As food and nutrition expert Dr. Wendeline Jones says, uncovering the full impact of dietary protein on human health is critical to not only extending our lifespans, but also improving our enjoyment of life.
A new study finds that multiple health conditions influenced by protein warrant further investigation, urging nutrition scientists to expand protein research beyond muscle maintenance and strength as we age.
The nutrition experts who authored the study praised the significant advances in understanding dietary protein and muscle over the past 30 years and encouraged future research to evaluate how to optimize protein intake throughout life to promote health and well-being. The Institute for the Advancement of Food and Nutrition Sciences (IAFNS) supported this research because generating science and evidence to promote health and well-being is core to its mission.
Historically, measurements of muscle protein synthesis have led to recommendations for the quality, quantity, source, and timing of protein intake to enhance muscle health in an aging population.
For example, past studies of free amino acids, protein-containing foods, or mixed meal intake have led to recommendations that advocate for evenly distributing protein intake between meals and how much protein to consume after each meal and exercise. However, nutrition experts say it is a target-rich environment that warrants more research on a variety of other health conditions that protein influences.
Refocusing: Beyond Muscle
Instead of focusing on the minimum protein intake required to maintain muscle, scientists can now define protein intake that more broadly optimizes health across the lifespan. The paper states that future protein research should include filling knowledge gaps in areas such as frailty, weight management, and cardiometabolic health.
The article was published in a recent issue of the peer-reviewed journal Advances in Nutrition and was supported by the IAFNS Protein Committee. While muscle maintenance and enhancement are key, shifting the focus to other related or disease-specific outcomes is an important step in refocusing the field, especially in light of recent studies on the effects of dietary protein on endpoints such as cardiovascular disease, frailty, type 2 diabetes, osteoporosis, and obesity.
Currently, there is a great deal of interest in protein intake, especially in relation to obesity. Protein intake can increase satiety after a meal by enhancing the secretion of appetite-regulating hormones such as glucagon-like peptide-1. Specific amino acids (i.e., leucine, lysine, threonine, and tryptophan) may have a greater effect on appetite hormones than others.
Protein sources such as whey, casein, soy, or pea may also affect satiety, suggesting that specific amino acids play a role in potential appetite responses. Some other studies suggest that the food matrix is also important, with solid foods generally more satiating than protein-rich beverages. Given that multiple adverse health outcomes have been associated with obesity, identifying causal relationships warrants further exploration.
The authors also suggest that frailty research could advance outcomes measures related to healthy lifespan. Assessing frailty using a continuum, while benchmarking and using validated measures, would allow researchers and clinicians to intervene in older adults who may be more frail before they have significant functional limitations.
In this area, it would be beneficial to combine multiple mobility measures, including self-report, laboratory-derived measures, and daily living measures through new wearable devices that can capture real-time information. Integrating these mobility assessment modalities would provide a more comprehensive view of how dietary protein, activity, or a combination of interventions affect patient function. The paper provides a roadmap for future research into a variety of health conditions that protein affects, beyond frailty and bone health.
A new science of healthy lifespan
The authors say that a broader focus on a variety of symptoms and health conditions could extend so-called “healthspan.” Healthy lifespan is defined as the amount of time a person is in good health, free of chronic disease and disability. It is intended to measure health, not just longevity.
The recommended dietary allowance (RDA) for protein is 0.8 grams per kilogram of body weight per day. The authors encourage research into how to determine optimal rather than minimum protein intake, which could impact a variety of health outcomes and extend healthy lifespan in populations. This could enhance the potential to positively impact health outcomes through interventions across the lifespan. For example, altering the amount, quality, and source of dietary protein (i.e., amino acids, isolated protein, protein-rich foods, or protein in mixed meals) could positively impact insulin sensitivity, cardiovascular disease, appetite, obesity, osteoporosis, and fracture risk.
Protein and Extended Healthy Lifespan
The authors conclude, “As the field shifts its focus toward elucidating the role of dietary protein in supporting and maintaining human health across the lifespan, past findings provide a foundation for innovative thinking and ways to continue to build an evidence base to best support future public health policy guidance and nutrition programs.”
Advancing dietary protein science will have major benefits in extending healthy lifespan. By improving our understanding of the role of protein and specific amino acids in cardiometabolic health, frailty prevention, bone health, and weight management, protein intake can be optimized to improve quality of life for all.
Related topics: