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TODAY•Human Nutrition•Synergy between nutrition and

disease•Especially vulnerable populations•Four faces of hunger•Global Hunger

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LAST TIME•Questions about local, market, or

niche agriculture in the US?

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Nutrition and Hunger• Biology of Nutrition

Active adults and growing children need most food/body weight

But, small children, infants, and the aged are most at risk to severe consequences of nutritional problems

Nutritional needs Energy: commonly measured in

kilocalories (kcal) or what we usually call “calories”

Protein: variable in “quality” for human use

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Energy• Body “burns” carbohydrates, fats, and

sugars for the energy to live • Proteins also can be converted by the liver

to sugars for energy if necessary, but not vice versa (not very efficient)

• Calories in excess of need => storage as fat

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Severely Insufficient Nutrition•Calorie or protein-calorie malnutrition

Severe forms of this in infants especially can lead to marasmus

Body breaks down lean muscle and tissue to produce calories

•Severe protein malnutrition can lead to kwashiorkor

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Marasmus• Stick-like limbs, bloated belly, wide eyes: • From Greek “to waste away”• Lacking calories (as well as protein),

children may weight less than half of normal

• Brings diarrhea, apathy, and brain damage• Bloated look as fluids are accumulated to

push against wasted muscles.

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Kwashiorkor• Severe protein deficiency• Bloated body• Fluids stuffed in cells against wasted

muscles• Results in diarrhea, apathy, brain damage

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Protein• There are 22 amino acids needed to create

the thousands of proteins humans need to create: e.g., blood, hormones, hair, muscle, antibodies, etc.

• We make all the amino acids needed except for 9 that must be in foods: leucine, valine, tryptophan, phenylaline,

isoleucine, threonine, lysine, cystine, and methionine

• Foods vary in their composition of these so vary in “quality” of protein (% protein that is usable)

• Foods also vary in total quantity of protein per gram

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“Quality” of protein I• Animal foods:

Quality is relatively high e.g., eggs = 98%; milk = 80%; fish =

80%; meat = 70%Quantity is relatively high as well

• Grains: Quality is relatively high

e.g., rice, wheat, oats = 70%; millet, rye = 55-60%

Quantity is relatively low ~ 10-15% by weight is protein

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“Quality” of protein II• Legumes (pulses):

Quality is so-so – usually deficient on one or more of the 9 amino acids e.g., soy beans = 60%; lima beans =

50%; lentils = 30%Quantity is relatively high

• Other vegetablesQuality is so-so to poor Quantity frequently low also

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Traditional diets I• Traditional Mesoamerican bean burrito

Beans Short of methionine, cystine Lots of lots of lysine, tryptophan,

isoleucineCorn (maize)

Short of tryptophan & lysine (OK otherwise)

So the beans balance the shortage of tryptophan and lysine in the corn making the overall protein quality very good

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Traditional diets II• Hamburger & wheat bun

Wheat Short of lysine Lots of methionine, tryptophan, isoleucine

Beef Lots of lysine

So the two balance each other out• Rice and Soy

Rice is short on lysine so mixed with most beans => good

Soybeans have lots of lysine and tryptophan so good with rice

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Vitamins & minerals• Chronic shortages may not show obvious

effects but at the biochemical level there are problemsVariety in diet best solution

• Shortages can be precipitated by some diseases (e.g., parasites such as hook worm, malaria, etc.)

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Historical acute deficiency diseases• Beri-beri: thiamine (vitamin B1)

Found in rice eating pops in AsiaMore varied diet => not a major problem

now Common vegetable sources are various

legumes and whole grains -- polished (white) rice is deficient

• Pellagra: niacin (vitamin B3)In populations who consume maize or

sorghum as main foods since both are lowNot in Mesoamerica, however, because of

the treatment of maize (nixtamalization) => increases niacin and beans have it as well

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Historical acute deficiency diseases• Scurvy: vitamin C

Formerly a major problem for sea-going navies and explorers Early 19th C British Navy solution –

eating limes => Brits commonly called “Limeys”

Sauerkraut also works fine!Periodically a problem in refugee pops

who don't get enough fresh fruits and vegetables

• Rickets: vitamin DLack of sufficient sunlight in winter

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Contemporary acute deficiency diseases: Iron

• Iron deficiency: Most common single nutrient deficiency

in the world > 1/3 of pop in many developing

countriesReduces cognitive performance, energy

and work ability, and resistance to infection (especially to diarrheal and respiratory diseases) even in mild cases

Severe forms = anemia

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Contemporary acute deficiency diseases: Iodine

• Iodine deficiency:Iodine is lacking in soils from some

mountain areas and in domr highly leached soils e,.g., Andes, Himalayas, C Africa, SE

Asia...Major consequences:

Swelling of thyroid (goiter) Important mental deficiencies

(cretinism) in kids if deficient in pregnant women

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Contemporary acute deficiency diseases: Vitamin A

• Vitamin A deficiency:Major consequences

To vision can lead to blindness Also decreased immune function Kids with severe protein-calorie

malnutrition often have impaired sight as a result of this

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Synergy: nutrition and disease• Poor nutrition (protein-calorie or other

nutrient shortages) => reduced ability to fend off new infections or makes existing ones more severe

