1. Structural 2. Transport 3. Enzyme 4. Hormone/neurotransmitter 5. Immune 6. Acid-base balance 7. Fluid balance 8. Energy (4kcal/g) 9. Movement (skeletal muscle)

Protein Intake And Metabolism Flashcards by Kiera Joy

AMDR for 1-3 years of age

45-65% CHO
5-20% protein
30-40% fat

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ADMR for 4-18 yrs

45-65% CHO
10-30% protein
25-35% fat

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ADMR for 19 years and older

45-65% Cho
10-35% protein
20-35% fat

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Practical issues/concerns with using 10-35% of total calories for protein

how would you know what to eat
how much protein to have at one time
would need to calculate energy needs (kcal/day)

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What do most sport dieticians do to calculate AMDR for protein

Use values based on an athletes body weight

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Example: energy needs 2,500 kcal/day, 21 yrs, protein range 250kcal to 875kcal

10%= 250kcal/4kcal per gram = 62.5g/day
35%= 875kcal/4kcal per gram = 218g/day

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9 Protein functions

Structural
Transport
Enzyme
Hormone/neurotransmitter
Immune
Acid-base balance
Fluid balance
Energy (4kcal/g)
Movement (skeletal muscle)

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Structural

Vital constituents of all cells

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Transport proteins

Of various substances in the blood

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Protein for enzymes

Form almost all enzymes in the body

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protein for hormone/neurotransmitters

Formation of insulin, etc

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Protein for immune

Formation of antibodies, etc

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Protein for acid-base balance

Buffering within the blood to maintain optimal pH

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Protein for fluid balance

Exerting osmotic pressure to maintain optimal fluid balance within the body

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What does protein contain

C,H,O and nitrogen

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What does protein digestion enable

Amino acids to enter the “amino acid pool”
- blood, liver, peripheral tissues (i.e. muscle)
- broken down to AAs

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Amino acids in one area are in constant

Equilibrium with another (tightly regulated)

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Upon food digestion, how are proteins degraded

To amino acids by proteases (enzyme) in stomach and small intestine

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What is protein broken down to in stomach

Polypeptides

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What are polypeptides broken down into

Tripeptides, dipeptides, amino acids

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Where does final breakdown to amino acids happen

In small intestine

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Where are the amino acids absorbed

In portal vein and transported to liver
(Liver is critical centre in AA metabolism)

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What is constantly clearing and moving AAs around body

Liver

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How fast amino acids cleared once enter blood

5-10 mins
- certain digested quicker than others

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Rate of digestion of protein is dependent on

Protein type and composition of the meal/snack

Fast absorption protein

Induce a large increase in whole body protein synthesis and oxidation with minimal affect on whole body protein breakdown

Example of fast absorption proteins

Whey or soy protein

Slow absorption protein

Induces a change in whole body protein turnover, small increase in synthesis and oxidation and a large reduction in protein breakdown

Example of slow absorption protein

Casein (e.g., chunks in cottage cheese)

How many amino acids

What is necessary for protein synthesis

All 20 amino acids

How many indispensable amino acids/essential amino acids (EAA)

What kind of AAs cannot be made in body

Indispensable amino acids/essential amino acids (EAA)

3 branches chain amino acids (BCAA) (are also EAAs)

Leucine Isoleucine Valine

What is ‘complete dietary proteins’

Food that contains all 9 EAAs - e.g., meat

Examples of 10-20g protein

2 eggs 3/4 cup Greek yogurt 48 almonds 1 1/2 cup tofu

Plant sources of protein may result

In lower muscle protein synthetic response vs. Animal based protein

Why may animal protein result in lower muscle protein synthetic response

EAA profile (lower leucine content) Lower digestibility

To get the quality of animal based protein what may you have to do with plant sources of protein

Portions may need to be larger

What do you have to do with plant based dairy products

Check label Make sure there is protein, calcium, vit d

What do most nut based dairy products have

Low protein content

Nitrogen balance

Ability of body to retain nitrogen (protein balance) If in balance must be getting enough protein

How to measure nitrogen balance

Dietary input (grams N2/day) = amount excreted - amount consumed matches amount in urine

Negative nitrogen balance

Amount excreted > dietary input

Examples for negative nitrogen balance

Disease state, trauma, over-training Individual is losing muscle protein

Positive nitrogen balance

Retaining protein to support growth and development Dietary input > amount excreted E.g. adults on caloric sufficient diet

How can nitrogen balance usually be maintained

When consuming 0.8 g/kg BW/day of protein in sedentary individuals (RDA)

Nitrogen balance depends on

Adequate protein intake and total energy intake (kcal/day) Need adequate nitrogen and amino acids

A diet deficient in energy (kcal), despite adequate protein will result in

A negative nitrogen balance

How long is protein digestion

Can take several hours Fat, fibre, and protein can slow digestion down

What is the most important metabolic fate of amino acids

Formation of body tissues, hormones, enzymes, antibodies, nucleotides, etc

Why can humans not store amino acids

Due to inability to store excess nitrogen

Since humans do not store AAs what occurs

Process of deamination in liver

Deamination

Nitrogen (amino group) on the amino acid is removed leaving a carbon molecule (alpha-ketoacid) for oxidation

What happens to excess nitrogen

Must be excreted So the liver forms ammonia (NH3) from excess nitrogen

What is pool of AAs in blood broken down into

Nitrogen and carbon residue(alpha keto acid) because of deamination

What does nitrogen become

Urea (excretion)

What happens to carbon residue (alpha ketoacids)

Become CHO Or oxidized for energy

What happens to the nitrogen group that travels to the liver in protein digestion

Gets converted to ammonia (NH3) and then converted to urea then enters kidneys to be excreted in urine

What have increased levels of ammonia been associated with

Fatigue

Glucogenic amino acids

Amino acids that can be used to form glucose via gluconeogenesis

Ketogenic amino acids

Amino acids that are metabolized to acetyl-CoA and can enter the Krebs cycle or be converted to fat and used for energy

What Alamo forms other nitrogen containing compounds

Amino acids

What can liver use nitrogen-containing amino groups from excess AAs for

Combine them with alpha-ketoacids (from fat or CHO metabolism)

When would an athlete need to use protein as a fuel source

Starvation

During low CHO diets and starvation/fasting, crash diets what can happen

Fat and lean tissue can be used to fuel body - when total amounts of CHO/fat/total calories limited

Loss of lean tissue

Loss of strength/endurance, compromised immune/endocrine/musculoskeletal function

When CHO availability is low=

Increased reliance on muscle/body protein stores for energy

If an exercising individual wishes to maintain muscle mass what is essential

To not only have adequate protein for muscle growth but all sufficient CHO, fat and total calories

What do calories from CHO and fat create

A protein sparing effect

Low CHO diet may cause

Muscle protein to be oxidized for energy - muscle - liver (glucose or acetyl-CoA formation)

Exercise may increase

Protein losses - urinary, sweat, gastrointestinal

What happens to protein at rest and exercise

Generally not oxidized to great extent and only contributes to ~5% of energy during exercise

As intensity/duration increases what happens to protein

Increased protein catabolism when muscle glycogen depleted

Although protein ca be incorporated to produced vast amounts of ATP what is problem

Rate of energy production is very slow vs CHO/fat

In later stages of prolonged endurance exercise how much energy does protein supply

Up to 15%

What does an increase in exogenous CHO intake during prolonged endurance exercise create

A muscle protein sparing effect - inhibition of enzymes for protein breakdown

Protein Intake And Metabolism Flashcards

(77 cards)