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.

Distribution of the microbiota varies according to the location in the gastrointestinal (GI) tract. Thus, dysbiosis during aging may not be limited to faecal microbiota and extend to the other parts of the GI tract, especially the cecum and colon. Lactobacillus acidophilus DDS-1, a probiotic strain, has been shown to modulate faecal microbiota and its associated metabolic phenotype in aging mice. In the present study, we investigated the effect of L. acidophilus DDS-1 supplementation on caecal- and mucosal-associated microbiota, short-chain fatty acids (SCFAs) and immunological profiles in young and aging C57BL/6J mice. Besides differences in the young and aging control groups, we observed microbial shifts in caecal and mucosal samples, leading to an alteration in SCFA levels and immune response. DDS-1 treatment increased the abundances of beneficial bacteria such as Akkermansia spp. and Lactobacillus spp. more effectively in caecal samples than in mucosal samples. DDS-1 also enhanced the levels of butyrate, while downregulating the production of inflammatory cytokines (IL-6, IL-1β, IL-1α, MCP-1, MIP-1α, MIP-1β, IL-12 and IFN-γ) in serum and colonic explants. Our findings suggest distinct patterns of intestinal microbiota, improvements in SCFA and immunological profiles with DDS-1 supplementation in aging mice.

Objectives: To investigate the effect of replacing lean meat with a soy product, tofu, on serum lipoprotein concentrations. Study and design: Randomized cross-over dietary intervention study. Subjects: Forty-two free-living healthy males aged 35 ± 62 y completed the dietary intervention. Three additional subjects were non-compliant and excluded prior to analysis. Interventions: A diet containing lean meat (150 gad) was compared with one with 290 gad tofu in an isocaloric and isoprotein substitution. Both diet periods were 1 month, and fat intake was carefully controlled. Results: Seven-day diet records showed the two diets were similar in energy, macronutrients and ®bre. Total cholesterol (mean difference 0.23 mmolal, 95% CI 0.02, 0.43; P 0.03) and triglycerides (mean difference 0.15 mmolal, 95% CI 0.02, 0.31; P 0.017) were signi®cantly lower on the tofu diet than the lean meat diet. However, HDL-C was also signi®cantly lower on the tofu diet (mean difference 0.08 mmolal, 95% CI 0.02, 0.14; P 0.01) although the LDL-C:HDL-C ratio was similar. Conclusion: The effect on HDL-C and the small LDL-C reduction differ from some other studies, where fat was often less controlled, and the comparison was of soy as textured protein or soymilk against casein. This suggests a differential effect of the various proteins compared to the soy may in¯uence the ®ndings. In practice, the replacement of meat with tofu would usually be associated with a decrease in saturated fat and an increase in polyunsaturated fat and this should enhance any small bene®ts due to the soy protein.Sponsor: Deakin University with some contribution from a Commonwealth Department of Veterans Affairs research grant.

Background: The health benefits of probiotics are well established and known to be strain-specific. However, the role of probiotics obtained from different origins and their efficacy largely remains unexplored. The aim of this study is to investigate the in vitro efficacy of probiotics from different origins.Methods: Probiotic strains utilized in this study include Lactobacillus acidophilus DDS-1 (human origin), Bifidobacterium animalis ssp. lactis UABla-12 (human origin), L. plantarum UALp-05 (plant origin) and Streptococcus thermophilus UASt-09 (dairy origin). Screening assays such as in vitro digestion simulation, adhesion, cell viability and cytokine release were used to evaluate the probiotic potential.Results: All strains showed good resistance in the digestion simulation process, especially DDS-1 and UALp-05, which survived up to a range of 107 to 108 CFU/mL from an initial concentration of 109 CFU/mL. Two human colonic mucus-secreting cells, HT-29 and LS174T, were used to assess the adhesion capacity, cytotoxicity/viability, and cytokine quantification. All strains exhibited good adhesion capacity. No significant cellular cytotoxicity or loss in cell viability was observed. DDS-1 and UALp-05 significantly upregulated anti-inflammatory IL-10 and downregulated pro-inflammatory TNF-α cytokine production. All the strains were able to downregulate IL-8 cytokine levels.Conclusion: Of the 4 strains tested, DDS-1 demonstrated superior survival rates, good adhesion capacity and strong immunomodulatory effect under different experimental conditions.

BACKGROUND: Gastroplasty results in a considerable reduction in food intake and dramatic weight loss. This is likely to have a nutritional impact, although it is expected that this may be minimised by good advice and supplement use. METHODS: Twenty six obese subjects were studied in detail before and after modi®ed long vertical gastroplasty (MLVG), in a setting where comprehensive nutritional advice on symptom avoidance was readily available and multivitamin supplements advised. Nutritional intake and anthropometry were measured preoperatively and at 2, 5 (n 22) and 12 months (n 11) postoperatively. RESULTS: Mean weight loss was 13%, 22% and 31% of initial body weight at the respective time points. Energy intake (EI) was signi®cantly reduced postoperatively, with the mean protein intake being only 40 gad. At 2 months, mean intakes of iron, calcium and zinc from food were 40%, 71% and 39%, respectively, of the Australian recommended dietary intake (RDI), and iron and zinc intake remained below half the RDI at 5 months. Only regular adherence to the vitaminamineral supplement, brought iron and calcium intakes close to RDI, but zinc remained low. Haemoglobin and serum ferritin concentrations did not alter signi®cantly and remained within the reference range, but serum folate fell signi®cantly between 5 months and 12 months. By 5 months, 60% of subjects never regurgitated or regurgitated less than once a week. Fresh bread was the least tolerated food. Frequency of regurgitation was not correlated with adequacy of nutrient intake. CONCLUSIONS: The results emphasise the need for regular follow-up of MLVG patients, and nutritional advice which includes diet quality as well as symptom management, and regular intake of the vitaminamineral supplement for at least a year postoperatively. Low protein intakes, however, remain of potential long-term concern.