Transcript 232-4-21-nutr trans

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TODAY
Nutrition Transition Theory: How does this all
come together?
Food Futures: Will there be enough food for
the 21st century?
Reasons for concern
Issues around raising outputs
© T. M. Whitmore
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Related historic processes of change
Interconnected “Transitions”
Demographic Transition (DT)
 Stages of change in mortality and
fertility => population growth over time
 Regional differences-geography
Epidemiologic Transition (ET)
 Shift in the patterns of causes of death
over time
 Regional differences-geography
Nutrition Transition
 Shifts in dietary and physical activityinactivity patterns
© T. M. Whitmore
 Regional differences-geography
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The Nutrition Transition’s “Stage 1:
“Collecting Food”
Hunter gatherers
High in carbohydrates and fiber and low in
fat, especially saturated fat
Activity patterns are very high with little
obesity
Stages 1-2 of DT
First phase in ET
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The Nutrition Transition’s
“Stage 2: “Famine”
Early agriculture and contemporary least
developed areas generally
Diet becomes much less varied and subject
to larger variations and periods of acute
scarcity of food
Little change in activity levels
Stages 1-2 of DT
First-Second phases in ET
© T. M. Whitmore
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The Nutrition Transition’s “Stage 3:
“Receding Famine”
Scientific agriculture, early industrialization,
and contemporary developing areas
Consumption of fruits, vegetables, and
animal protein increases, and starchy
staples become less important in the diet
Activity patterns start to shift and
inactivity and leisure becomes a part of the
lives of more people
Stages 2-3 in DT
Second/Third Phases of ET
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The Nutrition Transition’s “Stage 4:
“Nutrition-related Non-communicable
Disease (NR-NCD)”
Associated with “modern” industrial lifestyles
A diet high in total fat, cholesterol, sugar,
and other refined carbohydrates and low in
polyunsaturated fatty acids and fiber
Often accompanied by an increasingly
sedentary life
Stage 4 in DT
Third Phase of ET
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The Nutrition Transition’s “Stage 5:
“Behavioral Change”
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“Post-modern” industrial lifestyles
A new dietary pattern => changes in diet
associated with the desire to prevent or
delay degenerative diseases and prolong
health
May be associated with increased
“recreational” or health related exercise
Stage 4 in DT
Third Phase of ET
© T. M. Whitmore
Food Futures reasons for concern I:
Population Growth
• Population growth to 8-10 billion by
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2050 (50% more than today!)
All in less developed world (China = India
each ~ 1.5 b)
© T. M. Whitmore
Reasons for concern II:
Dietary transitions
• Moving up on the food chain
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Traditional diets => ~2400 kcal; 10%
animal
Improved diets => ~3000 kcal; 25%
animal
Increased animal fraction => 4-5 times
more animal feed (plant material) needs
to be produced
Overall need ~ 2x current harvest to get
improved diet by 2050 for everyone
© T. M. Whitmore
Reasons for concern III:
Changes in agriculture
• Increases in pollution, erosion, and
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decreases in water availability
potentially =>
Slow growth or even decrease
Already slowing rates of growth of grain
production per capita
© T. M. Whitmore
Can we raise Output?
4 major areas of concern
1. Photosynthesis and crop productivity
limits
2. Land, water, and nutrient (NPK) limits
3. Agroecosystems and biodiversity
4. Environmental change
© T. M. Whitmore
1) Photosynthesis & crop productivity
limits
• There is an energetic limit:
Photosynthesis is < 5% efficient in
converting sunlight to vegetative matter
(even less if water or nutrients are short)
One way to address this is to improve the
harvest index (= edible part/total biomass)
This is an area of possible progress
 traditional wheat 20 - 30%
 green revolution wheat 35 - 50%
© T. M. Whitmore
1) Photosynthesis & crop productivity
limits
• There is an energetic limit:
Photosynthesis is < 5% efficient in
converting sunlight to vegetative matter
(even less if water or nutrients are short)
One way to address this is to improve the
harvest index (= edible part/total biomass)
This is an area of possible progress
 traditional wheat 20 - 30%
 green revolution wheat 35 - 50%
© T. M. Whitmore
2) Land & soil limits I
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Agricultural land limits
~ 1.5 giga (109) ha now cultivated and 1.6
giga ha (rainfed) potentially usable
Most area available for expansion in S.S.
