Protein as We Age

Protein As We Age

By: Jeremy Partl, Registered Dietitian

By 2060, nearly one-quarter of the US population (~94 million) will be above the age of 65.[1] With age comes wisdom, certainly, but also a host of physical effects that we have to deal with—baldness for men, menopause for women, and the loss of muscle mass and strength for all. It is approximated that after the age of 50, muscle wasting occurs at a rate of 1% to 2% per year.[2]

The end result? The loss of strength and muscle wasting contributes significantly to weakness, disability, increased hospitalization, immobility, and loss of independence.[3] Even worse, the extent of muscle wasting and frailty often predicts earlier onset of adverse outcomes as well as a poorer prognosis of recovery and survival. Strength and durability go hand in hand, and the older we get, the more important the battle against muscular atrophy becomes. 

While this is not going to be the main focus of the article, it would be hard not to mention the rapid and powerful effects of resistance training on strength and muscle mass. In fact, a single bout of resistance training is associated with a two-to-threefold increase in muscle protein synthesis, the signal for muscle building.[4] 

Here at BLOC, we often see many seniors continue to be obsessed with “weight loss” when they should become obsessed with gaining or preserving muscle mass. Again, we already have plenty of articles that discuss the use of strength training on maintaining physical function, strength, and even muscle mass. Therefore, my focus here is to cover the nutrition aspect of keeping muscle mass on your frame as you age and show you why your diet is not to be neglected.

Tailoring Your Nutrition as You Age

When it comes to building and maintaining muscle mass, it’s important to remain on the positive side of muscle protein synthesis and breakdown (MPS and MPB). All muscle proteins degrade over time; when they break down, they become the amino acids that form the building blocks of new proteins. Within a muscle cell, when the rate of synthesis exceeds the rate of breakdown, your muscles grow. Shifting the balance toward protein synthesis results in the addition of muscle protein, whereas shifting the balance toward protein degradation results in the loss of muscle protein.[5]

Besides vigorous physical activity like strength training, consumption of adequate energy (i.e., food), especially dietary protein is key to outweighing the higher rates of catabolic stressors that occur as we age. 

Firstly, it is important that total calorie intake is kept up to minimize any weight loss. There are many reasons why calorie intake could go down during aging, including (but not limited to) low appetite, dentition and other medical conditions, functional limitations that limit shopping, lack of knowledge on food preparation, and food insecurity.[6] 

While it’s generally accepted that older individuals need fewer calories to maintain their weight (since they tend to move and exercise less and carry less muscle), staying active changes that game slightly. Due to the increased metabolic demands from strength training and theoretical maintenance of muscle mass, calorie needs should be roughly similar.

An active person expends more energy and consumes more food (including protein), and is, therefore, less likely to be consuming marginal amounts of protein, as usually there is a minimal or no increase in amino acid and nitrogen requirements due to the physical activity. In contrast, when energy expenditure is low, food consumption falls, and any imbalance between amino acid requirements and intake will be more likely to occur.[7] So, the first important step to good nutrition as you age is to maintain your caloric needs. If you are struggling to eat enough, make sure that you are adding in daily exercise and movement to help stimulate your appetite. While calorie intake is important, one of the most important factors to consider is protein intake. Unlike calorie and energy needs, this area has been studied extensively. 

While there are numerous factors that can result in a drop in overall protein and calorie intake (which are summarized in the figures below), one of the most notable changes that occurs actually happens physiologically. 

As we age, a phenomenon commonly referred to as “anabolic resistance” occurs, whereby a higher dose of protein is required to achieve the same muscle-building response as a younger person gets from a lower dose of protein.[8] Whereas it is generally accepted that ~20-25 grams of high-quality protein is enough protein to stimulate maximal rates of MPS in younger individuals (especially in the context of the post-exercise period), it has been proposed that older individuals need up to 40 grams to get the same maximal response.[9]

Several factors have been theorized to cause this phenomenon, including[10,11]

• Impairments in protein digestion and amino acid absorption
• Postprandial muscle tissue perfusion
• Reduced muscle uptake of dietary amino acids 
• Decreases in the amount or activation of anabolic signaling proteins
• Reduced physical activity
• Insulin resistance
• Inflammation

Therefore, unlike the 0.8 g/kg/day recommended for the general population, it is now considered consensus that a higher recommended daily amount be consumed by older individuals, with recommendations of 1.2- 2g/kg/day being recommended by the PROT-AGE Study Group.[12]  

In addition to total protein intake, it is important to consider the timing of protein consumption to maximize the benefits of the ingested protein and overcome any “anabolic resistance.” Just as with younger individuals, it is important to spread protein intake out generally evenly throughout the day, due to the cyclical rise and fall of amino acids in the bloodstream (as depicted below).[13] 

According to the latest position stand from the International Society of Sports Nutrition on protein intake:[14]

• Acute protein doses should strive to contain 700–3000 mg of leucine and/or a higher relative leucine content, in addition to a balanced array of the essential amino acids (EAAs).
• These protein doses should ideally be evenly distributed, every 3–4 h across the day.

