59-60: Micronutrition Flashcards by Brooke Thornburg

Dietary Reference intakes

-system of nutrition recommendations from IMNA
-replaced original recommended daily allowance (RDA)

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Reference values provided by Dietary Reference Intakes

-EAR
-RDA
-AI
-UL

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Estimated average requirement (EAR)

-amount of nutrient estimated to meet the need of 50% of the healthy individuals in an age and gender group

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Recommended Dietary Allowance (RDA)

-2 standard deviations ABOVE EAR
-sufficient to meet need of 97-98% healthy individuals in a group

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Adequate Intake (AI)

-used when not enough evidence to set an EAR
-approx the average nutrient intake of a healthy population

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Tolerable Upper Intake Level (UL)

-max level of daily intake of nutrient without any health risk

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Micronutrients

-vitamins
-minerals

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Vitamins

-fat-soluble (ADEK)
-water-soluble (B and C)

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Minerals

-macro: Ca and Mg
-trace: iron, iodine, zinc, copper, selenium

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Vitamin A

-retinol, retinal, retinoic acid
-produced from carotenoids, organic pigments in plants
-function as light sensor (cis retinal w opsins)

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Vitamin A deficiency

-night blindness

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Retinoic Acid (Vit A)

-like hormones (nuclear receptor_
-regulates cell growth/dif
-associated w nuclear and retinoid receptos

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Carotenoids

-vit A precursor
-effective antioxidant
-may reduce risk of cancer

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Vit A storage

-in liver
-as retinol palmitate

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Vitamin D

-function as steroid hormones maintaining calcium homeostasis
-made from cholesterol intermediate
-made photochemically in skin

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Vit A dietary sources

-dark green/ yellow veggies
-liver
-egg yolk
-butter
-whole milk

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Vit D defiency

-insuff exposure to sunlight
-rickets in young children
-osteomalacia in adults

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Vitamin D dietary sources

-Vit D milk
-saltwater fish
-liver
-egg yolk

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Vitamin E

-occurs in diet as tocopherols and tocotrienols
-antioxidants
-protecting unsaturated fatty acids
-accumulate in lipoproteins, cellular membranes, fat deposits
-reduce risk of CVD by stopping oxidation of LDL

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Vit E dietary sources

-veg oils rich in polyunsat fat
-deficiency is rare

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Vitamin K

-required for post-trans modification of glutamic acid residues to y-carboxyglutamic acid residues (allow binding to Ca)
-essential for blood clotting
-essential for bone mineralization

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Vitamin K epoxide reductase

-regenerates active form of vit K

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Vit K dietary sources

-K1 in green veggies
-K2 by intestinal bacteria
-deficiency rare

Warfarin

-anticoagulant
-vit K ANTAgonist
-prevent thrombosis
-inhibits reductase

Thiamin (B1)

-rapidly converted to thiamin pyrophosphate and TRIphosphate

Thiamin pyrophosphate

-cofactor in enzyme catalysis -thiazole ring strong nucleophile

Thiamin Triphosphate

-functions in transmission of nerve impulse in peripheral nerve membranes

Beriberi

-sever thiamin B1 deficiency -muscular atrophy and weakness -may occur in populations relying on rice or alcoholics

Riboflavin (B2)

-precursor of FAD and FMN -milk, meat, eggs, cereal

Riboflavin (B2) deficiency

-rare -angular chilitis, glossitis, and scaly dermatitis -seen in chronic alcoholics

Niacin B3

-converted to NAD and NADP -meats, peanuts, cereal

Pellagra

-severe Niacin B3 deficiency -dermatitis, diarrhea, dementia -rare -alcoholics, pt w malabsorption, elderly

Pyridoxine (B6)

-converted to pyridoxal phosphate (transamination in aa metabolism = make NTs and sphingolipids) -meat, veggies, whole grain cereal

Pyridoxine (B6) deficiency

-mild: irritability, nervousness, depression -severe: peripheral neuropathy and convulsions

Biotin (B7)

-serves as cofactor for activation of CO2 in enzymes -covalent bind to lysine in enzymes -lots of foods

Biotin (B7) deficiency

-rare -may occur when too much raw egg white -avidin in egg forms tight complex with biotin -preg women higher risk

Folic acid (B9)

-converted to tetrahydrofolate -DNA synthesis and cellular proliferation -rich in lots of food

Folic acid (B9) deficiency

-produces abnormal RBCs = anemia -inc the risk of birth defects esp neural tube defect -common in alcoholics

Cobalamin (B12)

-Co -complex w proteins -needed for methionine synthase and methylmalonyl-CoA mutase

Cobalamin B12 deficiency

-homocystein and methyl malonic acid accumulate =anemia and neurological damage -rare -malabsorption diseases and long-term vegetarians

Vitamin C

-ascorbic acid -needed for hydroxylation of lysine and proline side chains, which is necessary for collagen stability (healing) -reducing agent

Vit C as a reducing agent

-aids absorption of iron by reducing it to Fe2+ in tummy -protects vit A, E, B from oxidation

Vit C deficiency

-capillary fragility, easy bruising, dec immunocompetence -scurvy (severe) -smokers need more -using vit c to cure cold is controversial

Scurvy

-dec wound healing -osteoporosis -hemorrhaging -anemia

Calcium

-most abundant mineral in body -makes bones -serves as 2nd messenger -req for many enzymes -essential for blood coagulation and muscle contractility

Calcium serum level maintenace

-homeostasis -deficiency takes Ca away from bones -vit D needed to use Ca -exercise uses Ca for bone formation

Calcium deficiency

-resembles Vit D deficiency -may contribute to osteoporosis -muscle cramps -low-income kids

Calcium dietary sources

-dairy products -nuts, beans, seeds, seaweed

Iron

-needed for O2, energy metabolism, cell proliferation, immune defence -blood loss (menses) inc need

Iron homeostasis

-tightly regulated -essential but also toxic -free iron generates free radicals -but sequested in cell by ferritin and transferrin in blood

iron deficiency

-anemia

Iodine

-make thyroid hormones -fish and seaweed -added to table salt

Iodine deficiency

-inland populations -goiter and cretinism

Zinc

-needed for metalloenzymes and zinc finger proteins

Zinc deficiency

-poor growth and sexual development in children -poor wound healing, dermatitis, impaired immune function

Copper

-required for many enzymes -deficiency may cause anemia, bone demineralization, and blood vessel fragility

Selenium

-incorporated into 25 selenoproteins in humans -contain selenocystein residues that are incorporated during translation -selenocysyl-tRNA binds to UGA codons in mRNA w special seq in 3-untranslated region -defieciency rare