In a recent study, published in the British Journal of Nutrition (2016), 100 healthy adults consumed 2 synthetic compounds, 2′-O-fucosyllactose (2′FL) and/or lacto-N-neotetraose (LNnT), or placebo for 2 weeks in order to establish the safety, tolerance and effects of human milk oligosaccharides (HMO) on adult gut microbiota.
The human gut microbiota plays an important role in the host health and imbalanced gut microbiota has been linked to many diseases such as malnutrition, cancer, inﬂammatory diseases, metabolic diseases and gastrointestinal (GI) diseases. Human milk oligosaccharides (HMO) – the highly abundant solid constituent in breast milk – are a family structurally diverse unconjugated glycans. The beneficial effects of HMO in the large intestine include: providing selective substrates for gut bacteria, modulating the immune system, and protection from the intestinal pathogens.
A total of 100 subjects were randomised to participate in this study from a pool of 110 healthy male and female volunteers in Denmark. Inclusion criteria for this study required the volunteers to be aged 18-60 years and to sign the informed consent. Exclusion criteria included: participation in a clinical study during or 1 month before the study, abnormal screening in laboratory results, unsatisfied scoring on the Gastrointestinal Symptom Rating Scale (GSRS), severe diseases, being on a medication interfering with symptoms evaluation, 3 months’ prior use of a high dosed probiotic supplement or antibiotic, pregnancy/nursing or trying to conceive.
The participants were asked to complete a self-administered GSRS form at the screening, beginning and end of the study to evaluate the impact of HMO supplementation on GI symptoms. Blood samples for clinical chemistry and hematology analyses and fecal samples for biomarker analysis were collected before and after the study. Furthermore, 16S rRNA sequencing, bioinformatical analysis and statistical analyses were also performed.
All 100 participants completed the study and were included in the statistical analysis. Differences in GSRS scores, stool consistency scores, biomarker and clinical chemistry and hematology before and after study were analysed. No clinically significant change in any of the measured physical parameters or clinical chemistry and hematology analyses of blood samples was observed during the study which confirmed the safety of the tested compounds. A total of 56 reported adverse events mainly related to GI symptoms and were characterised as mild.
The study results showed that the use of 2′FL and LNnT in adults for 2 weeks can modify the gut microbiota, increase the relative abundance of biﬁdobacteria depending on the dose intake, and reduce the relative abundance of two phyla, Firmicutes and Proteobacteria. The biﬁdobacteria abundance increase may be related to the increase in a speciﬁc sequence (s1_r64) with high sequence similarity to B. adolescentis. Although B. adolescentis is not known to metabolise HMO, the 16S rRNA sequencing data showed that the s1_r64 sequence could possibly be another member of Biﬁdobacterium. Overall, this study suggests that HMO supplementation is safe and well tolerated in healthy adults and may be used as a strategy to promote the growth of beneﬁcial biﬁdobacteria.
Written By: Hummara Aslam, MSc