Higher fish consumption has been reported to be associated with a lower incidence of coronary artery disease. We hypothesized that a higher frequency of fish intake may be associated with lower peripheral white blood cell (WBC) counts, a marker of chronic inflammation, which is known to be involved in the development of atherosclerotic cardiovascular disease (ASCVD), and a healthy lifestyle. This cross-sectional study was conducted between April 2018 and August 2018 at the Health Planning Center of Nihon University Hospital in a cohort of 4105 apparently healthy subjects. The average frequency of fish intake was 2.3 ± 1.3 days per week. The WBC count decreased significantly as the frequency of fish intake (0–2 days, 3–4 days, or 5–7 days per week) increased (s < 0.0001). Multivariate linear regression analysis identified higher weekly frequency of fish intake as a significant independent determinant of a lower WBC count (β =  – 0.051, p = 0.001). Furthermore, as the weekly frequency of fish intake increased, the proportion of habitual cigarette smokers decreased (p = 0.021), that of subjects engaging in habitual aerobic exercises increased (p < 0.0001), and the weekly alcohol intake frequency increased (p < 0.0001). Moreover, the above-mentioned lifestyle behaviors were also independent determinants of the WBC count. These results suggest that a high frequency of fish intake might be associated with healthier lifestyle behaviors as well as lower WBC counts, and thus may both exert beneficial anti-inflammatory effects and represent a component of healthier lifestyle behaviors associated with a lower risk of ASCVD in Japanese. This association may be partially related to the preventive effects of a higher fish intake on ASCVD events.

UMIN (http://​www.​umin.​ac.​jp/​) Study ID: UMIN000039197 retrospectively registered 1 February 2020.