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A spatial gradient of bacterial diversity in the human oral cavity shaped by salivary flow.
Proctor, DM, Fukuyama, JA, Loomer, PM, Armitage, GC, Lee, SA, Davis, NM, Ryder, MI, Holmes, SP, Relman, DA
Nature communications. 2018;9(1):681
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Identifying spatial patterns in the human microbiota is necessary to provide insight into mechanisms that either maintain or disrupt its healthy state. The aim of this study was to identify the type and extent of oral spatial patterns formed by bacterial communities, as well as observe the impact of low salivary flow on the spatial patterns. Dental exams were performed on 31 participants to evaluate the oral health status and follow-up was dependent on group allocation. This study found bacterial communities were distinguishable depending on types of teeth and tissue. Further, bacteria on soft and hard tissues varied across the front and back of the oral cavity in a gradient-manner, implying that salivary flow plays a role in establishing the bacterial community gradient in the oral cavity. Based on these results, the authors recommend spatial patterns and processes be explored in other body parts to better understand health and disease.
Abstract
Spatial and temporal patterns in microbial communities provide insights into the forces that shape them, their functions and roles in health and disease. Here, we used spatial and ecological statistics to analyze the role that saliva plays in structuring bacterial communities of the human mouth using >9000 dental and mucosal samples. We show that regardless of tissue type (teeth, alveolar mucosa, keratinized gingiva, or buccal mucosa), surface-associated bacterial communities vary along an ecological gradient from the front to the back of the mouth, and that on exposed tooth surfaces, the gradient is pronounced on lingual compared to buccal surfaces. Furthermore, our data suggest that this gradient is attenuated in individuals with low salivary flow due to Sjögren's syndrome. Taken together, our findings imply that salivary flow influences the spatial organization of microbial communities and that biogeographical patterns may be useful for understanding host physiological processes and for predicting disease.
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Self-reported bovine milk intake is associated with oral microbiota composition.
Johansson, I, Esberg, A, Eriksson, L, Haworth, S, Lif Holgerson, P
PloS one. 2018;13(3):e0193504
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Dietary bovine milk consumption has been associated with both positive and negative health effects. The aim of this study was to explore the association between bovine milk intake and oral microbiota profile. Saliva and tooth biofilm samples were obtained from 154 Swedish adolescents and food frequency questionnaires were completed. A replication cohort of 31,571 was also studied to find patterns in diet intake, lifestyle factors and dental caries. The primary finding of this study was that bovine milk consumption can modulate oral microbiota, and that low milk intake was associated with higher prevalence of opportunistic bacteria. Interestingly there was no association between milk intake and dental caries, highlighting the complexity of this disease. Based on these results, the authors hypothesise milk consumption may also produce similar effects in the gut microbiome.
Abstract
Bovine milk intake has been associated with various disease outcomes, with modulation of the gastro-intestinal microbiome being suggested as one potential mechanism. The aim of the present study was to explore the oral microbiota in relation to variation in self-reported milk intake. Saliva and tooth biofilm microbiota was characterized by 16S rDNA sequencing, PCR and cultivation in 154 Swedish adolescents, and information on diet and other lifestyle markers were obtained from a questionnaire, and dental caries from clinical examination. A replication cohort of 31,571 adults with similar information on diet intake, other lifestyle markers and caries was also studied. Multivariate partial least squares (PLS) modelling separated adolescents with low milk intake (lowest tertile with <0.4 servings/day) apart from those with high intake of milk (≥3.7 servings/day) based on saliva and tooth biofilm, respectively. Taxa in several genera contributed to this separation, and milk intake was inversely associated with the caries causing Streptococcus mutans in saliva and tooth biofilm samples by sequencing, PCR and cultivation. Despite the difference in S. mutans colonization, caries prevalence did not differ between milk consumption groups in the adolescents or the adults in the replication cohort, which may reflect that a significant positive association between intake of milk and sweet products was present in both the study and replication group. It was concluded that high milk intake correlates with different oral microbiota and it is hypothesized that milk may confer similar effects in the gut. The study also illustrated that reduction of one single disease associated bacterial species, such as S. mutans by milk intake, may modulate but not prevent development of complex diseases, such as caries, due to adverse effects from other causal factors, such as sugar intake in the present study.
