Unit 1: Proteins Flashcards
What are proteins?
Proteins are the most diverse of all macromolecules serving numerous physical, chemical, and functional roles
Amino Acids
building blocks of proteins used to maintain bodily homeostasis via numerous mechanisms and pathways
Essential amino acids
must be consumed within the diet as the body cannot produce them internally at sufficient levels
Non-essential amino acids
can be produced internally to meet homeostatic needs and therefore do not need to be consumed in the diet
Conditional amino acids
need to be consumed during specific times during the lifespan (e.g., infancy) or in response to specific additional stresses (e.g., disease
Includes cysteine, glutamine, arginine, glycine, proline, serine and tyrosine
Functional amino acids
mixture of essential and non-essential amino acids known to promote optimized health, performance, and function due to the roles they fulfill
What are the functional amino acids?
- Arginine
- Glutamine
- Leucine
- Tryptophan
- Cysteine
- Glutamate
- Proline
What do function amino acids regulate?
protein synthesis, gene expression, cell signaling, nutrient transport/metabolism, immune responses, reproduction, antioxidant defense, hormone secretion, neurological functions, digestion, recovery from injury, blood flow, etc.
Protein Turnover
Constant protein synthesis and degradation occurs within the body in a process referred to as protein turnover – serves to maintain the health and function of all tissues
Protein synthesis
process of new protein creation or building of tissues in response to signaling stimuli such as nutrition or exercise
Proteins and anabolism?
Exercise greatly stimulates protein synthesis in muscle cells with timely intake of protein/amino acids post-exercise (anabolism)
Proteins and catabolism?
Without protein intake net balance will be negative (catabolism)
Branched chain amino acids (BCAA)
includes leucine, isoleucine and valine; are critical for triggering protein synthesis and account for a large portion of the free amino acid pool in muscle
BCAAs, and especially leucine, are recommended post-exercise for optimized protein synthesis
Protein degradation or proteolysis
breakdown of amino acids to create energy, produce a different type of amino acid based on need, limit unhealthy tissue decay or serve another homeostatic function
Transamination
conversion of an amino acid into a new amino acid following breakdown
Reverse Transamination
Reverse transamination occurs to create NEAAs in the body
How is nitrogen created during protein turnover cleared from the body?
Amino acids are broken down into ammonia, which the liver converts into urea, and mobilized by the kidneys in urine; this cycle clears nitrogen created during protein turnover
Complete protein
includes all of the essential amino acids and is therefore optimal for reducing the risk for deficiencies; includes meat, poultry, fish, soy, quinoa, and seafood
Incomplete protein
missing one or more essential amino acids and should be combined with other proteins to minimize the risk for a deficiency; includes beans, legumes, grains, nuts, vegetables, and fruits
Complementary proteins
sources that are incomplete when consumed in isolation but when appropriately combined provide all of the essential amino acids
Examples of complete proteins
animal based: meat, poultry, dairy. eggs, fish
Incomplete Proteins
plant based: vegetables, grains, legumes/beans, nuts/seeds
Complementary Proteins
Grains and legumes/vegetables, nuts/seeds and vegetables/legumes
Milk proteins
whey and casein possess a high leucine content, high bioavailability
Casein breaks down slower and is optimal before sleep to limit overnight catabolism, whey digests quicker and is useful pre/post-exercise
Egg protein
albumen is rich in easily-digestible amino acids including leucine and valine
High bioavailability makes a great source for anabolism among athletes – each egg white contains 4-6 g protein
Meat protein
beef and pork are rich in EAA including leucine, iron, creatine and vitamins; useful for inducing anabolism and hypertrophy but fat content must be considered
Soy protein
soybean is an attractive alternative to animal sources, contains less leucine than milk proteins
Complete protein, rich in BCAAs, useful for vegan/vegetarians and lactose intolerance, provides phytochemicals and fiber
Physiologic/metabolic responses to protein quality
- absorption-digesitbility
- metabolic utilization
- nitrogen balance
- lean mass/muscle/bone
- tissue turnover
- secretory proteins
- host defense/immunity
- growth and maturation
- tissue repair
Short-term outcomes of protein quality
- growth and tissue repair (wasting and stunting)
- immune function and host defense system (prevalence and severity of infection)
- muscle and skeletal mass capacity for physical work and athletic performance)
- mental performances, mood, sleep patterns
- detoxication of chemical agents and antioxidant systems
Long-term outcomes of protein quality
- life course events, linear growth, menarche, aging
- age-related functional losses, muscle, bone strength, immunity, cognitive decline
- nutrition-related chronic diseases. Cardiovasular disease, cancer, hypertension, oxidative damage, repair systems
How should protein intake be calculated?
Protein intake should be calculated in grams per kilogram of body weight per day (g/kg/day) - percentage of calories does not account for actual need
What is the best amount of protein intake for athletes? (for performance and recovery)
For athletes, protein intake above the recommended dietary allowance (RDA) 0.8 g/kg given to the general population will best support performance and recovery
Is protein quality, dosage, and timing important for intake?
yes
How much more protein intake than the RDA has been shown to be useful during periods of energy restriction for weight loss?
3x; Some research has shown protein intake 3x that of the RDA to be useful during periods of energy restriction for weight loss
What does protein above the RDA of 0.8 g/kg/BW seem beneficial for?
- maintaining muscle mass
- attenuating hunger via improved satiety
- improving body composition
- improving recovery
