Lec 2: Protein Flashcards
Hall Paper
Dietary fat restriction results in more body fat loss than carbohydrate restriction in people with obesity
Estimated cumulative fat change (6 days) vs. Predictive modelling (6 months)
Estimated cumulative fat change (6 days)-> difference between fat intake and fat oxidation= obese group had a larger decline in fat
Predictive modelling (6 months)-> there is a difference in favour of reduced fat in obese group, but not as significant as in estimated change
Protein’s roles (8)
-Enzymes
-Transport
-Hormones
-Antibodies/immune system
-Structural and mechanical (actin and myosin contractile elements)
-Channels and pumps
-Fluid balance
-Acid-base balance
Metabolic Fate of Dietary Protein
Body protein degradation, dietary proteins, synthesis of NEAA -> amino acid pool ->
Anabolism -> protein, nitrogenous compounds
or Catabolism -> ketone bodies and fatty acids, urea CO2 and H2O, glucose/glycogen
How many amino acids in humans
20 (9 essential, 11 non-essential)
Essential amino acids
-amino acids the body cannot synthesize
1. Phenylalanine
2. Valine
3. Threonine
4. Tryptophan
5. Isoleucine
6. Methionine
7. Histidine
8. Leucine
9. Lysine
PVT Tim Hall
Branched chain essential amino acids
- Leucine
- Isoleucine
- Valine
Nonessential amino acids
-amino acids the body can synthesize
1. Asparagine
2. Alanine
3. Glutamate
4. Glutamine
5. Cysteine
6. Aspartate
7. Glycine
8. Tyrosine
9. Proline
10. Serine
11. Arginine
Almost All Girls Go Crazy After Getting Taken Prom Shopping +Arginine
Estimated Average Requirement (EAR)
-The daily intake value that is estimated to meet the nutrient requirements of half the healthy individuals in a population
Recommended Dietary Allowance (RDA)
-The daily dietary intake level that is sufficient to meet the nutrient requirements of 97-98% of the healthy individuals in a population (2 standard deviations above the EAR)
Adequate Intake (AI)
-The AI is expected to meet or exceed the needs of most individuals in the population
Tolerable Upper Intake Level (UL)
-The highest daily nutrient intake level likely to pose no risk of adverse health effects to almost all individuals in a population
Dietary reference intakes on a normal distribution graph
-EAR at 1.0 (50%)
-RDA 2 SD above EAR, with AI
-UL maximum amount
RDA for protein
-0.8-0.9g of protein/kg/day in Canada and the U.S. for adults 19+
-current RDA may be insufficient for exercising populations (individual differences)
Skeletal muscle is a critical organ and is linked with… (5)
- Mortality and morbidity
- Diabetes
- Recovery from surgery
- Disability
- Athletic performance
Importance of skeletal muscle in insulin resistance
-skeletal muscle takes up to 80% of glucose from the body
-skeletal muscle is considered the primary whole-body insulin resistance
*Why resistance training is important
Regulation of skeletal muscle mass by nutrition and contractile activity
-amino acids transported into muscle from blood
-protein synthesis occurs in muscle (amino acids get recycled or broken down)
-build muscle by increasing protein synthesis
Feeding and contraction regulate skeletal muscle mass (fasted, fed, resistance training and both)
-at rest= negative energy balance after sleep (fasted losses in muscle protein balance; largest decrease)
-with amino acids= increase muscle protein balance
-with resistance training only= decrease balance
-with resistance training and amino acids= largest increase in balance (increased sensitivity for protein synthesis)
*muscle mass is lost when you decrease protein synthesis (breakdown rate stays relatively stable)
Essential amino acids effect on muscle protein synthesis (+ muscle full effect)
-drive increases in synthesis, but at a certain level more amino acids have no effect
-protein/amino acid feeding transiently elevate rates of synthesis
*muscle full effect: at a certain level of protein intake, the body turns off synthesis (certain genes determine this level), to stop transcription and prevent misfolding
MPS 48h after cessation of a bout of resistance exercise
-MPS still elevated 48h after exercise in the fasted state
-breakdown returns to baseline after 48h
Best source of amino acids for nutrition
-intact protein sources containing full complement of amino acids is best
-ex. Whey protein, milk better than BCAAs (waste of money because it stimulates mechanisms but doesn’t drive synthesis)
Optimal protein dosage to maximize anabolism
-20g
-extra (e.g. 40g in study) just gets oxidized
-timing: 20g every 3h
-0.3 g/kg BM
*study done in male university student, relatively healthy, using single leg extensions, so there a limitations including type of exercise
During sleep
-in a negative state of protein balance
-‘protein feeding opportunity’
-0.4g/kg optimal before bed (larger dose for feeding overnight)
-pre-sleep protein ingestion promotes gains in muscle mass and strength
*Example protein dose scenario: 85kg athlete, wants to maximize resistance training gains in muscle mass, what would you tell them for protein? (absolute dose, pre-sleep, recommended per day, optimal dose intake)
-have 4 meals plus a pre-sleep intake of protein
-absolute dose= 25.5g per meal (0.3g/kg protein per meal x 85kg)
-pre sleep= 34g (0.4g/kg x 85kg)
-recommended per day= 136g (25.5 x 4 + 34g)
-most optimal intake for this individual= 1.6g/kg (136g/85kg)
Optimal dose of protein to maximize hypertrophic response to exercise in healthy adults
-1.6g/kg/d
Endurance exercise
-protein synthesis is increased (constantly moving, plus other factors)
-optimal dose 0.5g/kg *need higher dosage
Type of protein: digestibility
-digestibility= how efficiently the body can extract nutrients from the ingested food
-plant-based protein are less digestible than animal-based protein, so a larger proportion of nutrients are not absorbed and utilized by the body
-100% energy consumed= 90% metabolized, 10% excreted
Amino acid composition: leucine content in plant-based proteins
-plant-based proteins tend to have lower essential amino acid content, especially leucine
-whey protein= highest %leucine
Wheat vs. Dairy protein
-Whey (dairy-faster absorption) 35g= 16.6 total EAA, 4.4 leucine
-Casein (dairy-slower absorption) 35g= 14.9 total EAA, 3.2 leucine
-Wheat 35g= 9.9 total EAA, 2.5 leucine (60g= 17 total EAA, 4.4 leucine) *need about double to be the same as whey
Strategy 2: blending different plant-based protein sources
-alone, plant-based sources are low in specific essential amino acids, each have different ones
-blending different types can even out the types and =meat source
Comparing chicken and tofu for 1.6g/kg/d
-Chicken= more protein, cheaper cost
-Tofu= less protein, more expensive
*plant-based usually more expensive for same amount of protein
Best approach for high quality protein sources
-mixed balance between plant-based and meat
-ex. Chicken, eggs, milk, beans, peas
-grass-fed or free range better because there’s more phytochemicals (which have other benefits)
In a negative energy balance, 30% of body mass loss can be
-lean tissue
*fats and carbs not much of a difference when losing fat (more amount of calories)
Why is protein so important (6)
- Nutrient dense
- Preserves lean tissue
- May promote fat loss
- Increased satiety
- Thermogenic effects (protein-rich meal= increased thermogenesis)
- Poor lipogenic structure (protein does not turn to fat)
Study looking at high protein diet during energy deficit and intense exercise training
-healthy young men, 4 weeks of resistance and interval training, 6d/week, 40% calorie restriction (mainly fat), compared high protein vs low protein
-lean body mass increased, total body mass and fat mass decreased
-found that you can be in a deficit and build muscle (mainly lose fat)
