Influence of consumption of probiotics on the plasma lipid profile: A meta-analysis of randomised controlled trials

Abstract

Aims

Human clinical studies have yielded mixed results on the effects of consumption of probiotics on the plasma lipid profile. We conducted a meta-analysis of randomised controlled trials that evaluated the effects of probiotics consumption on blood lipids.

Data Synthesis

A systematic literature search of Embase, Web of Science, PubMed and Cochrane Controlled Trials Registry was conducted for studies that investigated the efficacy of probiotics on the plasma lipid profile of subjects. With the help of Review Manager 4.2, data from 13 trials, which included 485 participants with high, borderline high and normal cholesterol levels, were examined. The pooled mean net change in total cholesterol for those treated with probiotics compared to controls was −6.40 mg dl⁻¹ (95% confidence interval (CI), −9.93 to −2.87), mean net change in low-density lipoprotein (LDL) cholesterol was −4.90 mg dl⁻¹ (95% CI, −7.91 to −1.90), mean net change in high-density lipoprotein (HDL) cholesterol was −0.11 mg dl⁻¹ (95% CI, −1.90–1.69) and mean net change in triglycerides was −3.95 mg dl⁻¹ (95% CI, −10.32–2.42).

Conclusion

These results indicate that a diet rich in probiotics decreases total cholesterol and LDL cholesterol concentration in plasma for participants with high, borderline high and normal cholesterol levels.

Introduction

Coronary heart disease (CHD) is a major cause of morbidity and a leading cause of premature death worldwide [1]. Although there are multiple risk factors for CHD, dyslipidemia remains a major determining factor for this pathology. Observational epidemiologic studies have shown that higher concentrations of total cholesterol and low-density lipoprotein (LDL) cholesterol are strongly associated with greater risk of future cardiovascular events.

Both pharmacologic and non-pharmacologic interventions can reduce the concentrations of cholesterol in serum. Multiple approaches to diet therapy have been initiated to improve hyperlipidaemia, such as the inclusion of ω-3 fatty acids [2], soy [3], vitamin C [4], non-soy legume [5], nicotinic acid [6] and red yeast rice [7] in the diet. The cholesterol-lowering effect of probiotics products has raised much interest in recent years. Probiotics are defined as “living micro-organisms, which upon ingestion in certain numbers exert health effects beyond inherent basic nutrition”. [8] Lactic acid bacteria (LAB), predominantly selected from the genera Lactobacillus and Bifidobacterium, constitutes a significant proportion of probiotic cultures in nutritional supplements, pharmaceuticals and functional foods, but certain Bacillus and Enterococcus may also be incorporated in probiotic products [9]. Probiotic-fermented foods, including milk and dairy products, have played important roles in the diet of humans worldwide for thousands of years and are consumed on a large scale. The cholesterol-lowering activity of fermented dairy products with probiotics has been demonstrated in rats [10], hamsters [11] and pigs [12]. However, human clinical studies using various probiotics have yielded mixed results, with some studies finding no effect [13], [14], [15], while others have identified a significant cholesterol-lowering effect [16], [17], [18]. Therefore, we conducted a meta-analysis of randomised controlled trials to quantify the direction and magnitude of the potential effect that the consumption of probiotics may have on serum cholesterol and triglycerides concentrations.