Recommendations in Nutrition - Homepage — Universiteit Gent

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Transcript Recommendations in Nutrition - Homepage — Universiteit Gent

Lesson 3.1 :
Recommendations in
Nutrition
Evolution of the Human Diet
• At the conclusion of this session you should
have an understanding of:
– the important characteristics of the hunter
gatherer diet and lifestyle
– the impact of the domestication of plants and
animals on the human diet and lifestyle
– the major changes in dietary composition
through human history
– the western diet in evolutionary perspective, and
the health implications
Paleolithic nutrition
• Is this the type of diet for which humans are
genetically programmed?
– the human genome has changed little since
paleolithic times
• Behaviours and preferences which favoured
survival of humans in the past may explain
why diet and lifestyle have evolved as they
have
– maximising energy intake
– minimising energy output
• The therapeutic and preventive potential of
the principles of the hunter gatherer diet (and
lifestyle)
Why study the evolution of the
human diet?
 Insights into:
• health implications of our current diet and
lifestyle
• role of diet in the pathogenesis, prevention
and treatment of a range of diet-related
chronic diseases
– CVD
– type 2 diabetes
– obesity
– cancers
HOW?
• archeological record
– plant analysis, DNA analysis, radiocarbon and
other dating techniques
• surviving hunter gatherer populations
– Australian Aborigines
• subsistence agriculture
• nutrient analyses of edible components of
uncultivated plant foods and nondomesticated animals
• molecular genetics
– wild progenitors of current staple foods
Limitations
• incomplete nature of archeological evidence
– animal remains more robust than plant remains
• large mammal bones most likely to survive
– limitations of dating techniques
• radiocarbon dating to 40,000 yr
• recent hunter gatherers retreated to marginal
locations
– may not be typical of paleolithic times
• PCR techniques - risk of contamination
Key events in human evolution
 Timeline
years b.p.
• Homo Habilis
• Homo Sapiens
• Homo Sapiens Sapiens
• Agriculture
• Industrial revolution
2 million
400,000
100,000
10,000
200
Transition to agriculture
• Paleolithic times
– focus on big game hunting
– over hunting, extinction of large species
• Shift to broader spectrum hunting and
gathering
– small game, fish and shell fish
– more plant food, including seeds
• grinding stones, mortars, pestles
• Agriculture developed in locally rich
locations, eg, Fertile Crescent
The emergence of agriculture
• developed independently in widely separated
locations around the world
• pressure on food supply
– over hunting
– climate change
– population growth
• sedentary communities in rich locales
• role of humans in selecting plants and
animals for domestication and in subsequent
breeding programs
– greater yields
– capacity to support larger populations
Plant and animal breeding
 Plants
 Animals
– already important in
– gregarious, nonthe diet
carnivorous
– selected to increase
– selected to increase
yield and improve
yield and
palatability
manageability
• energy density
• fibre
• starch
• fat
• smaller size
• more fat
• greater milk output
The western diet
• The consequence of human
evolution
–“Land of milk and honey”
–high energy density
–low energy output
The western diet
• The exception in human history
– high energy density
– reduced micronutrient density
– excess available energy
– high in saturated fat
– high in refined CHO, low in fibre
– high n-6/n-3 PUFA ratio
– high Na, low K
The ‘Mediterranean’ diet
• Based on the Cretan diet, 1960’s
• ‘modified fat’ rather than low fat
• high proportion of monounsaturated
fat (olive oil)
• high intake of vegetables and fruit
– vegetables consumed with olive oil
• increases the bioavailability of lipid
soluble phytochemicals such as
carotenoids
• legumes
• fish
• relatively low meat intake
Diet-related diseases of western
lifestyle
• Obesity
• Cardiovascular diseases
–CHD, stroke, hypertension
• Diabetes
• Certain cancers
–colon, prostate, breast
• Osteoporosis
• Non-infective bowel diseases
Evolution of the human diet: two
future scenarios
 Learn from history!
