Nutrition 02/10/2015©Cardiff University /SONMS/Nutrition/CSAN.

Nutrition

21/04/23 ©Cardiff University /SONMS/Nutrition/CSAN


FOOD for EnergyLearning Outcomes:

• Explain the fate of macronutrients in the body• Describe the route for absorption of macronutrients

State the• major forms of Macronutrients• optimal form & intake of carbohydrate• optimal form & intake of Fat• optimal form & intake of Protein• major forms of water intake• major forms of water loss


FOOD for Energy

• Nutrients: Biologically active substances made up of millions of Atoms

• They dissolve in water, making a chemical soup that our body can absorb


Macronutrients

• Water

• Carbohydrates

• Lipids

• Proteins


Organic compounds-5 major groups:

1) Carbohydrates

2) Lipids (Fats)

3) Amino Acids and Proteins

4) Nucleotides and Nucleic Acids

5) Complex organic molecules, often of some of the above e.g. lipoproteins


Macronutrients their fate in the bodyProteinsProteins

Polypeptides

Tri-peptides

Di-peptides

Amino acids

FatFat

Glycerol and fatty acids

• Small and Small and long chain long chain fatty acidsfatty acids

CarbohydratesCarbohydrates

Polysaccharides

Disaccharides Sucrose Maltose Lactose

Monosaccharides Glucose Fructose Galactose


Absorption of these foods- Small bowel


Energy production from food

With Oxygen- Aerobic

Carbohydrate to

Glucose molecule

2 Pyruvate molecules

4 Acetyl CoA Molecules

Without Oxygen-Anaerobic

Carbohydrate to

Glucose molecule

2 Pyruvate molecules

Lactate

16 times MORE energy 16 times LESS energy


Carbohydrates

• Western diets: 40 to 50% of total calories as carbohydrates, generally in the form of fruits, grains, and vegetables,

• More sugar is taken in the form of sweets (simple sugars). This is common and harmful.

• The primary fuel for Brain activity is Glucose– The brain can switch to fatty acid supplies for fuel,

particularly after a period of starvation • (approx. 8 days)


Three kinds of Carbohydrates: • Polysaccharides (Poly = many)

– (three or more simple sugars - forming• starch, fibre & the large animal glucose, glycogen

• Oligosaccharides (several) – Mostly Disaccharides (D1= 2)– (sugars such as sucrose, lactose, & maltose);

• Monosaccharides (mono= 1)– (sugars such as glucose and fructose)


How we ABSORB Carbohydrate

• Formula cnhnon

where n = the number e.g. Glucose contains a six-carbon

chain:C6H12O6This is small enough for us to absorb through cell gate mechanisms This

needs Insulin - more of this later

Carbon OxygenHydrogen

Simple sugars are chains (3 to 7in length) of carbon atoms with hydrogen & oxygen in the ratio of 2 to 1.


Energy for exerciseDuring exercise Muscles use Glucose

• Where can muscle cells find glucose?– In the cells But this soon runs out

• Where next?– In the blood plasma

• But this also runs out and so the body needs to store energy for such times. What is the store GLYCOGEN


GLYCOGEN

•As blood Glucose is lowered to around 35% of its normal value (approx. 5mmols/l)

increasing amounts of GLYCOGEN is broken down for use


Glycogen stores

• Muscle tissue

• The liver• Energy to sustain high levels of

aerobic exercise comes liver glycogen: Broken down during the exercise

How do athletes prepare for this?


What is Glycogen• It is mostly made from conversion of

plant sources of carbohydrate from our daily diet.

• What happen if this runs out?

• Individuals who undertake heavy exercise should consume about 60% of their daily calories as carbohydrates (that’s 400 to 600 g)

• We should advice unrefined carbohydrates - more of this later.


CLASSIFICATION - recap The basic sugar unit = saccharide.Classified according to the Number of units

1 sugar unit = Monosaccharide

2 sugar units = Disaccharide

Many sugar units = Polysaccharide


TERMINOLOGY -recap

• Di and Tri saccharides are also called Oligosaccharides. (Oligo = ‘Few’)

• The suffix (ending) OSE commonly used is the to indicate a Carbohydrate i.e.:

Glucose Cellulose Fructose etc.


Carbohydrates POLYSACCHARIDESTwo main divisions:• a Structural Polysaccharides e.g.

Cellulose, Chitin, Lignin (wood)• b Storage Polysaccharides e.g.

