The Association Between Dietary Fat Intake and Mild Cognitive Impairment in Japanese Men and Women: The Toon Health Study

Previous studies have shown that dietary fatty acid intake is associated with the risk of developing dementia. However, its association with mild cognitive impairment (MCI) remains controversial. Therefore, we aimed to examine the association between dietary fatty acid intake and MCI in an older Japanese population. We included 1144 participants aged 60 or older who participated in the Toon Health Study in 2014–2018 in the analysis. Dietary fatty acid intake was estimated using food frequency questionnaires (FFQs). MCI was assessed using the Montreal Cognitive Assessment in Japanese (MoCA-J) and defined as an MoCA-J score below 26. The multivariable-adjusted odds ratio (OR) and 95% confidence interval (CI) were calculated using logistic regression. We determined that 430 of the participants had MCI. Intake levels of polyunsaturated fatty acids (PUFAs), n-3 and n-6, fatty acids, and saturated fatty acid/PUFA ratio (SFA/PUFA) were not significantly associated with MCI. The multivariable-adjusted ORs (95%CI) for MCI in the highest quartile of PUFA, n-3 and n-6 fatty acid, and SFA/PUFA intake were 0.79 (0.55, 1.14, p for trend = 0.29), 0.96 (0.59, 1.54, p for trend = 0.85), 0.81 (0.56, 1.16, p for trend = 0.34), and 0.85 (0.59 1.22, p for trend = 0.24) compared with the lowest quartiles, respectively. SFA was significantly associated with lower odds of developing MCI. The multivariable-adjusted OR (95%CI) for MCI in the highest quartile of SFA intake compared with the lowest quartile was 0.63 (0.43, 0.93, p for trend = 0.03). Conclusions: SFA intake was inversely associated with MCI, while intake of PUFAs, including n-3 and n-6 fatty acids, was not associated with MCI. Further investigation is required to clarify these associations.