Microminerals Flashcards
Zinc function
Adequacy
DRI
enzyme component
structural integrity of proteins
regulation of gene expression
EAR found by factorial approach: is average intake required to absorb and balance obligatory losses (intake > absorbed)
Differences in RDA between sexes
- increased requirement due to endogenous semen losses
UL = 40 mg
adverse effects such as nausea due to competition for uptake with copper
Iodine Function
Adequacy
DRI
essential component of thyroid hormones (thyroxine, triiodothyronine)
Thyroidal radioiodine accumulation is used to estimate the average requirement
RDA for all adults
UL = 1100 mcg
- Iodine toxicity is not typically seen but can inhibit synthesis of thyroxine (supplements usually)
Se function
Adequacy
DRI
selenium-dependent enzymes (selenoproteins)
selenium-dependent deiodinases can activate/inactivate T4⇄T3 hormones
oxidant defense enzymes
maximized plasma glutathione peroxidase activity as indicator of adequacy
RDA for all adults
UL = 400 mcg
- excess hair loss, gastro symptoms
Copper function
Adequacy
DRI
Metalloenzyme component of oxidases which reduce O2
- monoamine oxidase, diamine oxidase, lysyl oxidase
Functional biochemical measures of copper status include: blood/platelet [Cu] and blood ceruloplasmin [Cu] (Cu storage protein in liver)
RDA for all adults
UL = 10 mg
Excessive Cu can block Zn uptake
Manganese Function
Adequacy
DRI
Metalloenzymes involved in AA, lipid and CHO metabolism
arginase, glutamine synthetase, PEP decarboxylase, superoxide dismutase
Bone formation with lycosyltransferases and xylosyltransferases
AI based on balance studies and usual intake in North America
- balance studies over estimate
Sex differences in AI
UL = 11 mg
- UL only achievable through supplementation or industrial exposures
soy-based infant formulas
- Abnormal gait, dizziness, neurotoxic effects
Chromium Function
Adequacy
DRI
Potentiates action of insulin by possibly activating insulin receptor activity (glucose tolerance)
Based on mean intake 13.4mcg/1000 kcal in well-balanced diet
- no established biomarkers
AI for ages 19-59 by sex
- kcal for diet estimated by sex
NO UL
Molybdenum function
Adequacy
DRI
enzyme cofactor in molybdoenzymes for catalyzing hydroxylation reactions
Ex. sulfite oxidase, xanthine oxidase, aldehyde oxidase
Balance data for average minimum requirement to achieve adequate Mo status
- added bit for sweat losses
- 75% bioavailability
RDA for all adults
UL = 2000 mcg
- adverse effects on pregnant animals (not found in humans)
- high soil content leading to gastro effects
Fluoride function
Adequacy
DRI
crystalline deposits in bone and teeth
F replaces hydroxy portion → fluorapatite making it decay resistant and well formed
AI based on relationship between dental caries and water [F] and F intake
AI for all adults
UL = 10 mg
- accidental exposure can cause adverse effects on bone health and fluorosis
Microminerals no UL
Microminerals AI
Microminerals differ btwn sexes
No UL: Cr
AI: Mn, Cr, F
Sexes: Zn, Mn, Cr
