BDNF and psychotic disorder: High intake of fruit and vegetables, and low intake of saturated fat, has also been postulated to affect mental health via modulation of inflammatory pathways, epigenetics, the HPA axis, BDNF expression, tryptophan–kynurenine metabolism and gut microbiota (Marx et al., 2021), although further research is needed into this relationship in people with psychosis (Van Der Pols, 2018).