Anti-Glycation Properties of Zinc-Enriched Arthrospira platensis (Spirulina) Contribute to Prevention of Metaflammation in a Diet-Induced Obese Mouse Model.

Advanced glycation end products (AGEs) exert a key pathogenic role in the development of obesity and insulin resistance. Thanks to its abundance in bioactive compounds, the microalga Arthrospira platensis (spirulina, SP) is proposed as a nutritional supplement. Here, we investigated the potential anti-glycating properties of SP enriched with zinc (Zn-SP) and the following impact on diet-induced metabolic derangements. Thirty male C57Bl6 mice were fed a standard diet (SD) or a high-fat high-sugar diet (HFHS) for 12 weeks, and a subgroup of HFHS mice received 350 mg/kg Zn-SP three times a week. A HFHS diet induced obesity and glucose intolerance and increased plasma levels of pro-inflammatory cytokines and transaminases. Zn-SP administration restored glucose homeostasis and reduced hepatic dysfunction and systemic inflammation. In the liver of HFHS mice, a robust accumulation of AGEs was detected, paralleled by increased expression of the main AGE receptor (RAGE) and depletion of glyoxalase-1, whereas Zn-SP administration efficiently prevented these alterations reducing local pro-inflammatory responses. 16S rRNA gene profiling of feces and ileum content revealed altered bacterial community structure in HFHS mice compared to both SD and HFHS + Zn-SP groups. Overall, our study demonstrates relevant anti-glycation properties of Zn-SP which contribute to preventing AGE production and/or stimulate AGE detoxification, leading to the improvement of diet-related dysbiosis and metabolic derangements.

Garlic consumption in relation to colorectal cancer risk and to alterations of blood bacterial DNA.

PURPOSE: Garlic consumption has been inversely associated to intestinal adenoma (IA) and colorectal cancer (CRC) risk, although evidence is not consistent. Gut microbiota has been implied in CRC pathogenesis and is also influenced by garlic consumption. We analyzed whether dietary garlic influence CRC risk and bacterial DNA in blood. METHODS: We conducted a case-control study in Italy involving 100 incident CRC cases, 100 IA and 100 healthy controls matched by center, sex and age. We used a validated food frequency questionnaire to assess dietary habits and garlic consumption. Blood bacterial DNA profile was estimated using qPCR and16S rRNA gene profiling. We derived odds ratios (ORs) and the corresponding 95% confidence intervals (CIs) of IA and CRC according to garlic consumption from multiple conditional logistic regression. We used Mann-Whitney and chi-square tests to evaluate taxa differences in abundance and prevalence. RESULTS: The OR of CRC for medium/high versus low/null garlic consumption was 0.27 (95% CI = 0.11-0.66). Differences in garlic consumption were found for selected blood bacterial taxa. Medium/high garlic consumption was associated to an increase of Corynebacteriales order, Nocardiaceae family and Rhodococcus genus, and to a decrease of Family XI and Finegoldia genus. CONCLUSIONS: The study adds data on the protective effect of dietary garlic on CRC risk. Moreover, it supports evidence of a translocation of bacterial material to bloodstream and corroborates the hypothesis of a diet-microbiota axis as a mechanism behind the role of garlic in CRC prevention.

Use of kefir-derived lactic acid bacteria for the preparation of a fermented soy drink with increased estrogenic activity.

Fermented foods are receiving growing attention for their health promoting properties. In particular, there is a growing demand for plant-based fermented foods as dairy alternatives. Considering that soy is a vegetal food rich in nutrients and a source of the phytoestrogen isoflavones, the aim of this study was to select safe food microorganisms with the ability to ferment a soy drink resulting in a final product with an increased estrogenic activity and improved functional properties. We used milk kefir grains, a dairy source of microorganisms with proven health-promoting properties, as a starting inoculum for a soymilk. After 14 passages of daily inoculum in fresh soy drink, we isolated four lactic acid bacterial strains: Lactotoccus lactis subsp. lactis K03, Leuconostc pseudomesenteroides K05, Leuconostc mesenteroides K09 and Lentilactobacillus kefiri K10. Isolated strains were proven to be safe for human consumption according to the assessment of their antibiotic resistance profile and comparative genomics. Furthermore, functional characterization of the bacterial strains demonstrated their ability to ferment sugars naturally present in soybeans and produce a creamy texture. In addition, we demonstrated, by means of a yeast-based bioluminescence reporter system, that the two strains belonging to the genus Leuconostoc increased the estrogenic activity of the soybean drink. In conclusion, the proposed application of the bacterial strains characterized in this study meets the growing demand of consumers for health-promoting vegetal food alternatives to dairy products.

