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DEMS Unit 2.2 > Micronutrients & Malnutrition > Flashcards

Micronutrients & Malnutrition Flashcards

1
Q

Iron - Functions and Distribution

A

Total body iron ~5g

50% as circulating hemoglobin, 50% stored

Functions: O2 transport in blood and muscle, electron transport, activation of O2 (oxidases)

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2
Q

Iron - Sources

A

Heme: Meats, liver; low in all milks

Non-heme: Plant sources (legumes, whole grains, nuts), fortified foods (cereals, grains)

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3
Q

Iron - Absorption / Bioavailability

A

Heme iron from animals is absorbed > non-heme iron from plants; insoluble complexes in plants (phytate, polyphenols) interfere with absorption of non-heme iron

Fe is absorbed better in the reduced state (Fe2+); ascorbic acid increases absorption by affecting redox state

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4
Q

Phytic Acid

A

Storage form of phosphorous in plants; contains 6 negatively charged phosphate groups which can bind cations in the gut lumen, reducing absorption of these ions (Zn, Fe, Ca); humans don’t have phytases

High in grains (maize, wheat), legumes; globally, a major cause of dietary Zn and Fe deficiencies

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5
Q

Iron - homeostasis

A

Absorption is the main point of regulation; absorption is increased in iron deficiency, decreased in inflammation due to increased hepcidin release from hepatocytes (hepcidin blocks iron absorption)

Loss - bleeding, cell sloughing

Stored by ferritin in liver, bone marrow, spleen; transported by transferrin

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6
Q

Iron Deficiency - Risk

A

Infants - especially ~6 months due to increased demand and low concentrations in breast milk
Children, adolescents (especially girls due to menstruation and poor intake)
Pregnant Women
Blood loss - bleeding, hemolysis
Obesity - due to chronic inflammation
Post bariatric surgery

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7
Q

Iron Deficiency

A

Most common micronutrient deficiency - worldwide & US

Anemia (microcytic, hypochromic) - decreased exercise tolerance, fatigue, attention deficit, impaired growth

Iron deficiency without anemia is associated with impaired cognitive functionin the developing brain; irreversible, even with correction

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8
Q

Iron Toxicity

A

Potent pro-oxidant - avoid unnecessary supplementation

Excess iron deposits as hemosiderin in reticuloendothelial cells; may interfere with absorption of Zn, Cu

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9
Q

Iron Deficiency - Diagnosis

A

Low Hb/Hct + microcytic/hypochromic anemia

Low ferritin (can be elevevated in infection/inflammation - check ESR/CRP)

Low serum Fe + high TIBC - low % saturation

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10
Q

Zinc - Functions & Sources

A

Regulation of gene expression (Zn fingers) - important in

Growth and tissue proliferation
Immune system
Wound healing
GI tract integrity
Skin

Sources: Animal products (beef > poultry > fish), plants (whole grains, legumes)

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11
Q

Zinc - Homeostasis

A

Absorption is crudely controlled - inhibited by phytate (like Fe); absorption is NOT increased by Zn deficiency

Excretion from pancreatic-biliary system with loss via the Feces; therefore less toxic than Iron, but increased loss may occur in diarrhea

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12
Q

Zinc Deficiency - Risk

A

Breastfed infants > 6 months (low supply, high demand)
Pregnant women
Monotonous, plant-based diets
GI illness - diarrhea
Wounds, burns - increased requirement for tissue repair

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13
Q

Zinc Deficiency

A

Mild: Growth delay/stunting, impaired immune function, poor neurocognitive development

Severe: Dermatitis, diarrhea, immune dysfunction, delayed sexual maturation, delayed wound healing, taste impairment

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14
Q

Acrodermatitis Enteropathica

A

Mutation in enterocyte Zn transporter ZIP4

Fatal if not treated but responds to high doses of Zn supplements; presents with severe dermatitis of groin and around the mouth, growth failure, diarrhea

