Beyond protein quantity and quality: does phosphorus matter?

PURPOSE OF REVIEW: Dietary protein manipulation, including protein restriction and replacing animal proteins with plant-based alternatives, has gained considerable attention because of its potential benefits. However, these dietary strategies alter phosphorus intake, bioavailability, and the phosphorus-to-protein ratio as plant-derived phosphorus is less bioavailable; whereas animal-derived phosphorus is more readily absorbed. This review highlights the role of phosphorus in the regulation of processes commonly attributed to dietary protein, emphasizing energy balance, body weight, growth, and protein metabolism in healthy subjects. RECENT FINDINGS: Recent human evidence suggests that phosphorus supplementation may influence satiety, energy intake, diet-induced thermogenesis, and body weight regulation. Animal studies further support a role for phosphorus availability in growth. Moreover, phosphorus availability supports ATP production, which is essential for protein turnover. Nevertheless, direct evidence demonstrating that dietary phosphorus modifies protein synthesis or degradation remains scarce. SUMMARY: Phosphorus may be an underrecognized factor accompanying changes in dietary protein quantity and source. Its effects on energy metabolism, growth, and cellular bioenergetics support a potential interaction with protein metabolism. Controlled studies independently manipulating protein and phosphorus are needed to determine whether phosphorus availability modifies metabolic and anabolic responses to dietary protein.