Here, we reviewed emerging evidence on the role of the microbial community in colorectal carcinogenesis. A healthy gut microbiota promotes intestinal homeostasis and can exert anti-cancer effects; however, this microbiota also produces a variety of metabolites that are genotoxic and which can negatively influence epithelial cell behaviour. Disturbances in the normal microbial balance, known as dysbiosis, are frequently observed in colorectal cancer (CRC) patients. Microbial species linked to CRC include certain strains of Bacteroides fragilis, Escherichia coli, Streptococcus gallolyticus, Enterococcus faecalis and Fusobacterium nucleatum, amongst others. Whether these microbes are merely passive dwellers exploiting the tumour environment, or rather, active protagonists in the carcinogenic process is the subject of much research. The incidence of chemically-induced tumours in mice models varies, depending upon the presence or absence of these microorganisms, thus strongly suggesting influences on disease causation. Putative mechanistic explanations differentially link these strains to DNA damage, inflammation, aberrant cell behaviour and immune suppression. In the future, modulating the composition and metabolic activity of this microbial community may have a role in prevention and therapy.

The Mediterranean diet (MedDiet) is considered as a good example of a healthy dietary pattern that has protective effects on obesity. The aim of the present study was to assess the adherence of adults from three Gulf countries (Saudi Arabia, Oman, and Kuwait) to the MedDiet and its association with obesity risk. A cross-sectional study was conducted on 961 men and women (75.7%) aged 20–55 years old. Waist circumference (WC), and hip circumference (HC) were measured waist/hip ratio (WHR) and body mass index (BMI) were calculated. A validated 14-item Questionnaire was used to measure adherence to MedDiet. The mean of the adherence to MedDiet score was 5.9 ± 2.03 for the total sample. An inverse association was observed between the adherence to MedDiet and BMI after adjusting for potential confounders (p = 0.0003 in total participants, and p = 0.001 in women only). A protective effect was seen with a higher adherence to the MedDiet on HC, suggesting that a greater adherence to the MedDiet was associated with a decreased HC (p = 0.04 in total participants, and p = 0.01 in women only). In conclusion, low adherence to the MedDiet among participants from three gulf countries was associated with increased obesity indicators, BMI, and HC.