May/June 2023

Protein Requirements for Older Adults
By Carrie Dennett, MPH, RDN
Today’s Geriatric Medicine
Vol. 16 No. 3 P. 22

Learn the latest on what, when, and how much protein older adults need to maintain muscle health, plus strategies for better nutrition counseling.

To stay active, vital, and strong during aging, good nutrition—in particular, adequate protein—is important. Evidence has demonstrated that to preserve lean muscle and prevent age-related declines in health and physical functioning, older adults need more dietary protein than do younger adults throughout the day.

Muscle is made of proteins that are in a constant state of turnover, with newly synthesized proteins replacing older, damaged proteins. Muscle protein synthesis, or anabolism, typically is stimulated by dietary protein and resistance exercise, with protein thought to be the main driver. However, as the body ages, it becomes resistant to the anabolic effects of these stimulants.1 Because of anabolic resistance, adults lose about 3% to 8% of muscle mass per decade after age 30, a rate that increases after age 60.2 Staying physically active and consuming adequate protein can help counter that trend.

“Protein is an essential nutrient for older adults and plays an important role in maintaining and building muscle mass,” says Katie Dodd, MS, RDN, CSG, LD, FAND, owner of The Geriatric Dietitian in Medford, Oregon. “Older adults have less muscle than younger adults, so it’s important to get enough protein along with resistance exercise to protect against further muscle loss.”

Pitfalls of Poor Protein Intake
According to the 2020–2025 US Dietary Guidelines for Americans, monitoring protein intake is especially important as older adults continue to age. That’s because average consumption of protein-rich foods is lower for individuals 71 and older compared with those aged 60 through 70, with about 50% of women and 30% of men 71 and older falling short of recommended intakes.3 Angel Planells, MS, RDN, a Seattle-based dietitian and national media spokesperson for the Academy of Nutrition and Dietetics, says that one of the primary goals of protein consumption in conjunction with physical activity for older adults is to prevent or minimize the age-related declines in muscle mass.

If muscle protein breakdown exceeds synthesis of new proteins from amino acids, muscle mass declines. To get enough amino acids, individuals need to eat enough protein. Protein shortfalls can have serious health consequences. “If older adults don’t get enough protein, they’re at an increased risk of muscle loss and malnutrition,” Dodd says. “Muscle is needed to maintain independence. Losing muscle can increase risk of falls, hospitalization, disability, and early death.”

Studies using imaging techniques such as CT or MRI to compare young and older adults suggest that at age 60, men have 14% less leg muscle than do those aged 20, and older adults will lose 0.7% to 0.8% of muscle per year. Longitudinal studies show similar results, suggesting that older women lose 1% of leg muscle mass per year and 0.2% to 0.4% of trunk muscle, with men losing double that amount of trunk muscle. Loss of strength is substantially greater—2.5% to 4% per year.1

Planells says aging and the declines associated with it place adults at an increased risk for not only falls but also fractures and other health issues. “The loss of muscle mass places an older individual at risk for increased inflammation, altered hormone levels, decreased quality of life, and more,” he says. Of particular concern is the development of sarcopenia or age-related musculoskeletal decline. Sarcopenia typically is characterized by low muscle strength, low quality/quantity of muscle, and limited capacity for activity.4

Planells says sarcopenia can lead to more catastrophic injuries as well as longer hospital and/or rehabilitation stays. And it’s not a problem that occurs in isolated cases. Planells refers to data from Aging in Motion, a coalition of organizations working to advance research and treatment of sarcopenia, stating that sarcopenia affects 11% of men and 9% of women who are community-dwelling, 23% of men and 24% of women who are hospitalized, and 51% of men and 31% of women who live in nursing homes.5 Risk of sarcopenia increases with age and is higher in females and underweight adults as well as those with lower education, lower socioeconomic status, and lower birth weight.

