PROTEIN Flashcards
6 Roles of Proteins
- structure
- transport
- immune function
- contraction
- metabolic regulation
- acid/base balance
2 Impacts of Protein on Health
- low muscle mass has been associated with increased morbidity, poorer quality of life and higher mortality
- low muscle strength was shown to be significant and independent predictor of mortality risk
Protein Intake decreases with
age
Amino Acid Structure
composition - very similar to carbs but has a nitrogen group and a side R group depending on the amino acids
Amino Acids
there are 20 amino acids, each with a different R group
- they are categorised as either essential and non-essential
Essential vs Non-Essential Amino Acids
refers to the diet
essential amino acids cannot be synthesised by the body and must be consumed in the diet
non-essential amino acids can be synthesised from other amino acids via transamination
What are the 3 Branched Chain Amino Acids (BCAAs) and what can they do
Isoleucine
Leucine
Valine
they can all easily cross the blood brain barrier
Leucine
triggers muscle protein synthesis
Protein Classification
Dipeptide - two amino acids joined by a peptide bond
Polypeptide - 20+ chains
Proteins - one or more polypeptides
Protein Structure
Primary - is the amino acid sequence in a chain
Secondary - is determined by the interactions between groups. either helix like DNA or fold
Tertiary - is determined by interaction between the side chains, mangles the chains together
Protein Digestion
Starts in the
Stomach - HCl breaks down the smaller polypeptides
Pancreas - enzymes (trypsin and chymotrypsin) degrade polypeptides to oligopeptides and amino acids
Small Intestine - where most of proteins are absorbed as amino acids. Aminopetidase degrades oligopeptides to peptides and amino acids, which AA and small peptides are transported across the membrane. Peptides are hydrolysed in the cytosol and so enter the circulation
Proteins Once Ingested
The come to an amino acid pool, as we store tiny amount in the blood otherwise we don’t store any. the amino acids are broken down and synthesised throughout this process forever. used in the liver and muscle .
Muscle Mass Maintenance vs Gain
Maintenance - muscle protein synthesis is equal to muscle protein breakdown
Gain - muscle protein synthesis is greater than muscle protein breakdown
what is the most important factor for muscle protein synthesis
exercise
as not matter what you eat you need exercise to stimulate the muscle protein synthesis to gain muscle
Muscle Protein Synthesis
- varies between different dietary protein sources
- depends on post-prandial rise in plasma essential amino acids concentrations
- plasma amino acid concentrations also provide the necessary precursors for protein synthesis rates to increase
- ingesting 20-25g why protein strongly increase muscle protein synthesis rates
Why is bread a primary source of protein when it has low protein
because we eat so much of it
Protein Quality
Complete vs Incomplete proteins
vegetarian’s - digestibility, cells walls of plant proteins and anti-nutritional factors
Complete vs Incomplete Proteins
complete - have all the essential amino acids present in them
incomplete - are deficient in one or more of the EAA
Dietary Protein Quality
Egg/meat/fish/dairy = no limiting amino acid
(has all methionine, lysine, tryptophan and cystein)
Soy - has all but methionine
Corn - doesn’t have lysine and tryptophan
Legumes - only has lysine
Rice and Wheat - have all but no lysine
Complementing Protein
match two sources to get all the EAA \
eg. corn and legumes
PDCAAs
1 = complete protein
Under 1 = incomplete protein
the greater the number the higher the quality
Heat and Protein
impact of heat negatively impacts a foods PDCAAs
Animal vs Plant Proteins
animal sources have higher saturated fat, but plant are more sustainable sources
Protein Type Effect on Muscle Protein Synthesis
Whey (animal) vs Casein (plant)
whey undergoes faster muscle protein synthesis as it has more leucine and empties faster from the stomach (faster rate of absorption)
Absorption of Protein
plant based foods have lower absorbability compared to animal whole foods due to the cell wall that needs to be broken down has a 10% factor
Wheat vs Whey
need to eat nearly double wheat to get the same muscle protein synthesis as whey but not statistically significant
Overall Animal Protein =
higher protein quality and better for building muscle mass
Healthcare Recommendations
replace red meat with plant to decrease CVD and be more sustainable
Protein Intake Recommendations
the more you exercise the more you should consume
Intakes over a day
the best is 4 times with moderate intake around 20g each 4 times for best stimulus for muscle protein stimulus
every 2-3 hrs is important as this is when the synthesis begins to decrease so by eating again stops this
eating before bed increase protein synthesis overnight
Should you consume protein within 30mins after exercise
promotes protein muscle synthesis
Does whole egg or eggs white synthesis better
whole egg as it has more fat
Recovery Amounts
Repair - muscle repair and regeneration
20-30g but others suggest other amount
20-40g area
Recovery Summary
timing and composition depends on every athletes differences
supplement can make this convenient
