Posted on by Joy Erdile

The Role of Protein in the Diet of Older Adults

Note: This article was originally posted on March 1, 2018, and was edited on November 23, 2025

This article is based largely on a lecture given by Dr. Donald Layman, PhD – Professor Emeritus from the University of Illinois (Nutrition Forum, June 23, 2013, Vancouver, British Columbia, Canada) [1].

People understand it’s important for children to eat enough protein because they’re growing, but adults and older adults need to eat enough protein each day, as well.

After youth have finished growing, they are at their maximum physical capacity between the ages of 20 and 30 years old, and after the age of 30 years old, adults begin to lose muscle mass at the rate of 1% per year [2].

We’ve come to expect that as people age, they will gain more fat, lose bone mass, and that they’ll have decreased muscle strength — leading to difficulty getting around, a greater risk of falls, and eventually to physical disability. We commonly see older people with spindly legs and bony arms and think of this as ‘normal,’ but we’ve mixed up what is “common” with what is “normal.” When we look at seniors in Okinawa, Japan, for example, we don’t see this. They continue to do manual jobs and practice martial arts well into their 80s and 90s. Aborigine elders in Australia also remain lean, fit, and active as seniors. This is normal.

The physical deterioration that we associate with aging — including weak bones (osteoporosis) and the loss of skeletal muscle mass (sarcopenia) — doesn’t develop suddenly, but takes place over an extended period of time, brought on by less than optimal practices in early middle age.

How Much Protein?

The Recommended Dietary Allowance (RDA) for protein is set at 0.8 g protein/kg per day and describes the minimum quantity of protein that needs to be eaten each day to prevent deficiency. Protein researchers propose that while sufficient to prevent deficiency, this amount is insufficient to promote optimal health as people age [3].

Several recent position statements issued by experts working with older adults indicate that protein intake between 1.0 and 1.5 g protein/kg per day may provide optimal health benefits during aging [4,5]. This appears at odds with the 2010 Dietary Guidelines Advisory Committee report [6], which states that ‘protein intake in the US is more than adequate’ and that ‘inadequate protein intake is rare.’ These seemingly contradictory positions are largely due to differences in how protein adequacy is assessed.

The RDA, more specifically the Estimated Average Requirement (EAR), is the minimum amount of protein intake required to prevent deficiency and is based on nitrogen balance studies (since nitrogen is the main component of amino acids that make up proteins). The EAR evaluates overall protein intake by measuring nitrogen balance (protein synthesis vs. protein breakdown). Evaluation of optimal protein intake not only considers total daily protein but also the metabolic roles of individual amino acids. While the EAR may suffice for healthy younger adults, higher intakes of specific essential amino acids (EAAs) — ones the body cannot make, such as leucine, isoleucine, and valine — have been reported to improve body composition (muscle mass and strength) in older adults [7,8].

Another factor is that nitrogen balance studies consider total protein consumed in a day but not the amount eaten per meal [9,10] nor the role of the essential amino acid leucine, which is required for protein synthesis to begin (including synthesis of new protein for muscle and bone) [10]. Leucine is indispensable in the making of all types of protein, but has a unique role in signalling the initiation of muscle protein synthesis. Much research has been done with large doses of free leucine; however, a 2012 animal study [10] found that in small meals with limited protein intake (common in older adults), a specific minimum amount of leucine is required before protein synthesis occurs. This “leucine threshold” must be met or exceeded before the body will engage in the energy-expensive process of building new proteins.

Typically, the average American eats only 10 g of protein for breakfast, 15 g of protein for lunch, and most of their daily protein at supper (~65 g). Since the minimum leucine needed in a meal (“leucine threshold”) is not met at breakfast or lunch, protein synthesis is only triggered after the evening meal. As elaborated below, this pattern is suboptimal for maintaining muscle mass.

A 2013 study of muscle protein synthesis in adults in their late 30s found that when protein is distributed evenly throughout the day (30 g per meal at breakfast, lunch, and dinner), significantly more muscle protein is synthesized [4]. Importantly, the amount of protein needed to trigger synthesis differs with age — older adults require higher intakes of protein and leucine than younger adults [4]. This reduced muscle protein synthesis has been referred to as “anabolic resistance.” This can be overcome by eating meals with higher amounts of essential amino acids, particularly leucine [4]. These findings led to dietary recommendations for older adults emphasizing a minimum of 20 g of protein per meal containing more than 2.3 g leucine to optimize muscle protein synthesis [4,10].

