The Role of Nutrition in Human Evolution: Highlights and Implications

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The Role of Nutrition in Human EvolutionHighligh
ts and Implications

• Iver Mysterud
• Trial lecture
• Dr.philos. degree
• Department of Biology, University of Oslo
• June 16, 2005

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Hardins figure
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Outline

• Natural diet
• Food and brain growth
• Paleolithic diet
• General
• Health
• Non-Paleolithic diet
• Health
• Grains
• Milk
• Sugar
• Conclusions and advice

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Zoo animal

• What does the good animal keeper do when a zoo
  animal becomes unhealthy or misbehaves?

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Zoo animal

• Recreate the environment to which it is adapted

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What is the natural diet for a lion?

• Carnivore
• Adapted to meat (animal foods)

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What is the natural diet for a moose?

• Herbivore
• Adapted to plant foods

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What is the natural diet for a brown bear?

• Omnivore
• Adapted to both plant and animal foods

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What is the natural diet for a human?

• ?

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What is the natural diet for a human?

• What can an evolutionary perspective offer?

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The main lines of diet adaptation in hominin
evolution

• Insectivore
• Frugivore/Herbivore
• Omnivore

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The importance of meat

• Two important parts of human evolution
• The progressive incorporation of more meat into
  the early human diet
• Going from scavenging to hunting
• Meat provides easy access to the full complement
  of nutrients our body needs
• More closely adapted to a meat based than a plant
  based diet

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Hominin brain size evolution

• How can we explain this?
• The brain is an expensive organ

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A metabolically costly organ

• Brain tissue has 16 times greater energy demands
  per unit weight than muscle tissue

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• How can we explain this brain size expansion?

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Two central questions

• Why did the brain expansion happen?
• What selective pressures lead to a steadily
  larger brain?

• How was it possible to expand it?

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The large human brain

• Much larger brain per body weight than other
  terrestrial mammals
• Still the total (resting) energy demands for the
  human body are no more than for any other mammal
  of the same size
• ?Humans allocate a larger share of their daily
  energy budget to feed their brains
• Brain metabolism in adult humans
• 20-25 of resting energy demands
• 8-10 in other primates
• 3-5 in other (non-primate) mammals

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• How have humans evolved to support the very high
  nutritional needs of our large brains?

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The expensive tissue hypothesis

• Aiello Wheeler 1995
• Both gut and brain are metabolically expensive
• Reduction in gut size may account for the lack of
  increase in resting metabolic rate (RMR) among
  humans and other primates

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The expensive tissue hypothesis

• Severely criticized
• Primates do not have systematically smaller
  gastrointestinal sizes that other non-primate
  mammals
• Energy costs of a large brain are compensated for
  by a reduction in the proportions of most body
  parts rather than by a mere reduction in gut size

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• How have humans evolved to support the very high
  nutritional needs of our large brains?

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Changes in two major domains

• Improvements in dietary quality
• Changes in body composition

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1. Improvements in dietary quality

• Diet quality energetic and/or nutrient density
  of the diet
• Increases in diet quality may result from
• changes in diet composition
• i.e. what you eat
• or
• the ways in which food is modified
• processing, cooking or genetic manipulation

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General primate food pattern

• Small primates
• Low total energy needs but very high energy
  demands per unit mass
• Eat foods that are limited in abundance but high
  in quality

• Large primates
• High total energy needs, but low mass-specific
  costs
• Eat large volumes of widely available, but low in
  nutritional density foods

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• What about humans?

