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60 Cards in this Set
- Front
- Back
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Vitamin definition
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Organic compound required in small amounts by an organism
-must be obtained in the diet |
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Beri Beri is associated w/ what vitamin?
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Thiamin (B1)
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Thiamin Food Sources?
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Lean Pork
Legumes Whole Grains, bran Brewer's yeast |
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Thiamin is absorbed in proximal ______ __________, especially the ________?
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small intestine
jejunum |
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Thiamin absorption can be inhibited by?
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Alcohol
Folate Deficiency Protein Deficiency |
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Thiamin Excretion:
Half life is ____ days Not stored in any tissue, so ___________ Excess excreted in urine |
9-18 days
must have a continuous supply |
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Thiamin Functions:
Thiamin Pyrophosphate (TPP) is a________________? TPP is also a coenzyme in a-ketoglutarate dehydrogenase complex a-ketoglutarate---> succinyl CoA |
coenzyme in pyruvate dehydrogenase complex
Pyruvate---> acetyl coA |
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Thiamin Functions Cont
Required for _______ oxidation Vital for neurotransmission and nerve conduction |
alcohol
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Thiamin Deficiency
Caused by Inadequate Intake: _______? ________? ________? |
Breast fed infants of deficient mothers
High CHO intake of milled rice Chronic ETOH |
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Increased Thiamin requirements?
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ETOH
Stenuous physical exertion Fever Pregnancy or lactation Adolescent growth |
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Thiamin Deficiency has 3 forms of beriberi, what are they?
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Dry (paralytic or nervous) beriberi
Wet (cardiac) beriberi Cerebral beriberi |
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Thiamin Toxicity?
Excessive amounts cleared by _______ No Evidence of oral thiamin toxicity |
kidneys
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Riboflavin is what vitamin?
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B2
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Riboflavin is a precursor to _____ & _______?
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Flavin Mononucleotide (FMN)
Flavin Adenine Dinucleotide (FAD) |
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Riboflavin Food Sources?
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Dairy
Eggs Meat Enriched breads and cereals |
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Riboflavin Digestion/Absorption?
FAD released from protein by _______________ Absorbed in proximal small intestine & absorbed in proportion to _____ Uptake is faciliated by _______ Absorption reduced by minerals _______,______,_____&,______ |
gastric acidification
needs bile salts copper, zinc, iron, manganese |
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Riboflavin Functions:
Component of FMN and _____ ______ _______ _______ for metabolism Required for fatty oxidation, conversion of succinate to fumarate, pyruvate to acteyl CoA |
FAD
Electron transport intermediary |
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Riboflavin Functions:
Antioxidant activity: protects against lipid perioxides Aids conversion of B6 & _____ to _____ forms |
folate to active forms
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Riboflavin Deficiency:
Occurs in combination w/ deficiences of other B vitamins Symptoms include? |
Sore throat
Edema of pharyngeal and oral mucosa Cheilosis Angular dermatitis Corneal vascularization |
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what are causes of inadequate intake of riboflavin?
what are causes of inadequate absorption? increased needs? |
alcoholism & anorexia/malnutrition
chronic malabsorption, alcoholism, thyroid dysfunction (reduced conversion to FAD/FMN) Athletes, laborers |
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Riboflavin Toxicity?
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not seen in human or animal studies
increased excretion w/ high intakes |
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Niacin is what vitamin?
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Vitamin B3
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Niacin structure occurs as _______ & _________?
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Nicotinic acid & nicotinamide
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Niacin: Digestion/Absorption
Simple diffusion and _______ Circulates in _____ _______ Can also be synthesized from _______ -requires thiamin, pyridoxine, riboflavin |
facilitated diffusion
free form tryptophan - |
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Niacin Functions:
Vital for coenzymes ______ & ______ |
NAD & NADP
-these are electron receptors -required for hexose monophosphate shunt |
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Niacin Functions:
Pharmacological doses for nicotinic acid are ____ ______ -however, side effect of flushing when using it as a lipid lowering drug |
lipid lowering
-raise HDL, lower LDL, and Lower TG |
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Niacin Need:
Niacin need is affected by age, gender, and _____ intake? -Low protein= low ________ |
protein intake
low=tryptophan |
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Niacin Deficiency is known as _______ ?
Symptoms include: dermatitis, diarrhea, dementia, and death! |
Pellagra
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Niacin Toxicity:
-there is a UL Chronic administration >3gm/day -Headache, heartburn, nausea, hives, fatigue, sore throat, dry hair, etc |
asdf
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Pyridoxine is what vitamin?
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Vitamin B6
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Vitamin B6 (pyridoxine) food sources?
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meats, cereals, legumes, lentils, nuts, fruits, and vegetables
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Vit B6 Digestion/Absorption
-passive diffusion -carried by ____ in ______ & albumin |
RBC in hemoglobin and albumin
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Vitamin B6 Functions:
Pyridoxal phosphate is a coenzyme in reactions that have ___ containing substrates Involved in amino acid metabolism |
N-containing substrates
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Vitamin B6 deficiency is rare.
