Purpose: We reviewed randomised controlled trials (RCTs) that have assessed the effects of yogurt containing Lactobacillus bulgaricus and Streptococcus thermophilus (LBST) on metabolic risk markers of chronic diseases in adults.
Methods: We performed a systematic search in July 2016 in the scientific databases PubMed, EMBASE and The Cochrane Library. Included studies were RCTs that assessed the impact of consuming yogurt containing LBST as a treatment, and that evaluated at least one metabolic risk marker for chronic diseases compared with a control diet or a diet supplemented in another food/ingredient in healthy or chronically ill adults.
Results: Seven RCTs involving 278 participants were included in the review. Studies were conducted in the USA, France, Spain, Iran and Canada. Five studies were undertaken in healthy adults, and two were conducted among lactose malabsorbers. All studies investigated changes in blood lipids and glucose homoeostasis, with different doses of yogurt, durations of the supplementation and risks markers assessed. Consumption of LBST yogurt significantly reduced total cholesterol concentrations, ratio of total cholesterol to HDL-C and plasma glucose compared to a control yogurt-free diet or diet supplemented in another food/ingredient in two out of the seven studies. The majority of included RCTs presented high to unclear methodological risks of bias, which raises questions about the validity of their findings.
Conclusions: Data from this systematic review indicate that the consumption of LBST yogurt shows either favourable or neutral effects on metabolic risk markers when compared with a control treatment in controlled research settings. RCTs investigating the effect of LBST yogurt consumption on metabolic risk markers of chronic diseases are scarce and presented considerable variation in methodologies making comparison between studies difficult. Further large-scale, well-designed studies assessing the impact of LBST yogurt, in particular in comparison with a control yogurt-free diet, are warranted to effectively evaluate the effect of yogurt consumption per se on risk markers of chronic diseases.
Keywords: Chronic diseases risk markers; Dairy products; Systematic review; Yogurt.