Associations of higher fish consumption and lifestyle with lower monocyte/HDL-C ratio in a Japanese population: Implication for the anti-atherosclerotic effect of fish consumption

Background: High fish consumption may be involved in lowering inflammation, resulting in the suppression of atherosclerotic cardiovascular disease (ASCVD) development. The monocyte/high-density lipoprotein cholesterol (HDL-C) ratio (MHR) is reported as a novel inflammatory marker of the development of atherosclerosis. We investigated the relationship between fish consumption, MHR, and lifestyle behaviors and explored the foundation of risk stratification of ASCVD using serum HDL-C, MHR, and fish consumption. Methods: We conducted a cross-sectional study among 6841 adults at the Health Planning Center of Nihon University Hospital between April 2019 and March 2020. We calculated the amount of fish consumption based on Japan's National Nutrition Survey results. Results: The median (interquartile range) fish consumption was 111.4 (67.2/169.2) g per week. As fish consumption increased, MHR decreased significantly (p < 0.0001). Multivariate linear regression analysis identified increased fish consumption as an independent negative determinant of a decreased MHR (β = −0.050, p < 0.0001). Additionally, healthier lifestyle behaviors (sleep duration and cigarette smoking habit) were also significantly associated with MHR (β = −0.025, p = 0.027 and β = 0.146, p < 0.0001, respectively). Furthermore, risk stratification of ASCVD could be developed by combining the HDL-C level and fish consumption with the MHR, indicating that even with similar HDL-C levels, higher MHR and lower fish consumption are associated with a higher risk of ASCVD. Multi-logistic regression analysis with the MHR quartile as an independent variable also showed that the increase in quartile was associated with the exacerbation of visceral obesity and glucose/lipid markers. Conclusions: A higher fish consumption may be associated with a lower MHR as well as healthier lifestyle behaviors. Moreover, we proposed the concept of risk stratification through relationships with MHR, HDL-C, and fish consumption to reduce ASCVD risk. Further studies are required to dissect the causal relationships between these results.