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15
Q

Iodine - Sources & Function

A

Sources: seafood, seaweed, iodized salt

Function: Integral component of thyroid hormones T3 and T4

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16
Q

Zn toxicity

A

Decreased HDL cholesterol
Decreased Fe and Cu absorption
Diarrhea

17
Q

Iodine deficiency

A

Goiter (enlarged thyroid gland) as compensation for decreased T3, T4 production; ‘goitrogens’ are foods that contain ions which compete with iodine uptake, i.e. SCN- in cassava; associated with goiter and hypothyroidism

Iodine deficiency in pregnancy associated with spontaneous abortion and stillbirth, as well as ‘cretin child’ - short stature, developmentally delayed, coarse facies, deaf/mute

18
Q

Copper deficiency

A

Intellectual disability, seizures

Connective tissue disease - osteoporosis, fractures

19
Q

Pathophysiology of marasmus

A

Normal physiological response to starvation; characterized by decreased insulin and increased counter-regulatory hormones, which mediate eventual shift to lipolysis and ketogenesis; decreased need for glucose in the brain spares muscle protein breakdown

Also associated with decreased energy expenditure (bradycardia, hypothyroidism, hypothermia)

20
Q

Pathophysiology of Kwashikor

A

Edematous protein energy malnutrition without wasting; associated with high insulin which inhibits lipolysis and increases fatty acid synthesis in the liver, causing an enlarged, fatty liver

Associated with hypoalbuminemia and edema

21
Q

Phenotypic findings of Kwashikor

A 
Edema, 'moon faces' 
Anorexia 
Psychological impairment 
Hepatomegaly 
Diarrhea 
Skin lesions - 'flaky paint' 
Hair changes - 'flag sign'
22
Q

Re-feeding syndrome

A

Increased insulin secretion in response to feeding drives glucose and K+ phosphorous intracellularly; may cause hypokalemia with associated nerve/muscle dysfunction and hypophosphatemia

Mg2+ requirements increase with metabolic rate as Mg is a co-factor for ATPase

23
Q

Malnutrition occurs in what percentage of hospitalized patients?

A

50%

24
Q

Stunting - Definition & Epidemiology

A

Height-for-age Z score < -2

More common than wasting; affects 26% of children worldwide; primarily occurs over the critical 1,000 Day window from conception through the first 2 years of life as a result of chronic malnutrition (not energy deficit), inflammation, recurrent infection, intergenerational effects

25
Q

3 myths of global malnutrition

A
  1. Malnutrition is a problem of inadequate food intake
  2. Improved nutrition can come about only as a by-product of poverty reduction
  3. Broad-based action to improve nutrition is not feasible given limited resources
26
Q

What is the SINGLE most important intervention to reduce childhood mortality under 5 years?

A

Promotion of exclusive breast feeding

27
Q

What are the 3 MDGs related to nutrition?

A
  1. Eradicate extreme poverty and hunger (“halve the proportion of people who suffer from hunger”
  2. Reduce childhood mortality by 2/3
  3. Improve maternal health
28
Q

Wasting - Epidemiology

A

Wasting (reduced weight-for-height) affects 8% of children worldwide; 3% of children are severely wasted

29
Q

Maternal undernutrition

A

BMI < 18.5 - affects 10-20% of women worldwide; underweight & short stature are independent risk factors for poor reproductive outcomes

Maternal undernutrition associated with ~20% risk of maternal mortality

30
Q

Evidence-based interventions to reduce deaths in < 5 year old children:

A

Maternal supplementation - Folic acid, protein, calcium, Vitamin A, Zinc, and multiple micronutrients (Iron, Iodine)

Promotion of breastfeeding and appropriate complementary feeding

Management of moderate-severe acute malnutrition

Handwashing and hygiene interventions

Interventions to reduce tobacco consumption and indoor air polution

31
Q

Who is at risk for malnutrition?

A

Infants
Children < 5
Women of childbearing age

32
Q

What are the 3 components of the impoverished gut?

A

Diarrhea
Stunting
Chronic disease

33
Q

Environmental enteropathy

A

Chronic, T-cell mediated inflammation resulting from repeated GI infections with low doses of organisms; leads to altered microbiota, leaky gut, and malabsorption

34
Q

Biofortification

A

Plant breeding to increase micronutrient content; i.e. golden rice (high Vitamin A), maize high in Zn and Fe, maize with reduced phytate content

DEMS Unit 2.2 (9 decks)

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