Download Chapter 1 The Macro-Nutrients This chapter is a review of basic

Chapter 1 The Macro-Nutrients
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This chapter is a review of basic nutrition, with some new twists that provides you with a foundation to
advance your understanding of nutrition
Objectives of Chapter
Carbohydrates, Fats, Proteins
o Know sources (quality and poor); Basic structures; Types; RDA’s; Function (specifically during
exercise); Misconceptions
Carbohydrates
All living cells contain carbs
Primary food source comes from plants
o sugar, starch, fiber
Small amount from animal sources
lactose & glycogen
Smallest units are: glucose, fructose, & galactose
Role of Carbohydrates
Primary energy source for nervous system
o under normal circumstances ONLY fuel
 body has back up system (ketones)
o only structure to NOT need insulin
Primary energy during high intensity exercise (>60% VO2max)
o role in lower intensities as well
o only fuel used anaerobically & aerobically
o lifting, sprinting, high intensity exercise
Protein sparing effect
“Metabolic primer” - “fats burn in flame of carbohydrates”
o w/o adequate carbs, fat can’t be completely metabolized producing “ketones”
Limited stores will deplete quickly
o metabolic needs
o high intensity exercise
o low carb, low energy diets or skipping meals
o Practice/exercise day after day
Should account for 55% of calories
o 4 kcals/gram
Monosaccharide (eval. sugar intake in diet)
Basic unit of all carbohydrates
o only these 3 forms are absorbed
Glucose (dextrose or blood sugar)
o all carbs ultimately converted to this form
o can be formed endogenously (inside body) via amino acids, lactic acid, glycerol through a
process called “gluconeogenesis”
o semi-essential (need approx. 50-100 grams to prevent ketosis)
Galactose - occurs lactating animals
Fructose (levulose) - fruit sugar (sweetest)
o absorbed slower into bloodstream causing less of a rise in blood sugar (lower insulin response)
o slowly converted to glucose by liver after absorption
o may cause gastro-intestinal distress
Fate of Mono-Saccharides
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Disaccharides
2 monosaccharides
o together with monosaccharides (called simple sugars)
o glucose is principle component
Sucrose - most common; glucose & fructose
25% of total caloric intake in U.S. (if carbs need to be reduced it is here)
Lactose - milk, least sweet; glucose & galactose
large % of world pop. lacks “lactase” enzyme needed to breakdown (“lactose intolerant”)
Polysaccharides
Many monosaccharide chains
Classified into plant & animal categories
o “complex carb”
Plant - starch & fiber
Starch - storage form of carbs found in cytoplasm of cell
o energy source for plants
o veg., grains (bread, cereals, pasta, rice), peas, beans, etc.
o most important source of carbs in U.S. diet
consumption has  while simple sugar consumption 
Starches
2 forms of starch
o amount of each determines digestibility & thus insulin response
Amylose - long straight chains; digested slowly
Amylopectin - branched; digested & absorbed quickly
**glycemic index
Glycemic Index vs Glycemic Load
GI – numerical system measuring how quickly blood sugars rise b/c of a particular food
o ≥70 is high; 56-69 medium; ≤55 low
o if need blood sugar to  quickly (during or recovery from exercise, diabetics who are
hypoglycemic) high GI is good.
o if don’t want blood sugar to rise quickly (diabetics, those sensitive to sugars, control hunger
cravings, most of time) low GI is good.
