Effects of lactoferrin on infectious diseases in Japanese summer: A randomized, double-blinded, placebo-controlled trial

Abstract

Purpose: To investigate the effects of lactoferrin (LF) on infectious diseases in Japanese summer.

Methods: An intake of placebo, 200 mg, or 600 mg of LF were administered to healthy adults in Kyushu University of Health and Welfare for 12 weeks in a randomized, double-blinded, placebo-controlled parallel-group comparative trial. The primary endpoints were the prevalence and duration of infectious diseases and changes in immune parameters.

Results: Three hundred and ten subjects were randomized (placebo, n = 104; 200 mg, n = 103; 600 mg, n = 103). Twenty subjects were lost to the follow-up, leaving 290 for a full analysis set (n = 99; n = 95; n = 96). The duration (day) of total infectious diseases was shorter in the 200 mg group (2.0, p = 0.045) and 600 mg group (2.0, p = 0.010) than in the placebo group (3.0). The duration of summer colds was shorter in the 600 mg group (2.0, p = 0.036) than in the placebo group (3.0). No significant differences were observed in the prevalence of infectious diseases or changes in immune parameters. In exploratory investigations, changes in the neutrophil phagocytic capacity, cortisol concentrations, and T score of "Vigor/Activity" in the Profile of Mood States 2 were greater in the 600 mg group than in the placebo group, when analysis was done on the lower half groups at the baseline. Adverse events were similar in each group and none had a causal relationship with the intake of the test foods.

Conclusions: In summer, the intake of LF attenuates infectious diseases, including summer colds.

Keywords: Cortisol; Lactoferrin; Summer cold; Vigor/Activity.