Effects of Citrus unshiu Intake on Serum Brain-Derived Neurotrophic Factor Levels and Mood States: A Pilot Randomized Controlled Trial

Brain-derived neurotrophic factor (BDNF) is a critical mood regulator; increasing BDNF levels may help improve mood states. We conducted a pilot randomized controlled trial to investigate the effects of Citrus unshiu intake on serum BDNF levels and mood states. Healthy participants were assigned to an intake group [n=13; two C. unshiu fruits daily (106.9±37.2 g each)] or a non-intake group (n=13). Serum BDNF levels and mood states were assessed at Weeks 0, 4, and 8. In the primary analysis, a linear mixed-effects model revealed no significant group-by-time interaction contrast for serum BDNF levels, and no significant between-group differences were observed at any time point. Serum BDNF levels declined in the non-intake group over time, whereas an increase occurred from Week 4 to Week 8 in the intake group. In exploratory and unadjusted analyses, we examined within-group changes in serum BDNF levels. In the intake group, the change from Week 4 to Week 8 (median: +0.636 ng/mL) was significantly greater than that from Week 0 to Week 4 (median: −2.453 ng/mL). Based on the Profile of Mood States 2nd Edition results, between-group comparisons of change scores showed significant improvements in Depression-Dejection and Vigor-Activity scores in the intake group compared with the non-intake group. Within-group analyses demonstrated decreases in Depression-Dejection and Total Mood Disturbance and an increase in Vigor-Activity following C. unshiu intake. The findings of our preliminary study suggest that C. unshiu intake may be associated with attenuating the decline in serum BDNF levels and inducing modest favorable changes in certain mood domains.