The effect of date seed powder supplementation on anxiety- and depression-like behaviours, sleep quality and tryptophan–kynurenine metabolism in patients with type 2 diabetes: targeting gut–brain axis

Recently, functional foods have been considered as an effective approach in management of type 2 diabetes mellitus. This trial aimed to evaluate the potential benefits of date seed powder (DSP) on inflammation anxiety- and depression-like behaviours, sleep quality and tryptophan (TRP)-kynurenine (KYN) metabolism in type 2 diabetes mellitus patients. In this trial, forty-three patients with type 2 diabetes were randomised to two groups: either 5 g/d of the DSP or placebo for 8 weeks. Depression, anxiety and stress scale, sleep quality, quality of life (QoL), levels of fasting blood glucose, endotoxin, anti-inflammatory/pro-inflammatory biomarkers, hypothalamus-pituitary-adrenal (HPA) axis-associated biomarkers (including brain-derived neurotrophic factor (BDNF)), KYN, TRP, cortisol and adrenocorticotropic hormone (ACTH) were assessed at baseline and after 8 weeks. An independent t test was used for baseline comparisons, while ANCOVA was used for post-intervention between-group comparisons. The results showed that supplementation with DSP significantly improved depression, anxiety and stress scale, sleep quality and QoL in comparison with placebo. In terms of biochemical parameters, the intervention group exhibited significantly reduced levels of endotoxin, and cortisol, KYN, KYN:TRP ratio as well as significantly elevated levels of IL-10, TRP concentrations and IL-10:IL-18 ratio compared to the placebo group. Changes in fasting sugar, C-reactive protein (hs-CRP), IL-18, ACTH, BDNF concentrations and cortisol:ACTH ratio were not different between groups. Supplementing with date seed may effectively improve anxiety- and depression-like behaviours, sleep quality and QoL by modulating metabolic endotoxemia, inflammation and HPA axis activity in patients with type 2 diabetes.