Effects of Bovine Lactoferrin on the Maintenance of Respiratory and Systemic Physical Conditions in Healthy Adults—A Randomized, Double-Blind, Placebo-Controlled Trial

Objectives: We investigated the effects of bovine lactoferrin (LF) on the maintenance of the respiratory and systemic physical conditions. Methods: A randomized, double-blind, placebo-controlled trial was conducted. Healthy adults at Kyushu University of Health and Welfare ingested a placebo or bovine LF (200 mg/day) for 12 weeks. The primary endpoints were the total respiratory and systemic symptom scores. The secondary endpoint was the activity of plasmacytoid dendritic cells (pDCs) in peripheral blood. Results: A total of 157 subjects were randomized (placebo, n = 79; LF, n = 78), of whom, 12 dropped out. The remaining 145 participants were included in the full analysis set (placebo group, n = 77; LF group, n = 68). The total scores for respiratory and systemic symptoms during the intervention were significantly lower in the LF group than in the placebo group. The expression of CD86 and HLA-DR on pDCs was significantly higher in the LF group than in the placebo group at week 12. Adverse events were comparable between the groups, and no adverse drug reactions were observed. Conclusions: These results suggest that orally ingested LF supports the normal immune system via maintaining pDC activity, and maintains respiratory and systemic physical conditions in healthy adults.