nutrition oct 9 module 4

protein and amino acids

in Canada, data suggests that about how much of dietary protein comes from mear, fish, eggs, dairy, and poultry

62%

more than how much percent of canadians consume protein above the amdr

97%

canadas food guide suggests consumption of more plant protein

true

functions of protein

1. provide structure: growth

2. movement: contraction

3. transport : lipoproteins

4. enzymes : digestion

5. hormones : insulin

6. antibodies: protection from infection

7. fluid and electrolyte balance : maintain fluid

8. acid base balance : maintain pH

9. energy: 4 kcal/gram

all amino acid composed of

carbon, hydrogen, oxygen, nitrogen (some contain sulfur)

what makes amino acids differ, considering they all have the same basic structure ?

The presence of different side chains (R groups) attached to the central carbon atom determines the unique properties of each amino acid.

proteins are made up of how many amino acids

20

how many amino acids (indispensable) are essential

9

how many amino acids are non essential (dispensable) amino acids

11

9 essential amino acids : cannot be synthesized by the human body is sufficient amounts, therefore, must be supplied in the diet 

histidine

threonine

valine

tryptophan

isoleucine

leucine

lysine

phenylalanine

methionine

memorize: 

h tv till pm 

watch tv until pm 

conditionally essential aa

an amino acid that is normally non essential, but must. be supplied by the diet in special circumstances

example: PKU (phenylketonuria) 

proteins that may harm certain individuals

PKU (phenylketonuria) PKU is an inherited condition attributed to a defective
gene.
• Aspartame, a sugar substitute, contains phenylalanine.

deamination

removal of the NH2 group

transamination

transfer of nitrogen

deamination and synthesis of a nonessential amino acid

Involves the removal of the NH2 group and the conversion of a keto acid into an amino acid.

given the source of NH3 , the body can make nonessential amino acids from keto acids

Transamination

Once the NH2 group is removed from the amino acid, (or deaminated),
nitrogen is transferred between amino acids and keto acids to produce non- essential amino acids

peptide bond

a covalent bond linking amino acids

example: dipeptide, tripeptide, or polypeptide, oligopeptide (4-9)

this requires a condensation reaction

digestion/absorption of protein

protein (food) —> amino acids —> protein (body)

an enzyme that hydrolyzes a protein is called a …

protease

where does protein digestion start in

the stomach

(reminder cho and fat starts in the mouth)

gastrin triggers the release of hydrochloric acid and pepsinogen.

pepsin is an example of a protease 

protein digestion - small intestine

Smaller polypeptides and aa move to
the SI where they release:
i) Secretin
• Signals the pancreas to release bicarbonate
into the SI to neutralize stomach acid and to
inactivate pepsin
ii) CCK (Cholecystokin)
• Activates enzymes to further breakdown
protein (example: trypsinogen to trypsin)

protein digestion 

proteins need to be completely broken down into amino acids to be absorbed
- Amino acids can be used for energy (N gets excreted), or joined together to form proteins required by the body

protein digestion and food allergies

Food allergies are triggered when a protein from the diet is absorbed without being completely digested.
• People with GI disease are prone to
allergies because their damaged intestines
allow for the absorption of whole proteins.

a rapid severe allergic reaction is called…

anaphylaxis

labelling for allergies 

Food manufacturers are required to clearly
state if a product contains any of the priority
food allergens.
• The 3 ways allergens can appear on the
label:
– Listed in the ingredient list
– Identified in a parenthetical statement
– With use of the word “contains.”

question: Amino Acid supplementation should be part of the athlete’s dietary regimen to build muscle.

false

Arginine shares a transport system with

lysine (essential).

