Association between methionine cycle metabolite-related diets and mild cognitive impairment in older Chinese adults: a population-based observational study

Homocysteine (Hcy) and folate, involved in a common metabolic pathway supplying essential methyl groups for DNA and protein synthesis, have been found to be associated with cognitive function. Moreover, diet may influence methionine cycle metabolites (MCM) as well as mild cognitive impairment (MCI), but MCM-related dietary patterns are unclear in an older population.The study aimed to identify MCM-related dietary patterns of older Chinese adults, and examine their association with the prevalence of MCI in a large population-based study.This study included 4457 participants ≥ 60 years of age from the Tianjin Elderly Nutrition and Cognition Cohort study. Dietary data were collected using a valid self-administered food frequency questionnaire, and factor analysis was used to identify major dietary patterns in the population. MCM-based dietary patterns were derived using reduced rank regression (RRR) based on serum folate and Hcy as response variables.Compared with the participants in the lowest quartile of vegetarian pattern and processed foods pattern, the odds ratios (ORs) of MCI in the highest quartile were 0.72 (95% CI 0.53-0.98) and 1.39 (95% CI 1.03-1.88), respectively. In the MCM-based dietary patterns derived using RRR, the ORs for MCI for the highest quartile of MCM patterns I and II were 0.58 (95% CI 0.44-0.78) and 1.38 (95% CI 1.04-1.83), respectively, compared with participants in the lower quartile.Findings from this large population-based study suggested that adopting an MCM-related dietary pattern, especially avoiding processed foods, can decrease the occurrence of MCI.