Kefir is fermented milk produced from grains that comprise a specific and complex mixture of bacteria and yeasts that live in a symbiotic association. The nutritional composition of kefir varies according to the milk composition, the microbiological composition of the grains used, the time/temperature of fermentation and storage conditions. Kefir originates from the Caucasus and Tibet. Recently, kefir has raised interest in the scientific community due to its numerous beneficial effects on health. Currently, several scientific studies have supported the health benefits of kefir, as reported historically as a probiotic drink with great potential in health promotion, as well as being a safe and inexpensive food, easily produced at home. Regular consumption of kefir has been associated with improved digestion and tolerance to lactose, antibacterial effect, hypocholesterolaemic effect, control of plasma glucose, anti-hypertensive effect, anti-inflammatory effect, antioxidant activity, anti-carcinogenic activity, anti-allergenic activity and healing effects. A large proportion of the studies that support these findings were conducted in vitro or in animal models. However, there is a need for systematic clinical trials to better understand the effects of regular use of kefir as part of a diet, and for their effect on preventing diseases. Thus, the present review focuses on the nutritional and microbiological composition of kefir and presents relevant findings associated with the beneficial effects of kefir on human and animal health.

SCFA provide energy to the host and influence lipid and glucose metabolism, suggesting that they may have an impact on the occurrence of metabolic risk factors. The aim of the present study was to determine the concentration of SCFA in faeces of lean and obese individuals and to analyse whether associations between faecal SCFA and metabolic syndrome parameters are present. Lean (n20) and obese (n20) women of similar age (28·5 (sd7·6)v.30·7 (sd6·5) years,P= 0·33) participated in the study. Anthropometric measurements, body composition, blood pressure and biochemical parameters were assessed. SCFA were extracted from faeces and quantified by GC. Blood pressure and blood glucose, although within the normal limits, were higher in the obese group compared to lean subjects (P< 0·05). Lower HDL concentration and higher insulin and homeostasis model assessment (HOMA) index were observed in the obese than in the lean group (P< 0·05). The median values of SCFA (% w/w) from the lean and obese groups were butyric (0·021v.0·044,P= 0·024), propionic (0·021v.0·051,P= 0·007) and acetic (0·03v.0·061,P= 0·01). SCFA correlated positively with metabolic syndrome risk factors such as adiposity, waist circumference and HOMA index (P< 0·05), and inversely with HDL (P< 0·05). Our results suggest that the higher faecal concentration of SCFA is associated with metabolic risk factors and thus may influence metabolic homeostasis.

Production and manufacturing methods and the food carrier may influence the properties of probiotic strains, and have an impact on the outcome of clinical intervention studies. The aim of the present study was to establish whether the properties of a specific probiotic strain,Lactobacillus rhamnosusGG, may differ depending on the product and source of the strain. In total, fifteen differentL. rhamnosusisolates, among them fourteen labelled asL.rhamnosusGG, were isolated from specific probiotic products. The micro-organisms were phenotypically and genotypically characterised. Their adhesion properties were compared using the human intestinal mucus model, and the ability of the isolates to influence model pathogen adhesion to human colonic mucus was assessed. AllL. rhamnosusisolates used were confirmed as members of the speciesL. rhamnosus. Except the reference strain OL, allL.rhamnosusisolates showed randomly amplified polymorphic DNA, enterobacterial repetitive intergenic consensus and pulsed-field gel electrophoresis profiles identical to that ofL. rhamnosusGG (ATCC 53103). AllL.rhamnosusisolates showed similar tolerance to acid and were able to bind to human colonic mucus. However, pathogen exclusion by inhibition and competition varied significantly among the differentL. rhamnosusisolates and pathogens tested. The results suggest that different sources of the same probiotic may have significantly altered strain properties. This should be considered inin vivostudies on human subjects and also for quality control of probiotic products.