Final Thoughts…

It is not only growing children who need adequate daily protein — older adults do as well. In many Indigenous cultures, elders are often served first and consume the best of the animal proteins, which may help preserve bone and muscle mass [1].

The average protein intake for men >20 years old in the US is ~98 g/day and for women ~68 g/day. Although this amount of total protein may be adequate for healthy young adults, it is often imbalanced in distribution across the day. Dr. Layman recommends that young and middle-aged adults distribute their protein intake evenly throughout the day, with ~25 g (women)– 30 g (men) of high-quality, animal-based protein per meal to stimulate muscle protein synthesis [1,10].

For older adults, a protein intake of 1.0–1.5 g/kg/day distributed across the day as three meals (i.e., ~30–40 g of animal-based protein per meal) supports optimal muscle protein synthesis and helps prevent sarcopenia [1,10].

How Much is Too Much Protein?

According to Dr. Layman, the Upper Limit of Protein, based on the Recommended Daily Allowance for Protein, is set at ~ 2.5 g protein/kg per day, which would put the maximum amount for most adult men at ~200 g protein per day.

Recommended Daily Allowance (RDA) for Protein [1]

Not Sure You are Eating Sufficient Protein?

Routine health packages, such as the Comprehensive Dietary Package, will enable me to help you achieve your nutrition goals while ensuring you are eating sufficient protein from optimal sources.

To your good health!

Joy

References

  1. Layman DK. Protein quantity and quality at meals are key to healthy aging. Nutrition Forum Lecture, University of Illinois, June 23, 2013, Vancouver, BC, Canada. [https://bcdairy.ca/2021-nutrition-forum-presentations/]
  2. von Haehling S, Morley JE, Anker SD. An overview of sarcopenia: facts and numbers on prevalence and clinical impact. J Cachexia Sarcopenia Muscle. 2010 Dec;1(2):129–133. doi:10.1007/s13539-010-0014-2. [https://pubmed.ncbi.nlm.nih.gov/21475695/]
  3. Volpi E, Campbell WW, Dwyer JT, et al. Is the optimal level of protein intake for older adults greater than the RDA? J Gerontol A Biol Sci Med Sci. 2013;68(6):677–681. doi:10.1093/gerona/gls229. [https://pubmed.ncbi.nlm.nih.gov/23183903/]
  4. Bauer J, 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;14:542–559. doi:10.1016/j.jamda.2013.05.021. [https://pubmed.ncbi.nlm.nih.gov/23867520/]
  5. U.S. Department of Agriculture. Dietary Guidelines Advisory Committee Report, 2010. [https://www.dietaryguidelines.gov/sites/default/files/2019-05/2010DGACReport-camera-ready-Jan11-11.pdf]
  6. Paddon-Jones D, et al. Role of dietary protein in the sarcopenia of aging. Am J Clin Nutr. 2008;87:1562S–1566S. doi:10.1093/ajcn/87.5.1562S. [https://pubmed.ncbi.nlm.nih.gov/18469288/]
  7. Luiking Y C, Deutz N. E. P., Memelink R, et al. Postprandial muscle protein synthesis is higher after a high-whey, leucine-enriched supplement than after a dairy-like product in healthy older people. Nutr J. 2014;13:9. DOI: 10.1186/1475-2891-13-9. [https://pubmed.ncbi.nlm.nih.gov/24450500/]
  8. U.S. Department of Agriculture. FoodData Central. Leucine content of common foods. https://fdc.nal.usda.gov.
  9. Volpi E, et al. Leucine supplementation chronically improves muscle protein synthesis in older adults consuming the RDA for protein.

    Clin Nutr. 2012;31(4):512–519. DOI: 10.1016/j.clnu.2012.01.005 [https://pubmed.ncbi.nlm.nih.gov/22357161/]
  10. Norton LE, Wilson GJ, Layman DK, et al. Leucine content of dietary proteins is a determinant of postprandial skeletal muscle protein synthesis in adult rats. Nutr Metab (Lond). 2012;9:67. DOI: 10.1186/1743-7075-9-67. [https://nutritionandmetabolism.biomedcentral.com/articles/10.1186/1743-7075-9-67]

 

 

 

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