Measuring UndernutritionChapter 4

From Chapter 3What we Learned

Biggest problem, Over- & under-nutrition

Total CaloriesProteinMicronutrients

Common methods of assessing undernutrition

Clinical Assessment: Looking for physical signs of nutritional disordersBiochemical: Examine blood and urine looking for metabolic changes that accompany nutritional disorders

Common methods of assessing undernutrition (cont.)

Dietary Assessment: Track what the person eatsAnthropometric Assessment: Measuring the human body and its parts. It is the most common method of assessing nutritional disorders

Clinical AssessmentLook at:

Hair color (lighter and thinner)Ankle swellingEnlarged necksPoor eye sight

Clinical Assessment (cont.)What is each an indicator of?

Hair color (Lighter and thinner)Protein deficiency

Ankle swellingProtein deficiency causing circulation problems

Enlarged necksGoiter, iodine deficiency

Poor eye sightVitamin A deficiency

Clinical Assessment (cont.)Be aware that other things can cause these symptomsWhen these symptoms show to this extent then the problem is advancedUsed to analyze:

most severe casesSpecific types of malnutrition

Biochemical AssessmentBlood and urine testsShow micronutrient deficienciesAccurate but relatively expensive

Dietary Assessment2 Methods:

Survey – recall by the person, after-the-factReview dietary records

Dietary Assessment (cont.)

Problems with both methodsPeople can’t recall exactly People liePeople adjust their eating habits when they are in a studyBreast feeding – difficult to determine how much the baby eatsSeasonal variations (price & availability)

Dietary AssessmentUseful in:

Doing comparisons of diet and incomeAlso useful to track food allocations within the family

Anthropometric Assessment

Most commonly-used methodSize – indicator of calories & protein intake

Anthropometric (cont.)Acute undernutrition

Short-term inadequate foodCaused by famine or warPeople can recover

Chronic undernutritionLong-term inadequate foodEven moderate, effects are permanent

StuntingDef.: low height-for-age

Shows that the person has experienced chronic undernutrition during growth yearsIt is a symptom of past undernutrition

Stunting (cont.)People born in 1910 were 4 cm (1.6 in) shorter than those born in 1930People born in 1950 1 cm (1/2 in) taller than those in 1930

What does that tell you?

WastingDef.: low weight for heightThis is a symptom of current undernutrition

Under weightDef.: low weight for ageA symptom of present undernutrition

What about Inheritance?Part of people’s height is determined by their genesAre there ethnic differences?These factors are less important than other factors

Nature vs. nurture

Other FactorsPovertyPoor food intakeInfectious & parasitic diseasesOther environmental factors

Use of AntropometryMost useful in comparisons of infantsOlder children, less soIn developed countries useful in measuring overnutrition of adults

Antropometry (cont.)What is measured?

HeightWeightArm circumference

One of the better measures of fat in the body

Skin-fold thickness

Antropometry (cont.)Measurements are easy and cheapNeed:

ScaleTape measureCalipers (know what they are)

Antropometry (cont.)Training someone to recognize undernutrition by clinical means takes a lot more timeComparisons to a Reference Group

“You are shorter than average”“You weigh less than average”

What is the purpose of all this?

Identify those in need of helpEither those who are undernourishedOr Those who are overnourished

Method 1Measuring Large Groups

(Note: Method 1 is not labeled, but is described in the paragraph on p. 51 Drawing Inferences from a sample)

A continent?A country?A region?Among demographic groups

Def: characteristics of a population or segment of the pop.

Among ethnic groups

Measuring (cont.)Cannot measure everyoneStatistics – SamplingIf our sample is representative then inferences can be made of the whole population

Method 2Examine Aggregate DataLook at data on:

Birth weightInfant mortalityMorbidity

Def.: the rate of incidence of a diseaseThese are not direct measures of nutritional status

Method 3 Aggregate Nutrient IntakeOr: average nutrient intakeFAO keeps such data on each country

FAO Food and Agriculture OrganizationPart of the UN

These food-balance sheets show sources and types of food – over 100 different foods

Aggregate (cont.)FAO keeps stats on sources of food:

Beginning stocksProductionImports

Aggregate (cont.)FAO keeps stats on uses of food:

Ending stocksExportAnimal feedConsumption

Aggregate (cont.)They use the word balance sheet because sources and use are in balance

Aggregate data: These measures imply undernutrition in a region

1. High IMR 2. Low birth-weights3. High morbidity (illness) rates

Look at food availability to infer the existence of undernutritionFood balance sheets estimate human consumption1. Add up the supply of a specific food beginning stocks + production + imports

2. Subtract the amount used for: exports + livestock feed + seed + ending

stocksWhat about food stocks used for fuel?

What is left can be assumed to go for human consumption

3. Convert this to calories• do for all foods, to calculate available

calories per capita per day (a widely used measure of malnutrition)• Remember: Carbohydrate and protein

has 4 calories/gram & Fats and oils have 9 calories/gram

This is a mean, it could be that some people are consuming above the average and some people are undernourisheda. Studies of individuals need to be done to infer the percentage of the population that have inadequate food intake

IV. Undernutrition & child health

A. Undernourished mothers are likely to produce malnourished babies1. Low birth weight2. 40 times more likely to die

before their first year

B. Undernutrition leads to high under-five mortality rates

Worldwide average (1999) = 78 per 1,000 live births

• Industrialized countries = 7Developing countries = 85

• Least developed countries = 161(Sub-Saharan Africa)

C. Undernutrition results in a weakened immune system which leads to death from childhood diseasesInfant mortality rate (IMR; children who die before their 1st birthday per 1,000 live births) goes up as a child’s percent of the median weight-for-age goes down

IMR in the U.S. is 2.1%– before five = 2.5%IMR in Guinea = 21.6%– before five = 36.7%

V. Effects of undernutrition A. Mental development

impaired in undernourished children

B. Educational achievement lowered

C. Childhood undernutrition results in smaller adults who can do less physical work & who earn less money

D. Undernourished adults are less productive when working and lose more work time to sickness and so have less money to buy food

(note the cycle)

Measuring nutritional status for large groupsA. Draw inferences from a

sample using statistics1. Use info from a subset of the population to infer characteristics of the whole population2. Sample must be representative

B. Use aggregate data on the effects of undernutrition to infer how much undernutrition existsAggregate data: data compiled from several measurements