Abstract: Milk fat globule membrane (MFGM) contains bioactive lipids and glycoproteins that may support mucosal immunity and reduce the risk of post-exercise infection. Experimental and clinical studies indicate that MFGM can modulate inflammatory responses and support epithelial integrity, suggesting a potential role in host defence. However, evidence for these effects in physically active populations remains limited and inconsistent. Purpose: This study investigated whether 12 weeks of daily MFGM-rich whey protein supplementation modulates salivary immune markers. Methods: In a double-blind, randomized design, participants (n = 13; PLA = 8, MFGM = 5) consumed either an MFGM-enriched whey protein supplement or an isoenergetic, macronutrient-matched control for 12 weeks. Saliva samples were collected at baseline (T0), week 4 (T4), week 8 (T8), and week 12 (T12) to assess osmolality, lysozyme activity (absolute, osmolality-adjusted, and secretion rate), and immunoglobulin A (IgA) concentration (absolute, osmolality-adjusted, and secretion rate). Results: Absolute lysozyme activity remained stable (p = .767), and osmolality-adjusted lysozyme showed no significant time or group effects (p = .278). In contrast, lysozyme secretion rate decreased significantly over time (F(1.59, 17.45) = 9.59, p = .003, ηp² = .452), independent of supplementation. Absolute IgA concentration (p = .626) and secretion rate (p = .403) did not change significantly, and no time × group interaction effects were detected (p = .495). However, osmolality-adjusted IgA was significantly lower in the MFGM group (F(1, 11) = 8.59, p = .014, ηp² = .439), though this difference was already present at baseline. Self-reported illness incidence did not differ between groups across the intervention period. Twelve weeks of MFGM-rich whey protein supplementation did not significantly influence mucosal immune function or reduce illness incidence in physically active adults. While a significant reduction in lysozyme secretion rate was observed over time, this effect was unrelated to supplementation. Future studies should employ larger sample sizes, longer intervention periods, and broader immune assessments to clarify the potential immunomodulatory role of MFGM in active populations.
Lilliana Folan (Sat,) studied this question.