This same principle applies to older individuals as well. Additionally, there are two other suggestions on improving dietary protein intake by the muscle to overcome this “anabolic resistance.”

1. Studies have shown exercise augments the body’s response, allowing more of the ingested protein-derived amino acids to be used for MPS in aging muscles.[15]
2. Ingesting protein prior to sleep may increase overnight muscle protein synthesis rates.[16]

Summarizing the above, one 2019 paper suggests that older individuals should “ingest at least 1.2 g of protein/kg/day, evenly distribute their meals into protein boluses of 0.40 g/kg, and consume protein within 2 hours of retiring for sleep.”[17]

From Theory to Practice

While this seems all well and good, with larger protein quantities being needed in a single meal and the previously mentioned factors causing decreased intakes of food, it may be difficult for older people to actually meet these requirements to keep muscle mass on. Even with a perfect understanding of the physiology, we must be able practically to put these suggestions into practice.

One of the biggest things that older individuals can do is make sure that they are consuming the equivalent of ~6-8 ounces (~40-50 grams) of animal-based protein per meal (red meat, dairy, pork, poultry, seafood, eggs, etc.). Evidence indicates that protein intake from animal sources has been associated with increased muscle mass with aging.[18]

Given that the anabolic potential of protein varies based on essential amino acid content, digestibility, and absorption, these findings are not surprising. Gram for gram, animal proteins are typically more anabolic than equivalent doses of plant-based proteins (beans and legumes, grains, etc.). For example, animal-based proteins generally are greater sources of lysine, leucine, and methionine relative to plant-based sources; thus, even larger amounts of plant-based protein are needed to have a similar influence on muscle size compared with animal-based proteins.[19]

One additional strategy experts recommend to overcome this disparity is to consume additional specific amino acids such as leucine via supplementation when “suboptimal” doses of protein are consumed.[20]

Again, while protein timing in healthy and young individuals seems not to make a huge difference, ensuring that protein is consumed post-exercise may help to improve protein absorption.[21]

Finally, theoretically, the use of protein supplements by older individuals would be a great strategy to boost calorie and protein intake to allow them to meet both energy and protein needs (as they can be dense and concentrated sources). For example, a 2018 paper found that protein supplementation improved physical performance and muscle mass in older individuals.[22] While they could consume the same protein powders as younger individuals, there are now higher protein versions of the typically consumed Boost and Ensure nutritional beverages. 

Wrapping Up

It is true that your nutritional needs change as you age. Contrary to some popular beliefs, the older you get, the more protein you need, and the more you probably need to pay attention to when and how you include that protein in your diet. Also, the catalyst for maintaining your caloric needs and, by extension, your muscle mass is physical exercise. We prefer barbell-based strength training for older adults due to its enormously positive effects on muscle protein synthesis. Investing in muscle mass and good nutritional habits now—no matter your age—is very likely to help you out later in life. 

Resources

[1] Vespa, J., Armstrong, D. M., & Medina, L. (2018). Demographic turning points for the United States: Population projections for 2020 to 2060. Washington, DC: US Department of Commerce, Economics and Statistics Administration, US Census Bureau.

[2] Baumgartner, R. N., Koehler, K. M., Gallagher, D., Romero, L., Heymsfield, S. B., Ross, R. R., … & Lindeman, R. D. (1998). Epidemiology of sarcopenia among the elderly in New Mexico. American journal of epidemiology, 147(8), 755-763.

[3] Strasser, B., Volaklis, K., Fuchs, D., & Burtscher, M. (2018). Role of dietary protein and muscular fitness on longevity and aging. Aging and Disease, 9(1), 119.

[4] Strasser, B., Volaklis, K., Fuchs, D., & Burtscher, M. (2018). Role of dietary protein and muscular fitness on longevity and aging. Aging and Disease, 9(1), 119.

