Proteins play an important role in supporting health throughout all stages of life. With an ageing population the focus is on maintaining quality of life and independence for as long as possible. This article considers the role of proteins along with physical activity in maintaining muscle mass and strength in older adults, which is essential for staying mobile and active. Protein is also critical for recovery from illness and recovering the muscle tissue lost. An adequate intake of protein along with physical activity helps provide the resilience needed to cope with critical periods of inactivity associated with illness, injury, infection and hospitalization.
According to the World Health Organisation, the number of people aged 60 and over is expected to double in the next few decades. It is estimated that by 2050 more than 1 in 5 people will be 60 years or older.1 Adequate nutrition along with physical activity plays an important role in preventing muscle decline and the development of sarcopenia in older adults.2
Sarcopenia is the loss of muscle mass, strength and physical function below a critical threshold and increases the risk of falls and bone fractures.3 The European Working Group on Sarcopenia in Older People defined sarcopenia as probable when a person has low muscle strength. The additional presence of low muscle mass or low muscle quality confirms the diagnosis. If low physical performance is observed as well as low muscle strength and low muscle quantity/quality, sarcopenia is considered severe.2
From the age of 50 years the age related decline in muscle mass typically occurs at a rate of 1-2% per year with an accelerated decline after the age of 70 years (figure 1).
Sarcopenia increases the risk of falls and bone fractures which can lead to loss of independence or need for long-term care.2 Public Health England (2017) reported around 255,000 falls-related emergency hospital admissions among patients aged 65 with an annual cost to the National Health Service (NHS) of 4.4 billion, of which 25% is for social care associated with fragility fractures.4 Preventing falls and fractures is important for maintaining the health, wellbeing and independence of older people. A key goal of healthy ageing is therefore to limit the loss of muscle mass which in turn leads to a decline in physical endurance and strength. This can be accomplished with a combination of exercise to improve strength and balance and a regular intake of nutrient dense foods providing a good source of high quality protein in accordance with the UK Reference Nutrient Intakes (RNI).5 Along with protein, vitamin D also has an important role in muscle strength and function as well as bone strength.6 The RNI for the UK adult population is 10 micrograms per day and a daily vitamin D supplement of 400 IU is advised for older people aged 65 and over, especially for those who are not exposed to much sun and at increased risk of deficiency.7,8
Causes of muscle loss with ageing
The causes of sarcopenic muscle loss in older people are complex and a number of factors potentially may affect the rate of age related loss of muscle mass, strength and function: 9,10
- Reduced physical activity
- Reduced utilization of protein (anabolic resistance)
- Increased protein requirement due to inflammation and catabolic conditions associated with chronic and acute diseases
- Insufficient protein intake
Impact of inactivity
Muscle contraction is an important stimulus for muscle protein synthesis along with protein intake. General guidelines advise 30 minutes of endurance exercise per day and resistance exercise for 10 to 15 minutes or more per session two to three times per week.9
However, with advancing age, older adults may become less physically active. Acute periods of muscle disuse are associated with illness and/or surgery and bed rest can result in loss of muscle, with or without loss of fat mass and further contribute to the progression of sarcopenia.11 The combination of exercise to improve strength and balance and nutrient dense foods providing a good source of high quality protein, such as lean meat, fish, eggs and dairy foods, helps to slow down the decline of muscle mass and strength (sarcopenia) associated with ageing.
Anabolic resistance with ageing
Muscle in older adults is less sensitive to dietary protein intake than in young people, a phenomenon called ‘anabolic resistance’. Older adults need a higher dosage of essential amino acids, including leucine, to elicit the stimulation of muscle protein synthesis. In addition, physical inactivity desensitizes muscle protein to the anabolic properties of dietary proteins during ageing.10 Physical activity performed prior to protein ingestion has been shown to enhance uptake and utilization of amino acids in older adults, suggesting that the level of physical activity may be critical to maintaining the anabolic responsiveness to protein intake with ageing.
How much protein should older adults consume? Currently, the UK adult Reference Nutrient Intake (RNI) for protein is 0.75 g/Kg body weight/day for adults of all ages.5 However, there is increasing evidence that a higher protein intake is beneficial for older adults to maintain muscle mass and international expert groups have more recently presented revised protein recommendations for older people (> 65 years) as follows: 9,12
- Healthy older adults are advised to consume 1.0 to 1.2 gram of protein per kg bodyweight/day.*
- For malnourished elderly or elderly at risk of malnourishment due to (chronic) illness, a higher protein intake is recommended: 1.2 to 1.5 gram of protein per kg bodyweight/day.*
- The recommended amount of protein for older adults per meal or after exercise is 25 to 30 grams of high-quality protein, with 2.5 – 2.8 grams of leucine.
