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Objectives and questions: Leukocyte-poor platelet-rich plasma (LP-PRP) is frequently applied in orthopedic and sports medicine; however, reported clinical outcomes remain inconsistent. One key factor underlying this heterogeneity is the substantial interindividual variability in PRP composition. Beyond known demographic factors, lifestyle-related exposures such as alcohol and caffeine consumption may influence platelet biology, leukocyte distribution, and inflammatory signaling. Both have been reported to affect platelet activation, cytokine release, and growth factor levels; however, their impact on PRP composition has not been systematically examined. This study aimed to assess whether alcohol and caffeine consumption are associated with differences in the cellular and molecular composition of LP-PRP.

Material and methods: In this prospective observational study, 103 healthy volunteers were enrolled. Participants were stratified based on self-reported alcohol and caffeine consumption. Whole blood and LP-PRP samples were analyzed for platelet and erythrocyte counts, leukocyte subpopulations, and LP-PRP–to–whole blood platelet concentration ratios. Additionally, concentrations of interleukin-6 (IL-6), insulin-like growth factor-1 (IGF-1), platelet-derived growth factor-BB (PDGF-BB), and hepatocyte growth factor (HGF) in LP-PRP were quantified by enzyme-linked immunosorbent assay (ELISA). Between-group comparisons were performed using the Mann–Whitney U test or chi-square test, as appropriate (p < 0.05).

Results: The study population consisted of 48.5% women and 51.5% men, with a mean age of 24.7 ± 4.4 years and a mean body mass index (BMI) of 23.4 ± 4.1 kg/m². Groups stratified by alcohol and caffeine consumption did not differ significantly in age, sex, or BMI. The prepared LP-PRP was almost erythrocyte-depleted and exhibited low leukocyte concentrations, with a mean LP-PRP–to–whole blood platelet ratio of 2.08 ± 0.34. Platelet concentration and LP-PRP platelet enrichment ratio were not significantly associated with alcohol and caffeine consumption. In addition, alcohol consumption was not associated with differences in IL-6 and growth factor concentrations in LP-PRP. However, habitual caffeine consumption was significantly associated with the molecular composition of LP-PRP, with significant differences observed for IL-6 and HGF.

Discussion and conclusions: Caffeine intake but not alcohol consumption was associated with the molecular composition of LP-PRP. Given the immunomodulatory and regenerative relevance of IL-6 and HGF, the present findings suggest that habitual caffeine intake may represent a relevant preanalytical source of biological variability in PRP preparations. However, owing to the observational design of this study, controlled interventional trials incorporating standardized exposure protocols and clinical outcome measures are warranted to clarify the causal relevance and therapeutic implications of caffeine intake in PRP-based musculoskeletal treatments.