This systematic review aimed to evaluate the effectiveness and safety of probiotics for glycemic control in adults with impaired glucose control, including prediabetes and type 2 diabetes mellitus (T2DM). We searched PubMed, Embase, and Cochrane databases, and trial registries up to February 2019. We included randomized controlled trials (RCTs) of participants with prediabetes or T2DM. Eligible trials compared probiotics versus either placebo, no intervention, or comparison probiotics, or compared synbiotics versus prebiotics. Primary outcomes were mean change in fasting blood glucose (FBG) and glycated hemoglobin (HbA1c) from baseline to short term (<12 wk) and long term (≥12 wk). We performed meta-analyses using the random-effects model. We included 28 RCTs (1947 participants). Overall, probiotics reduced FBG more than the placebo/no intervention group with a mean difference (MD) of –12.99 mg/dL (95% CI: –23.55, –2.42; P value: 0.016) over the short term; and –2.99 mg/dL (95% CI: –5.84, –0.13; P value: 0.040) over the long term. There was also some evidence for reduced HbA1c in the probiotics group at both short term (MD: –0.17; 95% CI: –0.37, 0.02; P value: 0.084) and long term (MD: –0.14; 95% CI: –0.34, 0.06; P value: 0.172), however, these did not reach statistical significance possibly because only a few trials reported HbA1c as an outcome. Subgroup analyses showed a greater reduction in HbA1c in participants not receiving insulin therapy than those receiving insulin therapy. Furthermore, the effect of probiotics on the reduction of FBG was more pronounced in participants with FBG >130 mg/dL and those not receiving insulin therapy than their counterparts. Probiotics were also effective in lowering serum cholesterol over the short and long term. In conclusion, we found that probiotics may have a glucose-lowering effect in T2DM participants. The effect appeared to be stronger in participants with poorly controlled diabetes and those not on insulin therapy. Systematic review registration: CRD42019121682.

Fat reduction and anti-inflammation are commonly claimed properties of probiotics. Lactiplantibacillus plantarum and Enterococcus faecium were tested in high fat-induced obesity mice and in vitro experiments. After 16 weeks of probiotics, L. plantarum dfa1 outperforms E. faecium dfa1 on the anti-obesity property as indicated by body weight, regional fat accumulation, serum cholesterol, inflammatory cytokines (in blood and colon tissue), and gut barrier defect (FITC-dextran assay). With fecal microbiome analysis, L. plantarum dfa1 but not E. faecium dfa1 reduced fecal abundance of pathogenic Proteobacteria without an alteration in total Gram-negative bacteria when compared with non-probiotics obese mice. With palmitic acid induction, the condition media from both probiotics similarly attenuated supernatant IL-8, improved enterocyte integrity and down-regulated cholesterol absorption-associated genes in Caco-2 cell (an enterocyte cell line) and reduced supernatant cytokines (TNF-α and IL-6) with normalization of cell energy status (extracellular flux analysis) in bone-marrow-derived macrophages. Due to the anti-inflammatory effect of the condition media of both probiotics on palmitic acid-activated enterocytes was neutralized by amylase, the active anti-inflammatory molecules might, partly, be exopolysaccharides. As L. plantarum dfa1 out-performed E. faecium dfa1 in anti-obesity property, possibly through the reduced fecal Proteobacteria, with a similar anti-inflammatory exopolysaccharide; L. plantarum is a potentially better option for anti-obesity than E. faecium.

Microalgae are a diverse group of photosynthetic eukaryotic organisms that are widely distributed globally. They are prolific sources of highly valuable compounds with fascinating chemical structures. Due to their balanced nutritional compositions and health benefits, they are increasingly being used as functional food ingredients. Carotenoid‐based pigments and polyunsaturated fatty acids (PUFAs) are examples of high‐value nutrients that can be accumulated abundantly in microalgae. Here, the effects of potassium chloride‐induced stress on the productions of lipids and carotenoids in the green microalga of the Chlorococcaceae family were investigated. Under normal BG11 medium, this green microalga strain TISTR 9500 accumulated high levels of PUFA and primary carotenoid lutein. Stress tests revealed that KCl enhanced and modulated lipid and carotenoid accumulation levels. The liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) analysis revealed that secondary carotenoids astaxanthin and canthaxanthin were robustly produced under KCl stress with the similar content of lutein. Further, this stress led to a significant increase in the total FA amount with the higher proportion of unsaturated FA than saturated FA. Thus, this green microalga could be an attractive and alternative natural biosource for canthaxanthin and astaxanthin, as well as for functional lipids.

The utilization of microalgae as a source of carotenoid productions has gained increasing popularity due to its advantages, such as a relatively fast turnaround time. In this study, a newly discovered Coelastrum sp. TISTR 9501RE was characterized and investigated for its taxonomical identity and carotenoid profile. To the best of our knowledge, this report was the first to fully investigate the carotenoid profiles in a microalga of the genus Coelastrum. Upon use of limited nutrients as a stress condition, the strain was able to produce astaxanthin, canthaxanthin, and lutein, as the major carotenoid components. Additionally, the carotenoid esters were found to be all astaxanthin derivatives, and β-carotene was not significantly present under this stress condition. Importantly, we also demonstrated that this practical stress condition could be combined with simple growing factors, such as ambient sunlight and temperature, to achieve even more focused carotenoid profiles, i.e., increased overall amounts of the aforementioned carotenoids with fewer minor components and chlorophylls. In addition, this green microalga was capable of tolerating a wide range of salinity. Therefore, this study paved the way for more investigations and developments on this fascinating strain, which will be reported in due course.

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