[5] Hackney, K. J., Trautman, K., Johnson, N., Mcgrath, R., & Stastny, S. (2019). Protein and muscle health during aging: benefits and concerns related to animal-based protein. Animal Frontiers, 9(4), 12-17.

[6] Deutz, N. E., Bauer, J. M., Barazzoni, R., Biolo, G., Boirie, Y., Bosy-Westphal, A., … & Singer, P. (2014). Protein intake and exercise for optimal muscle function with aging: recommendations from the ESPEN Expert Group. Clinical nutrition, 33(6), 929-936.

[7] Nowson, C., & O’Connell, S. (2015). Protein requirements and recommendations for older people: a review. Nutrients, 7(8), 6874-6899.

[8] Ni Lochlainn, M., Bowyer, R. C., & Steves, C. J. (2018). Dietary protein and muscle in aging people: the potential role of the gut microbiome. Nutrients, 10(7), 929.

[9] Strasser, B., Volaklis, K., Fuchs, D., & Burtscher, M. (2018). Role of dietary protein and muscular fitness on longevity and aging. Aging and Disease, 9(1), 119.

[10] Strasser, B., Volaklis, K., Fuchs, D., & Burtscher, M. (2018). Role of dietary protein and muscular fitness on longevity and aging. Aging and Disease, 9(1), 119.

[11] Morton, R. W., Traylor, D. A., Weijs, P. J., & Phillips, S. M. (2018). Defining anabolic resistance: implications for delivery of clinical care nutrition. Current opinion in critical care, 24(2), 124-130.

[12] Bauer, J., Biolo, G., Cederholm, T., Cesari, M., Cruz-Jentoft, A. J., Morley, J. E., … & Visvanathan, R. (2013). Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. Journal of the American Medical Directors Association, 14(8), 542-559.

[13] https://vive-nutrition.com/the-best-protein-article-ever/

[14] Jäger, R., Kerksick, C. M., Campbell, B. I., Cribb, P. J., Wells, S. D., Skwiat, T. M., … & Smith-Ryan, A. E. (2017). International society of sports nutrition position stand: protein and exercise. Journal of the International Society of Sports Nutrition, 14(1), 1-25.

[15] Yang, Y., Breen, L., Burd, N. A., Hector, A. J., Churchward-Venne, T. A., Josse, A. R., … & Phillips, S. M. (2012). Resistance exercise enhances myofibrillar protein synthesis with graded intakes of whey protein in older men. British Journal of Nutrition, 108(10), 1780-1788.

[16] Snijders, T., Trommelen, J., Kouw, I. W., Holwerda, A. M., Verdijk, L. B., & Van Loon, L. J. (2019). The impact of pre-sleep protein ingestion on the skeletal muscle adaptive response to exercise in humans: an update. Frontiers in Nutrition, 6, 17.

[17] Morton, R. W., Traylor, D. A., Weijs, P. J., & Phillips, S. M. (2018). Defining anabolic resistance: implications for delivery of clinical care nutrition. Current opinion in critical care, 24(2), 124-130.

[18] Lord, C., Chaput, J. P., Aubertin-Leheudre, M., Labonte, M., & Dionne, I. J. (2007). Dietary animal protein intake: association with muscle mass index in older women. The journal of nutrition, health & aging, 11(5), 383.

[19] Hackney, K. J., Trautman, K., Johnson, N., Mcgrath, R., & Stastny, S. (2019). Protein and muscle health during aging: benefits and concerns related to animal-based protein. Animal Frontiers, 9(4), 12-17.

[20] Churchward-Venne, T. A., Breen, L., Di Donato, D. M., Hector, A. J., Mitchell, C. J., Moore, D. R., … & Phillips, S. M. (2013). Leucine supplementation of a low-protein mixed macronutrient beverage enhances myofibrillar protein synthesis in young men: a double-blind, randomized trial. The American journal of clinical nutrition, 99(2), 276-286.

[21] Yang, Y., Breen, L., Burd, N. A., Hector, A. J., Churchward-Venne, T. A., Josse, A. R., … & Phillips, S. M. (2012). Resistance exercise enhances myofibrillar protein synthesis with graded intakes of whey protein in older men. British Journal of Nutrition, 108(10), 1780-1788.

[22] Park, Y., Choi, J. E., & Hwang, H. S. (2018). Protein supplementation improves muscle mass and physical performance in undernourished prefrail and frail elderly subjects: a randomized, double-blind, placebo-controlled trial. The American journal of clinical nutrition, 108(5), 1026-1033.