Saffron
Saffron is a plant with purple or white flowers and aromatic stigmas used as a seasoning in food. It is rich in antioxidants and studies have shown [14] that it may be effective in improving symptoms of depression. In particular, it has been found to increase the levels of serotonin in the brain. Serotonin is a neurotransmitter that improves mood, among other things. It is not clear how this process works, but it is thought that saffron inhibits serotonin reuptake and lets the neurotransmitter remain in the brain for longer periods.
This review of studies [15] found that treating adults who suffer from major depressive disorder with saffron improved symptoms of depression and was more effective than placebo treatments. Saffron supplements were also found to be about as effective as antidepressants.
While there are positive effects associated with using saffron supplements for depression, more studies are needed on the subject. Consuming high doses of saffron may also cause significant side effects [16].