Flash Nutrition Flashcards
Vitamin purpose, deficiency and toxicity
Are vitamins organic or inorganic?
Minerals INORGANIC vitamins ORGANIC
How many people are effected with v/m deficiencies?
1/3 in developing countries
Steroid receptors cytosolic vs nuclear
I Cytosolic respond to steoid hormones i.e. estrogen. II nuclear steroid and non-steroid ligands i.e. thyroid hormone
Iodine why an issue? Sources?
Foods have low content. NA: iodized salt
Iodine deficiency?
TSH signals for T3 and T4. I deficience prolonged elevation of TSH-> hyperplasia of the thyroid (GOITER)
How does iodine make thyroid hormones?
Tyrosine in thyroglobulin. Action of iodide peroxidase. Activated to a free radical, chemically attacks thyroglobulinprotein. Spontaneous crosslinking and iodination reactions amongst the side chains. Mess is cut by T3 T4 structures
THS on metabolism and GH’s role?
Metabolic effects via mineral ATPases. GH is anabolic, low amount has catabolic effect
Goiter cause, effect, impact?
Thyroid enlargement, iodide deficiency 13% of population effected. Cretinism (50 million) mental retardation. Growth and deveopmental abnormalities
Too much iodide?
Minamal toxicity effects of iodide at high levels of intake reported although UL established
Vitamin A-> ?
Carotenes (plants) and Retinyl Esters (animals)
Carotenes ->?
Beta carotene, main. Other carotenes
Retinyl Esters->?
Retinol, retinyl palmitate, all-trans retinal, 11-cis Retinal, Retinoic Acid
What cleaves beta-carotene to 2 molecules of retin AL?
15, 15’ dioxygenase
What is involved with vit. A and night vision?
Retinol-> all-trans retinal-> 11-cis-retinal->rhodopsin (light) ->nerve impulse and all-trans
What can Retinoic acid bind and activate?
RAR (retinoic acid receptor) retinoid Xreceptor (RXR) at least 14 members
What causes large variation in RA signaling?
homo and heterodimerize
How does vit D increase complexity of gene expression?
heterodimerize with vit. D receptors
What is the main effect of vit A deficiency?
Imparied epithelial differentation
Where are epithelial cells found?
Lungs, trachea, cornea & sclera, GIT, esophagus, skin. Rapidly dividng stem cells are in ALL epithelial tissues
What are the results seen with vit. A deficiency?
cornea: Xerophthalmia. Lungs: resp. infections like pneumonia. GI: diarrhea. Skin: folliculosis
What protein accululates with vit. A deficiency?
KERATIN
Consequences of Vit. A deficiency?
Night blindness, impaired cell differentation (blindness), imparied growth and fertility, fetal developmental defects
Why do fetal development defects differ ?
Can occur from too high or too low vit A -> due to loss of control differentation
World effects of vit. A deficiency?
100-140 mil childrren deficient. 250 000-500 000 becoming blind, half dying within 12 months of blindness
What is the consequences of vit. A toxicity?
liver cell death. Retinyl palmitat stored in stellate cells of liver, cell is full to capacity with excess of vit. A, spills out local hepatocytes damaged and die, fatal liver failure
Excessive intake of beta-carotene?
toxic-> cause hypercarotenosis
Acutane -> acne drug causing birth defects?
13-cis retinoic acid-> birth defects
Estimated average requirment (EAR)
estimated median. Application with planning and assesing intakes for groups of people
Recommended Dietary allowance (RDA)
derived from EAR meets or exceeds req. for 97.5 % of pop
Tolerable upper intake level (UL)
intake above the UL is potentail risk of adverse effects, highest daily intake that won’t cause harm in general pop
Adequate intake (AI)
used when EAR/RDA cannot be developed, average intake level based on observe or exp. Intakes
Vit A DRI
RDA 700 W, 900 M ug/day RAE. UL 3000 ug/day retinol
Theraputic Index (TI) Vit. A
UL/RDA 3000/900 = 3.3. Small les than 10 TI difficult to maintain
How many vit. D sources are there?
5
- From plants
ergosterol (plant sterol) -UV-> ergocalciferol (D2)
- In/from animals
7-dehydrocholesterol (made in sebaceous glands of skin)-UV and heat -> cholecalciferol(D3)
- SUN
7-dehydrocholesterol -> pre vit D3 -> lumisterol, tavhysterol (into skin as D3 in blood DBP- DBP- D3)