Epidemiologi Medicin 6'8' semester Fedme og diabetes

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Epidemiologi Medicin6.-8. semesterFedme og
diabetes
Lektor Henrik Friis, læge, PhD Afdeling for
Epidemiologi, Institut for Folkesundhedsvidenskab
h.friis_at_pubhealth.ku.dk
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Epidemiologic transition theory

• A complex of development transitions
• Economy, nutrition, epidemiologic and demography
• Stages and models
• Pleasant Island a natural experiment
• Practical theories
• Thrifty genotype and antagonistic pleiotropy
• Thrifty phenotype Barkers theory
• The global obesity and diabetes pandemic

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Development transitions

• Economy transition
• Hunter-gatherer ? Agricultural ? Industrial
• Hard physical work ? sedentary life style
• Nutrition transition
• Nutrient-dense ? cereal-based ? high fat-energy
  diet
• Epidemiologic transition
• Famine/pestilence ? chronic diseases
• Demographic transition
• High mortality/fertility ? low mortality/fertility
  

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Stages of transition

• Age of pestilence and famine
• High mortality and fertility
• Life expectancy low (lt40 yrs)
• Age of receding epidemics
• Lower mortality
• Life expectancy increasing (30-55 yrs)
• Age of degenerative and man-made diseases
• Lower mortality, fertility critical to population
  dynamics
• Life expectancy high (70)
• Omran A, 1982

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Models of transition

• Classical western countries
• Socio-economic and sanitary improvements
• Not health care improvements
• Delayed developing countries
• Health care little socio-economic -
  improvements
• Less decline in fertility population growth
• Accelerated Japan
• Socio-economic, sanitary and health care
  improvements
• Omran A, 1982

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Mortality in New York City
Figure 1
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Nutrition transition
Popkin BM, 2001
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An evolutionary perspectiveon human nutrition
Agriculturalists
Hunters and gatherers - on palaeolithic diet
(99.6)
0.4
2½ mya 2 mya
1 mya 0.
1 mya 0.01-0
Stone tools
Brain expansion
Homo
Origin of
Signs of meat eating
Agriculture
Use of fire
Leaky, 1992
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Palaeolithic diet

• 100 food items
• 1/3 (wt 0.9 kg) animal foods
• Insects, molluscs, seafood, game incl organs and
  bone marrow)
• No dairy products!
• 2/3 (wt 1.6 kg) vegetable foods
• Green leaves, fruits, incl. berries, nuts,
  tubers, legumes
• No cereals!
• Eaton SB, 1996
• Man is genetically adapted to a balanced diet
  with
• high energy-nutrient density, phytochemicals,
  etc.

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Palaeolithic diet
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Third world diet

• Few food items
• Mainly cereals, roots, legumes
• Maize, rice, sorghum, etc
• Cassava, beans
• Little vegetables and fruits
• Rarely animal products

FAO Media Archive, 2002
Ghana rice and beans cooked together
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Third world diet

• Bulky - low energy-nutrient density
• High anti-nutrient content
• Low in content and bioavailability
• vitamin A, iron, zinc, etc
• Example
• 12 months child, 10 kg
• Energy requirements 4000 kJ/d
• Plain porridge 1-2 kJ/g
• Needs 2-4 kg of porridge/day

FAO Media Archive, 2002
Michaelsen Friis, 1998
Ghana child eating rice
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Western diet

• High in fat especially saturated fat
• High in refined carbohydrates
• Low in complex carbohydrates and fiber
• Low in micronutrients and phytochemicals
• More than 70 of our energy from foods
• not available during evolution

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Pleasant Island Nauru a natural experiment
20 km2 80 covered by phosphate rocks 10
arable land 10 populated 5000 inhabitants
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Phosphate deposits
Mining began in 1906
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Nauru Pleasant Island

• Micronesians originating from the Philippines
• Hunter-gatherer community until end of 19th
  century
• fish, shellfish, birds, coconuts, fruits
• starvation common - feast and famine
• fatness a mark of distinction
• Phosphate mining began in 1906
• Labourers were imported, as Nauruans preferred
  working as clerks, merchants and teachers
• Co-operative store established in 1922
• Nauruans could now buy food
• tinned food, navy biscuits, sugar, snacks
• Today, all foods - and water - are imported

