Micronutrients and Trace Elements Flashcards
function of iron
- oxygen transport in blood/ muscle
- electron transport
function of iodine
thyroxine (T4)
triiodothyronine (T3)
ability of thyroid gland to concentrate iodine
function of zinc
- gene expression
- zinc metalloenzymes
- cell membrane structure/ fxn
- induce metallothionein synthesis
function of copper
oxidative enzymes
function of selenium
- important antioxidant
- glutathione peroxidase
- thyroid function ( interaction with I)
function of molybdenum
xanthine oxidase
sulfite oxidase
function of manganese
- mitochondrial SOD
- CHO metabolism
- mucopolysaccharide synthesis
function of chromium
-facilitates binding of insulin to receptors
function of fluoride
integrity of teeth/ skeleton
function of cobalt
structure of cobalamin b12
heart failure, anorexia, slow growth
severe iron deficiency
anemia, impaired cognitive development, decreased exercise tolerance
mild iron deficiency
hypothyroidism
severe iodide deficiency
goiter
mild iodide deficiency
spontaneous abortion, cretinism, deafness, mental retardation
fetus iodide deficiency
acro-orficial dermatitis, diarrhea, increased infections, poor wound healing, delayed sexual maturations, personality changes
severe zinc deficiencies
growth retardation, anorexia, increased infections
mild zinc deficiency
intra-uterine growth retardation, congenital malformations
fetus zinc deficiency
mental retardation, seizures, connective tissue defects, fractures
severe copper deficiency
anemia, neutropenia, osteoporosis, seborrheic skin lesions
mild copper deficiency
connective tissue defects baby
fetus copper deficiency
cardiomyopathy, skeletal myopathy
severe selenium deficiency
macrocytosis, loss of hair pigment, hypothyroidism
mild selenium deficiency
sources of iron
Heme Iron:
-Cellular animal protein
Non-heme Iron:
-legumes, nuts, whole grains
Iron Absorption:
Dietary Factors:
insoluble complexes
phytate, tanins
Iron Absorption:
Oxidation state
- ascorbic acid: Fe3+ –> Fe2+
- absorption enhanced for reduced state
Iron Absorption:
Mineral Mineral Interactions
-excessive Zn or Cu decreases Fe absorption
Iron Absorption:
Host Factors 2
- Fe deficiency –> increased absorption
2. inflammation–> increased hepcidin from liver –> decreased absorption at enterocyte
Iron Absorption:
Quantity in Gut lumen
inverse relationship
main site of iron regulation
intestinal absorption
major route of iron loss
bleeding
major iron stores
liver, bone marrow, spleen
Iron transport and storage form
transport: transferrin
Storage: ferritin/ hemosiderin
most common nutritional deficiency in the world
iron
iron deficiency in men or post-menopausal women
merits investigation for source of bleeding
iron deficiency manifestation
- Anemia: microcytic, hypochromic
- W.o anemia: impaired cognitive function, growth
iron deficiency diagnosis
Severe Deficiency:
-low Hb/Hct & microcytic/ hypo chromic rbc
Mild, moderate/ Severe Defic:
-low ferritin
Low % Sat:
-low serum Fe with high TIBC
labs to check with ferritin
- ferritin is an acute phase protein elevated with inflammation
- need to also check ESR or CRP for accurate interpretation
Iron is a potent pro-
oxidant
large doses of supplemental iron interfere with absorption of
zinc and copper
hereditary hemochromatosis
- defect in hepcidin
- excessive Fe absorption
- accumulated Fe damages liver and increases risk of HCC
medicinal FE overdose
-hemorrhagic gastroenteritis
-shock and acidosis
coag defects
-hepatic failure
lethal Fe dose in children
1-2grams
especially critical during periods of growth and cellular/ tissue proliferation & immune function
zinc
sources of zinc
animal products (oysters) beef> poultry> fish/milk/ eggs
zinc absorption is impaired by
phytate, a dietary complex involved in iron absorption
found only in plants,~corn, legumes, nuts
Zinc Absorption:
Systemic levels
unlike iron absorption, since absorption is not increased with deficiency
zinc homeostasis maintained by what paired processes
absorption and excretion
- zinc secreted into go tract with digestion as part of pancreatic-biliary secretions
- some is reabsorbed and some is excreted
how is zinc homeostasis different from iron
there is a route to excrete zinc, whereas with iron the body has to be careful how much iron to take in because it can be toxic and is difficult to get rid of
7 populations at risk for iron deficiency
- infants > 6 mths: low stores & high requirement
- premature infants: low stores & high requirement
- adolescents: high requirement & poor intake
- pregnant women: increased requirement (27mg/day)
- chronic infestations
- bariatric surgery
- elderly
9 populations at risk for zinc deficiency
- infants
- young children
- breastfed infants >6mths
- pregnant women
- monotonous plant diets: esp high in phytate
- bariatric surgery
- elderly
- GI illness/ injury: diarrhea
- Wounds, burns
why are breastfed infants > 6mths at risk for zinc deficiency?
after 6mths because human milk has low Zn levels after 6mths
contrast risk populations iron (2) deficiency vs zinc deficiency (4)
Iron:
- adolescents
- Chronic infestations
Zinc:
- breastfed infants >6mths
- monotonous plant diets: esp high in phyla
- Diarrhea
- Wounds/ burns
poor zinc status in the elderly is associated with a higher risk of what?
pneuonia
Copper ot zinc ratio (CuZ)
increased ratio in the elderly associated with higher mortality, may be a biomarker of aging
Zinc deficiency and death
worldwide
-estimated to account for 0.4 million deaths/ year in children younger than 5
(second only to vitamin A which is estimated to be responsible for 0.6 million deaths/ year)
acrodermatitis enteropathica
- mutation in zinc transporter ZIP4
- fatal if not treated
- responds to high doses of Zn supplements (lifetime)
acrodermatitis enteropathica presentation
severe dermatitis, growth failure, diarrhea
zinc toxicity
- relatively low
- >50mg/d can decrease HDL, impair absorption of Fe and Cu, cause nausea, diarrhea
zinc within first 24hours of symptoms of a cold
- decrease duration of illness by 1-4 days
- reduce severity of symptoms
- may prevent viral replication or attachment to nasal membranes
iodine sources
- seafood
- grown things: depends on content of soil- especially low in mountainous areas
- Today: iodized salt
cassava
- goitrogen
- contains ions that compete with iodide (like SCN-)
- associated with widespread goiter and hypothyroidism
Absorption process iodine
Iodide Uptake –> binding to T3, T4 –> Circulation
iodine worldwide deficiency
common–> endemic goiter and cretinism in children (5.7 million cretins exist; 1 billion persons at risk for I deficiency disorders)
Cretin child: deaf mutism
- dwarfed, mentally retarded, dull facies, large tongue
- I deficiency during pregnancy
I deficiency on fetus
-increased abortions, stillbirths, congenital abnormalities
goiter
-enlarged thyroid gland to compensate for decreased I for thyroid hormone synthesis
populations with endemic iodine deficiency
mean IQ loss: 13.5 points
Copper food source
shellfish, meats, nuts
low in milk
Copper absorption and metabolism
30-40% absorption from mixed diet, stored in liver, excreted in bile
Selenium
foods associated with with amino acids
keshan disease
-cardiomyopathy in china prevented with Se supplementation
Cause:
-interaction with other nutritional deficits or viral infection
*Viral mutation increases virulence in Se deficient host
selenium absorption and metabolism
- 60-80% absorbed from diet
- Kidneys main site of homeostasis
- urine excretion