Co-administration of vitamin D3 and Lacticaseibacillus paracasei DG increase 25-hydroxyvitamin D serum levels in mice.

PURPOSE: Subclinical vitamin D (vitD) deficiency enhances the predisposition to a myriad of acute and chronic pathologies in many people worldwide. Due to the scarcity of vitD-rich foods, the consumption of supplements or fortified foods can be required to maintain healthy serum levels of 25-hydroxyvitamin D [25(OH)D], and the major circulating form of vitD that is commonly measured in serum to determine the vitD status. Since the vitD absorption seems to resemble that of lipids, improved emulsification in the gut could favor vitD permeation through the enterocyte membrane. Contextually, we hypothesized that a microorganism with cholecalciferol (vitD3)-solubilization properties may potentially result in enhanced serum vitD levels. METHODS AND RESULTS: Six probiotic strains were screened for their ability to create a stable suspension of vitD3 in water: Lacticaseibacillus paracasei DG, L. paracasei LPC-S01, L. paracasei Shirota, L. rhamnosus GG, Limosilactobacillus reuteri DSM 17938, and Lactobacillus acidophilus LA5. The DG strain displayed the strongest vitD3 solubilization ability and, consequently, were used in an in vivo trial where a commercial preparation of vitD3 in refined olive oil was administered by gavage to CD-1 mice with or without the concurrent administration of L. paracasei DG. ELISA measurements showed that the DG strain significantly increased the serum levels of 25(OH) D when administered once a day for 1 week in association with the vitD3 supplement. CONCLUSION: This preliminary pre-clinical study suggests that the combined administration of L. paracasei DG with an oil-based cholecalciferol supplement could contribute to the maintenance of the adequate 25(OH) D serum levels in people at risk of vitD deficiency.

Discriminatory and cooperative effects within the mouse gut microbiota in response to flaxseed and its oil and lignan components.

Gut microbial processing of dietary flaxseed (FS) contributes to its health benefits, but the relative effects of its bioactive components (lignans, omega-3 fatty acids, fiber) on the microbiota are unclear. We investigated the gut microbial compositional and functional responses to whole FS and its isolated components, FS oil (FSO) and secoisolariciresinol diglucoside (SDG) (precursor to microbial-derived enterolignans) to help understand their contribution to whole FS benefits. Cecum content and fecal samples were collected from C57BL/6 female mice fed a basal diet (AIN93G) or isocaloric diets containing 10% FS or 10% FS-equivalent amounts of FSO or SDG for 21 days. Cecal and fecal microbiota composition and predicted genomic functions, and their relationship with serum enterolignans were evaluated. Only FS modified the community structure. Shared- and diet-specific enriched taxa and functions were identified. Carbohydrate and protein processing functions were enriched in FS mice, and there was a positive correlation between select enriched taxa, encompassing fiber degraders and SDG metabolizers, and serum enterolignans. This was not observed in mice receiving isolated FSO and SDG, suggesting that FS fiber supports SDG microbial metabolism. In conclusion, the cooperative activities of a diverse microbiota are necessary to process FS components and, when administered at the amount present in FS, these components may act together to affect SDG-derived enterolignans production. This has implications for the use of FS, FSO and SDG in clinical practice.

In vitro assessment of the ability of probiotics, blueberry and food carbohydrates to prevent S. pyogenes adhesion on pharyngeal epithelium and modulate immune responses.

Group A streptococci (GAS) cause 20-30% of pediatric pharyngitis episodes, which are a major cause of ambulatory care visits. Therefore, a strategy to prevent GAS dissemination in children could significantly benefit public healthcare. Contextually, we assessed the possibility of employing alternative food-grade strategies to be used with the oral probiotic L. helveticus MIMLh5 for the prevention of pharyngeal infections. First, we demonstrated through an antagonism-by-exclusion assay that guaran may potentially prevent S. pyogenes adhesion on pharyngeal cells. Subsequently, we showed that an anthocyanin-rich fraction extracted from wild blueberry (BbE) exerts anti-inflammatory effects on the human macrophage cell line U937. Finally, we showed that BbE reduces interferon-ß expression in MIMLh5-stimulated murine dendritic cells, resulting in a reduction in the pro-inflammatory cytokines IL-12 and TNF-α. In conclusion, this proof-of-concept study indicates that different food-grade strategies may be concomitantly adopted to potentially prevent GAS colonization and modulate local immune defences.

