Association Between the Dutch Mediterranean-Dietary Approaches to Stop Hypertension Intervention for Neurodegenerative Delay (MIND-NL) Diet Adherence and Systemic Tryptophan Metabolites in Older Adults at Risk of Cognitive Decline: An Exploratory Study.

Tryptophan (TRP) metabolism is emerging as a focus of investigation in Alzheimer's disease research. In addition, diet might impact TRP's metabolic fate. The aim of this study was to explore the association between adherence to the Dutch Mediterranean-Dietary Approaches to Stop Hypertension (DASH) Intervention for Neurodegenerative Delay (MIND-NL) diet and systemic TRP metabolite levels and their related ratios in older adults at risk of cognitive decline. Data of the HELI multidomain lifestyle intervention study (n = 82) were used. Dietary intake data (FFQ) and fasted plasma levels were collected at baseline and 26 weeks follow-up. Bivariate Latent Change Score Models (LCSMs) were applied to assess both level-level and change-change associations, adjusted for lifestyle factors. Changes in MIND-NL diet adherence were significantly inversely associated with changes in the kynurenine:large neutral amino acids ratio (path coefficient -0.457, SE:0.206, p = 0.03) and kynurenine:tryptophan ratio (path coefficient -0.558 SE:0.235, p = 0.02). In addition, MIND-NL diet adherence was associated with lower levels of the neurotoxic metabolite quinolinic acid (path coefficient -0.186, SE:0.0700, p = 0.008), but within the crude model only. Our findings suggest that greater adherence to the MIND-NL diet may contribute to decreased activation of the kynurenine pathway.