NK cell activity of effector cells before and after the 8-week Chlorella supplementation. Mean ± SE, tested by paired t-test (intra group comparison) or independent t-test (intergroup comparison). There were no significant differences in the baseline values between the Chlorella group and the placebo group. *P <0.05, compared with the value at baseline in each group; ϕP <0.05, comparison of Δ change value between the Chlorella group and the placebo group. E: effector cells (peripheral blood mononuclear cells from subjects), T: target cells (K562 cells).