Food and NutritionFood and Nutrition

An IntroductionAn Introduction

Why do we eat?Why do we eat?

Why do we eat?Why do we eat?

Satisfy physiological needsSatisfy physiological needs HabitHabit Social InfluencesSocial Influences Psychological InfluencesPsychological Influences Sensory AppealSensory Appeal

What are our dietary What are our dietary needs?needs?

Meet basic physiological needsMeet basic physiological needs Body functionBody function Maintenance Maintenance Temperature regulationTemperature regulation

GrowthGrowth Physical activityPhysical activity

What should our diet What should our diet contain?contain?

Essential Dietary componentsEssential Dietary components Lipids (fats)Lipids (fats) CarbohydratesCarbohydrates ProteinsProteins VitaminsVitamins MineralsMinerals

DesirableDesirable ColourColour FlavourFlavour

Food ComponentsFood Components

Fats, Proteins and Carbohydrates are sometimes Fats, Proteins and Carbohydrates are sometimes called the “Macro components”called the “Macro components”

They are required in large quantities and form the They are required in large quantities and form the bulk of your foodbulk of your food

Minerals and vitamins are the “Micro Minerals and vitamins are the “Micro components”components”

They are required in small quantities (ranging from a They are required in small quantities (ranging from a few grams to a few milligrams/day)few grams to a few milligrams/day)

They are nevertheless essential to the proper They are nevertheless essential to the proper functioning of the bodyfunctioning of the body

LipidsLipids

Lipids are a diverse group of biomolecules which Lipids are a diverse group of biomolecules which share the property of being insoluble in watershare the property of being insoluble in water

The main classes of lipids areThe main classes of lipids are Oils and fatsOils and fats WaxesWaxes PhospholipdsPhospholipds SteroidsSteroids

All except steroids are based on fatty acids.All except steroids are based on fatty acids.

Oils and FatsOils and Fats

Oils and fats are esters of Fatty acids and glycerolOils and fats are esters of Fatty acids and glycerol Fatty acids comprise a hydrocarbon chain with a Fatty acids comprise a hydrocarbon chain with a

carboxylic acid group (COOH) at one end.carboxylic acid group (COOH) at one end. The hydrocarbon chain length can range from 4 to 22 The hydrocarbon chain length can range from 4 to 22

carbon atoms.carbon atoms. There are two types of fatty acid; saturated and unsaturatedThere are two types of fatty acid; saturated and unsaturated Unsaturated fatty acids have one or more double bonds in Unsaturated fatty acids have one or more double bonds in

their hydrocarbon chaintheir hydrocarbon chain Certain unsaturated fatty acids are essential to our dietCertain unsaturated fatty acids are essential to our diet

CarbohydratesCarbohydrates

Carbohydrates are a major source of energy in Carbohydrates are a major source of energy in our diet and are used in the body as a store of our diet and are used in the body as a store of available energyavailable energy

There are three main categories of carbohydrateThere are three main categories of carbohydrate MonosaccharidesMonosaccharides OligosaccharidesOligosaccharides PolysaccharidesPolysaccharides

MonosaccharidesMonosaccharides

Monosaccharides are the basic building blocks of Monosaccharides are the basic building blocks of carbohydratescarbohydrates

They have the general formula (CHThey have the general formula (CH22O)O)nn

Two common monosaccharides are glucose and Two common monosaccharides are glucose and fructose (fruit sugar)fructose (fruit sugar)

Both have the formula CBoth have the formula C66HH1212OO66

The difference between them is in their structural The difference between them is in their structural arrangementarrangement

OligosaccharidesOligosaccharides

Oligosaccharides are carbohydrates formed from Oligosaccharides are carbohydrates formed from the combination of a few monosaccharide the combination of a few monosaccharide moleculesmolecules

Of these some disaccharides are common. Of these some disaccharides are common. Common examples include;Common examples include;

Sucrose (glucose + fructose)Sucrose (glucose + fructose) Maltose (2 glucose)Maltose (2 glucose) Lactose – milk sugar (glucose + galactose)Lactose – milk sugar (glucose + galactose)

PolysaccharidesPolysaccharides

Polysaccharides comprise a very large number of Polysaccharides comprise a very large number of monosaccharide units combined togethermonosaccharide units combined together

Polysaccharides includePolysaccharides include StarchStarch GlycogenGlycogen CelluloseCellulose

Starch is a energy source of plant origin, glycogen is the Starch is a energy source of plant origin, glycogen is the animal equivalent and is our main internal energy sourceanimal equivalent and is our main internal energy source

Cellulose is a structural polymer found in many plants. Cellulose is a structural polymer found in many plants. Cellulose is a significant component of food, but is not Cellulose is a significant component of food, but is not

digestible by humans.digestible by humans.

