Linia Patel looks at the role of nutrition in the prevention of sarcopenia.
Sarcopenia is a Greek term meaning ‘poverty of the flesh’. It is the progressive loss of muscle mass that often leads to diminished strength and decreased activity levels, which can then contribute to mobility issues, osteoporosis, falls and fractures.
Sarcopenia is intricately linked with frailty, loss of physical function and the ability to do daily activities, and ultimately a poorer quality of life and even death.1
Between the ages of 30 and 60, the average adult loses about 250g of muscle each year. At the age of 70, muscle loss accelerates to about 15% per decade.2
Whilst it is normal to lose some muscle as you age, sarcopenia that includes a loss of muscle mass and overall weakness which profoundly affects physical activity levels is thought to have a prevalence of 4-25 % in older, free-living adults in the UK – a number that will continue to increase as the population ages.3
In some settings (i.e. acute), body composition can be assessed using CT scans, DEXA scans or even skin fold analysis. However in community settings other screening tools like the SARC-F questionnaire can be used. Physical performance and assessments to determine one’s ability to balance can also be used to identify sarcopenia. For malnutrition, early screening to identify individuals at nutritional risk for unintended weight loss and undernutrition or malnutrition is essential. Validated screening tools like the Malnutrition Universal Screening Tool (MUST) should be used.
1 Protein2,5,8 – Muscle mass is maintained by a balance between protein synthesis and protein breakdown, therefore eating sufficient protein is vital. There is an increased body of research indicating that protein requirements for older adults may be higher than the current UK recommendations. Bauer et al. have suggested that, to maintain and regain lean body mass, older adults (>65 years) require 1.0-1.2g protein/kg body weight, with higher amounts for active/exercising older adults (≥ 1.2 g/kg/day) an in acute or chronic disease (1.2-1.5g/kg body weight/day).
2 Whole diet approach8,9,10 – A recent UK dietary survey indicated that older adults fail to meet the recommendations for intake of fruit, vegetables, fibre, and oily fish, with evidence of low intakes of vitamin A, vitamin D, riboflavin, and folate. Intakes of intakes of saturated fat, free sugars and salt were also reported to be excessive. The Mediterranean dietary approach has the potential to be an effective strategy to improve the quality of the diet and prevent sarcopenia.
3 Vitamin D11,12 – This nutrient deficiency is the most prevalent nutritional deficiency for older adults regardless of race or ethnicity. Current UK recommendations encourage all adults to take a daily supplement of vitamin D (10 micrograms μg); 400 international units (IU)/day between October and early March. Frail and housebound adults and those who always cover their skin when outdoors and people with dark skin (African, African-Caribbean or South Asian family origin) should take a daily supplement (10 μg; 400 IU/day) throughout the year.
4 Oral nutritional supplements13 – Current NICE guidance advises the consideration of oral nutritional support for those at risk of malnutrition. This includes dietary advice and the use of oral nutritional supplements where appropriate.
Movement in combination with diet is important to help preserve muscle mass or help it grow. Exercise is recommended on most days of the week, but a minimum of three times per week is suggested to slow muscle loss and prevent sarcopenia. Exercise programmes including strength and balance have been shown to decrease frailty and improve strength in older adults.
Age-associated muscle mass
The main cause of sarcopenia is ageing as the motor neurones in the body gradually die and no longer communicate to the brain. This causes muscle fibres to then deteriorate (atrophy). This process can then be accelerated by factors like poor diet or inactivity.
Testosterone appears to be the central hormone involved in the development of sarcopenia. Growth hormone deficiency leads to loss of muscle mass but not strength. Menopause in women is a period of immense hormonal transition that is linked to a loss in muscle mass and increase in fat mass.
In men, there is a reduction in testosterone by 1% each year leading to reduced muscle mass.
Recent evidence suggests that chronic, low-grade inflammation also contributes to the loss of muscle mass, strength and functionality.
Sedentary behaviour can further accelerate age-related decline in muscle mass, leading to a decrease in metabolic rate.
Malnutrition (from under or over nutrition) increases the risk of developing sarcopenia by three or four times.
The prevalence of obesity in combination with sarcopenia – or ‘sarcopenic obesity’ – is on the rise.
When assessing the risk of malnutrition in those with overweight or obesity the following must be taken into consideration as an increased risk of sarcopenic obesity: