Dietary Patterns Are Associated with Blood Cell Profiles and the Molecular Composition of Platelet-Rich Plasma

Background/Objectives: Platelet-rich plasma (PRP) is increasingly used in musculoskeletal medicine. Variability in PRP composition, driven by preparation- and donor-related factors, is considered a major contributor to inconsistent clinical outcomes. This study investigated whether habitual dietary patterns are associated with the cellular and molecular composition of leukocyte-poor PRP (LP-PRP). Methods: In this cross-sectional study, 75 healthy adults (25 vegans, 25 vegetarians, and 25 omnivores) who adhered to their dietary patterns for ≥6 months were enrolled. LP-PRP was prepared by a standardized protocol. Cell profiles were quantified in whole blood and LP-PRP; LP-PRP proteins (IL-6, IGF-1, HGF, and PDGF-BB) were measured by ELISA. Group differences, correlations, and multivariable regressions were performed. Results: Whole blood differed by diet with respect to total leukocytes, lymphocytes, and basophils, while platelet and erythrocyte counts did not. In LP-PRP, platelet enrichment ratios and leukocyte counts were comparable across diets. IL-6 in LP-PRP was lower in vegans vs. omnivores (p = 0.017); the Animal-Based Diet Score correlated positively with LP-PRP IL-6 and remained independently associated in regression (β = 0.35, p = 0.004). While IGF-1, HGF, and PDGF-BB did not differ between dietary groups, intake-based analyses revealed associations between specific dietary components and LP-PRP proteins; notably, the fruit and vegetable intake correlated inversely with PDGF-BB, and platelet–growth factor coupling was most pronounced among omnivores. Conclusions: Dietary patterns were associated with selected molecular components of LP-PRP—most consistently IL-6—while cell counts remain largely unchanged. However, interventional studies are needed to establish causality and determine whether dietary modification can influence clinical outcomes.