Macronutrients

Unit 2: Applying the principles of nutrition to a physical activity programme

Session

Aims

To understand the principles of nutrition in relation to the macronutrients

Learning Objectives

By the end of the session the learner will

• be able to describe the function and metabolism of macronutrients

• be able to explain the main food groups and the nutrients they contribute to the diet

• be able to explain the relationship between nutrition, physical activity, body composition and health including:

• links to disease/disease risk factors• cholesterol• types of fat in the diet

Protein

The structure of protein:

• proteins are made from molecules or building blocks called

amino acids

• there are 20 amino acids available from the natural diet

• the body uses these amino acids to build and repair the many proteins from which we are comprised

Peptides

Free amino acid

Dipeptide

Oligopeptide

Polypeptide

Amino Acids

Essential amino acids • these are the 9 amino acids which the body is unable to

synthesise it’s self

Amino Acid

HistidineIsoleucineLeucineLysine

MethioninePhenylalanine

ThreonineValine

Tryptophan

Amino Acids

Non - essential amino acids • these are the 11 amino acids which the is able to synthesize

when sufficient essentials are ingested

Conditionally essential amino acids

Glycine Alanine Tyrosine Serine Cysteine Proline

Glutamic acid Glutamine Aspartic acid Asparagine Arginine

Complete proteins

• these are protein foods which contain all 9 essential amino acids in sufficient amounts

Complete proteins

Animal sources

Non-animal sources

eggs meat poultry dairy fish

soy foods buckwheat quinoa

Incomplete Proteins

• these are always plant foods

• plant foods are mostly made from carbohydrate however, they also contain some amino acids and therefore, protein

• These are deficient in one or more amino acidse.g. beans or pulses are deficient in methionine

• plant foods therefore, have a lower biological availability

Complementing Proteins

Combining suitable incomplete protein foods together in the diet can provide the full range of essential amino acids

Rice and pulses

Vegetables and seeds

Vegetables and nuts

Grains and pulses

Protein Task

Identify from the following list which foods are complete proteins and which are incomplete proteins

egg lentils mackerel

soy beans cheese oats

chick peas beef tofu

liver olives buck wheat

Protein: Functions

Proteins have 3 basic functions in the human body

Structural – collagen, muscle, skin

Homeostatic – hormones, immunity

Fuel - back up to carbohydrates and fats

Protein: Catabolism

• described as the breaking down of large structures into smaller structures

• an example is the breakdown of a protein into individual amino acids

SS

SS

Protein Amino acids

Catabolism

Protein: Anabolism

Described as a building up of smaller structures into larger structures

Amino Acids

Amino acids used to repair muscle

Amino acids used to build other key proteins

Protein Requirements Task

How much? Depends on activity levels/type and body size

Determine your grams of protein per kilogram of bodyweight

RDA sedentary adult : 0.8

Recreational exerciser 0.8 -1.5

Endurance athlete: 1.2 - 1.6

Teenage athlete 1.5 - 2.0

Adult building muscle mass 1.5 - 1.7

Estimated upper limit 2.0

Carbohydrates Structure

monosaccharide

‘Single sugar’

Fructose

Galactose

Glucose

=Sucrose Fructose + Glucose

=Galactose + GlucoseLactose

Maltose =Glucose + Glucose

disaccharide

‘double sugar’

They consist of a glucose molecule joined to another saccharide

Carbohydrates Structure

Monosaccharides and disaccharides

simple sugars

Fruit - healthy option

• natural produce with sugars packaged within

• contain vitamins and minerals assist metabolise the CHO as energy

• contain fibre

Sources - Simple Sugars

Monosaccharides and disaccharides

simple sugars

Unhealthy sources of refined sugar

• white refined sugar added

• no vitamins or minerals to utilise the energy

• lack fibre

• anti-nutrient: draws on nutrient stores to metabolise food

Sources - Simple Sugars

Complex Carbohydrates

Starch

Larger molecules made comprising of the monosaccharides

Glucose

Fructose

Galactose

Multiple molecules of glucose are called polysaccharides

Sources of unrefined carbohydrate Properties

• wholemeal or whole grain products• whole grain rice• frozen vegetables• fresh vegetables• sweet potatoes• yams• pulses• quinoa

• source of energy• good source of dietary fibre• good source of vitamins and minerals• slower, sustained insulin response

Sources of refined carbohydrate Properties

• white bread• white pasta• cakes, biscuits and pastries• rice cakes• CHO content of processed foods• white rice

• source of energy• deficient in dietary fibre• largely stripped of their vitamin and

mineral content• produces faster insulin response

CHO Task

Identify which of the following foods contain simple or complex carbohydrates

Additionally identify which are refined or unrefined foods

wholemeal bread maple syrup mango

honey French fries lentils

pasta ice cream doughnut

chocolate cornflour banana

Fibre

Definition:

Fibre is indigestible plant material or the parts of unrefined carbohydrate foods which we are unable to digest as we lack the necessary enzymes

Soluble fibre

• dissolve in water• found in the inside of the

plant

• fruit• broccoli• pulses• oats• barley

Fibre

Fibre

Insoluble fibre

• does not dissolve in water• found in the outer skin of

plants or fruits

• fruit skins• veg skins• outer coating of grains

Fats: Key Functions• formation of virtually all cell membranes

• formation of myelin sheath within the nervous system

• synthesis of steroid hormones

• assists in the regulation of enzymes

• insulation through subcutaneous adipose tissue

• protection of internal organs

• transportation, storage and utilisation of fat soluble vitamins A, D, E, K

• fuel source during lower intensity work loads

• storage of energy within the adipose tissue

Triglycerides

This is the type of chemical structure most fats exist in naturally

TriglyceridesG

lyce

rol

Fatty acids occur

naturally in groups of

three

A triglyceride is simply three fatty acids attached to a carbohydrate back bone called glycerol

Saturated fats can pack closely together and are hard at room temperature

Saturated Fat

Saturated fat

Saturated fat Saturated fat

Saturated fat

Saturated fat Saturated fat

Saturated fat

What are naturally occurring sources of fat?