Some systematic reviews and meta-analyses have found that protein supplementation or high-protein diets in elderly subjects suppress the sarcopenia/frailty indicators (muscle mass and muscle strength loss) and increase muscle fiber production.6 However, other research has found no such associations, perhaps because, in some populations, protein intake already is adequate, and different studies use different types and amounts of protein as well as different dosage timings.7

How Much Protein Is Enough?
Countering age-related muscle loss through appropriate physical activity and optimal protein intake is important to preserve muscle mass and prevent age-related declines in health and physical functioning—especially since research has demonstrated that older adults need more protein to stimulate muscle synthesis.8,9 The Recommended Dietary Allowance (RDA) for protein is 0.8 g per kg of body weight per day (g/kg/d), but many researchers say 1 to 1.2 g/kg/d is a more optimal intake for older adults, with room to go higher.10,11

A 2013 position paper from the PROTAGE Study Group,10 an international group of experts from different clinical and research specialties assembled to review dietary protein needs with aging, stated that a one-size-fits-all recommendation doesn’t consider age-related changes in metabolism, immune health, hormone levels, or frailty. The group concluded that older adults need protein levels of 1 to 1.2 g/kg/d, with the higher end of the range recommended for physically active older adults, while older adults with acute or chronic diseases may need up to 1.5 g/kg/d. The European Society for Clinical Nutrition and Metabolism made similar recommendations.12

Unfortunately, the often-cited daily protein needs for healthy adults—46 g for women and 56 g for men—aren’t adequate for most people. The RDA of 0.8 g/kg/d makes that 46 g appropriate for a 126 lb woman and 56 g appropriate for a 154 lb man. Plus, research is increasingly finding that “adequate” isn’t the same as “optimal.” The RDA is defined as the level of protein required to offset deficiency in 98% of people but may do little to help maintain or build muscle mass or promote healthy aging.11 There’s also more to getting enough protein than just hitting a daily target. Research shows that timing matters because the body is constantly making and breaking down muscle, so stimulating muscle protein synthesis at every meal may be important.

In healthy muscles, protein consumption stimulates an increase in muscle protein synthesis in a dose-response manner. In healthy young adults, there’s a plateau of muscle protein synthesis at about 0.25 g/kg/meal, whereas that synthesis doesn’t plateau until about 0.4 g/kg/meal in older men8—that’s 27 g of protein per meal for a 150 lb older adult or 36 g per meal for a 200 lb older adult. This is similar to the 25 to 30 g/meal recommendation from PROT-AGE to meet the anabolic threshold for older adults.10 Any extra dietary amino acids consumed in one meal would be converted to energy or stored as fat,13 so eating patterns that lack in protein at breakfast but contain excess protein at dinner—think toast and coffee for breakfast, but a 12 oz steak at dinner—would fail to maximize the body’s muscle repair and building machinery.14

In research studies, an uneven distribution of protein—too low at some meals, higher than necessary at others—is associated with frailty, slower walking speed, and fatigue.10,12,15 Data from the National Health and Nutrition Examination Survey suggest that older adults who consumed two or more meals with 30 to 45 g protein in each were stronger and had more muscle mass compared with those who consumed one or no meals with at least 30 g protein.16 The failure of many studies to look at protein distribution, not just total protein intake, may account for some inconsistent findings among studies looking at associations between total protein intake and frailty or sarcopenia.

Protein Plus Physical Activity
A systematic review and meta-analysis of randomized controlled trials published in 2022 in the American Journal of Clinical Nutrition found that on its own, protein supplementation didn’t have a significant positive effect on muscle or strength, but in interventions that also used resistance exercise, improvements were observed in muscle in the arms and legs in sarcopenic/frail populations, as well as in general hand grip strength.17 Research also suggests that the interaction of higher physical activity and higher total protein intake is associated with higher quality of life, even when there’s no observed association with physical functioning.15 Adults who maintain high levels of physical activity into their 60s and beyond have more muscle and are fitter and stronger than their more sedentary peers.1

According to the Physical Activity Guidelines for Americans, the recommendations for adults older than 65 who have good fitness and no chronic conditions essentially are the same as for all active adults: at least 150 to 300 minutes of moderate-intensity or 75 to 150 minutes of vigorous-intensity aerobic physical activity—or an equivalent combination—per week, plus muscle-strengthening activities that involve all major muscle groups on two or more days per week.18 Older adults also are encouraged to incorporate a multicomponent physical activity that includes balance training as well as aerobic and muscle-strengthening activities.

The guidelines also state that older adults should determine their level of effort for physical activity relative to their level of fitness, and older adults with chronic conditions should understand whether and how their conditions affect their ability to do regular physical activity safely and be as physically active as their abilities and conditions allow.

Plant-Based vs Animal-Based
While there’s no observed benefit to consuming more than the above mentioned protein intake of 0.4 g/kg/meal, there are questions about whether the type of protein matters. With increased emphasis on plant-based diets for health, do plant-based proteins perform as well as animal-based proteins for preserving muscle? The answer may hinge on one specific amino acid—leucine.

