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 non-domesticated 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 2 million

• Homo Sapiens 400,000

• Homo Sapiens Sapiens 100,000

• Agriculture 10,000

• Industrial revolution 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– already important in

the diet– selected to increase

yield and improve palatability

• energy density• fibre• starch• fat

Animals– gregarious, non-

carnivorous– selected to increase

yield and manageability

• 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 29%

– CHO 30%

– protein13%

– fiber 11%

Cultivated – fat 59%

– CHO 7%

– protein17%

– fiber 7%

Brand-Miller et al, 1998

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

ProteinFunctions: 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: 60%Fair: 65%Avg: 70%Good: 75%Exc.: 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