Lecture 4: Micronutrient Malnutrition Flashcards
Micronutrient Deficiencies focus on what?
AKA as what?
Focus: Iron, iodine, Vitamin A
AKA “hidden” malnutrition
Define anemia
Not having enough healthy RBCs/hemoglobin to carry oxygen to body’s tissues.
Causes tiredness, weakness, shortness of breath
____ part of many proteins involved in oxygen transport and energy metabolism reactions
Iron
Myoglobin
protein similar to hemoglobin found in cytoplasm of muscle cells
_____ and ____ in the energy metabolism pathway
Enzymes and electron carrie molecules
Regarding iron: ____ involved in frug metabolism, immune system, and protection against free radicals
protein
What needs iron to carry oxygen and for energy metabolic reactions?
Hemoglobin, myoglobin, enzyes/electron carrier molecules, proteins
When does iron deficiency occur?
When diet doesn’t provide enough to meet needs
“Absence of iron stores + signs of iron-deficient RBC production = insufficient supply of iron to various tissues”
Iron deficiency Anemia
Not enough hemoglobin produced due to lack of iron.
No more iron stores left ~12mg/dL
Causes of Iron Deficiency and Iron Deficiency Anemia
Insufficient intake (lack of iron in your
diet) to cover normal needs or to meet
the increased needs for
- Blood loss
- Menses, GI bleeding, parasites (esp. hookworm)
- Growth
- Pregnancy
Other causes of anemia
- Malaria: destroys RBCs + reduces RBCs production
- Other parasites: feed on host blood OR causes damage -> loss
- Other Infections: inflammation -> change in immunity + how body use Iron
- Other nutrient deficiencies for blood production (A, B Vitamins, …)
Ideal levels of iron
2/3 functional: usable
1/3: stored
How can iron be stored?
Attached to protein “Ferritin” -> in mucosal clinic -> of intestine + liver
How is iron transported through blood?
attach to protein “Transferrin”
Stages of iron deficiency
- Decrease of ferritin (stores)
- Iron deficiency hematopoiesis
- Iron stores depleted with insufficient absorption to counteract normal losses
- Leads to decreased hemoglobin production - Iron deficiency anemia
- Hemoglobin falls below a set standard
A Negative Balance Leads to progressively more severe conditions: draw the graph
Know recommended intakes for iron
birth to 6mo: 0.27 mg
4-8 yrs: 10 mg
9-13 yrs: 8 mg
14-18 yrs: 11mg (male), 15mg (female)
Food sources of iron
Total cereal: passes RDA
Cooked spinach
Lentiis
_________ is part of hemoglobin and
myoglobin and is obtained from meat of all
types; about ___% absorbed
Heme iron, 25%
_______ iron is found in grains, leafy
green vegetables, legumes, and meat and
is absorbed at about half (or less) the rate
of heme iron.
Non-heme iron
____ iron can also leach out of iron cookware into food
non-heme
Iron deficiency anemia symptoms
Brittle/spoon shaped nails
Cold hands/feet
Headache
Fatigue
Weakness
Shortness breath
Pica
Pallor
Poor appetite
Plant foods are different regarding iron absorbability + #iron
- Fiber, phytate, tannins, oxalate do what regarding iron?
- Milk, calcium can do what?
- bind iron and prevent absorption
- decrease absorption
Concurrent intake of Vita can do what to non-heme iron?
enhance absorption
___ also increases absorption of non-heme and henna iron
“meat factor”
- heme iron taken into cells more efficiently than non-heme iron
Possible interventions?
*Diet containing adequate amounts of bioavailable iron
*Oral iron supplements (women of child-bearing age)
*Malaria control; Deworming
*Fortification of wheat/maize flours, and rice
*Delayed cord clamping
*Early interventions targeting adolescent females
*Good hygiene reduces risk of infection
*Education on reproductive health, family planning services to encourage dialogue,
adequate birth spacing.
Doninent Effects of lack of iron?
- Cognitive defects in kids
- Poor motor control
- Maternal deaths <- severe anemia
- Decreased productivity
Problem results from iodine
Goiter
Iodine is needed for synthesis of what?
Thyroid hormones -> controls metabolic activity of all cells
What regulates metabolic activities of all cells>
Thyroid hormones <- iodine
Iodine availability depends on what?
Also abundant in what?
soil concentrations
also abundant in seawater making seafood and seaweed good sources
Extremely high intakes of iodine also causes what?
Impaired thyroid function
What plays key role in cell replication?
Most relevant for what?
iodine, especially relevant for brain
Fetal iodine deficiency leads to what?
