Research Advances With Regards to Clinical Outcome and Potential Mechanisms of the Cholesterol-Lowering Effects of Probiotics

Guo Zhuang; Xiao-Ming Liu; Qiu-Xiang Zhang; Feng-Wei Tian; Hao Zhang; He-Ping Zhang; Wei Chen

Disclosures

Clin Lipidology. 2012;7(5):501-507. 

In This Article

Clinical Outcome

The online databases, Web of Science and Medline, were used to search for clinical randomized controlled studies that investigated the efficacy of probiotics on the plasma lipid profile of subjects. Studies were excluded if probiotic products contained prebiotics or plant sterols. The designs of the randomized controlled trials are presented in Table 1 . Although there is some clinical evidence for the role of probiotics in lowering cholesterol, the results are conflicting. Some studies have identified a significant cholesterol-lowering effect,[11–15] while others have found no effect.[16–21] Agerbaek et al. used a randomized, double-blind, placebo-controlled and parallel design trial involving 58 normocholesterolemic male volunteers to study the effect of fermented milk containing Enterococcus faecium on serum cholesterol.[11] In this 6-week study, the researchers found that the daily consumption of 200 ml of a fermented milk product significantly (p < 0.05) reduced plasma total cholesterol and LDL-cholesterol by 6 and 10%, respectively, compared with the control. In another study, Anderson and Gilliland evaluated the effects of fermented milk containing Lactobacillus acidophilus L1 on the lipid profiles of 40 subjects (baseline serum total cholesterol 5.40–8.32 mmol/l, fasting serum triglyceride concentrations were <5.65 mmol/l).[12] Results from this randomized, single-blind, placebo-controlled and crossover study demonstrated that consumption of oral probiotic fermented products resulted in a 2.9% decline in serum total cholesterol when compared to the control (p < 0.05). Similarly, another double-blind, randomized, placebo-controlled crossover study involving 32 mild-to-moderate primary hypercholesterolemia volunteers with a daily consumption of 200 g daily of Gaio® (MD Foods, Aarhus, Denmark), a new yogurt-like product fermented by Enterococcus faecium and two strains of Streptococcus thermophilus, for 8 weeks, has also reached the same conclusion.[13] Total and LDL cholesterol concentrations were significantly (p < 0.05) lower compared with the placebo. Agerholm-Larsen and Raben also indicated that Gaio® reduced LDL-cholesterol in overweight subjects at 450 ml consumption daily for 8 weeks.[17] Ataie-Jafari et al. evaluated the hypocholesterolemic effect of a probiotic yogurt (containing Lactobacillus acidophilus and Bifidobacterium lactis) in a randomized, single-blind, placebo-controlled and crossover study involving 14 healthy subjects.[14] The research indicated that the daily consumption of 300 g of probiotic yoghurt for 4 weeks significantly reduced (p < 0.05) serum total cholesterol by 11.9%. In another study, Sadrzadeh-Yeganeh et al. conducted a randomized, placebo-controlled, double-blind and parallel designed study involving 59 female volunteers with mean total cholesterol of 180 mg/dl and LDL-cholesterol of 106 mg/dl.[15] In this study, the researchers found that daily consumption of 300 g of probiotic yogurt (fermented with Bifidobacterium lactis Bb12 and Lactobacillus acidophilus La5) resulted in a significant decline in total cholesterol (p < 0.05) of 7.9%. The researchers also observed a 9.6% increase in HDL-cholesterol when compared to the control (yogurt only fermented by Lactobacillus bulgaricus and Streptococcus thermophilus). Although these clinical studies have indicated convincing cholesterol-lowering effects of probiotics, controversial results have been reported. A study by de Roos et al. indicated that the administration of Lactobacillus acidophilus L1 did not influence blood lipid profiles in 78 adult men and women with cholesterol levels of 3.9–7.8 mmol/l after a 6-week treatment period.[16] In another study involving 36 healthy volunteers, Naruszewicz et al. found that the consumption of Lactobacillus plantarum 299v did not contribute to serum cholesterol changes after 6 weeks.[18] In a study evaluating the effect of Bifidobacterium longum BL1 on serum cholesterol, 32 subjects with serum total cholesterol ranging from 220 to 280 mg/dl were randomly assigned to two treatments, consuming either 3 × 100 ml/day probiotic or ordinary yogurt (fermented by Streptococcus thermophilus and Lactobacillus subsp. bulgaricus) for 4 weeks.[19] The authors found no significant change in serum lipid concentration during the experimental period. Similarly, Fabian and Elmadfa reported that although several lipid parameters changed after oral probiotic or conventional yogurt for 4 weeks, no significant differences between the groups were observed.[20] Simons et al. conducted a single-center, double-blind, placebo-controlled, parallel design trial to determine the effect of Lactobacillus fermentum on human lipid profiles.[21] In this study, 44 volunteers (baseline total cholesterol of ≥4.0 mmol/l) consumed two capsules twice daily for a period of 10 weeks. The authors indicated that Lactobacillus fermentum capsules did not significantly change serum cholesterol of the subjects.

Meta-analysis is a statistical method that can analyze a large collection of results in order to integrate the overall findings.[22] One previous meta-analysis evaluated the hypocholesterolemic effects of Gaio, a fermented probiotic dairy product containing the bacterial culture Causido® (MD Foods) and found that its consumption resulted in reductions in total and LDL-cholesterol (-0.22 mmol/l [-8.51 mg/dl] and -0.20 mmol/l [-7.74 mg/dl], respectively).[23] A meta-analysis of randomized controlled trials was conducted in order to quantify the direction and magnitude of the proposed effect that the consumption of probiotics may have on serum cholesterol concentrations.[24] This meta-analysis indicated that a diet rich in probiotics significantly (p < 0.05) decreases total (-6.40 mg/dl) and LDL (-4.90 mg/dl) cholesterol concentrations in the plasma of subjects.

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