Common sources of saturated fat

Animal Non animal

meat – beef, pork, lamb, venison poultry – chicken, duck dairy – milk, cheese, yoghurt, cream, butter eggs

palm oil coconut oil

Saturated Fat

Some Functions of Saturated Fat

• effective immune function

• protects the liver from alcohol, pesticides and other toxins

• provision of energy

• antimicrobial properties – fight harmful micro-organisms in our digestive tract

Unsaturated Fats

• carbon chain is not completely full of hydrogen atoms

• these ‘gaps’ in the chain make the fatty acids more able to react

• a double bond causes a bend in the molecule

UNSATURATED FATTY ACID

Double bond

Monounsaturated Fats

• have a single double bond in the carbon chain – one bend

• liquid oils at room temperature

Sources:

Peanut oil

Rapeseed oil(LEAR)

Olive oil

Avocado oil

Monounsaturated Fats

• have many health promoting benefits for the body

• helps to keep arteries clean and free from plaques

Polyunsaturated Fats

• several double bonds along the carbon chain – several bends in the molecule

• different shapes again mean different functions

POLYUNSATURATED FATTY ACID

Double bond

Double bond

Polyunsaturated Fats

• several double bonds along the carbon chain – several bends in the molecule

• different shapes again mean different functions

Sources:

Sunflower oil Vegetable oil Safflower oil Corn oil

Soya bean oil Rapeseed oil(original seed)

Essential Fatty Acids

All EFA’s are polyunsaturates!!

The name ‘essential can be misleading!!

Implies we need this more than other fats

EFA’s are vital, but only in small amounts for good health

Essential Fatty Acids

• must be ingested in the diet - we cannot synthesize them

• categorised as:

Omega 3 Omega 6

Cod liver oil

Linseeds Organic eggs

Sunflower oil Vegetable oil

Safflower oil Corn oil

Identify from the following list the dominant type of fat found in each food product and in those that are polyunsaturated whether it is omega 6 or omega 3 dominant

chicken butter flaxseed

herring olive oil margarine

pork vegetable oil coconut

salmon beef peanuts

Fats Task

• sunflower or vegetable margarines are solid at room temperature!

• manufacturers change the properties and consistency of oils to increase marketability

Margarines

Hydrogenation

Oils with catalyst subjected to hydrogen gas in a high-

pressure, high-temperature reactor.

Oils mixed with a nickel

catalyst

Oils, now rancid, steam cleaned to remove all vitamins & anti-oxidants (but pesticides

and solvents remain!)

Soy beans, corn, cottonseed or

rapeseeds

Remaining fraction of oils removed with hexane and

other solvents

Oils extracted by high temperature & pressure

Soap-like emulsifiers mixed

in

Oil steam cleaned again to remove horrible odour

Gray colour removed by bleaching

Advertising promotes margarine

as a health food

Mixture is packaged in blocks

or tubs

Artificial flavours, synthetic vitamins and natural colour

added

Saturated Fatty Acid

Unsaturated Fatty Acid

Hydrogenation

Hydrogen attachesat the double bond

When fully hydrogenated the molecule becomes a straight saturated fatty acid

Hydrogenation

• oils are only partially hydrogenated, so that some fatty acids remain unsaturated

• this allows them to still market it as a polyunsaturated spread!

Trans Fats

• during hydrogenation, the double bonds not saturated by hydrogen are still affected

• a hydrogen atom flips to the opposite side of the double bond altering the molecular shape

Straight, unsaturated fatty acid!!

Natural fats contain maximum of 2% trans fatty acids

Hydrogenated oils may contain up to 50 – 60% trans fatty acids

Trans Fats

• linked to a deterioration in blood lipids profiles and heart disease

• implicated in increased insulin resistance – type 2 diabetes

• implicated in causing cancer, obesity and bone loss

Trans Fats

Sources:

• 80% of all hydrogenated oils are Soy

• biscuits and cakes

• sweet and savoury sauces and syrups

• pies and pastries

• take away meals

• boxed meals and TV dinners

• ice creams

Cholesterol

Cholesterol

Membrane formation

Steroid hormones

Bile saltsVitamin D

Synthesis75-80%

Diet20-25%

Lipoproteins

• liver is the control centre for fats - it can increase or decrease cholesterol synthesis according to needs

TG

Chol / TG

VLDL

Chol

LDL

‘mops up’HDL

Adipose

Cells

Cholesterol Levels

• total cholesterol will be measured

healthy < 5.0healthy upper limit 5.2

• identify LDL and HDL count

Healthy HDL at least 25%

Learning Check

Can the learner

• describe the function and metabolism of macronutrients

• explain the main food groups and the nutrients they contribute to the diet

• explain the relationship between nutrition, physical activity, body composition and health including:

• links to disease/disease risk factors• cholesterol• types of fat in the diet