Growing older with health and vitality
This is summary of the following paper:
- The preservation of skeletal muscle mass and strength with advancing age are critical aspects of ageing with health and vitality.
- Physical inactivity and poor nutrition are known to accelerate the gradual age-related decline in muscle mass and strength (sacropenia)
- A daily protein intake of 1.2–1.5 g/kg BM/day, which are levels 50–90 % greater than the current protein Recommendation Dietary Allowance (0.8 g/kg BM/day), are likely to help preserve muscle mass and strength and are safe for healthy older adults.
- In order to maximize muscle protein synthesis (MPS), assuming three meals are consumed daily, a protein dose of 0.4–0.5 g/kg BM should be contained in each meal.
- Increase the utilization of ingested protein for the stimulation of MPS by increasing the proportion of leucine contained in a given dose of protein, co-ingesting other nutrients (e.g., carbohydrate and fat or supplementation with n-3 polyunsaturated fatty acids) or being physically active prior to protein intake.
Why does being healthy as we age matter?
It important to take care of your health as you age to ensure the gift of longevity does not turn into a burden.
Humans’ lifespans are increasing due to improvements in healthcare. This has resulted in a larger aged population which has economic and social consequences.
Fundamentally, this ageing demographic is testament to continued improvements in healthcare services. However, a disproportionate use of healthcare services by older people highlights the economic cost of population ageing, alongside the high prevalence of morbidity that can reduce quality of life with advancing age. As a consequence, there is a perception that society (in some European countries more than others) often views older people as a societal and economic burden.
Sarcopenia and the threat of physical disability
Age-related sarcopenia or sarcopenia with aging results in loss of muscle strength and function. This results in an increased fall risk and reduced mobility, which translates into a lower quality of life.
The onset of muscle mass loss typically begins by the fourth decade of life (Janssen et al. 2000), having peaked between 20 and 30 years of age. Thereafter, the average rate of muscle mass loss is estimated at 8 % per decade (~0.5–1 %/year) until the age of 70 years (Mitchell et al. 2012), increasing to ~15 % per decade in octogenarians and beyond (Delmonico et al. 2009). Hence, most individuals 70–80 years old possess only 60–80 % of the muscle mass they had at ~30 years old, declining to <50 % in octogenarians…. the trajectory of strength loss is even more precipitous, with annual declines of 3–4 % reported in men and 2.5–3 % in women (Goodpaster et al. 2006).
Symptoms of Sarcopenia:
- Low skeletal muscle mass, muscle strength and physical performance = reduced mobility, strength, size
- Poor balance, difficulty doing simple tasks, increased rates of falls
- Muscle mass loss increases with age.
- 40-70s – 8% per decade
- >70 – 15% per decade
- Strength loss
- ~35% per decade for men
- ~27% per decade for women.
- Muscle/strength loss expedited by periods of inactivity/disuse
- Net Muscle Protein Balance, the difference between Muscle Protein Synthesis (MPS) vs Muscle Protein breakdown (MPB), is the main determinant for muscle loss
How to reduce Sarcopenia
- Increase Muscle Protein Synthesis by:
- Consuming a diet high in protein
- Regular physical activity
- Using pharmaceutical anabolic agents
Physical activity and exercise guidelines and benefits
- Increase physical exercise has been associated with:
- Better cardiovascular health
- Increased strength
- Reduced risk for chronic diseases
- Resistance exercise is effective for building both muscle mass and strength even in the elderly
- Endurance exercise has shown to improve blood sugar levels and cardiovascular fitness. And may have anabolic potential.
For instance, one study reported a significant increase in quadriceps muscle volume and muscle power in older individuals who cycled for 20–45 min, at 60–80 % heart rate reserve, 3–4 times per week for 12 weeks (Harber et al. 2012). Similarly, older women who performed 12 weeks of progressive cycling showed increased quadriceps size (~12 %) and aerobic capacity (~30 %) (Harber et al. 2009). It is important to acknowledge that other studies have failed to detect an impact of aerobic exercise training on muscle mass in older adults (Short et al. 2004; Sipila and Suominen 1995).
Increasing Muscle Protein Synthesis by optimizing protein intake
- Older adults require more protein to stimulate MPS. Approximately 40 to 50g of protein per meal.
- A balanced meal pattern is associated with better MPS stimulation. For example, having 3 meal with 40g of protein each is better than 3 separate meals with 20g, 30 and 50g of protein, despite total protein intake being equal.
- It is important to reach/exceed leucine threshold to “switch on the muscle anabolic signalling proteins that stimulate MPS”
A recent study in young adults (Mamerow et al. 2014) demonstrated a greater 24 h response of MPS to a balanced meal pattern that distributed 90 g of protein evenly between three meals (3 � 30 g), spaced 3.5–4 h apart versus a conventional (Tieland et al. 2012; Valenzuela et al. 2013) skewed meal pattern that biased daily protein intake (~63/90 g) towards the evening meal
Accordingly, a retrospective analysis of serial dose-response studies revealed the optimal relative dose of protein in a single serving for the maximal resting postprandial stimulation of myofibrillar-MPS to be 0.40 g/kg BM in older adults; ~68 % greater than calculated in young adults (0.24 g/kg body mass) (Moore et al. 2014). Thus, assuming three meals are consumed each day, a relative protein dose of 0.4–0.5 g/kg BM/meal is consistent with recent expert opinions concerning the optimal daily protein intake (1.2–1.5 g/kg BM/day) for healthy older adults (Bauer et al. 2013; Deutz et al. 2014).
How to Optimize quality and utilization of protein intake on a per meal basis
Why older adults have trouble hitting protein requirements:
- Reduced appetite
- Reduced ability to perform tasks – cooking, shopping, food preparation
- Satiating value of protein
Therefore, it is important to emphasize protein quality i.e. the protein’s ability to stimulate MPS.
Protein quality is determined by the protein’s:
- AA profile
- leucine content
The ideal protein is one that is rapidly digested and rich in leucine as that has shown to best activate mTOR and post-meal MPS response.
What is mTOR?
The mammalian target of rapamycin (mTOR) signaling pathway integrates both intracellular and extracellular signals and serves as a central regulator of cell metabolism, growth, proliferation and survival. 
Increasing the utilization of ingested protein with other nutrients
- Combined ingestion of fat and carbohydrate may enhance the utilization of a suboptimal amount of Essential Amino Acids (EAAs) for Muscle Protein Synthesis (MPS) or even suppress Muscle Protein Breakdown (MPB)
- Omega-3s have shown to potentiate MPS rates which translate into increased strength
Daily protein recommendations
Studies suggest for older adults, the recommended daily intake should be around 1-1.5g/kg bodyweight. In addition, there is lack of evidence that high protein intake will result in negative health incomes. In fact, higher protein intake have been associated with higher bone mass.
Lyle McDonald – What Are Good Sources of Protein? – Protein Quality
WebMD – Sarcopenia With Aging
Brad Schoenfeld – High Protein Diets – Myths, Half-Truths and Outright Lies
Updated 17th August 2018