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Nauru Pleasant Island
.. the natives live in idleness, driving
expensive cars over the phosphate roads of the
island and watching the labours of others daily
increasing their wealth Commentary, 1938 ..
in the last 30 years the tin-opener has become
the chief tool with which Pacific Islanders feed
themselves, not the digging fork or fish
hook Commentary, 1982
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Transport
In 1922 everybody had a bicycle In 1978 the
5000 inhabitants had more than 2000 motor
vehicles (on 2 km2)
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Thomas Drivsholm Københavns Amts Center for
Sygdomsforbyggelse
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Diabetes
Thomas Drivsholm Københavns Amts Center for
Sygdomsforbyggelse
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Evolutionary modelsof chronic degenerative
diseases

• An evolutionary model is based on the principle
  of natural selection
• Alleles most succesful in securing reproduction
  are maintained in gene pool
• Alleles less succesful in securing reproduction
  are selected against
• Two evolutionary models explain the widespread
  occurence of CDD
• Antagonistic pleiotropy G.C. Williams, 1957
• Thrifty genes hypothesis J.V. Neel, 1962

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Antagonistic pleiotropy theory

• Pleiotropic genes, i.e. genes with multiple
  effects
• Antagonistic pleiotropi, i.e. opposite effects in
  different environments
• alleles with beneficial pre-reproductive effects
  on early survival, growth, maturation and
  reproduction - were retained in the gene pool,
  despite possible detrimental effects at later age
• alleles with beneficial post-reproductive effects
  on disease resistance or longevity were
  selected against, if detrimental pre-reproductive
  effects
• Man is not genetically adapted to a healthy
  post-reproductive life

Williams, 1957
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Thrifty genes hypothesis

• Thrifty genes, i.e. efficient in extracting and
  storing scarce nutrients
• especially fat and other sources of energy
• Advantage in times of shortage
• retained in the gene pool after repetitive cycles
  of feast and famine
• Disadvantage in times of plenty
• obesity and diabetes become widespread

Neel, 1962
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Fetal origin hypothesis(or thrifty phenotype
hypothesis)

• Impaired fetal and infant growth leads to adult
  disease
• impaired glucose tolerance
• diabetes
• hypertension
• ischemic heart disease
• Early malnutrition changes glucose-insulin
  metabolism
• insulin resistance

Barker DJ. Fetal origins of adult disease
strength of effects and biological basis. Int J
Epidemiology 2002 http//ije.oupjournals.org/cgi/r
eprint/31/6/1235.pdf
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Epidemiologic transition
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Obesity in US adults, 1990-2000
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Television viewing and obesity
obese
TV hours per day
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Television viewing and obesity

• Television may increase risk of obesity
• displace physical activity
• consume excessive amounts of energy-dense foods
• adversely affects dietary habits
• US and UK children exposed to 10 food commercials
  per hour

A positive energy balance of 500 kJ per day
produce a 50 kg increase in body weight over 10
years
Ebbeling CB, Lancet, 2002
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Ebbeling CB, Lancet, 2002
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The worlds population in 1950 and 1998
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Global burden of diabetes
WHO, 1998
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The global diabetes epidemic

• Type 1 diabetes
• autoimmune destruction of pancreatic ?-cell
  islets
• still the most common chronic disease in children
  
• lt10 of all diabetes cases
• Type 2 diabetes
• insulin resistance and/or abnormal insulin
  secretion
• part of metabolic syndrome
• (hyperinsulinaemia, dyslipidaemia, hypertension,
  visceral obesity)
• gt90 of all diabetes cases
• increasing in developed and developing countries

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The global diabetes epidemic

• Rural-urban migration ? sedentary lifestyle
• Impaired glucose tolerance ? diabetes (40)
• In developing countries, type 2 diabetes
• occur at younger age
• may occur at all levels of BMI obesity not
  necessary
• progress faster
• infection and renal failure are main causes of
  death
• not CHD or stroke as in developed countries