Starch, Glycogen Properties:

1 Non sweet tasting

2 Non truly soluble in H2O3 Do not form crystals


Storage polysaccharides

Starch: Granules in a large variety of plant cells

in all parts of the plant

especially:• Leaves• Endodermis (tissue)

= Starch sheath in both roots & stems • Roots - CORTEX of the roots


Storage polysaccharides GLYCOGEN (Animal Starch Molecular Formula

(C6H10O5)n)Many glucose molecules linked together

to from chains

Location in Mammals• Brain Cells • Liver Cells (hepatocytes)• Muscle Cells


Hormonal role in Homeostatic blood sugar regulation

Insulin from beta cells of islets of Langerhan (in the pancreas)

Glucagon from Alpha cells if islets of

Langerhan(in the pancreas)

More of this later

Glucagon converts GLYCOGEN to glucose

Driven by INSULIN to Glycogen(cells)

Glucose(in plasma)


DISACCHARIDE sources • Sucrose-

– sugar beet/cane & in variable amounts from fruit & vegetables

• Hydrolysed to form Fructose & Glucose

• Lactose-– milk

• Hydrolysed to Glucose & Galactose

• Maltose– wheat & barley

• Hydrolysed to form 2 Glucose molecules


Monosaccharide sources for the body

• Fructose

• Glucose &

• Galactose


MONOSACCHARIDES are building blocks of Carbohydrate’s

Monosaccharides:

1 Sweet tasting

2 Soluble in water

3 Form crystals


Polysaccharide recap Starch, Fibre = plant typesGlycogen = Animal type.

Glycogen is stored within the body as Potential energy: The average adult contains enough to power a 20-mile

run.

During exercise, glycogen becomes the major source of carbohydrate (Glycogenolysis).

Vegetable polysaccharides are converted to glucose & glycogen maintain supply of glucose for energy &

glycogen in the body.


Carbohydrate & Brain function

– Glucose = the fuel for the central nervous

– Hypoglycaemia produces hunger, dizziness, anxiety, tachycardia, tiredness, irritability and weakness & conversion to fat based energy sources takes time

– Blood glucose levels


Importance of carbohydrates

Protein may be used as an energy source (gluconeogenesis) if

carbohydrates are not available.

Vegetable carbohydrate breakdown also

helps to efficiently breakdown fat without the accumulation of ketones


Why are these food so interchangeable as energy sources?

Carbon, Oxygen, Hydrogen and Nitrogen are the primary structural units for most of the biologically active substances in the body.

Specific combinations of: Carbon with Oxygen and Hydrogen form carbohydrates and lipids.

With the addition of Nitrogen, they also form proteins


Dietary Fibre.

• The typical Western diet contains a daily fibre in take of about 12 g, whereas diets in Africa and India range between 40 and 150 g per day).

Dietary fibre intake requirement • 20 to 35 g per day (ratio of 3:1 for water-

insoluble to soluble fibre)


Rationale for Fibre intake It bulks food in the small intestine, increasing stool weight and volume by 40%- 100%.

•Scrapes cells of the gut wall- cleaning

•Binds/dilutes harmful chemicals

•Shortens transit time for the passage of food residues through the the digestive tract


Fibre slows carbohydrate digestion

• Carbohydrate is absorbed into the bloodstream more slowly from the intestine.

• Fibre decreases the total number of calories that will be consumed in subsequent meals by creating a greater sense of fullness.


Glucose- the essential fuel• The adult brain requires 140 g Glucose per

day• Red blood cells require 40 g per day• The body can make 130 g per day

Therefore the absolute minimum requirement of glucose per day is 50 grams.

Hypoglycaemia produces hunger, dizziness, anxiety, tachycardia, tiredness, irritability &

weakness


Lipids (Fats)Fat adds flavour, texture, & appeal to foods.

Fat tastes good! For athletes, it is an important fuel & consuming fat helps meet daily energy requirements.

Fat carries fat-soluble vitamins Dietary fat supplies essential fatty acids (linoleic & linolenic).

A daily fat intake of 1g/kg BW/day is more than adequate to meet dietary needs.


Types of Lipids in the body•Lipids are non-polar (no electrical charge)•Lipids are insoluble in water

Digestion transforms lipids into fatty acids + glycerol.

