Effects of Greek Yogurt Versus Whey Protein Supplementation on Markers of Bone Turnover and Inflammation in University Athletes: A 24-Week Intervention Study

The effects of Greek yogurt and whey protein supplementation on markers of bone turnover and inflammation were compared in university athletes over a competitive season. Participants (n = 32, 16 females) followed their habitual diets for an 8-week control period and were then randomly assigned to one of two trial arms: two servings per day of either 175 g of Greek yogurt (17 g protein) or isonitrogenous whey protein for a 16-week intervention period. Morning, fasting blood was collected at Weeks 0 (precontrol), 8 (postcontrol/preintervention), 16 (midintervention), and 24 (postintervention) and analyzed for osteocalcin, amino-terminal propeptide of Type I collagen, insulin-like growth factor 1, osteoprotegerin, C-telopeptides of Type I collagen, sclerostin, receptor activator of nuclear factor kappa-B ligand, tumor necrosis factor-alpha, interleukin 6, and interleukin 10. No main effects or interactions were found for markers of bone formation. In the Greek yogurt group, C-telopeptides of Type I collagen increased from pre- to postcontrol and returned to baseline concentrations postintervention while remaining stable throughout the study in whey protein (Time × Group interaction, p = .048). Receptor activator of nuclear factor kappa-B ligand increased from pre- to postcontrol (time effect, p = .014), returning to baseline by midintervention across groups. Males had higher sclerostin (sex effect, p = .021) and interleukin 10 (sex effect, p = .004) with no interactions. Interleukin 6 showed no main effects or interactions. Tumor necrosis factor-alpha increased pre- to postcontrol (time effect, p = .053) then decreased to baseline levels postintervention. Although protein supplementation, independent of source (wholefood or isolates), showed potential bone and inflammatory benefits during athletic training, it remains unclear whether these effects were solely attributable to the supplements.