How Much In Vitro Cholesterol Reducing Activity of Lactobacilli Predicts Their In Vivo Cholesterol Function?

Background: Based on literature, in vitro cholesterol removal of lactic acid bacteria has been accounted for their in vivo cholesterol reduction. But recently it has been proposed that such in vitro characteristic may not be directly relevant to their in vivo activity. The objective of this study was to find how much in vitro cholesterol reducing potential of Lactobacillus plantarum A7 (LA7), a native strain isolated from an infant fecal flora, reflects its in vivo efficiency. LA7 previously showed serum cholesterol reducing capability in mice subjected to fatty diet. Here, we investigate whether the given strain is capable of in vitro cholesterol assimilation or consumption. Method: LA7 was cultured in whole milk and de-Man-Rogosa- Sharpe (MRS) added with water-soluble cholesterol. Colorimetric method was adopted for cholesterol determination in both cultured media during incubation period. Results: No cholesterol assimilation was detected by growth and incubation of the active culture in either of the medium. Thus, in vivo cholesterol function of LA7 was not caused by cholesterol consumption. A comprehensive review of literature on the related studies also showed that there are other documented studies which evidenced the uncertainty of the direct relation between in vitro and in vivo studies. Conclusion: Cholesterol removal from the cultured media may not be considered as an appropriate integral index for selection of Lactobacillus strains with cholesterol-lowering activity.