Recombined, fatty acids & glycerol form:•Triglycerides a mixture of fatty acids & glycerol

•Phospholipds – same but phosphate is added

•Cholesterol –has no fatty acids but makes up Steroid Hormones which act like fat e.g. all are hydrophobic )

•Free fatty acid molecules long or short chain

•Prostaglandins types of fatty acids


Daily Fat Requirements

• Consuming even low levels of fat will met this requirement. In general, a daily fat intake of 1g/kg BW/day is more than adequate to meet dietary needs.

• Example 70 Kg person maximum lipid intake should be 70 grams/day


Saturated or Unsaturated Fatty Acid

• Unsaturated fatty acids generally come in liquid form

• Saturated fatty acids hold the maximum amount of hydrogen ions as possible -


Fatty acids - saturated or unsaturated.

Those with one single bond linking carbons together are known as saturated:

H H H H OH H - C - C - C - C - C = O

SATURATED

H H H H

Chains with at least one double bond in the chain are unsaturated.

H H H H H H OHC = C - C - C = C - C - C = O

UNSATURATED H H H


FAT (lipid) Sources Unsaturated fatty acids

• Monounsaturated or Polyunsaturated. predominantly from plant sources

• Monounsaturated are Olive oils and peanut oils

• Polyunsaturated oils are safflower, soybean, sunflower and corn oil


Modifying Unsaturated fats • Generally, liquids• Hydrogenation solidifies them,

– (Hydrogen gas reduces the double bonding in an unsaturated fatty acid to a single bond)

• This firms fat, as more hydrogen ions cling to the carbon chains.

• The hardening of the fat helps it behave more like butter but softer.


Lipoproteins & health

• High-density lipo-proteins (HDL) is considered to have a high amount of protein to fat.

• Low-density lipo-proteins (LDL) is considered to have a high amount of fat compared to protein)


Fish oils & health• Tuna, sardines mackerel & herring

contain Polyunsaturated fatty acids, belonging to the OMEGA-3 group.

• As a Polyunsaturated Fatty Acid, this is beneficial in reducing cholesterol & may also reduce blood clotting


Sources of Fatty AcidsSaturated fatty acids:

Beef, lamb, pork, chicken, egg yolk, dairy fats, coconut oil and palm oil.

Unsaturated fatty acids :

mostly from plant sources.

Polyunsaturated fatty acids are contained in soybean oil and corn oil.


Burning FatFat is a highly concentrated energy source

It is the body's primary fuel at rest & low intensity physical activity.

• Muscle tissue burns (oxidises) fat.

• High fat oxidation occurs during aerobic exercise, – this spares muscle glycogen. – Aerobic training improves fat use as a fuel

source -


Activity & FAT

- Source of the energy to support rapid cellular repair & active lifestyles.

• linoleic and linolenic acid are essential for growth & must be supplied by food because the body can’t make them


Amino Acids & Proteins• Proteins in foods supply amino acids

from which the body makes its own proteins.

• The body needs 20 amino acids • Non-essential amino acids are those that

the body can synthesise and need not be taken in the diet.

• There are 8 amino acids that the body does not seem to be able to manufacture & these must be taken in the diet.


Sources of Protein

• Protein from

• other animals

• milk,

• eggs,

• grains ,

• legumes &

• vegetables


Breaking Protein down-

• Enzymes

break protein down into smaller chains,

- from polypeptides to smaller chains

e.g. Tri and Di peptides & eventually to

amino acids.


Protein Shapes • Protein (Polypeptide) chains twist into

a variety of complex & tangled shapes.

• Shapes have unique chemical character : either attracting or repelling amino acids or fluids.

• Some carry electrical charges that attract water(hydrophilic) – other parts of the same chain may be

neutral & repel water (hydrophobic)


Protein FunctionsDifferent shapes allow for different functions• Some are hollow balls that can hold

substances

• Some are very long and thin and can form rod like structure (as in tendons)

• Some are functioning proteins in their individual state

• Others need to associated with other chains to from a working complex

• Some require minerals to activate them


Particular Functions• Structural Proteins

- Collagen- fibrous protein -gives strength to tissue e.g. tendons & ligaments

- Keratin- outer layer of the skin-epidermis- water proofs the skin

• Receptors – for particular molecules e.g. hormones

• Carriers- transport of molecules across cell membrane

• Antibodies- part of our defence mechanism• Enzymes - very varied function • Hormones - very varied function