• Incorporate the best
of traditional diets
and cuisines
– hunter gatherer
– Mediterranean
– Asian
– Middle east
• Incorporate other
features of
traditional lifestyles
• Ecological
sustainability
 Continue as before
• More and better
ways of processing
foods
• The illusion of great
variety
• ‘Foodaceuticals’
• Health claims
• Health
consequences
Nutrient composition of wild and
uncultivated nuts
 Wild
– fat
– CHO
– protein
– fiber
 Cultivated
29%
30%
13%
11%
Brand-Miller et al, 1998
– fat
– CHO
– protein
– fiber
59%
7%
17%
7%
Nutrition
 Deficiency Diseases are rare
 Current Problems:
– Excessive Calorie Intake
– Nutrient Imbalance
• Too much of a good thing!!
RDAs
 Recommended Dietary Allowances
– Average amount of nutrients that should
be consumed over time
 2 ways to meet RDA
– Follow 7 Dietary Guidelines
– Follow Food Guide Pyramid
Nutrients
6 Basic Elements:
 Carbohydrates
 Fat
 Protein
 Vitamins
 Minerals
 Water
Calories provided by:
 Carbohydrates (1 gram: 4 calories)
 Fat (1 gram: 9 calories)
 Protein (1 gram: 4 calories)
*1 gram of Alcohol provides 7 calories
(non-nutritive/empty calories)
Recommended % of calories to
obtain from each macronutrient
 Carbohydrates: 50 - 55%
– 45% complex
– 10% simple
 Fat: 25 - 30%
– 10% Monounsaturated
– 10% Polyunsaturated
– <10% Saturated
 Protein: 15 - 20%
Daily Reference Values (DRVs)
 Recommended grams or mg for selected
nutrients
2000 Calorie a day diet:
–
–
–
–
–
–
Fat: 65 grams
Cholesterol: <300 mg
Sodium: <2400 mg
Carbohydrate: 250 - 300 g
Fiber 20 - 30 g
Potassium: 3000 - 3500 mg
Protein
Functions:
 Tissue growth/repair; forms parts of
blood, hormones, enzymes, cell
membranes
Made up of amino acids (approx. 20)
 9 essential amino acids (must be
supplied by foods)
“Complete Protein
 Contains all essential amino acids
 Animal sources (careful with fats)
 Combined plant sources
– Plant proteins are incomplete
– e.g. peanut butter sandwich is a
protein complement
How much protein is necessary?
How much?
 .8 grams per kilogram of body weight
(wt in lbs/2.2)
Excess Protein:
 Converted to fat
 Strains kidneys
 Body excretes calcium
Major Sources
 Meat, poultry, fish, eggs, milk and
milk products, dry beans and peas,
nuts
 Choose low fat sources!
Carbohydrates
 Functions:
– Major source of energy
– Essential for functioning of CNS
Simple Carbohydrates
 Sugars
 Rapidly absorbed
 Major sources: corn syrup, sugar,
honey, "ose" endings
Complex Carbohydrates
*Starch:
 Converts to glucose
 Provides steady energy source
*Glycogen:
Storage form of glucose
Sources
Plant foods:
 Grains
 Tubers (potatoes)
 Legumes (beans and peas)
Fiber
 Part of food that resists digestion
 Insoluble fiber
– Not digested by the body
– Whole grains, wheat bran, skin of fruits &
vegetables
– Aids gastrointestinal function
– Increases bulk in stool & prevents
constipation
– Reduces risk of colon cancer
 Soluble fiber
– Found in grains (oats), fruits, vegetables
– Lowers cholesterol levels
– Prolongs sense of fullness
Fats
Functions:
 insulates
 cushions organs
 carries fat soluble vitamins
 energy source
 raw material for hormones
Negative effects
 Obesity
 Increased cancer risk (breast, colon,
uterus)
 Gall bladder disease
 Coronary disease (elevated cholesterol)
Types of Fats
 Saturated
– mostly animal origin, egg yolks, lard, etc.
