Week 10: Nutrition in special populations Flashcards
Healthspan
Amount of time an individual spends in a state of good health
(what matters and can be modified)
Lifespan
Number of years in an individuals life
Lifestyle behaviours that influence health
- Sleep
- Eating well-balanced diet
- Physical activity
- Not smoking
- Not using alcohol
- Healthy body weight
Sarcopenia
Age-related continuous involuntary decline in muscle mass, quality and strength
What is sarcopenia characterized by?
Decreased size and number of type 2 skeletal muscle fibres and an infiltration of adipose tissue in skeletal muscle
When do we begin to lose skeletal muscle?
40 years old
How much muscle mass is lost per year after age 40?
0.5-1.0%
How much muscle strength is lost per year after age 40?
1.2%
What is the best predictor of falling?
Muscle strength
Frailty
Reduction of the physiological functional reserve and a decreased homeostatic capacity leading to greater vulnerability to adverse health outcomes and increased risk of death
Characteristics of a frail adult
- Impaired mobility
- Loss of strength
- Slow gait speed
- Unintended weight loss
What is one reason we lose skeletal muscle mass as we age?
Energy intake is reduced
How is energy intake reduced in older adults?
- Decreased REE due to a reduction in FFM
- Reduction in appetite
- Reduction in physical activity levels
Why is there a reduction in appetite in older adults?
- Diminished hunger and satiety mechanism
- Age-related gastrointestinal motility changes
- Other factors (ie. depression)
Why is there diminished hunger and satiety mechanism in older adults?
Altered hormonal response such that the production of orexigenic hormones are decreased and anorexigenic hormones are increased
Which hormones are altered in older adults appetite reguation?
Decreased ghrelin and NPY
Increased CKK, PYY, insulin and leptin
What are age-related gastrointestinal changes?
Delayed gastric emptying–> postprandial satiety–>reduced antral stretch (food in GI tract longer=feel full)
Where is CKK produced and in response to what?
Small intestine in response to fat and protein
Anorexia of aging
Decrease in appetite and food intake in old age
What does anorexia of aging lead to?
Muscle wasting
Impaired immune function
Cognitive decline
Decreased function in respiratory muscles
Reduced gut function
Disability
What is another reason we lose skeletal muscle mass as we age?
Lack of protein intake
How do we increase muscle mass?
MPS>MPS such as with resistance training
Why does muscle mass decrease?
MPS<MPB such as after an immobilization injury
RDA for protein intake
0.8 g/kg/day
Designed to prevent deficiency but is not the optimal dose
Rates of MPS and muscle mass in older adults
Older adults are less responsive to the protein they consume and therefore have less stimulation of MPS and less muscle mass
MPS curve in older adults
Less elevation in MPS
Same elevation in MPB
Anabolic resistance
Reduced rise in MPS in response to the ingestion of protein/amino acids
Solutions to reduced muscle mass in older adults
More protein to maximally stimulate muscle in a single meal
How much protein was found to maximally stimulate muscle mass in older adult per meal?
0.4g/kg/per meal
Protein intake in older adults
Skewed
But balancing it across meals may result in improvements in MPS
Study 1: Protein intake and MPS in middle aged adults
Consuming even protein intake across meals maximally stimulated MPS
Study 2: Protein intake and timing on MPS in older adults
Protein intake is a signifiant predictor of stimulating MPS
Balanced protein intake did not alter skeletal MPS in older adults
Oral nutritional supplements
For those with dysphagia (difficulty swallowing) these can be used to increase nutrition and calorie intake
Agility and physical activity
2 weeks of acute physical inactivity (step reduction) reduces rates of MPS and skeletal muscle mass in older adults
EAA and MPS
Eating whey protein that contains all the EAA protects against declines in MPS
Catabolic crisis model
Older adults have a harder time returning to lean muscle mass baseline after an injury due to anabolic resistance
Gradual sarcopenia
The normal decline in skeletal muscle mass as we age
Fat infiltration of skeletal muscle
Associated with negative health outcomes
More prevelant in sedentary older adults
Resistance training and protein
Both stimulate muscle growth even in older adults