• Diseases interfere with nutrient absorption and/or actively deplete nutrients from our bodies

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How poor nutrition => disease• Reduction in the body's innate immunities

(that react to general patterns of proteins in pathogens) Less effective phagocytosis (process by

which microorganisms are engulfed and encapsulated)

Weakened epithelial barriers (protective coverings on body surfaces inside and out)

Lowered lysozyme production (a bodily protein that functions as an antibacterial)

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How poor nutrition => disease II

• Reduction in ability to generate acquired immunities - the specific immunities one acquires to a particular disease pathogenReduced production of humoral

antibodiesImpaired cell-mediated immunity

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How disease => poor nutrition• Most infections interfere with the body's

ability to absorb nutrition and/or actively deplete nutrientsReduced appetitePoorer quality of diet ingestedDiseases deplete bodily tissueFevers => increased metabolic rate

thus, the body needs more kcal but they may not be there

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Special case of GI tract diseases• 1.8 billion cases/yr of infant/weanling GI

diseases • Predominantly diarrheas, but also

intestinal parasites, cholera, & various types of dysentery Impede absorption of nutrients

(diarrheas just don't let food sit in gut long enough)

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Special case of GI tract diseases II• Many if not most deaths (perhaps 1 million/

yr in the world) can be averted with adequate treatment (called Oral Rehydration Therapy) According to The Lancet (1978), ORT is

"potentially the most important medical discovery of the 20th century"

Clean water with 60 cent packets of salts/sugars to recover health

Full recovery => increased nutrition above basic levels – often hard to get

Oral Rehydration Therapy(packet for addition to water)

Oral Rehydration Therapy(home made)

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Especially vulnerable populations I• Increased likelihood of malnutrition and

more serious consequences• Women in general due to cultural traditions

that privilege food to males• Pregnant women

Poor nutrition => low birth weight babiesDevelopmental problems for baby

physically and mentallyReduced resistance to diseasesLess able to breast feed (=> less

resistance for the baby as well)

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Especially vulnerable populations II• Lactating women

Poor nutrition seldom greatly interferes with ability to produce milk

But, poor nutrition does deplete the mother's body of necessary nutrients

If nutrition is not better between end of lactation and next pregnancy => spiral down to chronic anemia etc.

• ElderlyAbility to fend off infections is reduced

with great age and malnutrition hurts that as well

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Especially vulnerable populations III• Children

Malnutrition in infants and children very problematic if timing coincides with critical growth processes Up to age 5 risk is greatest

Especially at weaning age (approx 2 yrs)Due to impure water used to make

weaning foods (not sufficiently boiled due to lack of fuel) and general low hygiene => Kids die from diarrheal diseases and

dehydration and malnutritionWeaning foods are typically not nutrient-

rich enough (e.g., maize gruels)

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Four Faces of Hunger I• I. Starvation/Famine

Widespread to complete lack of protein/calorie nutrition

A small percentage of global hunger – perhaps 1% at risk annually

Leads to increased mortality (usually to infectious diseases not starvation per se)

Great social disruption => increased problems with diseases and access to food

In any famine not all starve – the well off can buy food -- thus NOT usually only a simple shortage

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Four Faces of Hunger II• II. Malnutrition/Undernutrition

Seasonal or periodic P/C under-nutritionMost serious effects on kids and special

needs adults (pregnant and lactating women, the elderly)

measures of malnutrition in children Stunting - stature too short for age/sex

(adjusted for local norms) => chronic Wasting – weight too light for age/sex

(adjusted for local norms) => acute

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Four Faces of Hunger III• III. Micro-nutrient deficiencies

Vitamin and mineral shortagesSometimes called “hidden hunger”

• IV. Nutrition-depleting illnesses Secondary malnutritionMost common nutrient depleting

diseases are infant/weanling diarrheas – 5 million deaths annually world wide

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Global Hunger• Global situation late 1990s • Data drawn from FAO’s SOFA report 2002• http://www.fao.org/DOCREP/004/y6000e/

y6000e00.htm• The International Food Policy Research

Institute:• http://www.ifpri.org/pubs/fpr/fpr24.pdf• The concept of “food security”

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Global Trajectories of Hunger I• Proportions undernourished (or food

insecure)Late 1970s ~ 28%Late 1990s ~17%Thus, real progressLess progress in absolute numbers

• Micro-nutrient deficienciesIron: 40% of global southIodine: 12% of global southVitamin A: 14% of kids in global south

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Global Trajectories of Hunger II• Absolute numbers undernourished (or food

insecure)1970s ~ 900m; 2000 ~ > 800 m => decrease of ~ 100m in absolute

numbers (but smaller %)• Children 1993 ~ 200 m; now ~ 175 m• World food summit target in 2015 =>

400mCurrent trajectory => 475-500m by 2015

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Regional differences malnourished or food insecure

• Global SouthSub-Saharan AfricaE. Asia, SE Asia, & PacificSouth AsiaLatin America & CaribbeanNear East & N. Africa

• Developed Economies (mostly N America)

Countries with food shortfalls – requiring assistance

Source: FAO

Source: FAO

Source: FAO

Number of malnourished children, 1993, 2010, and 2020

Source: IFPRI IMPACT simulations.