Consumption of a Bifidobacterium bifidum Strain for 4 Weeks Modulates Dominant Intestinal Bacterial Taxa and Fecal Butyrate in Healthy Adults.

UNLABELLED: Modulation of the intestinal microbial ecosystem (IME) is a useful target to establish probiotic efficacy in a healthy population. We conducted a randomized, double-blind, crossover, and placebo-controlled intervention study to determine the impact of Bifidobacterium bifidum strain Bb on the IME of adult healthy volunteers of both sexes. High-throughput 16S rRNA gene sequencing was used to characterize the fecal microbiota before and after 4 weeks of daily probiotic cell consumption. The intake of approximately one billion live B. bifidum cells affected the relative abundance of dominant taxa in the fecal microbiota and modulated fecal butyrate levels. Specifically, Prevotellaceae (P = 0.041) and Prevotella (P = 0.034) were significantly decreased, whereas Ruminococcaceae (P = 0.039) and Rikenellaceae (P = 0.010) were significantly increased. We also observed that the probiotic intervention modulated the fecal concentrations of butyrate in a manner dependent on the initial levels of short-chain fatty acids (SCFAs). In conclusion, our study demonstrates that a single daily administration of Bifidobacterium bifidum strain Bb can significantly modify the IME in healthy (not diseased) adults. These findings demonstrate the need to reassess the notion that probiotics do not influence the complex and stable IME of a healthy individual. IMPORTANCE: Foods and supplements claimed to contain health-promoting probiotic microorganisms are everywhere these days and mainly intended for consumption by healthy people. However, it is still debated what actual effects probiotic products may have on the healthy population. In this study, we report the results of an intervention trial aimed at assessing the modifications induced in the intestinal microbial ecosystem of healthy adults from the consumption of a probiotic product. Our results demonstrate that the introduction of a probiotic product in the dietary habits of healthy people may significantly modify dominant taxa of the intestinal microbiota, resulting in the modulation of short-chain fatty acid concentrations in the gut. The overall changes witnessed in the probiotic intervention indicate a mechanism of microbiota modulation that could have potential effects on human health.

Immunomodulatory effect of a wild blueberry anthocyanin-rich extract in human Caco-2 intestinal cells.

Intestinal inflammation is a natural process crucial for the maintenance of gut functioning. However, abnormal or prolonged inflammatory responses may lead to the onset of chronic degenerative diseases, typically treated by means of pharmacological interventions. Dietary strategies for the prevention of inflammation are a safer alternative to pharmacotherapy. Anthocyanins and other polyphenols have been documented to display anti-inflammatory activity. In the present study, three bioactive fractions (anthocyanin, phenolic, and water-soluble fractions) were extracted from a wild blueberry powder. The Caco-2 intestinal model was used to test the immunomodulatory effect of the above fractions. Only the anthocyanin-rich fraction reduced the activation of NF-κB, induced by IL-1ß in intestinal epithelial Caco-2 cells. Specifically, concentrations of 50 and 100 µg mL(-1) decreased NF-κB activation by 68.9 and 85.2%, respectively (p ≤ 0.05). These preliminary results provide further support for the role of food bioactives as potential dietary anti-inflammatory agents.

Aspartate biosynthesis is essential for the growth of Streptococcus thermophilus in milk, and aspartate availability modulates the level of urease activity.

We investigated the carbon dioxide metabolism of Streptococcus thermophilus, evaluating the phenotype of a phosphoenolpyruvate carboxylase-negative mutant obtained by replacement of a functional ppc gene with a deleted and inactive version, Deltappc. The growth of the mutant was compared to that of the parent strain in a chemically defined medium and in milk, supplemented or not with L-aspartic acid, the final product of the metabolic pathway governed by phosphoenolpyruvate carboxylase. It was concluded that aspartate present in milk is not sufficient for the growth of S. thermophilus. As a consequence, phosphoenolpyruvate carboxylase activity was considered fundamental for the biosynthesis of L-aspartic acid in S. thermophilus metabolism. This enzymatic activity is therefore essential for growth of S. thermophilus in milk even if S. thermophilus was cultured in association with proteinase-positive Lactobacillus delbrueckii subsp. bulgaricus. It was furthermore observed that the supplementation of milk with aspartate significantly affected the level of urease activity. Further experiments, carried out with a p(ureI)-gusA recombinant strain, revealed that expression of the urease operon was sensitive to the aspartate concentration in milk and to the cell availability of glutamate, glutamine, and ammonium ions.