NSP or Dietary FibreNSP or Dietary Fibre

NSP; “non-starch polysaccharides” comprises a NSP; “non-starch polysaccharides” comprises a range of complex polysaccharides range of complex polysaccharides

These are not broken down by the digestive These are not broken down by the digestive enzymes in the small intestines, though some are enzymes in the small intestines, though some are broken down by bacteria in the large intestinebroken down by bacteria in the large intestine

A diet high in NSP has beneficial effects on A diet high in NSP has beneficial effects on health particularly protecting against a range of health particularly protecting against a range of chronic bowel disorders. chronic bowel disorders.

CarbohydratesCarbohydrates

Carbohydrates are a major source of energy in Carbohydrates are a major source of energy in our diet and are used in the body as a store of our diet and are used in the body as a store of available energyavailable energy

There are three main categories of carbohydrateThere are three main categories of carbohydrate MonosaccharidesMonosaccharides OligosaccharidesOligosaccharides PolysaccharidesPolysaccharides

MonosaccharidesMonosaccharides

Monosaccharides are the basic building blocks of Monosaccharides are the basic building blocks of carbohydratescarbohydrates

They have the general formula (CHThey have the general formula (CH22O)O)nn

Two common monosaccharides are glucose and Two common monosaccharides are glucose and fructose (fruit sugar)fructose (fruit sugar)

Both have the formula CBoth have the formula C66HH1212OO66

The difference between them is in their structural The difference between them is in their structural arrangementarrangement

OligosaccharidesOligosaccharides

Oligosaccharides are carbohydrates formed from Oligosaccharides are carbohydrates formed from the combination of a few monosaccharide the combination of a few monosaccharide moleculesmolecules

Of these some disaccharides are common. Of these some disaccharides are common. Common examples include;Common examples include;

Sucrose (glucose + fructose)Sucrose (glucose + fructose) Maltose (2 glucose)Maltose (2 glucose) Lactose – milk sugar (glucose + galactose)Lactose – milk sugar (glucose + galactose)

PolysaccharidesPolysaccharides

Polysaccharides comprise a very large number of Polysaccharides comprise a very large number of monosaccharide units combined togethermonosaccharide units combined together

Polysaccharides includePolysaccharides include StarchStarch GlycogenGlycogen CelluloseCellulose

Starch is a energy source of plant origin, glycogen is the Starch is a energy source of plant origin, glycogen is the animal equivalent and is our main internal energy sourceanimal equivalent and is our main internal energy source

Cellulose is a structural polymer found in many plants. Cellulose is a structural polymer found in many plants. Cellulose is a significant component of food, but is not Cellulose is a significant component of food, but is not

digestible by humans.digestible by humans.

NSP or Dietary FibreNSP or Dietary Fibre

NSP; “non-starch polysaccharides” comprises a NSP; “non-starch polysaccharides” comprises a range of complex polysaccharides range of complex polysaccharides

These are not broken down by the digestive These are not broken down by the digestive enzymes in the small intestines, though some are enzymes in the small intestines, though some are broken down by bacteria in the large intestinebroken down by bacteria in the large intestine

A diet high in NSP has beneficial effects on A diet high in NSP has beneficial effects on health particularly protecting against a range of health particularly protecting against a range of chronic bowel disorders. chronic bowel disorders.

ProteinsProteins

Proteins include the largest and most complex Proteins include the largest and most complex molecules knownmolecules known

They are the main functional component of the They are the main functional component of the bodybody

Proteins may be divided into two main categoriesProteins may be divided into two main categories Structural, e.g. muscle, connective tissueStructural, e.g. muscle, connective tissue Functional, e.g. enzymesFunctional, e.g. enzymes

Proteins are built up from amino acids linked Proteins are built up from amino acids linked together by peptide bondstogether by peptide bonds

Polypeptides and Polypeptides and ProteinsProteins

A chain of amino acids linked via the peptide A chain of amino acids linked via the peptide bond is called a “Polypeptide”bond is called a “Polypeptide”

Proteins are formed from one or more Proteins are formed from one or more polypeptides linked together as a consequence of polypeptides linked together as a consequence of the properties on the “R” groups on the amino the properties on the “R” groups on the amino acidsacids

The structure and properties of proteins is The structure and properties of proteins is dependant on the structure which arises as a dependant on the structure which arises as a result of the folding of the polypeptide chains.result of the folding of the polypeptide chains.

VitaminsVitamins

Low molecular weight organic substancesLow molecular weight organic substances required in small amounts in the diets of higher required in small amounts in the diets of higher

animals for normal growth, maintenance of health, animals for normal growth, maintenance of health, and reproduction.and reproduction.

