High serum cholesterol concentrations are associated with the development of coronary heart disease. It has been reported that some cultures of Lactobacillus spp. actively take up cholesterol from laboratory media. In the present study, the abilities of ten probiotic lactic acid bacteria to assimilate cholesterol in broth medium, cream, and butter were tested and compared. The cholesterol reduction ratios of these human-origin bacteria were determined in MRS-THIO broth supplemented with 150 mu g/mL cholesterol. The amount of cholesterol assimilated by the bacteria was measured by gas chromatography. Cholesterol assimilation of these ten bacteria in broth was found to be similar to assimilation in cream. Two of these ten bacteria (Lactobacillus maltaramicus AC 3-16 and L. casei subsp. casei AB16-65) were chosen for making soured butter. The results indicate that the probiotic bacteria applied to cream and butter, as well as to the broth medium, caused a reduction of the cholesterol level of the product's fat content. This study provides some evidence that probiotic cultures have a cholesterol level-reducing effect, and soon we will be able to produce butter without cholesterol via microorganisms.