Losing their shape & their function• Heat

• Acid

• Certain other conditions serve to denature proteins

• They uncoil, lose shape and function


Amino Acids• The base units of proteins

– Amino acids consist of two compounds

Amino Radical compound & Organic Acid compound

• They contain– at least one amino radical and one

organic acid


Amino Acid Structure

• The amino radical is two Hydrogen atoms and one Nitrogen atom

• = NH2

• The organic acid = 1 Carbon atom , 2 Oxygen atoms and 1 Hydrogen atom

• = COOH


Nucleic Acids & Nucleotides

Formed from amino acids

Nucleotides are sub units of Nucleic acids

DNA is made up of 4 Nucleic acids arranged to form a DNA blue print for life


Complex Organic MoleculesProtein Non protein Function

Haemoglobin Polypeptide Haem pigmentCarries O2

chainsMyoglobin “ Haem pigment Stores O2 in

muscle

Blood group “ Carbohydrate Produces Blood

Proteins types

Lipoproteins “ Lipids Transports lipids in blood

Hydrogen, Nitrogen, Carbon and Oxygen form bonds to define shape and function


Protein

• Sustains growth, maintenance & repair.

• Provides nitrogen; responsible for the role of amino acids, nucleic acids, proteins, co-enzymes.

• Provides energy when glycogen is diminished; gluconeogenesis is generated from protein.

However, a by-product from protein breakdown is nitrogen and the kidney has to work harder to excrete this.


Water- the indispensable nutrient

Its structure makes it a super solvent for most organic compounds, except for lipids & hydrocarbons

H OH

negative charge O HH positive charge

= a polar molecule


Water In The BodyWater makes up 50-70% of body weight depending on how much fat is presentWater Fat85% - pre term baby 1%70% - full term baby & infant 15%65% - child 15%60 % - young adult 20%45 % - elderly adult 10%


Body Fluids INSIDE CELLS

Water is the medium for all chemical reactions in the cell

OUTSIDE CELLSExtracellular Fluid• Transport & Communication - Nutrients, Metabolites,

Heat, Gases, Hormones, Waste products( Cell to cell & Cell to Environment)

• Lubrication • Cooling (sweating) involves losing water• Excretion (urine) involves losing water


Water Balance • All cells lose Water and Shrink if

body water is lost via e.g. sweating

–Intake• Solid food 1 litre per day

• Metabolic water 0.3 litres per day

• Drinks 1 Litre or more per day depending on

voluntary intake

• Regulate according to losses


Water BalanceOutput• Evaporation 1 litre per day at rest

from skin & lungs

• Sweating up to 15 litres per day may be secreted by sweat

glands to get rid of heat• Faeces Normally 0.11 litre per day• Urine as much as can carry the days

soluble waste products As rule Intake should balance output


Key Terms• Metabolism is the sum total of all chemical

reactions (using enzymes to speed up chemical processes) within the cell

• Metabolism enables the cell to convert some of the energy found in nutrients to a from that support cell work

• Glucose is the key molecule for action

• Glycogenolysis (GLYCO-GEN-OL-ISIS) is the process of reconverting glycogen to glucose

• Gluconeogenesis (GLUCO-NEO-GENESIS) refers to the process of glucose synthesis, especially from protein sources (but also fat).


Food Group Serving SizeBread-1 slice bread, 1 ounce ready to eat cereal, 1\2 cup cereal, rice or pasta, or 5-6 small crackers Vegetable--1 cup raw, leafy vegetables, 1\2 cup cooked or chopped raw vegetables or 3\4 cup vegetable juice Fruit--1 medium piece of fruit e.g. apple or 3\4 cup fruit juice Milk--1 cup milk or yoghurt, 11\2 ounces natural cheese or 2 ounces process cheese Meat--2 - 3 ounces cooked lean meat, poultry or fish (about the size of a deck of cards) Other foods which count as 1 ounce meat: 1\2 cup cooked dry beans, 1 egg, 2 tablespoons peanut butter or 1\3 cup nuts (Cup = tea cup size)

Fruit Vegetables2-4 servings 3-5 servings

The Eating Right Pyramid adapted fromMcArdle & Katch 1993

Cheese Cheese Poultry Poultry yoghurt, fish, eggs’yoghurt, fish, eggs’2-3 servings 2-3 ervings2-3 servings 2-3 ervings

FatsFats oils, oils,

sugarsugar sparinglysparingly

Grains - bread, cereal, pasta, rice Grains - bread, cereal, pasta, rice 6 - 10 servings6 - 10 servings


The Food PYRAMID

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Nutrition 02/10/2015©Cardiff University /SONMS/Nutrition/CSAN.

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