All animals require vitaminsAll animals require vitamins Not all vitamins are required by all animalsNot all vitamins are required by all animals

e.g. Vitamin Ce.g. Vitamin C

VitaminsVitamins

Heterogeneous group of substancesHeterogeneous group of substances They vary greatly in terms of their:They vary greatly in terms of their:

Chemical nature Chemical nature FunctionFunction

2 Types2 Types Water-solubleWater-soluble Fat-solubleFat-soluble

VitaminsVitamins

Requirements for vitamins differ during growth Requirements for vitamins differ during growth and maturityand maturity

Additional; quantities required under special Additional; quantities required under special circumstance e.g. pregnancy circumstance e.g. pregnancy

Other factorsOther factors inheritanceinheritance microbial flora of the intestinemicrobial flora of the intestine eating habitseating habits

RDA differ between countriesRDA differ between countries

MineralsMinerals

A number of mineral salts and metals are A number of mineral salts and metals are essential to proper functioning of the body.essential to proper functioning of the body.

They perform a variety of functions They perform a variety of functions includingincluding Ion transportIon transport Essential to certain enzymesEssential to certain enzymes

Balanced dietsBalanced diets

A Healthy DietA Healthy Diet

What nutrients are needed What nutrients are needed and in what amounts?and in what amounts?

In practice the majority of people have no idea about the In practice the majority of people have no idea about the actual nutrients they require each day.actual nutrients they require each day.

Nutritionists require more specific informationNutritionists require more specific information Nevertheless, balanced diets should contain appropriate Nevertheless, balanced diets should contain appropriate

amounts of amounts of FatsFats ProteinsProteins CarbohydratesCarbohydrates MineralsMinerals VitaminsVitamins

The problem is what is an “appropriate amount”?The problem is what is an “appropriate amount”?

These are the intakes of nutrients which are required to These are the intakes of nutrients which are required to maintain balance in the bodymaintain balance in the body Amounts needed to reverse deficiencyAmounts needed to reverse deficiency Amounts needed for normal biochemical functionAmounts needed for normal biochemical function

There are three measuresThere are three measures Estimated Average Requirements EAREstimated Average Requirements EAR Reference Nutrient Intake RNI Reference Nutrient Intake RNI

Ensure that he needs of nearly all the group (97.5%) are being metEnsure that he needs of nearly all the group (97.5%) are being met

Lower Reference Nutrient Intake LRNILower Reference Nutrient Intake LRNI The amount of a nutrient that is enough for only the small number The amount of a nutrient that is enough for only the small number

of people that have low requirements (2.5%)of people that have low requirements (2.5%)

Dietary Reference Dietary Reference ValuesValues

Level of requirement

Perce

nta

ge o

f ind

ivid

uals Low High

ERA

Distribution on nutritional Distribution on nutritional requirements in a requirements in a

populationpopulation

LRNI RNI 97.5%

The intakes of nutrients which are required to maintain The intakes of nutrients which are required to maintain balance in the bodybalance in the body Amounts needed to reverse deficiencyAmounts needed to reverse deficiency Amounts needed for normal biochemical functionAmounts needed for normal biochemical function

Amount to provide energy requirementsAmount to provide energy requirements Basal Metabolic RatesBasal Metabolic Rates Physical Activity LevelsPhysical Activity Levels

The ERA is an average so The ERA is an average so 50% of the population will require more and50% of the population will require more and 50% will require less50% will require less

ERA’s and dietERA’s and diet

Eating a balanced dietEating a balanced diet

Enjoy your foodEnjoy your food Eat a variety of different Eat a variety of different

foodsfoods Eat the right amount to be a Eat the right amount to be a

healthy weighthealthy weight Eat plenty of foods rich in Eat plenty of foods rich in

starchstarch

Don’t eat too much fatDon’t eat too much fat Don’t eat sugary foods too Don’t eat sugary foods too

oftenoften Look after the vitamins and Look after the vitamins and

minerals in your foodminerals in your food if you drink, keep within if you drink, keep within

sensible limitssensible limits

MAFF produced Eight guidelines for a MAFF produced Eight guidelines for a healthy diet in 1990healthy diet in 1990

Meal selection guidesMeal selection guides Grouping together foods that provide Grouping together foods that provide

(generally) nutrients, and that may be (generally) nutrients, and that may be interchangeable in the dietinterchangeable in the diet

Making a quantitative statement about the Making a quantitative statement about the number of servings of foods from each group to number of servings of foods from each group to be taken dailybe taken daily

Dietary planningDietary planning

Dietary planning – UK Dietary planning – UK food platefood plate

33%33%

12% 15%8%

AlcoholAlcohol

Men Regular consumption of between 3 and 4 units a day by

men of all ages will not carry significant health risk. Women

Regular consumption of between 2 and 3 units a day by women of all ages will not carry any significant health risk

Dietary planningDietary planning

The guide is concerned with proportions of food The guide is concerned with proportions of food in the diet for the average healthy personin the diet for the average healthy person

Does not take into accountDoes not take into account special dietary needsspecial dietary needs infants and children under 5infants and children under 5 frail elderlyfrail elderly