The leucine content of a dietary protein source has been shown to affect the degree to which it triggers muscle protein synthesis, although all essential amino acids need to be available to maximize leucine’s anabolic potential.13 Dairy, eggs, lean meat, and fish contain more leucine generally than do plant-based proteins, with soyfoods containing the most leucine of the plant-based proteins. While plant-based proteins can provide enough protein and leucine, consumption may need to be higher to maximize muscle protein synthesis.

Data from a systematic review and meta-analysis of cross-sectional and longitudinal studies involving 46,469 community-dwelling adults aged 60 and older found that frail older adults consume less animal protein, on average, than do their nonfrail peers but found no difference when looking at total protein intake.19

“Eating animal-based proteins makes it easier for older adults to get enough protein. Plant-based proteins may require more intention to get adequate protein, though it’s completely possible to meet protein needs on a plant-based diet,” Dodd says. “I think it’s important to support individuals based on their diet preferences, helping them to get enough protein regardless of the foods they prefer to eat.”

Planells says he sees pros and cons to both animal and plant proteins. Cost may be an issue with specific protein options, patients with chewing or swallowing difficulties may find some animal-based proteins too tough to eat, and patients from the “meat and potato generation” may be less open to plant-based proteins.

Earlier muscle protein metabolism studies emphasized isolated sources of protein, demonstrating that whey protein is more anabolic than casein. But newer research is finding that when it comes to muscle protein synthesis, the beneficial effects of whole protein foods are greater than the sum of their amino acids. This may be because of the protein food matrix, which also includes fat, carbohydrates, micronutrients, and other bioactive molecules. So, the basis of a muscle-friendly diet should be on whole protein foods, with isolated protein supplements, such as shakes or bars, used if needed to reach per-day and per-meal protein recommendations.13 Some plant-protein blends, isolates, and amino-acid-enriched plant proteins may offer muscle-related benefits comparable to those of animal proteins.20,21

Recommendations
When helping older adults increase protein intake, Planells says, basic nutrition education is important, as some people may associate “protein” with only animal-based meats, not recognizing that foods such as chickpeas, lentils, nut butters, nuts and seeds, beans, and tofu also count. If the toughness of meats is a problem, dietitians can educate clients on how to soften meat, such as cooking it slowly at low temperatures, using a meat tenderizer, grilling, cutting across the grain, or slicing the meat thinly before cooking.

However, it’s important to remember that older adults aren’t homogenous. Some are community-dwellers, while others are in long term care. Some are active while others have limited mobility or are struggling with frailty. Some are enjoying good health, while others are managing multiple chronic conditions. So, approaches to improving protein intake aren’t a one-size-fits-all.

Some of the unique challenges are ensuring older adults get enough protein from good protein sources at breakfast, lunch, and dinner. Dodd says some older adults, especially community-dwellers, may eat one large meal per day because cooking is challenging due to disability, or eat little to no protein at certain meals, such as having only toast and coffee for breakfast.

Planells says many of the older adults he has worked with throughout the years struggle to get protein to 1 g/kg/d due to financial barriers and limited preparatory facilities, knowledge, or control over food prep. He suggests helping each individual eat what they can when they can. “People residing in adult family homes or nursing homes will have three meals with snacks available to try to get adequate protein,” he says. “This may be different for an older adult residing alone with a limited budget and awaiting the end of the month for their next check.” He recalls one home visit with a patient who wanted to eat more protein but had a mini-fridge, microwave, limited storage capacity, and $15 for the rest of the month—and it was the 10th of the month. Planells says, “Everyone is different and we need to individualize our approaches to help meet the person where they’re at. Someone could be eating fast food, someone could be eating one meal per day, someone could be grazing on snacks all day long, someone could have limited cooking skills, someone could have no food preparation facilities, or someone could be undomiciled. We have to be able to think and be crafty with our approach.”

In addition to focusing on protein intake, Dodd says all dietitians working with older adults should be completing nutrition-focused physical exams (NFPEs) on a regular basis. “Older adults are at an increased risk of malnutrition, and the most effective way to identify malnutrition and start treatment is through the nutrition-focused physical exam. The NFPE allows us to identify bilateral muscle wasting, loss of subcutaneous fat, and fluid accumulation that can mask weight loss.”

— Carrie Dennett, MPH, RDN, is the nutrition columnist for The Seattle Times, owner of Nutrition By Carrie, and author of Healthy for Your Life: A Holistic Guide to Optimal Wellness.

