vitamins and minerals biochemical assessment

zinc status

- cofactor for >300 enzymes

- difficult to assess status in the body

how is zinc play a role in the body?

- protein synthesis

- wound healing

- immune function (T-lymphocytes)

- tissue growth and maintenance

why is zinc difficult to assess status in the body?

- tightly regulated in the body

- on-nutritional factors influencing serum levels

- little functional reserve, no reliable functional zinc status tests (zinc status tied to copper status)

Iodine status

- essential for synthesis of thyroid hormones

Iodine deficiency disorders

- mental retardation (leading cause of MR in the world)

- hypothyroidism

- cretinism

- Goiter

iodine deficiency during pregnancy results in

- spontaneous abortion, stillbirth, congenital anomalies, increased perinatal and infant mortality

what is the most common indicator to assess iodine?

urinary iodine

- requires 24-hr urine collection

vitamin C roles in the body

- formation of collagen

- maintenance of capillaries, bone, teeth

- promotion of iron absorption

- protection of vitamins and minerals from oxidation

what does vitamin C deficiency result in?

weakness, hemorrhaging (skin and gums), poor bone development in children

serum concentration of ascorbic acid is used to assess

vitamin C status

total ascorbic acid in leukocytes is the

index of tissue stores

lactic dehydrogenase

- enzyme found in cells of skeletal muscle, myocardium, liver, pancreas, spleen, brain

- released when cellular damage in organs occur

what does elevation of lactic dehydrogenase indicative of?

- myocardial infarction

- hepatitis, CA, kidney disease, burn, trauma

vitamin A

group of compounds that affect vision, bone growth, reproduction, cell division, immunity, mucous membranes

- fat-soluble vitamin

preformed vitamin A

absorbed as retinol

plant foods

- provitamin A (carotenoids)

- can be converted to retinol and other active forms in the body

- B-caroten, a-carotene, B-cryptoxanthin

clinical signs of vitamin A deficiency

- xerophthalmia, night blindness, poor healing

- leading cause of preventable blindness in children

hypervitaminosis A

due to extreme intake of preformed vitamin A

- can be deadly, liver damage may not be reverisble

beta carotene

supplements can increase CVD mortality and deaths from lung cancer

vitamin A status: plasma levels

- 95% in plasma is retinol form, bound to retinol binding protein

- 5% unbound in retinyl ester form

- predictive of vitamin A status only in extreme deficiency or reserves are overfilled

- concentrations may be in "normal" range despite low vitamin A concentrations within the liver

relative dose response test

- when retinol stores high, plasma, retinol concentration not very affected by oral supplementation of vitamin A

- when retinol stores low, plasma retinol concentration increases greatly 5 hours after oral dose

>50% is indicative of what is relative dose response test (RDR)?

of acute deficiency

conjunctival impression cytology

Microscopic examination of conjunctival cells to detect morphological changes indicative of vitamin A deficiency.

dark adaptation

rhodopsin = retinol + opsin protein (in rods of eye)

- when vitamin A deficient, less rhodopsin forms, poor adaptation

Retinol Isotope Dilution

- determine whole body stores of vitamin A

- best approach, non-invasive

- ratio of labeled and unlabeled used to estimate size of total vitamin A pool