BDNF and depressive symptom measurement: From the perspective of depression, besides demonstrating a plethora of antioxidative and anti-inflammatory effects, polyphenols from the diet may regulate the activity of the HPA axis and normalize levels of glucocorticoids, stimulate BDNF production and neurogenesis, inhibit the activity of MAO isoforms, restore neurotransmitter balance, mitigate clinical symptoms, and improve cognitive deficits [175,183,184].