NTRK2 and major depressive disorder: Plasma analysis before and after consumption of rosemary tea (5 g dry weight once daily) by healthy volunteers for 10 days revealed significantly higher concentrations of a reliable biomarker of depression, the brain-derived neurotrophic factor (BDNF), an effect that may be related to its signalling through the neurotrophic tyrosine kinase receptor 2 (TRKB), which is essential for potential antidepressant actions [48,49].