The effect of a probiotic milk product on plasma cholesterol: a meta-analysis of short-term intervention studies

Introduction: Certain fermented dairy milk products may have beneficial effects on plasma cholesterol levels. However, a number of studies have produced conflicting results as to whether dietary supplementation by a probiotic dairy product containing the bacteria culture Causido(R) reduces plasma cholesterol. Objective: To conduct a meta-analysis of intervention studies to evaluate the effect of the Causido(R) culture on plasma total cholesterol and low-density lipoprotein (LDL)-cholesterol. The probiotic milk product: The yoghurt product Gaio(R) is fermented with Causido(R), composed of one strain of Enterococcus faecium (human species) with the proposed cholesterol-lowering effect, and two strains of Streptococcus thermophilus. Study inclusion and data extraction: Six studies were identified from a literature search and from the yoghurt producer. All studies met the inclusion criteria. Summary data for plasma concentrations of total cholesterol and LDL-cholesterol were extracted from the original publications or by personal request to the authors. Data from 4-8 weeks of treatment duration was used. Statistical analysis: We performed a traditional meta-analysis where mean differences between intervention and control of the pre-post changes in total cholesterol and LDL-cholesterol were calculated, as well as 95% confidence intervals (CIs). Results: In the six studies included in the meta-analysis, the Gaio(R) interventions produced changes in total cholesterol above those of the control groups ranging from -0.02 to -1.02 mmol/l and in LDL-cholesterol ranging from -0.02 to -1.15 mmol/l. After inclusion of an open-label study, the meta-analysis of the double-blind studies showed that Gaio(R) as compared to the control group changed total cholesterol by -0.22 mmol/l (95% CI: -0.35 to -0.08, P<0.01) and LDL-cholesterol by -0.20 mmol/l (95% CI: -0.33 to -0.06, P < 0.005). The outcome was essentially the same if all studies were included. Conclusions: The present meta-analysis of controlled short-term intervention studies shows that the fermented yoghurt product produced a 4% decrease in total cholesterol and a 5% decrease in LDL-cholesterol when the open-label study is excluded. To demonstrate sustained effects on blood lipids, long-term studies are required.