GL –new way to asses impact of carbs
o GI tells us how quickly carbs are absorbed but nothing about total amount of carbs in food
(limited info)
o GL tells us how much total  blood sugars a food causes and how quickly
 ≥ 20 is high; 11-19 medium; ≤10 is low
Example – watermelon has a HIGH GI but a low GL. Not bad in terms of how much it raises total
blood sugar
Common Foods & Their Glycemic Load
Diabetics Should Pay Careful Attention to Foods Affect on Blood Sugar
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Fiber
Structural polysaccharide
o only in plants (cell wall)
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o resists breakdown by digestive enzymes
Cellulose (most common)
Soluble – oats, legumes, fruits
o delays gastric emptying
o creates satiety
o delays small intestine emptying
o lowers serum cholesterol (binds bile)
Insoluble – whole wheat, bran, vegetables
o normalizes transit time through large intestine
 risk of developing GI problems
o absorbs water
o colon cancer
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Fiber (evaluate in project)
Health links (25-30 g/day; 3:1 insoluble to soluble ratio)
 occurrence of obesity
o maybe because of satiety
o good for “snackers”
o May help with diabetes
 *slows rate of carb. digestion/absorption
 may be high in Mg+, improving insulin sensitivity
 hypertension rates
 intestinal disorders/colon cancer
 heart disease rates
 cholesterol levels
Sources: p. 9 (9 servings F/V; 6-10 servings whole grains)
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HMG-CoA reductase
o enzyme responsible for cholesterol synthesis
Inhibiting this enzyme stimulates LDL receptors to uptake cholesterol from blood stream
“Statin” medications work similarly just more potent
Bacteria in large intestine feeding on fiber may  HMG-CoA reductase
Insulin ↑’s HMG-CoA reductase
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Animal Polysaccharides (Glycogen)
Major source of energy during exercise
Muscle glycogen is immediately available
Liver glycogen - broken down to dump glucose into bloodstream which then used by cells
(“glycogenolysis”)
o controlled by “glucagon”
o “insulin” reverses process
Gluconeogenesis production of new glucose from non-carb sources: A.A., glycerol, lactate
Glycogen
Each gram of glycogen stores  2.7 g of water
o weight loss (~ 3 lbs of water weight)
o hydration for exercise
 carbohydrate overloading has potential to double glycogen storage (~ 6 lbs of water
weight)
Overnight fast greatly  liver glycogen (by half) stores causing dehydration
o ~ 1-2 lbs of water weight loss overnight
 affect on morning exercise or practice?
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Misconceptions of Carbohydrate
Carbohydrates cause obesity
Carbohydrates cause diabetes
Carbohydrates cause excessive insulin responses associated with heart disease
Protein intake is more important than carbohydrate intake for athletes
Reducing dietary carb intake allows one to rely more on fat, so you will burn more fat during exercise &
lose more fat weight
Eating carbohydrates makes you hungry
Energy & Carbohydrate Requirements
Resting energy expenditure
o Teenage Females (12.2 x kg) + 746
o Teenage Males (17.5 x kg) + 651
o College Females (14.7 x kg) + 496
o College Males (15.3 x kg) + 659
Activity factor b/t 1.3 - 2.1
o 1.3 – sedentary
o 1.6 – light exercise
o 1.7 – moderate exercise
o 2.1 – heavy exercise
Three Main Groups of Lipids
Lipid is a general term for a group of compounds insoluble in water
oils, fats, waxes, and related compounds
Three Main Groups of Lipids
o Simple lipids
 Neutral fats – consist primarily of triglycerides
 98% of dietary lipid
 Major storage form of fat in adipose cells
o Compound lipids
 Phospholipids and lipoproteins
o Derived lipids
 Formed from simple and compound lipids
 Fatty acids and steroids (ie cholesterol)
Role of Lipids in Body
Ideal fuel (9 kcals/g)
Primary fuel at rest & light exercise (<50% VO2max)
Protection of organs
Insulation (subcutaneous fat)
Key component creating cell membranes
Transports fat soluble vitamins (A, D, E, K)
Hunger depressor - 3.5 hrs to digest (satiation)
Triglycerides
Major lipid in body (& diet)
o storage form
Glycerol
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Fatty acids
Saturated
 primarily in animal products
 may  cholesterol levels
Unsaturated
 primarily plant sources