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The exceptional primate

• Humans have higher quality diets than expected
  for a primate of our size
• ? We need to eat less volume of food to get the
  energy and nutrients we require

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Humans in primate perspective

• Bigger brains require better quality diets
• Humans are the extreme example of this.
• The largest relative brain size and the highest
  quality diet relative to body weight
• Brain size expansion during human evolution
• Has necessitated a sufficiently high quality diet
  to support the elevated energy demands

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Evidence from the fossil record

• First major increase in brain size with emergence
  of the genus Homo
• 2.0-1.7 mya

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Teeth and jaws

• Homo erectus was consuming a richer, more
  calorically-dense diet with less low quality
  plant material and more animal foods
• Evidence
• Smaller teeth and jaws, but a bigger body than
  the australopithecines

KNM-ER 3733
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• A dietary change alone cannot explain the
  evolution of large hominin brains, but a
  sufficiently high quality diet was probably
  necessary for supporting the increased energy
  demands of larger brains

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2. Changes in body composition

• Changes in relative proportions of adipose and
  muscle tissue may help accommodate the metabolic
  demands of larger brains
• More fat
• Less muscle

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Humans an under-muscled species

• Relatively low levels of skeletal muscle for a
  primate of our size
• At the same body weight, humans have
  systematically lower levels of muscle mass than
  other primates
• Primates as a group are relatively under-muscled
  compared to other mammals

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Fatter than other mammals

• Brain metabolism is stable
• May not be down-regulated to conserve resources
  during periods of starvation or negative energy
  balance
• How to get enough energy to the brain in infancy,
  at weaning and in early childhood?
• Maintain a larger energy reserve at birth
• Continue to gain body fat after birth

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Percent body fat at birth of 15 mammalian species

• At 15-16 humans have the highest body fat level
• of the 15 species shown

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Improvements in dietary quality with Homo erectus

• Likely resulting from
• More animal foods
• Improved tool technology
• Food sharing associated with a hunting and
  gathering lifeway

• Other improvements
• Use of fire and development of cooking?
• Makes food more digestible
• Provides more usable calories than if the same
  food had been consumed raw

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Alternative brain expansion scenario

• Whatever the changes in meat intake, plants would
  have remained critical, especially during times
  of resource stress
• Calculations
• A diet of raw food could not supply sufficient
  calories for a normal hunter-gatherer lifestyle

Richard W. Wrangham, PhD
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Tubers

• Tubers would have been abundant on the African
  plains 2 mya
• Digging sticks to get access to deeply buried
  tubers
• Controlled use of fires to cook them
• Turns hard-to-digest carbohydrates into sweet,
  easy-to-absorb calories
• ?Evolution of
• large brains
• smaller teeth
• modern limb proportions
• male-female bonding

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Criticisms 1

• No convincing evidence of digging sticks for
  gaining access to tubers

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Criticisms 2

• Would have found evidence of cooking if tubers
  were important in hominin brain expansion

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Criticisms 3

• When did hominins control fire?
• Unquestionable evidence only 250000 years ago

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Conclusion brain expansion

• 1. Improvements in dietary quality
• probably resulted from
• changes in diet composition
• more meat
• combined with
• the ways in which food is modified
• improved food technology
• use of fire and development of cooking
• and
• food sharing

• 2. Changes in body composition
• What happened in the body?
• Increased body fatness
• Reduced muscle mass
• Benefits for brain expansion
• Ready supply of stored energy to feed the brain
• Less muscle and more fat means reduced total
  energy costs of the rest of the body
• Muscle is more metabolically expensive than fat

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2 requirements for brain expansion

• Dietary need of a more concentrated energy source
• Dietary need of enough of the structural building
  blocks
• Fatty acids
• DHA and AA
• Both must simultaneously be accomplished

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• How did our ancestors get enough fatty acids for
  the brain expansion?