 Polyunsaturated
– safflower, corn oil
 Monounsaturated
– canola, olive oil
 Omega-3 Fatty acids
– fish oils from fish not supplements
 *The less saturated the better!
Cholesterol
 Fat-like substance
 Used to form cell membranes,
hormones
 Endogenous and exogenous sources
 Carried by lipoproteins
LDL and HDL
 LDL:
Low density lipoprotein
 Most likely to cause atherosclerosis
 HDL:
High density lipoprotein
 Removes excess cholesterol
Cholesterol Lowering Tips
 To Lower LDL
– Lower saturated fat intake
– Lower dietary cholesterol intake
 To Raise HDL
– Exercise
– Quit smoking
– Moderate alcohol intake
Nicotine
 Contributes to 30% of coronary deaths
 Adversely affects LDL/HDL
 Constricts blood vessels
 Increases oxygen requirement
 Increases blood viscosity
 Linked with osteoporosis
Vitamins
 Organic compounds
 Helpers of bodily processes
 Fat soluble (A,D,E,K)
 Water soluble (B vitamins, C)
– Folate helps prevent neurological birth
defects
 Antioxidants (C, E, beta carotene)
– Destroy free radicals
Minerals
 Inorganic
 7 Major minerals
– calcium, phosphorous, sodium, potassium,
sulfur, sodium, chloride, magnesium
 Trace minerals
– Very small amounts needed
– 14 are essential to good health
– iron, zinc
 Be weary of mineral supplements!
*Calcium and iron: especially important for
women.
Water
 “The forgotten nutrient”
 8-10, 8-ounce glasses per day (minimum)
 Alcohol, caffeine, increases need for H2O
 Functions:
– transport nutrients
– carries away waste
– regulates body temperature
Health Related Fitness
 Cardiorespiratory endurance
– the ability to use oxygen for physical work
 Muscular strength
– ability to exert maximum force against resistance
 Muscular endurance
– ability of a muscle to exert sub-maximal force
repeatedly
 Flexibility
– range of motion at a joint
 Body Composition
– amount of lean vs fat tissue in the body
Aerobic Capacity
 Decreases with age
 Decreases rapidly when training is
discontinued
Benefits of Aerobic Exercise
 Research has proven all of the following
benefits:
–
–
–
–
–
–
Lowers LDL, triglycerides
Raises HDL
Improves body composition
Reduces BP
Platelets less sticky
Improves functioning of CV system
• Stronger heart
• Lowers resting heart rate
Benefits of Aerobic Exercise
–
–
–
–
–
–
–
Helps control diabetes
Strengthens bones
Promotes joint stability
Reduces stress
Improves self-concept
Helps prevent lower back problems
Encourages other positive lifestyle changes
Principles of Conditioning
 Intensity: how vigorous
Karvonen Formula
THR= (MHR-RHR = HRR) X TI% + RHR
MHR= 220-age; HRR= heart rate reserve
 Choose intensity based on fitness level:
Low:
Fair:
Avg:
Good:
Exc.:
60%
65%
70%
75%
80-90%
Daily Routine
 Warm-up
– 5-10 minutes
– Gradually elevate heart rate
– Increase muscle temperature
– Mild stretching
 Exercise component
– 20 to 30 minutes
 Cool-Down
– 5-10 minutes of Light activity
– Returns blood from muscles back to heart for
redistribution
– Aids in removal of metabolic waste products
– No cool down? Possible dizziness, fainting
 Frequency:
How often?
3-5 days per week
 Duration:
20-30 minutes
 Intermittent activity is OK
 Low intensity/longer duration is
better for health enhancement!
Hypertension
 Silent Killer
 No symptoms
 Blood pressure: force exerted against
arterial walls
 Systolic: pressure when heart contracts
 Diastolic: pressure in between beats
Treatment








Weight loss
Smoking cessation
Reduce salt
Reduce alcohol
Potassium and calcium supplementation
Relaxation
Exercise
Medication