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..
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Pantothenic Acid is found in all foods!
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Incorporated into Coenzyme A
-required to convert pyruvate to actely coA |
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Pantothenic acid deficiency:
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Experimentally induced by antagonists
-loss of feeling in toes and feet -depression -fatigue -insomnia -vomiting -muscle weakness NO TREATMENT SINCE ISOLATED DEFICIENCY NEVER OCCURS NO KNOWN TOXICITY |
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Biotin is the only vitamin that does not go through any __________ before it is used in the body.
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metabolism
-Biotin is present in all living cells |
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Biotin: Digestion/Absorption
Free form or protein-bound -facilitated diffusion in jejunum -gut flora also creates biotin -can be bound by avidin in raw egg whites |
Biotin is excreted in urine
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Biotin Deficiency only seen in genetically deficient biotinidase.
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-Supplement normal amounts of biotin for bitinidase deficiency
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Folic Acid recognized as essential to all living _____?
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cells
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Folic Acid Food Sources?
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Meats, Legumes, dry beans, vegetables, peas, nuts, whole grains
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Folic Acid Excretion:
-excreted by kidney in urine |
High intake of folic acid causes reduced absorption, increased excretion
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Folic Acid Functions:
-coenzyme in 1-C transfer -THF can give a methyl to vitamin B12, which then converts homocysteine to methionine |
-THF required for thymidine (DNA)
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Folic Acid Deficiency:
Inadequate Intake -no fresh vegetables or enriched grains -etoh Impaired absorption -celiac disease or malabsorption Increased demand -pregnancy, lactation -infancy Increased excretion -dialysis |
Folic acid deficiency causes neural tube defects
-spinal cord does not close w/out folic acid and fluid filled pouch of nerves can growth through opening |
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Bread and brkfast cereals fortified w/ folic acid to reduce neural tube rates by 50%, which is controversial
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-folic acid supplementation recommended for all women capable of becoming pregnant
-contraceptives may also reduce folic acid status |
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Folic Acid Toxicity:
overconsumption masks vitamin B12 deficiency -corrects megoblastic anemia w/out correcting underlying deficiency |
B12 def rare in young women, so consumption of UL likely not problematic
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Neural tube defects are caused by inadequate amounts of which vitamin?
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Folic Acid
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What is the toxic effect of excessive folic acid intake?
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Corrects megaloblastic anemia w/out correcting underlying B12 deficiency
Look for Mean Corpuscular Volume lab-if you eat a lot of folic acid it will force those RBCs to get smaller, which will mask the B12 deficiency |
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Who does not take in enough vitamin B12 from food?
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Vegetarians/Vegans
Why not? produced by bacteria; B12 permeates meat |
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What is the protein we require for absorption of B12 in the stomach?
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Intrinsic Factor
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Who might not be able to produce enough intrinsic factor?
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Elderly
Gastric bypass gastrectomy chronic antacid use (especially protein pump inhibitors) |
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Why doesn't taking megadoses of vitamin c seem to work?
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reduced absorption w/ higher intakes
& the body pool can only hold 1500 mg |
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What is the biochemical role of vitamin c?
How does it fxn in reactions in the body? |
Vitamin C is a hydrogen donor or acceptor. The body adds/takes off hydrogens when you need to convert between ascrobic acid and dehydroascorbic acid.
Vitamin C keeps iron in Ferrous state for absorption. When we eat iron, we want it in this ferrous state so it can be absorbed. Having vitamin C present in the gut will cause it to pick up with extra hydrogen, and keep the iron in its ferrous state. Vit C also serves as an antioxidant, picking up that extra hydrogen to keep it from doing damage to our tissues. |
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Vitamin B12 is also called?
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cyanocobalamin
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Vitamin B12 food sources?
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Foods of animal origin
Synthesized by bacteria in gut and permeates meat |
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Vitamin B12 Digestion/Absorption
Must be bound to _______ for absorption Carrier protein if created by gut flora Most absorption in distal ileum (active transport), some in colon (passive diffusion) Vitamin B12 is stored where? |
protein
liver, kidney, heart, spleen, brain |
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Vitamin B12 is excreted in ______?
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bile
-not much excreted! Recycle in enterohepatic circulation |
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Vit B12 Functions:
-coenzyme methylcobalamin which works to assist in methyle trasfers -with folate, makes homocysteine into methionine -REQUIRED IN REACTIONS FOR FAT AND PROTEIN OXIDATION FOR ENERGY -REQUIRED FOR SYNTHESIS OF HEMOGLOBIN |
-daily requirements are small since turnover is small
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Pernicious anemia/ Megaloblastic anemia is usually caused by lack of___________ ____________?
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intrinsic factor
-Genetic predisposition -Long term use of acid reducing drugs -Gastrectomy -Age Also associated w/ loss of peripheral sensation -loss of lipid coating around nerves |
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How is vitamin B12 deficiency treated?
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-Injectable
-Sublingual -Nasal gel -Oral -Infants of vegan mothers need supplement from birth |
