Gut microbiota is established during birth and evolves with age, mostly maintaining the commensal relationship with the host. A growing body of clinical evidence suggests an intricate relationship between the gut microbiota and the immune system. With ageing, the gut microbiota develops significant imbalances in the major phyla such as the anaerobic Firmicutes and Bacteroidetes as well as a diverse range of facultative organisms, resulting in impaired immune responses. Antimicrobial therapy is commonly used for the treatment of infections; however, this may also result in the loss of normal gut flora. Advanced age, antibiotic use, underlying diseases, infections, hormonal differences, circadian rhythm, and malnutrition, either alone or in combination, contribute to the problem. This nonbeneficial gastrointestinal modulation may be reversed by judicious and controlled use of antibiotics and the appropriate use of prebiotics and probiotics. In certain persistent, recurrent settings, the option of faecal microbiota transplantation can be explored. The aim of the current review is to focus on the establishment and alteration of gut microbiota, with ageing. The review also discusses the potential role of gut microbiota in regulating the immune system, together with its function in healthy and diseased state.

Chemotherapy is still the first line of treatment for most cancer patients. Patients receiving chemotherapy are generally prone to infections, which result in complications, such as sepsis, mucositis, colitis, and diarrhoea. Several nutritional approaches have been trialled to counter the chemotherapy-associated side effects in cancer patients, but none have yet been approved for routine clinical use. One of the approaches to reduce or avoid chemotherapy-associated complications is to restore the gut microbiota. Gut microbiota is essential for the healthy functioning of the immune system, metabolism, and the regulation of other molecular responses in the body. Chemotherapy erodes the mucosal layer of the gastrointestinal tract and results in the loss of gut microbiota. One of the ways to restore the gut microbiota is through the use of probiotics. Probiotics are the ‘good’ bacteria that may provide health benefits if consumed in appropriate amounts. Some studies have highlighted that the consumption of probiotics in combination with prebiotics, known as synbiotics, may provide better health benefits when compared to probiotics alone. This review discusses the different nutritional approaches that have been studied in an attempt to combat chemotherapy-associated side effects in cancer patients with a particular focus on the use of pre-, pro- and synbiotics.

Gastroesophageal reflux disease (GERD) affects approximately 20% of Australians. Patients suffer a burning sensation known as heartburn due to the movement of acidic stomach content into the esophagus. There is anecdotal evidence of the effectiveness of prebiotic sugarcane flour in controlling symptoms of GERD. This pilot study aimed to investigate the effectiveness of a prebiotic sugarcane flour in alleviating symptoms in medically-diagnosed GERD patients. This pilot study was a single center, double-blinded, placebo-controlled randomized trial conducted on 43 eligible participants. The intervention group (n = 22) were randomized to receive 3 g of sugarcane flour per day, and the control group (n = 21) received 3 g of cellulose placebo per day. Symptoms of gastroesophageal reflux disease were assessed before and after three weeks treatment using the validated Gastroesophageal Reflux Disease-Health Related Quality of Life questionnaire (GERD-HRQL). After three weeks there were significant differences in symptoms for heartburn, regurgitation, and total symptoms scores (p < 0.05) between the sugarcane flour and placebo. Mean GERD-HRQL scores increased in the placebo group for regurgitation (mean increase 1.7; 95% CI 0.23 to 3.2; p = 0.015) and total symptom scores (2.9; 95% CI 0.26 to 5.7; p = 0.033). In contrast, there were significant reductions in heartburn (mean decrease −2.2; 95% CI −4.2 to −0.14; p = 0.037) and total symptom scores (−3.7; 95% CI −7.2 to −0.11; p = 0.044) in the intervention group. This pilot study has shown significant positive effects of sugarcane flour in the reduction of GERD symptoms, and a larger randomized controlled trial is warranted.