References
1. Palmer AK, Jensen MD. Metabolic changes in aging humans: current evidence and therapeutic strategies. J Clin Invest. 2022;132(16):e158451.

2. Volpi E, Nazemi R, Fujita S. Muscle tissue changes with aging. Curr Opin Clin Nutr Metab Care. 2004;7(4):405-410.

3. US Department of Agriculture; US Department of Health and Human Services. Dietary Guidelines for Americans, 2020–2025. https://www.dietaryguidelines.gov/sites/default/files/2021-03/Dietary_Guidelines_for_Americans-2020-2025.pdf. Published December 2020.

4. Sayer AA, Cruz-Jentoft A. Sarcopenia definition, diagnosis and treatment: consensus is growing. Age Ageing. 2022;51(10):afac220.

5. Aging in Motion. Sarcopenia facts and figures. https://www.aginginmotion.org/app/uploads/2021/07/Sarcopenia-Facts-and-Figures-2.pdf

6. Park YJ, Chung S, Hwang JT, Shon J, Kim E. A review of recent evidence of dietary protein intake and health. Nutr Res Pract. 2022;16(Suppl 1):S37-S46.

7. Ten Haaf DSM, Nuijten MAH, Maessen MFH, Horstman AMH, Eijsvogels TMH, Hopman MTE. Effects of protein supplementation on lean body mass, muscle strength, and physical performance in nonfrail community-dwelling older adults: a systematic review and meta-analysis. Am J Clin Nutr. 2018;108(5):1043-1059.

8. Moore DR, Churchward-Venne TA, Witard O, et al. Protein ingestion to stimulate myofibrillar protein synthesis requires greater relative protein intakes in healthy older versus younger men. J Gerontol A Biol Sci Med Sci. 2015;70(1):57-62.

9. Wall BT, Cermak NM, van Loon LJ. Dietary protein considerations to support active aging. Sports Med. 2014;44 Suppl 2(Suppl 2):S185-S194.

10. 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. 2013;14(8):542-559.

11. Phillips SM, Chevalier S, Leidy HJ. Protein "requirements" beyond the RDA: implications for optimizing health. Appl Physiol Nutr Metab. 2016;41(5):565-572.

12. Deutz NE, Bauer JM, Barazzoni R, et al. Protein intake and exercise for optimal muscle function with aging: recommendations from the ESPEN Expert Group. Clin Nutr. 2014;33(6):929-936.

13. Paulussen KJM, McKenna CF, Beals JW, Wilund KR, Salvador AF, Burd NA. Anabolic resistance of muscle protein turnover comes in various shapes and sizes. Front Nutr. 2021;8:615849.

14. Arentson-Lantz E, Clairmont S, Paddon-Jones D, Tremblay A, Elango R. Protein: a nutrient in focus. Appl Physiol Nutr Metab. 2015;40(8):755-761.

15. Ten Haaf DSM, van Dongen EJI, Nuijten MAH, Eijsvogels TMH, de Groot LCPGM, Hopman MTE. Protein intake and distribution in relation to physical functioning and quality of life in community-dwelling elderly people: acknowledging the role of physical activity. Nutrients. 2018;10(4):506.

16. Loenneke JP, Loprinzi PD, Murphy CH, Phillips SM. Per meal dose and frequency of protein consumption is associated with lean mass and muscle performance. Clin Nutr. 2016;35(6):1506-1511.

17. Kirwan RP, Mazidi M, Rodríguez García C, et al. Protein interventions augment the effect of resistance exercise on appendicular lean mass and handgrip strength in older adults: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2022;115(3):897-913.

18. US Department of Health and Human Services. Physical Activity Guidelines for Americans, 2nd edition. https://health.gov/sites/default/files/2019-09/Physical_Activity_Guidelines_2nd_edition.pdf. Published 2018.

19. Coelho-Junior HJ, Calvani R, Picca A, Tosato M, Landi F, Marzetti E. Protein intake and frailty in older adults: a systematic review and meta-analysis of observational studies. Nutrients. 2022;14(13):2767.

20. Carbone JW, Pasiakos SM. The role of dietary plant and animal protein intakes on mitigating sarcopenia risk. Curr Opin Clin Nutr Metab Care. 2022;25(6):425-429.

21. Berrazaga I, Micard V, Gueugneau M, Walrand S. The role of the anabolic properties of plant- versus animal-based protein sources in supporting muscle mass maintenance: a critical review. Nutrients. 2019;11(8):1825.