How could diet affect PPD?

A healthy diet, i.e., a balanced diet that is rich in fruits and vegetables and low in processed foods, may help reduce the risk of perinatal depression. A 2015 systematic review found an association between poor or unhealthy diets and prenatal depression/stress. However, the postnatal evidence they reviewed was mixed.^[1] A 2019 review found an inverse association between a “healthy” diet and perinatal anxiety and depression.^[2] Finally, a 2020 systematic review noted an inverse association between healthy postpartum diet and postpartum depression.^[3] All three reviews concluded that more research is needed: more longitudinal studies with plenty of participants, as well as studies of specific dietary interventions.