetables
    • fruits
    • cabbage
    • French beans
  168. what are the animal sources of vitamin B9?
    • liver
    • eggs
    • milk
  169. what are the microbial sources of vitamin B9?
    • Brewer's yeast
    • synthesized by intestinal bacteria
  170. what are the 3 main parts of folic acid that are biologically important?
    pteridine, PABA, and glutamate
  171. what is the biologically active form of vitamin B9?
    tetrahydrofolate (THF)
  172. by which mechanism does THF work in the body?
    • acts as a C-1 carrier
    • unlike biotin that carries CO2, THF carries C-1 groups in the form os -CH3, -CH2, H-C=O (i.e. methyl, methylene, and formyl groups)
  173. what is THF a cofactor for?
    • essential in the metabolism of biological molecules (like fats, nucleic acids, amino acids)
    • breakdown of uneven numbered fatty acid chains, and a 3-C compound (propionyl CoA) is the end product
    • THF enables the propionyl CoA to be elongated to the 4-C methylmalonyl CoA mutase
    • ethylmalonyl CoA thus formed is isomerized to succinyl CoA by methylmalonyl CoA mutase, succinyl CoA then goes into the TCA cycle
    • succinyl CoA then goes into the TCA cycle
  174. what is vitamin B9 in the form of THF reqiured in the synthesis of?
    required in the synthesis of homocysteine
  175. what is the toxicity of vitamin B9?
    generally regarded as non toxic
  176. why is vitamin B9 deficiency important?
    sufficient folate must be present in the diet to prevent deficiency because of the high demand for its use in the synthesis of biological molecules, for example by pregnant and lactating women
  177. what does vitamin B9 deficiency manifest as?
    • impaired synthesis of nucleic acid and ultimately in anemia
    • blood levels of homocysteine rise and may cause cardiovascular problems
  178. what processing conditions is vitamin B9 stable under?
    acidic conditions
  179. what processing conditions is vitamin B9 unstable under?
    • heat
    • air
    • light
    • neutral and alkaline conditions
  180. what is vitamin B12?
  181. what is vitamin B12 made up of?
    • porphyrin ring (or tetrapyrol ring) structure with cobalt as the central atom
    • known as a corrin ring
  182. vitamin B12 is synthesized exclusively by ________
  183. how do animals obtain vitamin B12?
    obtain them from microbial sources and accumulate them in the liver, where it is in the bound form either as methyl cobalamin or 5'-adenosyl cobalamin
  184. what are the animal sources of vitamin B12?
    • fish and shellfish
    • lean meat
    • eggs
    • dairy products
    • liver
    • kidney
  185. do the methyl or 5'-adenosyl forms of vitamin B12 have activity?
    no, must be released from its association with these groups to have activity
  186. what are the plant sources of vitamin B12?
    there are no plant sources
  187. what does vitamin B12 deficiency manifest as?
  188. what processing conditions is vitamin B12 stable under?
    • heat
    • acid
    • neutral conditions
  189. what processing conditions is vitamin B12 unstable under?
    • destroyed when boiled under alkaline conditions
    • unstable to air, oxygen, and light
  190. what are the different forms of vitamin C?
    • L-ascorbic acid (most acitivity)
    • dehydro-L-ascorbic acid (reduced activity)
    • ketogulonic acid (no activity)
  191. what are the 2 species incapable of synthesizing vitamin C de novo?
    • humans
    • guinea pigs
  192. what are the plant sources of vitamin C?
    • most fruits and vegetables
    • citrus fruits, strawberries, peppers, cauliflower, tomatoes
  193. what are the animal sources of vitamin C?
    • organ meats (like liver)
    • milk and dairy products
  194. how does vitamin C work as an antioxidant?
    scavenges free radicals from the body to protect against oxidation to biological molecules and tissues
  195. how does vitamin C work as a reducing agent?
    plays an important role in the interconversions between the oxidized and reduced forms of cytochromes ('a' and 'e') in the electron transport chain
  196. how does vitamin C work for the hydroxylation of biological molecules, and why is this important?
    • hydroxylation of proline into hydroxyproline
    • hydroxylation of lysine into hydroxylysine
    • as a result these resulting molecules are able to undergo extensive hydrogen bonding to stabilize/strengthen biological molecules (ex hydroxyproline in collagen for muscles, vascular tissues, and cartilage)
  197. what does vitamin C enhance the uptake of?
    • Cu and P (important in bone/teeth formation)
    • Fe (important in formation and functioning of blood cells)
  198. vitamin C helps prevent the formation of ______ in the stomach
  199. which groups are most at risk for a vitamin C deficiency?
    • heavy smokers
    • elderly people
    • individuals on long-term drug therapy
  200. what are the symptoms of vitamin C deficiency?
    • impaired formation and functions of collagen and RBCs
    • oxidative damage to biological molecules
  201. what does vitamin C deficiency manifest as?
    scurvy - symptoms of scurvy include bleeding gums, loose teeth, susceptibility to colds and infections, reddish eyes and skins (from the breakdown of blood cells)
  202. what does excess vitamin C in the body turn into?
    ascorbic acid turns into uric acid
  203. what do high levels of uric acid in the blood/urine result in?
    • crystallization of uric acid
    • accumulation of uric acid crystals in the joints results in a painful condition known as GOUT
  204. what does vitamin C toxicity result in?
    since vitamin C enhances uptake of Fe (especially from plant foods), individuals for whom high iron levels are a problem, high levels of vitamin C can be toxic and lead to dark/bloody stools, dizziness, loss of consciousness, and even coma
  205. what processing conditions is vitamin C unstable to?
    • very unstable, lost under most processing conditions
    • heat
    • neutral to alkaline conditions
    • exposure to light and air
    • lost to cooking water
  206. destruction of vitamin C in foods is enhanced by ________
  207. what does oxidation of the active form of vitamin C result in?
    • oxidization to the dehydro- form, which has reduced biological activity
    • futher oxidation leads to the formation of the diketo-L-gulonic acid form, which means total loss of activity