Africa & S. America savanna
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2) Land limits II
Land needed per-capita
Traditional vegetarian diet =>
 0.7-0.8 ha /capita
Chinese diet (2800 kcal; 15% animal)
 ~ 1.1 ha/capita
Rich Western diet
 ~ 4.0 ha/capita (much wasted and high
meat fraction)
Better diet with some animal protein
 ~ 1.5-3.0 ha/capita
if 10 b people in 2050 =>
 need 800 million ha to 3 gig ha (3000
© T. M. Whitmore
million)
2) Land limits III
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If 10 b people in 2050 =>
Need 800 million ha to 3 gig ha (now use 1.5
gig ha)
Thus, no absolute limit due to amount of land
if diet not excessive & all available land used –
AND food can be moved from surplus areas to
deficit areas
Regionally per-capita land availability is more
problematic for 2050
OK in Latin America
Adequate in Sub-Saharan Africa & Mid-East
Problematic in South & East Asia
© T. M. Whitmore
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2) Water limits I
Water: – in most systems water is the most
important limit most years
Photosynthesis uses/needs lots of water
also add evaporation and transpiration
250 - 500 mm water needed per ha for lowyielding crops
800 - 1000 mm water needed by high
yielding crops
Current irrigation
~ 250 million ha (only 8 m ha in 1800)
~ 17% of all agriculture land
Creates 40% of all food
© T. M. Whitmore
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2) Water limits II
Current Water Use
Currently 5-7% of all available fresh water
runoff used for agriculture
Even if water use only grew to match
population =>
 by 2050 agriculture will need 1/3 of all
available fresh water
© T. M. Whitmore
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2) Water limits III
Crop and animal water use efficiency
Small grains and pulses =>
 0.25 m3 of water /million joules energy to
humans (or about 1 liter per kcal)
Animals via grain and feed =>
 25.4 m3 water/m joules energy to humans
(100x more!) or ~ 100 liters per kcal
© T. M. Whitmore
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2) Water limits IV
Water use in diets
Vegetarian diet (2500 kcal/day) =>
 0.9m – 1.2 million liters/capita/year
Rich world diets (more kcal and more animal
foods) =>
 >> 2.0 m l/capita/year
Improved diets (more kcal and more animal
foods than traditional vegetarian) =>
 ~ 2 million l/capita/year
So – 10 b people =>
 20,000 m3 water or ~ 2/3 of ALL global
runoff (assumes 2000 m3/capita/yr)
© T. M. Whitmore
Demographic Transition Model
Nutrition Patterns
1 & 2
Nutrition
Patterns 3, 4, & 5
Nutrition Patterns 1 & 2
Nutrition Patterns 3, 4, & 5
New York Times
New York Times
Stages of Health, Nutritional, and Demographic
Change
Demographic Transition
Epidemiologic Transition
Nutrition Transition
High
fertility/mortality
High prevalence
infectious disease
High prevalence
undernutrition
Reduced mortality,
changing age structure
Receding pestilence, poor
environmental conditions
Receding famine
Focus on family planning,
infectious disease control
Reduced fertility,
aging
Focus on healthy aging
spatial redistribution
2
3
Focus on famine
alleviation/prevention
Chronic diseases
predominate
Diet-related
noncommmucable
diseases predominate
Focus on medical intervention, policy
initiatives, behavioral change
Source: Popkin, Barry M. ( 2002) Public Health Nutrition 5:93-103.
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Stages of the Nutrition Transition
Urbanization, economic growth, technological changes for work, leisure,
& food processing, mass media growth
Pattern 3
Receding Famine
• starchy, low variety,
low fat,high fiber
• labor-intensive
work/leisure
MCH deficiencies,
weaning disease,
stunting
Slow mortality decline
Pattern 4
Degenerative Disease
• increased fat, sugar,
processed foods
• shift in technology of
work and leisure
obesity emerges,
bone density problems
accelerated life expectancy,
shift to increased DR-NCD,
increased disability period
Source: Popkin, Barry M. ( 2002) Public Health Nutrition 5:93-103.
Pattern 5
Behavioral Change
• reduced fat, increased
fruit, veg,CHO,fiber
• replace sedentarianism
with purposeful changes
in recreation, other activity
reduced body fatness,
improved bone health
extended health aging,
reduced DR-NCD
700
600
500
400
Average daily caloric intake of added fats and sugars in the USA
300
200
100
0
1965
1970
1975
1980
1985
1990
Source: Source: USDA/Economic Research Service
1995
2000
2005
2010
4,500
Average caloric intake in USA: 1909-2004
4,000
3,500
3,000
2,500
1900
1920
1940
1960
1980
2000
Source: USDA/Center for Nutrition Policy and Promotion, March 3, 2006
160
140
120
100
Average per capita daily calories (net) from fruits and vegetables in US
80
60
40
20
0
1965
1970
1975
1980
1985
1990
1995
2000
2005
2010
250
200
150
Average daily calorie intake of red meat and chicken in USA
100
50
0
1965
1970
1975
1980
1985
1990
Source: Source: USDA/Economic Research Service
1995
2000
2005
2010