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21/01/09 © UWCM/SONMS/Nutrition/MJohn
FOOD for Energy
Learning Outcomes:State the major forms of Macronutrients
State the optimal form & intake of carbohydrate
State the optimal form & intake of Fat
State the optimal form & intake of Protein
State the major forms of water intake
State the major forms of water loss
21/01/09 © UWCM/SONMS/Nutrition/MJohn
FOOD for Energy
• Nutrients are biologically active substances made up of millions of Atoms
• These dissolve in water & this makes the chemical soup that our body can absorb
21/01/09 © UWCM/SONMS/Nutrition/MJohn
Macronutrients
• Water
• Carbohydrates
• Lipids
• Proteins
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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)
21/01/09 © UWCM/SONMS/Nutrition/MJohn
Three kinds of carbohydrates:
• Polysaccharides (Poly = many)– (three or more simple sugars) forming:
• starch, fibre & the large animal glucose, glycogen
• Oligosaccharides (several) – Mostly Disaccharides (Di = 2)– (sugars such as sucrose, lactose, & maltose)
• Monosaccharides (mono= 1)– (sugars such as glucose and fructose)
21/01/09 © UWCM/SONMS/Nutrition/MJohn
How we ABSORB Carbohydrate
• Formula cnhnon
where n = the number e.g. Glucose contains a six-carbon
chain:C6H12O6
This 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 7 in length) of carbon atoms with hydrogen & oxygen in the ratio of 2 to 1.
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
GLYCOGEN
•As blood Glucose is lowered –to around 35% of its normal value (which is approx. 5mmol/L range 4-6 mmol/L)
–Increasing amounts of GLYCOGEN is broken down for use
21/01/09 © UWCM/SONMS/Nutrition/MJohn
Glycogen stores
• Muscle tissue
• The liver• Energy is required to sustain high
levels of aerobic exercise & liver glycogen is broken down during such exercise
• How do athletes prepare for this?
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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 involved in heavy exercise should consume about 60% of their daily calories as carbohydrates (that’s 400 to 600 g) - We should advise unrefined carbohydrates - more of this later.
21/01/09 © UWCM/SONMS/Nutrition/MJohn
CLASSIFICATION - recap –basic sugar unit = saccharide.
–Classified according to the Number of units
–1 sugar unit = Monosaccharide
–2 sugar units = Disaccharide
–Many sugar units = Polysaccharide
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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.
21/01/09 © UWCM/SONMS/Nutrition/MJohn
Carbohydrates POLYSACCHARIDESTwo main divisions:• a Structural Polysaccharides e.g.
Cellulose, Chitin, Lignin (wood)• b Storage Polysaccharides e.g.
Starch, Glycogen Properties:
1 Not sweet tasting
2 Not truly soluble in H2O3 Do not form crystals
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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)
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
Monosaccharide sources for the body
• Fructose
• Glucose &
• Galactose
21/01/09 © UWCM/SONMS/Nutrition/MJohn
MONOSACCHARIDES are building blocks of Carbohydrate’s
Monosaccharides:
1 Sweet tasting
2 Soluble in water
3 Form crystals
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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.
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
Why are these food so interchangeable as energy sources?
Carbon, Hydrogen, Oxygen, 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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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)
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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.
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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.
21/01/09 © UWCM/SONMS/Nutrition/MJohn
Types of Lipids in the body•Lipids are non-polar (no electrical charge)•Lipids are insoluble in water
Digestion transforms lipids into fatty acids and glycerol.
Recombined, fatty acids & glycerol form:•Triglycerides a mixture of fatty acids & glycerol•Phospholipds – same buy 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 a type of fatty acids
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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 -
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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 HChains with at least one double bond in
the chain are unsaturated.
H H H H H H OH H C = C - C - C = C - C - C = O
UNSATURATED H H
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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.
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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)
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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.
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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 -
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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.
21/01/09 © UWCM/SONMS/Nutrition/MJohn
Sources of Protein
• Protein from
• other animals
• milk,
• eggs,
• grains ,
• legumes &
• vegetables
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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.
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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)
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
Losing their shape & their function• Heat
• Acid
• Certain other conditions serve to denature proteins
• They uncoil, lose shape and function
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
Nucleic Acids & Nucleotides
• These are formed from amino acids
• Nucleic acids include large molecules DNA & RNA which carry genetic codes
• Nucleotides are sub units of such nucleic acids
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
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Protein• Protein sustain growth, maintenance & repair.
• Provides nitrogen; responsible for the role of amino acids, nucleic acids, proteins & co-enzymes.
• Provides energyWhen glycogen is diminished; gluconeogenesis can be generated from protein.
A by-product from protein breakdown is nitrogen. The kidney has to work harder to excrete this.
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
Water In The Body• Water makes up 50-70% of body weight -
depending on how much fat is present
Water Fat
85% - pre term baby 1%
70% - full term baby & infant 15%
65% - child 15%
60 % - young adult 20%
45 % - elderly adult 10%
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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).
21/01/09 © UWCM/SONMS/Nutrition/MJohn
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
21/01/09 © UWCM/SONMS/Nutrition/MJohn
The Food PYRAMID