Transcript 11-2-Nutrition & hun..

TODAY
• Human Nutrition
• Synergy between nutrition and disease
• Especially vulnerable populations
• Four faces of hunger
• Global Hunger
© T. M. Whitmore
LAST TIME
• Questions about local, market, or niche
agriculture in the US?
© T. M. Whitmore
•
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
© T. M. Whitmore
•
•
•
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
© T. M. Whitmore
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
© T. M. Whitmore
•
•
•
•
•
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.
© T. M. Whitmore
Kwashiorkor
•
•
•
•
Severe protein deficiency
Bloated body
Fluids stuffed in cells against wasted muscles
Results in diarrhea, apathy, brain damage
© T. M. Whitmore
•
•
•
•
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
© T. M. Whitmore
•
•
“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
© T. M. Whitmore
“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 vegetables
Quality is so-so to poor
Quantity frequently low also
© T. M. Whitmore
•
Traditional diets I
Traditional Mesoamerican bean burrito
Beans
 Short of methionine, cystine
 Lots of lots of lysine, tryptophan,
isoleucine
Corn (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
© T. M. Whitmore
•
•
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
© T. M. Whitmore
so good with rice
•
•
Vitamins & minerals
Chronic shortages may not show obvious
effects but at the biochemical level there are
problems
Variety in diet best solution
Shortages can be precipitated by some
diseases (e.g., parasites such as hook worm,
malaria, etc.)
© T. M. Whitmore
Historical acute deficiency diseases
•
•
Beri-beri: thiamine (vitamin B1)
Found in rice eating pops in Asia
More 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 low
Not in Mesoamerica, however, because of
the treatment of maize (nixtamalization) =>
T. M. Whitmore
increases niacin and beans have it as©well
•
•
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 D
Lack of sufficient sunlight in winter
© T. M. Whitmore
•
Contemporary acute deficiency
diseases: Iron
Iron deficiency:
Most common single nutrient deficiency in
the world
 > 1/3 of pop in many developing countries
Reduces cognitive performance, energy and
work ability, and resistance to infection
(especially to diarrheal and respiratory
diseases) even in mild cases
Severe forms = anemia
© T. M. Whitmore
•
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
© T. M. Whitmore
•
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
© T. M. Whitmore
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
© T. M. Whitmore
•
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)
© T. M. Whitmore
How poor nutrition => disease II
•
Reduction in ability to generate acquired
immunities - the specific immunities one
acquires to a particular disease pathogen
Reduced production of humoral antibodies
Impaired cell-mediated immunity
© T. M. Whitmore
•
How disease => poor nutrition
Most infections interfere with the body's
ability to absorb nutrition and/or actively
deplete nutrients
Reduced appetite
Poorer quality of diet ingested
Diseases deplete bodily tissue
Fevers => increased metabolic rate thus,
the body needs more kcal but they may not
be there
© T. M. Whitmore
•
•
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)
© T. M. Whitmore
•
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
© T. M. Whitmore
Oral Rehydration Therapy
(packet for addition to water)
Oral Rehydration Therapy
(home made)
•
•
•
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 babies
Developmental problems for baby physically
and mentally
Reduced resistance to diseases
Less able to breast feed (=> less resistance
for the baby as well)
© T. M. Whitmore
•
•
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.
Elderly
Ability to fend off infections is reduced
with great age and malnutrition hurts that
as well
© T. M. Whitmore
•
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 malnutrition
Weaning foods are typically not nutrient© T. M. Whitmore
rich enough (e.g., maize gruels)
•
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
© T. M. Whitmore
•
Four Faces of Hunger II
II. Malnutrition/Undernutrition
Seasonal or periodic P/C under-nutrition
Most 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
© T. M. Whitmore
•
Four Faces of Hunger III
III. Micro-nutrient deficiencies
 Vitamin and mineral shortages
•
Sometimes called “hidden hunger”
IV. Nutrition-depleting illnesses
Secondary malnutrition
Most common nutrient depleting diseases
are infant/weanling diarrheas – 5 million
deaths annually world wide
© T. M. Whitmore
•
•
•
•
•
•
Global Hunger
Global situation late 1990s
Data drawn from FAO’s SOFA report 2002
http://www.fao.org/DOCREP/004/y6000e/y600
0e00.htm
The International Food Policy Research
Institute:
http://www.ifpri.org/pubs/fpr/fpr24.pdf
The concept of “food security”
© T. M. Whitmore
•
•
Global Trajectories of Hunger I
Proportions undernourished (or food insecure)
Late 1970s ~ 28%
Late 1990s ~17%
Thus, real progress
Less progress in absolute numbers
Micro-nutrient deficiencies
Iron: 40% of global south
Iodine: 12% of global south
Vitamin A: 14% of kids in global south
© T. M. Whitmore
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 => 400m
Current trajectory => 475-500m by 2015
© T. M. Whitmore
•
•
Regional differences malnourished
or food insecure
Global South
Sub-Saharan Africa
E. Asia, SE Asia, & Pacific
South Asia
Latin America & Caribbean
Near East & N. Africa
Developed Economies (mostly N America)
© T. M. Whitmore
Countries with food shortfalls – requiring assistance
Source: FAO
Source: FAO
Source: FAO
Number of malnourished children, 1993, 2010, and 2020
Source: IFPRI IMPACT simulations.