Collagen peptides from marine by-products: From waste to functional ingredients

The valorization of marine by-products represents a critical intersection of environmental sustainability and the burgeoning wellness industry. This review provides a comprehensive assessment of recent literature in the past five years concerning the production, bioactivity, and application of collagen peptides (CPs) derived from marine processing side streams. It critically examines the entire value chain, from the diverse vertebrate and invertebrate sources to the extraction and hydrolysis methodologies that dictate the final product's physicochemical and biological properties. A detailed analysis of the clinical evidence supporting the efficacy of marine CPs in dermatological, musculoskeletal, and bone health is presented, highlighting a clear hierarchy of validation. We also explore a spectrum of other promising bioactivities, including antioxidant and antihypertensive effects, which are primarily supported by preclinical data. Major challenges, such as inconsistent clinical outcomes, are deconstructed through a root cause analysis that links variability in raw materials and processing to a lack of product standardization. Finally, critical knowledge gaps were identified while proposing a future research trajectory focused on elucidating structure-function relationships, optimizing processing for targeted peptide profiles, and conducting methodologically robust clinical trials. The central idea is that this area of research is moving from the discovery of a valuable bioresource to precision to unlock its full potential as a source of evidence-based nutraceuticals. This review also underscores the industrial potential of marine collagen peptides in promoting sustainable bioprocessing and creating high-value nutraceuticals, aligning with circular economy goals.