Trans-fatty acids (hydrogenation)
o behaves as saturated
Lipids in Diet
Ideal
o <30% fat; but >20%
o <10% saturated
o <300 mg of cholesterol
Essential fatty acids that must be obtained through food
Omega 3’s
o EPA & DHA
 cold water fish
o Linolenic acid
 plants, can be converted to EPA & DHA in body
o structural parts of cells, major part of lipids in brain, nerves, essential for normal growth &
hormones
Evaluate in Project
Essential Fatty Acids
Omega-6 – type of fatty acid Linoleic acid is a part of
o vegetable oils, seeds, nuts, wheat germ & whole grains
Omega-3 – includes Linolenic acid, EPA, DHA
o fish (cold water): mackerel, salmon, bluefish, mullet, anchovy, herring, lake trout, sardine, *tuna,
nuts (almonds/walnuts) & seeds (flax, mustard, pumpkin)
o important for brain function, heart & immune function, vision,  risk for heart disease
 Lower total serum cholesterol & triglycerides
 Interfere with blood clotting & so interferes with atherogenesis
o smooth muscle relaxation
o blood vessel dilation (blood pressure)
 excessive inflammation
o more likely to be deficient (recommend 10 oz of fish/wk)
Essential Fatty Acids
DRI
o Omega 6 (Linoleic acid)
 5% of total calorie intake (1-2% prevents deficiency)
 Young men: 17 g/day
 Young women: 12 g/day
o Omega 3 (Linolenic acid)
 0.5%-1% of total calorie intake
 Men: 1.6 g/day
 Women: 1.1 g/day
Salmon oil (1 tbsp) 4.4g; Herring 1.5g; Canola oil (tbsp) 1.1g; Shrimp (3oz) 1g; Walnuts (1 tbsp)
.5g; Tuna (3 oz) .25g
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Fish Oil Supplements
Taking fish oil supplements may not be recommended???
o high doses may raise LDL cholesterol
o high omega-3 polyunsaturated fatty acid intake may
 increase bleeding time
 interfere with wound healing
 suppress immune function
Lack other beneficial nutrients found in fish
o iodine & selenium
Often made from fish skins and liver
o may have accumulated toxic concentrations of
 pesticides, heavy metals, such as mercury, other industrial contaminants
Fish oil naturally contains high levels of two of the most potentially toxic vitamins
 Vitamin A & Vitamin D
May be expensive
Compound Lipids
Lipoproteins
o transport lipids in blood
Chylomicrons - carry lipids from small intestine to liver
o also carry fat soluble vitamins A, D, E, K
HDL - carry lipids from cells to liver
o contain greatest amount of protein, least amount of lipid
LDL - carry lipids from liver to cells (most lipid, least protein)
Lipoproteins
Protein
Primarily found in skeletal muscle
Similar to carbs & lipids (carbon, oxygen, & hydrogen), also nitrogen
o amine group (N), carboxyl group & side chain
Amino acids (basic building blocks)
o 20 A.A., 8 essential
o sequence determines function
o held together by peptides bonds
Transamination allows A.A. to be converted to other A.A.
Deamination – removal of nitrogen group in order to use protein for energy, carb or fat formation
Function of Proteins
Enzymes; Antibodies; Transport molecules; Fluid & acid base balance; Hormones; Oxygen carriers
Structural proteins
o building tissues
o tendons, muscles, hair, other tissues
Energy ??
**we DON’T store protein, use it or convert it
Proteins
Complete – contains all essential A.A.
o meat, dairy, fish, poultry, eggs
Biological Value
o completeness for supplying essential amino acids
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Getting all essential A.A. not problem for those regularly eating complete proteins, but..
Incomplete proteins (grains, greens, legumes)
Complementary Proteins
Quality of Protein
Recommended Intake for Protein
RDA = .8 grams/kg: covers 98% of population (~.4 grams/lb)
o 160 lb sedentary person= ~ 64 grams
Includes 25% reserve for differences
Infants, children, pregnant (nursing) higher
Vegetarian needs higher
o must also make sure protein is complete or complementary
What about athletes?
1.2-1.8 grams/kg (.5-.8 grams/lb)
o 160 athlete = ~ 80 – 130 grams
>2 grams/kg waste (>1 grams/lb waste = 160 grams)
Role of Protein as Energy Source
Anabolic – build up muscle
Catabolic – break down muscle
o rest 2-5% of energy comes from muscle catabolism
o exercise can be up 10-15% in high intensity long duration
o deamination*
o urea – dehydration*
Nitrogen balance
o Positive – N+ intake exceeds excretion
o Negative – N+ excretion exceeds intake
Protein Energy Malnutrition
Alanine-Glucose Cycle