Protein Flashcards
What are the functions of protein
Digestive enzymes help facilitate chemical reactions
Antibodies support immune function
Regulation and expression of dna and rna
Support muscle contraction and movement
Provide support for the body
Move essential molecules around the body
Coordinate bodily functions
How many calories per gram of protein
4 / 17kj
What are proteins
Large molecules made up of amino acids
Amino acids are links of peptide bonds which form polypeptide chains
What is an amino acid
Consists of a central carbon bound to the following four components
- hydrogen
- nitrogen containing amino group
- a carboxylic acid group
- an r group or side chain which makes each amino acid unique
What are the two classifications of amino acids
Essential - indispensable = cannon be synthesises by the human body so adequate dietary intake is needed
Non essential- dispensable =
Can be synthesised by the human body
What is the third classification of amino acids
Conditionally indispensable
- body cannot produce is sufficient quantities, e.g when ill
List the indispensable amino acids
Histidine
Isoleucine
Leucine
Lysine
Methionine
Phenylalanine
Tryptophan
Valine
List the dispensable amino acids
Alanine
Aspartic acid
Asparagine
Glutamic acid
Serine
List the conditionally indispensable amino acids
Arginine
Cysteine
Glutamine
Glycine
Proline
Tyrosine
How are proteins broken down
Mouth - mechanical
Stomach - hydrochloric acid denatures proteins (unfolding 3D structures to reveal polypeptide chains)
+ enzymatic digestion by pepsin forms shorter polypeptides
Small intestine (main site)
- digestion by pancreatic enzymes (trypsin and chyme trypsin) + proteases
= form tri/dipeptides and individual amino acids
Intestinal lining
- tri and di broken found into individual amino acids Intestinal
What is the reference nutrient intake for adults
0.75/kg per day
56/45
Which populations need more protein
Children
Pregnant and feeding
Athletes
Older adults
What are the two types of protein deficiency
Kwashiorkor
Marasmus
What are the features of kwashiorkor
Caused byProtein deficiency
6mo to 3 years
Subcutaneous fat preserved
Odema present
Enlarged fatty liver
Mild muscle wastage
Fluid retention and swelling
What are the features of marasmus
Caused by protein and energy deficiency
Less than 1y old
Subcutaneous fat not preserved
Oedema absent
No fatty liver
Servers muscle wastage
What are the risks of excessive protein intake
Over 2g/kg
Decreased bone health, increased calcium secretion
Kidneys strained due to filtering excess nitrogen
Liver: overburdened metabolism
Heart disease and cancer
What is protein quality
How many amino acids are present in a biologically visible format
Dependent on proportion of protein derived aas from digestion and absorption process
What is a high quality or complete protein
Provide adequate amounts of all 9 essential AAs
What are the high quality protein sources
Animal proteins
Soy
Myoprotein
What is protein complementation
Combining incomplete protein sources to provide all 9 AAs
What are the three elements of protein quality and sorting
Amino acid composition
Digest ability of indispensable amino acids
Human requirement of indispensable amino acids
What are the two methods of protein quality sorting
DIASS (new) digestible indispensable aa score - amino acids Human requirement quality of food proteins based on ileal digest ability
PDCASS - based of of faecal digestion
Protein digest ability corrected AA score
What animals do each protein quality sorting method use
DIASS pigs
PDCAAS rats
Why is DIAAS better than PDCAAS
Look at quality in ileum, more representative as Dosent have gut microbiome interactions added yet, rather than in stool
PDCAAS can underestimate high quality proteins, can’t score higher than 1
Why is PDCAAS still widely used
Not all food sources have been used for DIAAS
What are limitations of both protein sorting methods
Result in different digest-ability scores
Only measure 1g of protein, don’t coincided larger quantities, mixed meals or blending proteins
What is the largest reservoir for amino acids
Skeletal muscle
What is muscle protein turnover
- Muscle protein synthesis- building new muscle protein
- Muscle protein breakdown - degradation of muscle proteins
+ anabolic stimuli, protein ingestion and resistance both stimulate MPS
Explain muscle protein metabolism in younger vs older
Older adults have less muscle building synthesis in response to anabolic stimuli
What is sarcopenia
Biological aging process, loss skeletal muscle
Reduced mobility, independence, reality, metabolic adaptation to illness and disease, mortality
- effect 45% of over 60s
- reduced anabolic stimulus muscle adaptation
- muscle dispersed with fatty tissue
Explain anabolic resistance in older adults
Reduced ability to synthesise muscle in response to anabolic stimuli
Need more protein for same stimulus response
Breakdown may outweigh synthesis
How can sarcopenia be minimised in older adults
Protein, constant training
Dairy, calcium for bones and potassium for muscle function
Dexa scan, ricotta cheese group more lean mass
What are the protein requirements for older adults
1-1.2 g
1.2-1.5g if ill
What are the pros of animal derived protein
- high quality and essential amino acids
- highly digestible
- micronutrient intake
What are the cons of animal protein
- red and processed meat = risk colorectal cancer
- greenhouse gases and nitrogen pollution
- heart disease
What is eat lancet
Links diet, human health, and environmental
What does eat lancet recommend
Less animal protein
Plant protein
Mycoprotein, complete
What is biomass fermentation
Used for mycoprotein
Uses the rapid growth of some microorganisms to make large amounts of protein