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Source of fatty acids 1

• Freshwater fish and invertebrates available at
  land/water interfaces
• Both energy and fatty acids for brain expansion

Michael Crawford, PhD
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Evaluations

• Fish
• A rich source of DHA and AA, but not energy
• Fishing increased later in human evolution
• Plant foods
• Of low energetic density, little or no DHA and AA
• No reliable fossil evidence of cooking
• Subcutaneous fat of large ruminants
• Of high energetic density, with trace amounts of
  DHA and moderate amounts of AA
• Unlikely to have been encountered
• Muscle tissue of large ruminants
• Good sources of AA, but not of DHA or energy
• Marrow of large ruminants
• Concentrated energy, but no DHA and AA
• Brain of large ruminants
• Rich in DHA and AA, moderate energy source
• No single food simultaneously fulfills both of
  these requirements

Lauren Cordain, PhD
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Source of fatty acids 2

• Brains of scavenged sculls
• Main source of DHA and AA
• Marrow from scavenged ruminant longbones
• Main energy source

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Field study from Serengeti, Tanzania

• 260 large herbivore carcasses
• Consumption patterns of large carnivores
• Marrow and head contents the last items to be
  consumed
• Defleshed marrowbones and defleshed heads were
  the items most likely to be abandoned

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• How do we explain the creative explosion in human
  culture 100.000-30.000 ago?

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The cultural/creative explosion at the
Middle/Upper Palaeolithic transition

• Sudden emergence of creativity, religion, war,
  art and perhaps music
• Started 50.000-100.000 years ago
• Not linked to increase in brain size per se
• Better connectivity
• Fatty acids essential

David F. Horrobin, MD, PhD
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The importance of fatty acid metabolism

• Mutations in certain genes before 100000 years
  ago
• Before the spread of humans from Africa
• New biochemical variants related to changes in
  fatty acid metabolism
• The same changes can be identified today in the
  range of high-achieving and disordered
  individuals to be found in the families where
  schizophrenia is present
• Variations in phosopholipid biochemistry are
  responsible both for schizophrenia and our
  humanity

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• Madness, badness, creativity and leadership goes
  together in the same family trees
• In all populations

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• Paleolithic nutrition

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Paleolithic nutrition

• Long history
• Momentum after 1985
• S. Boyd Eaton, MD, and Melvin J. Konner, MD
• Seminal paper in New England Journal of Medicine
• Paleolithic nutrition

S. Boyd Eaton, MD
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• The prevalence in modern societies of many
  chronic diseases is the consequence of a mismatch
  between modern dietary patterns and the type of
  diet that our species evolved to eat as
  prehistoric hunter-gatherers

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• Humans have evolved not to subsist on a single,
  Paleolithic diet, but to be flexible eaters

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Paleolithic nutrition

• Seminal paper from 2000
• 229 hunter-gatherer societies
• 73 obtained 56-65 of the energy from animal
  foods

Loren Cordain, PhD
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Critical decisions for hunter-gatherers

• Get more energy from hunting or gathering than
  the energy expended to obtain it
• Prioritize food choices relative to their energy
  return rate
• Optimal foraging theory
• Data
• Large animals are preferred over small animals
• Animal foods are almost always preferred over
  plant foods
• because of their increased energy yield
• Conclusion
• Whenever and whereever it was ecologically
  possible, hunter-gatherers always preferred
  animal food over plant food
• Also
• No doubt that hunter-gatherers favored the
  fattiest part of the animals they hunted and
  killed

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Paleolithic diet Variations

• Variations due to differences in geography,
  season and glaciations

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Paleolithic diet

• Meat, fish, fowl, vegetables, berries, fruits,
  nuts, roots, insects and seafood
• Approximately 20 more energy
• More nutritious food
• More protein-rich food
• Less carbohydrates (from lt5 E to 40 E)
• High intake of fiber/phytochemicals

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Paleolithic diet Fats

• Fats of high quality
• Between 10 and 80 E
• More long-chain polyunsaturated fatty acids
  C20-C22
• Much lower n-6n-3 ratio
• 1-21 Paleolithic
• 101 USA
• 6-71 Norway?
• 11 optimal?

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What Paleolithic people didnt eat

• Cows milk, cereal grains (after 10 000 BP)
• Table salt (NaCl)
• White sugar (after 1800)
• Potatoes (after 1750)
• Highly processed foods (mostly after 1800)
• Pesticide residues (after 1930), radioactive
  foods (after 1945)
• Artificial/synthetic additives (mostly after
  1950)
• Genetically modified food (since the 1990s)

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• How is human health when eating Paleolithic diet
  and unprocessed foods?

