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What Are Proteins? The word “Protein” comes from the Greek word
proteios, meaning primary. Play arguably the most critical roles in the body The make up of our cells and tissues Found in our:
MusclesBonesHairBoneNailsSkin
20 Percent of our total body weight
Protein Functions
Antibodiesspecialized proteins involved in defending
the body from antigens Contractile Proteins
responsible for movement Enzymes
proteins that facilitate biochemical reactionsreferred to as catalystsex. Lactase and Pepsin
Protein Functions (cont.) Hormonal Proteins
proteins which help to coordinate certain bodily activities
ex. Insulin Structural Proteins
provide supportex. keratin, collagen
Storage Proteinsstore amino acids
Transport Proteins carrier proteins which move molecules ex. hemoglobin
The Structure of Proteins Proteins are polymers of amino acids covalently
linked through peptide bonds into a chain. 20 different amino acids that make up all proteins Amino Acids are composed of a central carbon
atom bonded to:hydrogen carboxyl group amino group unique side chain or R-group
The unique side chains create different chemical properties on amino acids
Protein Digestion
Digested by enzymes called proteases Protein digestion begins in stomach Broken down by pepsin into polypeptides Left over proteins digested by trypsin in
small intestine Polypeptides produced are further
digested to amino acids by erepsin in intestinal juices
End product = Absorbable Amino Acids
Proteins in our Diet Two types of Amino Acids: Essential
8 – cannot be made in sufficient amounts in the body, must be supplied through food
Non-essential12 – can be made from other amino
acids in the diet Foods with animal protein satisfy
the essential amino acid needsMeat, Milk, Eggs, etc.
Vegetable protein sources have less than the necessary amounts
Proteins in our Diet (cont.) 10-15% of total caloric intake
0.75g of protein per kg of body weight per day
2-3 servings of animal protein foods will reach requirements
4-5 servings of vegetable protein sources will reach requirementsWhole grain cereals, legumes, nuts,
vegetables, etc.
Protein Related Health Concerns
High protein diets can lead to: Unpleasant body odour and bad breath Increased risk of high blood fat levels Loss of muscle tissue Risk of deficiency diseases
Excessive animal protein intake has been associated with: Mineral loss - leading to cancer Osteoporosis kidney stones Arthritis Diabetes Cataracts Arteriosclerosis
The average North American should reduce intake by 15% Less animal proteins more vegetable proteins
Protein Related Health Concerns (cont.)
Protein Deficiency:Your body cannot survive without adequate amounts of
protein, a lack of this macronutrient will result in serious health problems
Symptoms: Weight loss, Thinning or brittle hair, hair loss, Skin rashes, dryness, flakiness, General weakness and lethargy, Muscle soreness and weakness, cramps, Slowness in healing, Bedsores and other skin ulcers, Difficulty sleeping, etc.
Risks: Gallstones, Arthritis, Heart problems, Muscle deterioration, Organ failure, Death
An Athlete’s Protein Needs
Athletes require protein to repair/rebuild muscle that is broken down during exercise
Should not be a substitute for carbohydrates
More effective to abide by the “less more often” rule
Average adult requires 0.8g per kg of body weight per day
Strength training athletes need 1.4 - 1.8
Endurance athletes need 1.2 – 1.4
Common Misconceptions: You can not get enough protein on a
vegetarian diet You can only assimilate 30 grams of protein
at one sitting.The body has the ability to digest and assimilate
much more than 30 grams of protein from a single meal.
Protein must be rapidly digested to build muscle.Both rapidly and slowly digested proteins offer
significant benefits to athletes