BATON ROUGE — Researchers at LSU's Pennington Biomedical Research Center have published a new perspective on how limiting dietary protein may promote healthy aging and extend lifespan.

The paper, published in the journal Cell Metabolism, was authored by Dr. Chris Morrison, Dr. Sora Kim and Dr. Sangho Yu. It argues that the effects of protein restriction, including changes in metabolism, glucose regulation, energy expenditure, growth and food preferences, should be seen as interconnected parts of a broader response to protein scarcity rather than isolated biological pathways.

"The question that drives our work is deceptively simple: How does an animal know it isn't getting enough protein?" said Morrison, John S. McIlhenny endowed professor in nutritional neuroscience and associate executive director for basic science. "After years of work, we now believe the brain plays a critical role in coordinating the body's response to protein restriction and that these same adaptive changes turn out to extend lifespan."

Protein restriction is increasingly recognized as a potential driver of longevity independent of calorie restriction, with lifespan-extending effects demonstrated across multiple species.

Much of aging research has focused on the "Hallmarks of Aging," a set of 12 cellular processes associated with aging that represent target opportunities for anti-aging therapies.

Pennington Biomedical's Neurosignaling Laboratory has studied protein restriction from a whole-organism perspective, examining how organisms adaptively change growth, food preference or metabolism when faced with reduced protein availability. That work led to the discovery that the hormone FGF21 acts in the brain to help coordinate the body's response to protein scarcity, with FGF21 required for the effects of protein restriction on lifespan, metabolism and food preferences.

Similar mechanisms exist in other species. Gut-derived signals in fruit flies also communicate nutritional status to the brain, impacting both food preferences and longevity.

"Viewing protein restriction as a coordinated physiological state shifts the focus toward how cellular nutrient sensing, endocrine signaling, neural circuits and tissue physiology work together," the authors wrote. "These individual pathways are best understood as components of a larger physiological system whose coordinated engagement ultimately determines the response to protein restriction."

The framework also points toward a potential path for personalized dietary interventions. If the benefits of protein restriction depend on activating a coordinated adaptive response, measurable changes such as FGF21 responsiveness, metabolic changes or shifts in protein and essential amino acid appetite could potentially serve as biomarkers of that response.

"Protein appetite need not itself cause the health benefits of protein restriction, but its magnitude may provide an observable readout of how effectively the broader adaptive program has been engaged," the authors wrote. Such measures could eventually help explain differences in response based on sex, genetics, age and metabolic health.