*Exercise caution in people with severe kidney disease (i.e. estimated Glomerular Filtration. Rate <30ml/min/1.73m2), as their protein needs should be calculated differently.
Protein intake in older adults
Ageing can be associated with reduced food intake and older adults may be compromised in their ability to consume sufficient protein, especially during illness.13 Studies show that around 10% of community-dwelling older adults and one-third of those living in care homes do not achieve a protein intake of 0.7 g/kg bodyweight/day and many older adults are not consuming protein at the levels required to meet the new recommendations for protein intake.14 Findings also showed that protein distribution tended to be skewed towards the evening meal. Research shows that a more even distribution of protein intake over the day of 25 to 30 g of protein at each meal is required to maximize muscle protein synthesis. Therefore it is advisable for older adults to also include high quality protein sources at breakfast and lunchtime meals.9
As well as the quantity of protein, the quality of the protein source also becomes more important in older adults in order to supply sufficient amounts of all the essential amino acids, including leucine. High-quality proteins which are highly digestible, meaning that the protein is accessible for digestive enzymes in the gastrointestinal tract and all the amino acids, including the essential ones, can be absorbed, are preferable.15 Animal products such as the dairy proteins, casein and whey, are a good source of highly digestible protein (figure 3), whereas many plant proteins contain anti-nutritional factors that impair the digestion and absorption, not only of protein, but also micronutrients.
The availability of specific essential amino acids, in particular leucine are also important for optimizing muscle protein synthesis. Therefore leucine rich protein sources, such as dairy are of key importance in ageing.16,17,18
Role of protein during illness and recovery
Protein requirements are elevated during illness, inflammation and infection and as a result of injury. Malnourished elderly or elderly at risk of malnourishment due to (chronic) illness are advised to have a protein intake of 1.2 to 1.5 gram of protein per kg bodyweight/day. Patients with severe illness or injury or with marked malnutrition may need as much as 2.0 g/kg bodyweight/day.12
The consequences of disease related malnutrition include an impaired immune function and wound healing, reduced respiratory and muscle strength and impaired recovery with poorer clinical outcomes.19 Appetite may also be compromised and due to low food intake patients may struggle to meet protein targets.20,21,22
The loss of muscle mass and strength following illness, infection and injury is associated with poorer health outcomes and an increased risk of falls and fractures. Nutritionally the most important factors for patients to optimise their recovery are an adequate energy intake and additional protein. This helps patients to regain lost muscle mass and strength when leaving the hospital, enabling them to re-start daily activities and improve quality of life.23
Education on the important role that nutrition can play, in particular protein in combination with physical activity, in preventing sarcopenia and recovering muscle strength and function following illness or injury is important for enabling older adults to live independently for as long as possible.24
Optimising protein intake in older adults is a key dietary strategy to preserve muscle required for healthy ageing and recovery from illness. It is important to educate older adults on the benefits of nutrient dense sources of high quality protein in combination with physical activity and ways to achieve a higher protein intake using a food first approach.24
- WHO. Ageing and Life Course. WHO. Published 2020. Accessed September 12, 2020. http://www.who.int/ageing/en/
- Cruz-Jentoft AJ, Bahat G, Bauer J, et al. Sarcopenia: Revised European consensus on definition and diagnosis. Age Ageing. Published online 2019. doi:10.1093/ageing/afy169
- Santilli V, Bernetti A, Mangone M, Paoloni M. Clinical definition of sarcopenia. Clin Cases Miner Bone Metab. 2014;11(3):177-180. doi:10.11138/ccmbm/2014.11.3.177
- Public Health England. Falls and Fracture Consensus Statement Supporting Commissioning for Prevention.; 2017. Accessed August 15, 2020. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/586382/falls_and_fractures_consensus_statement.pdf
- Dietary reference values for food energy and nutrients for the United Kingdom. Report of the Panel on Dietary Reference Values of the Committee on Medical Aspects of Food Policy. Rep Health Soc Subj (Lond). Published online 1991.
- Rizzoli R, Biver E, Bonjour JP, et al. Benefits and safety of dietary protein for bone health—an expert consensus paper endorsed by the European Society for Clinical and Economical Aspects of Osteopororosis, Osteoarthritis, and Musculoskeletal Diseases and by the International Osteoporosis Fou. Osteoporos Int. Published online 2018. doi:10.1007/s00198-018-4534-5
- Morley JE, Vellas B, Abellan van Kan G, et al. Frailty consensus: A call to action. J Am Med Dir Assoc. Published online 2013. doi:10.1016/j.jamda.2013.03.022
- Scientific Advisory Committee on Nutrition (SACN). Vitamin D and Health 2016. Sci Advis Comm Nutr. Published online 2016:56-116. doi:10.1007/s00198-015-3440-3
- Bauer J, Biolo G, Cederholm T, et al. Evidence-based recommendations for optimal dietary protein intake in older people: A position paper from the prot-age study group. J Am Med Dir Assoc. Published online 2013. doi:10.1016/j.jamda.2013.05.021
- Burd NA, Gorissen SH, Van Loon LJC. Anabolic resistance of muscle protein synthesis with aging. Exerc Sport Sci Rev. Published online 2013. doi:10.1097/JES.0b013e318292f3d5
- Oikawa SY, Holloway TM, Phillips SM. The impact of step reduction on muscle health in aging: Protein and exercise as countermeasures. Front Nutr. 2019;6:75. doi:10.3389/fnut.2019.00075
- Deutz NEP, Bauer JM, Barazzoni R, et al. Protein intake and exercise for optimal muscle function with aging: Recommendations from the ESPEN Expert Group. Clin Nutr. Published online 2014. doi:10.1016/j.clnu.2014.04.007
- Giezenaar C, Chapman I, Luscombe-Marsh N, Feinle-Bisset C, Horowitz M, Soenen S. Ageing is associated with decreases in appetite and energy intake— A meta-analysis in healthy adults. Nutrients. Published online 2016. doi:10.3390/nu8010028
- Cruz-Jentoft AJ, Kiesswetter E, Drey M, Sieber CC. Nutrition, frailty, and sarcopenia. Aging Clin Exp Res. Published online 2017. doi:10.1007/s40520-016-0709-0
- EFSA NDA Panel (EFSA Panel on Dietetic Products N and A. Scientific Opinion on Dietary Reference Values for protein. EFSA J. Published online 2012. doi:10.2903/j.efsa.2012.2557
- Devries MC, Phillips SM. Supplemental protein in support of muscle mass and health: Advantage whey. J Food Sci. 2015;80(S1):A8-A15. doi:10.1111/1750-3841.12802
- Churchward-Venne TA, Burd NA, Mitchell CJ, et al. Supplementation of a suboptimal protein dose with leucine or essential amino acids: Effects on myofibrillar protein synthesis at rest and following resistance exercise in men. J Physiol. Published online 2012. doi:10.1113/jphysiol.2012.228833
- Phillips SM. The impact of protein quality on the promotion of resistance exercise-induced changes in muscle mass. Nutr Metab. 2016;13(1):1-9. doi:10.1186/s12986-016-0124-8
- Medical Nutrition International Industry. Better Care through Better Nutrition: Value and Effects of Medical Nutrition.; 2018. Accessed September 3, 2020. www.medicalnutritionindustry.com
- Cederholm T, Jensen GL, Correia MITD, et al. GLIM criteria for the diagnosis of malnutrition – A consensus report from the global clinical nutrition community. Clin Nutr. Published online 2019. doi:10.1016/j.clnu.2018.08.002
- Argilés JM, Campos N, Lopez-Pedrosa JM, Rueda R, Rodriguez-Mañas L. Skeletal Muscle Regulates Metabolism via Interorgan Crosstalk: Roles in Health and Disease. J Am Med Dir Assoc. Published online 2016. doi:10.1016/j.jamda.2016.04.019
- Dirks ML, Wall BT, Van De Valk B, et al. One week of bed rest leads to substantial muscle atrophy and induces whole-body insulin resistance in the absence of skeletal muscle lipid accumulation. Diabetes. Published online 2016. doi:10.2337/db15-1661
- Volkert D, Beck AM, Cederholm T, et al. ESPEN guideline on clinical nutrition and hydration in geriatrics. Clin Nutr. Published online 2019. doi:10.1016/j.clnu.2018.05.024
- Goisser S, Guyonnet S, Volkert D. The Role of Nutrition in Frailty: An Overview. J frailty aging. Published online 2016. doi:10.14283/jfa.2016.87