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• What happens when humans start eating a modern
  and processed diet?

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Historical experience of indigenous/traditional
peoples

• No cancer, cardiovascular diseases, type 2
  diabetes or dental caries
• Independent observations of anthropologists,
  physicians, missionaries, explorers, etc.
• E.g. !Kung San people in the Kalahari desert
• Appears as soon as such humans change environment
  and lifestyle, particularly diet

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Nutrition and health among people on traditional
diets in the 1930s

• 14 human groups
• From isolated Irish and Swiss, to Eskimos and
  Africans
• Almost every member enjoyed superb health
• Free of chronic diseases
• Free of dental decay
• Free of mental illness
• Strong, sturdy and attractive
• Produced healthy children with ease

Weston A. Price, D.D.S.
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Comparison groups

• Members of the same racial/ethnic groups who had
  become civilized
• Ate the products of the industrial revolution
• Refined grains
• Canned foods
• Pasturized milk
• Sugar

Weston A. Price, D.D.S.
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Highly valuable data

• Civilized humans in comparison groups
• Infectious disease
• Degenerative illness
• Infertility
• Tooth decay
• Children with
• Crowded an crooked teeth
• Narrow faces
• Deformities of bone structure
• Susceptibility to many medical problems
• Malnutrition affects all human groups in similar
  ways

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Seminole Indians in Everglades (FL) on
traditional (left) or white mans diet
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Adult Melanesians at Kitava

• Tubers, fruits, vegetables, fish and coconuts
• Unaffected by western diet
• No oils, margarine, cereals, sugar and salt

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Adult Melanesians at Kitava

• PhD study 1994
• Apparent absence of
• stroke and heart attacks
• hypertension
• overweight
• malnutrition
• acne

Staffan Lindeberg, MD, PhD
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Paleolithic diet

• A natural point of departure
• Not something which needs to be tested at the
  outset
• This is parsimoneous and compatible with
  evolutionary biology
• Important implications for nutrition science
• Burden of proof

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How well do we tolerate our most important foods
that was not eaten by our Paleolithic ancestors?
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Grains
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From meat-dominated to grain-dominated diet

• Reduction in stature
• Ca. 15 cm in the Middle East 10000 years ago
• Increase in infant mortality
• An increased incidence of infectious diseases
• An increase in iron deficiency anemia
• An increased incidence of osteomalacia and other
  bone mineral disorders
• An increase in the number of dental caries and
  enamel defects

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From meat-dominated to grain-dominated diet
Conclusions

• A general decline in tooth health and general
  health
• Probably caused by a diet dominated by cereal
  grains

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Humanitys double-edged sword

• Cereal grains made it possible to provide enough
  food for an increasing population
• May have been a necessary condition for
  technological and cultural evolution in many
  parts of the world
• Nutritional needs cannot fully be met by grains
• Hypothesis
• Many humans became ill/functioned at a lower
  level as a direct consequence of eating too much
  grains
• Many grain-eaters developed significant dietary
  deficiencies

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Some main problems with cereal grains

• Insufficient content of many key nutrients
• No vitamin A, C, D, K or B12
• Low level of key amino acids, e.g. lysine,
  isoleucine
• Unfavorable n-6n-3 fatty acid ratio (7-181)
• No long-chain unsaturated fatty acids
• Arachidonic acid (AA), EPA, DHA
• Low bioavailability of many vitamins and minerals
• May be contaminated by mycotoxins
• E.g Claviceps, Fusarium
• Contain many antinutrients
• Alpha-amylase inhibitors, lectins, protease
  inhibitors, alkylresorcinols
• May be reduced by ferentation/processing
• High gluten content
• Increased by breeding
• High starch content
• More problematic (higher GI), the higher the
  extraction rate after refining
• Hyperinsulinaemia and insulin resistance
• Insulin mimics in foods
• Lectins in wheat and corn

Loren Cordain, PhD
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Hyperinsulinaemia - the big bad wolf

• Carbohydrate-dominated diets with high glycaemic
  index (GI) ? hyperinsulinemia ? insulin
  resistance
• May lead to
• cancer breasts, prostate, colon/rectum
• acne
• polycystic ovaries
• myopia
• obesity
• type 2 diabetes
• hypertension
• high blood triglycerides
• cardiovascular disease

• High-glycaemic foods is a novel environmental
  factor which humans are not well adapted to
• Tip of the iceberg?

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Gluten -- problematic proteins in grains

• Autoimmune diseases
• Celiac disease, skin problems, type 1 diabetes,
  Sjögrens syndrome and reumatoid arthritis
• Psychopathological diseases
• Epilepsy, autism, schizophrenia and depression
• Norwegian pioneer
• Karl-Ludvig Reichelt

Karl-Ludvig Reichelt, MD
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187 gluten diseases/problems

• Review of research and clinical experience
• Controlled research urgently needed!

• James Braly, MD
• Ron Hoggan, PhD

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Emergence of agriculture

• Middle/Near East
• 10 000 years ago
• 400-500 generations
• Scandinavia, England
• 5 500 years ago
• 220-275 generations

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3 reasons for lack of adaptation to grains as a
staple food

• Too few generations
• Diseases of civilization affect people late in
  life
• Diseases of civilization involve many genes

• Conclusion
• Present-day humans are genetically similar to
  Paleolithic people
• Reasonable assumption

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Milk
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Domestication

• Sheep
• 11000 BP
• Goats and cows
• 10000 BP
• Chemical evidence for dairying
• 6100-5500 BP in Britain
• Residues of dairy fats on pottery

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Milk use an exception

• Only Europeans and some African tribes
• Lactose tolerance in adults
• In populations with a history of dairying
• Co-evolution of dairying and lactose tolerance
  genes
• Fermentation the norm in all cultures

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Casein -- problematic proteins in milk

• Psychopathological diseases
• Epilepsy, autism, schizophrenia and depression
• Norwegian pioneer
• Karl-Ludvig Reichelt

Karl-Ludvig Reichelt, MD
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Why cows milk intolerance in modern European
populations?
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Milk intolerance

• Pasteurization the problem?
• Chemical residues in milk?
• Raw milk better?

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Milk intolerance

• How big is the problem?
• Cause of what diseases?
• Research urgently needed

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Sugar
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Why are we attracted to sugar?

• Proximate mechanism for sweetness
• Ripe fruits and berries
• Useful nutrient content
• Energy substrates, vitamins, minerals,
  antioxidants
• Co-evolution
• Mutually beneficial
• The plants get their seeds spread, we get useful
  nutrients

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In an ever more rapid cultural evolution, the
initial sweetness response became maladaptive
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Sugar consumption

• Any refined sugar intake is new in human
  evolution
• A high intake of refined sugar only for 100 yrs
• Average sugar intake in Norway 43 kg/capita/yr

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The main problems with sugar

• Upsets the hormone balance
• Depletes us of key vitamins and minerals
• Weakens the immune system
• Contributes to
• lifestyle diseases
• behavioral problems
• mental diseases

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Conclusions and advice

• Fatty acids are important for the brain
• Both in the past and today
• Paleodiet as a point of departure
• Not modern foods
• Grains
• Problematic for many
• Milk
• Problematic for many, even people with lactase as
  adults
• Sugar
• Problematic for all, particularly when eaten in
  excess
• Adaptation in local populations?
• Same advice to everybody?
• Individual focus
• Genetic/biochemical individuality
• Organic produce
• Unprocessed foods
• Traditional food preparation techniques
• Fermentation, milk culturing, sprouting, soaking,
  roasting, cureing
• Decide what is healthy

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