Onion significantly decreased the levels of total cholesterol within each group ; however , these changes were stronger in the high-onion group ( weighted mean differences [ WMD ] : -5.60 [ 95 % confidence interval [ CI ] : -9.16 , -2.03 ] ; P = 0.003 ) than in the low-onion group ( WMD : -6.42 [ 95 % CI : -11.97 , -0.87 ] ; P = 0.025 ) .