Environmental and Physiological Influences on Human Natural Killer Cell Activity in Relation to Good Health Practices

We examined the association of natural killer (NK) cell activity with a number of life style factors by a cross‐sectional analysis on 2892 Japanese individuals. The following habits were found to be associated with increased NK activity: 1) alcohol drinking (males, P<0.05), 2) not smoking cigarettes (males and females, P<0.001), 3) increased intake of green vegetables (females, P<0.001), 4) increased intakes of meat, milk, dairy products, and soyabean products (males, P<0.01), 5) daily workload of less than 3 hours per day (females, P<0.05), 6) regular meals (females, P<0.05), 7) regular sleep of more than 7 hours (females, P<0.05), 8) proper body weight. In addition, systolic blood pressure showed a positive correlation with NK activity (P< 0.001), while proportion of helper/ inducer (OKT4(+)) T cells and fraction of β‐globulin showed negative correlations (P< 0.001). We thus found that the living habits associated with increased NK activity were consistent with generally accepted good health practices, except alcohol drinking.