Lysine absorption is impaired due to the large amounts of what taken as a supplement?

arginine

estimated recommended protein requirements: sedentary adults

0.89 g/kg body weight (non atheletes)

estimated recommended protein requirements: moderate endurance athletes 

1.0 g/kg

estimated recommended protein requirements: top elite endurance athletes 

1.6 g/kg

estimated recommended protein requirements: top elite strength athletes 

1.76 g/kg

AMDR for protein

10% to 35%

calculating protein intake

body weight x 2.2 (to convert from pound to kg)

then multiply the kg by the needed g of protein to meet their erpr (estimated recommended protein requirements)

that total number x by 4 kcal/g = x

x divided by entire kcal needed multiplied by 100 = percentage of protein intake

question: Athletes need to increase total kcal, which will increase the total grams of protein

true

question: Athletes do not need to increase the total percentage of protein in the diet

true

question: Excess protein will not be used to
“build” muscle

true

question: protein supplements help build muscles

false

question: muscle work builds muscle, NOT supplements

true

question: Nitrogen balance indicates whether the amount of protein in the body is remaining constant, decreasing, or increasing.

true

nitrogen balance

nitrogen intake = nitrogen output

total body protein does not change 

nitrogen balance

nitrogen intake < nitrogen output 

total body protein decreases 

positive nitrogen balance 

nitrogen intake > nitrogen output 

total body protein increases 

question: if you eat a bunch of protein and have a protein shake later that day, the protein shake will not get absorbed 

true

protein metabolism

protein can be used as an energy source if converted to gluclose via gluconeogenesis

what is gluconeogenesis

making of gluclose from a non-cho source 

some amino acids are converted directly to acetyl CoA ; they are ketogenic and goes directly into what

the Krebs cycle for energy production.

lipogenesis

the process of converting excess carbohydrates or proteins into fatty acids for storage as fat.

how much protein for energy during rest and exercise does the Body use?

very little (less than 5% to 10%

Most amino acids can be used to synthesize glucose;
they are glucogenic. what cycle do they enter?

They can enter the Krebs cycle through gluconeogenesis.

Some amino acids can enter the TCA cycle directly; they are glucogenic.

entering the TCA cycle via specific pathways.

Glucogenic:

An amino acid that can be converted to glucose via gluconeogenesis.

Ketogenic:

an amino acid that can be used to make ketones

question: In order for the body to use amino acids as an energy source, the nitrogen-containing amino group must be removed.

true

if you lose weight on a high protein diet whats happening 

weight loss is often due to water loss rather than fat loss, as high protein diets can lead to increased water excretion.

protein excess over a long period of time 

can result in:

dehydration

kidney function issues

bone health issues

kidney stones

increased risk of heart disease and cancer 

protein deficiency

Protein-energy malnutrition (PEM) is a
term that covers a range of protein
deficiency conditions that may include only
protein deficiency or protein deficiency
plus energy deficiency.
• Kwashiorkor is a pure protein deficiency.
• Marasmus is an energy and protein
deficiency.

protein metabolism

glucose - pyruvate - acetyl CoA - krebs cycle

protein - amino acids - deamination - chos or NH2 

NH2 - NH2 - NH3 - urea 

chos - pyruvate or acetyl CoA , or krebs 

deamination meaning

the process of removing an amino group from an amino acid, converting it to ammonia and a keto acid.

urea synthesis and excretion : 

in the liver, the amino group (NH2) is
removed via deamination.

H is added producing NH3 (ammonia) to
form non-esential aa

Ammonia (NH3) is converted to a less toxic
substance called urea.

Urea is released into the blood.

The kidneys filter urea out of the blood.

Urea is excreted in the urine. (removes Nitrogen)

Urea is synthesized in the liver and excreted by the kidneys in the urine.

during urea synthesis and excretion:
Damaged liver =

blood ammonia

during urea synthesis and excretion:

Damaged kidney =

blood urea

protein quality - complete proteins

Proteins that contain all the essential
amino acids in the same amounts that
humans require
• Highest quality proteins:
• i) ovalbumin - the main protein in eggs
• ii) casein - the main protein in milk
• Others in meat, fish, poultry

protein quality - incomplete proteins

• Lacks one or more of the essential
  amino acids

• most proteins in vegetables and
  grains are incomplete proteins