Increased rates of spontaneous abortion
Stillbirths
Congenital anomalies
Congenital hypothyroidism
Psychomotor deficits
Neonatal mortality
Thyroid hormones contain ____ atoms of iodine
3-4 atoms
Adult iodine deficiency leads to what
Goiter and its complications
Hypothyroidism
Impaired mental function
Interventions and considerations for iodine deficiency
- Salt iodization
Law mandates
Quality assurance standards - Target populations: Pregnant women, children under the age of 3
- Soil testing
- Iodine toxicity-not usually a concern
- Too much salt? Hypertension, Heart Disease.
______________ is the leading
cause of preventable blindness in children
and increases the risk of disease and death
from severe infections.
Vitamin A deficiency (VAD)
A major role of vitamin A is as part of
the visual pigment ______
Rhodopsin
Other responsibilities of Vitamin A
Maintenance of epithelial tissue
(Skin, lungs, blood vessels, GI tract, etc.)
Regulation of growth and
differentiation/specialization of cells (Including some cells of the immune
system)
As part of rhodopsin, retinol
binds with the protein
opsin: Describe visual and light in terms of these
(?????)
Rhodopsin absorbs light, which
signals visual cortex of brain
Reconversion and replenishing of
rhodopsin must occur before it can
respond again to light
When Vitamin A pool is low, dark
adaptation is slowed down
When amt. of rhodopsin is limited,
difficult to see in dim light “night
blindness”
Deficiency of ___ is // with decreased resistance to infection
VitA
plays important role in maintenance of epithelial cells
Why is it crucial to maintain epithelial tissues and mucus production?
Act as barriers to invading pathogens
___ is often accompanied by cell proliferatio: continuous development of cells in tissue formation
vit A
____ is needed for production, structure and normal function of epithelial cells in lungs, trachea, skin GI tract, …
Essential for production fo mucous-forming cells in these organs
Vit A
Vit A is fat-soluble or non-fat? How is it transported?
Fat-soluble, via lipids
Where is VitA stored>
in liver
___ is also needed for Retinal binding protein (RBA): needed for storage/transport of VitA in body
Zinc
Several forms fo Via A
Retinoids, BEta-carotene, Antioxidant
Describe retinoids
Common in animal tissues, can serve VitA functions directly
Describe Beta-carotene
is a precursor of VitA founding plant tissues
converted/split by intestine into retinal and retinol
What is pre-formed VitA?
from animal sources
How much is pre-formed VitA (animal sources) absorbed?
about 90%
Describe Pro-vitamin A sources (carotenoids from plants)
- Dependent on type of plant source and fat content of the meal
- Absorption of beta-carotene about 1/3 of retinol and conversion to vitamin A about 1/2
Good diet courses for VitA
beef liver
carrots (as beta-carotene)
mustard greens (as beta-carotene)
Egg yolk
apricots (as beta-carotene)
What is much less toxic
in higher doses than is the preformed
animal forms of vitamin A
BEta-carotene
Symptoms of VitA deficiency
Impaired immune function
Night blindness (insufficient retinal
for rhodopsin formation)
Dry, hard skin
Dry cornea and eventual blindness
(Xerophthalmia)
Steps in VitA Deficiency
Body stores are depleted
leading to impairment of
physiologic functions
1st integrity of the epithelial
barriers and then the immune
system is compromised
Finally, the visual system is
impaired
Xeropthalmia –Sequence of
Events
Night blindness is a common early symptom of low levels of Vitamin A
Mucus forming cells deteriorate and are no longer able to synthesize the mucus that
lubricates the body
The eye especially needs mucus to keep the surface moist and to wash away dirt and other particles that settle on the eye
Deterioration of the eye results from
bacterial invasion
- Role of A in resistance to infection
Conjunctival xerosis (abnormal dryness
of the lining of the eyelids and the outer
surface of the eyeball) and Bitot’s spots
(drying out of the eye and appearance of
hardened epithelial cells) appear as VAD
worsens
Finally, corneal ulcerations and
keratomalacia (softening of the
cornea) results in scarring
- Can see effects from barely
detectable to blindness
Other problems with VitA Deficiency
Keratinized cells in the outer layer of skin
replace the normal epithelial cells in the
underlying skin layers
Hair follicles become plugged with keratin
Skin has a bumpy appearance and rough
texture and is very dry
Deficiency also causes a decrease in appetite
and poor growth
Mortality and severity of measles worsened with vitamin A deficiency
Treating VitA Deficiency
15,000 to 60,000 micrograms of Vitamin A
every 6 months can prevent deficiency in
children
Common dose is 200,000 IUs periodically
Improving the Vitamin A status of young
children reduces mortality rates by about 20% in populations where there is vitamin A
deficiency
What are the major source of pro-VitA in kids where animal products are limited?
veggies
Can you have too much VitA?
Toxic levels can be reached by excess
consumption of liver and supplements of
preformed vitamin A (not beta-carotene)
- recorded instances of toxicity involve excess consumption of polar bear liver by Arctic explorers and supplement use
Symptoms of VitA toxicity include:
Nausea, vomiting
Headache, blurred vision
Lack of muscular coordination