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Bifidobacterium bifidum YIT 10347 fermented milk exerts beneficial effects on gastrointestinal discomfort and symptoms in healthy adults: A double-blind, randomized, placebo-controlled study.
Gomi, A, Yamaji, K, Watanabe, O, Yoshioka, M, Miyazaki, K, Iwama, Y, Urita, Y
Journal of dairy science. 2018;101(6):4830-4841
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Probiotics have been found to have beneficial effects in adults with functional gastrointestinal (GI) disorders, however little evidence exists regarding its effects on healthy adults. The aim of this prospective, randomised, double-blind, placebo-controlled, parallel-group trial was to clarify the beneficial effects of Bifidobacterium bifidum (B bifidum) on gastric symptoms in 100 healthy Japanese adults who experience temporary GI symptoms. Participants were randomised to consume active fermented milk or placebo milk matched for colour, taste and packaging daily for four weeks and various qualitative and quantitative measurements were assessed. This trial found the group consuming B bifidum experienced significantly better relief from upper GI symptoms compared with the placebo group. These findings suggest daily consumption of milk fermented with B bifidum helps relive GI discomfort and symptoms in healthy adults with no risk of side effects. Based on these results, the authors conclude fermented milk drinks can be recommended to patients who experience temporary GI pain.
Abstract
In a preliminary open-label trial by our group, Bifidobacterium bifidum YIT 10347 (YIT10347) relieved gastric symptoms in patients with functional gastrointestinal disorders. Hence, in this study, we investigated the effects of YIT10347 on gastrointestinal symptoms in healthy adults. In this prospective double-blind, randomized, placebo-controlled trial (UMIN000024654), 100 healthy Japanese adults were randomly assigned to a YIT10347 group or placebo group and consumed 100 mL of YIT10347-fermented milk or placebo fermented milk, respectively, every day for 4 wk. Gastrointestinal symptoms were evaluated by using the modified Frequency Scale for Symptoms of Gastroesophageal Reflux Disease (m-FSSG) and Gastrointestinal Symptom Rating Scale (GSRS) as primary endpoints. Mental symptoms, quality of life, salivary stress markers, and gastric emptying were evaluated as secondary endpoints. Effectiveness and safety were analyzed in a per-protocol set (YIT10347 group, n = 39; placebo group, n = 40) and full analysis set (YIT10347 group, n = 50; placebo group, n = 50), respectively. In the m-FSSG evaluation, the YIT10347 group had a significantly higher relief rate of postprandial discomfort and greater changes in postprandial epigastric pain score from baseline than the placebo group. In the GSRS evaluation, the YIT10347 group had significantly higher relief rates of overall gastrointestinal symptoms, upper gastrointestinal symptoms, flatus, and diarrhea than the placebo group. We detected no significant differences in scores or relief rates of mental symptoms and quality of life, a salivary stress marker, or gastric emptying between the 2 groups. No severe adverse events associated with test beverage consumption were observed in either group. These findings suggest that daily consumption of YIT10347-fermented milk exerts beneficial effects on gastrointestinal discomfort and symptoms such as postprandial discomfort and epigastric pain in healthy adults.
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Substituting whole grains for refined grains in a 6-wk randomized trial has a modest effect on gut microbiota and immune and inflammatory markers of healthy adults.
Vanegas, SM, Meydani, M, Barnett, JB, Goldin, B, Kane, A, Rasmussen, H, Brown, C, Vangay, P, Knights, D, Jonnalagadda, S, et al
The American journal of clinical nutrition. 2017;105(3):635-650
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Increased whole grain consumption has been associated with reduced levels of inflammation. This randomised, controlled trial aimed to assess the effects of a whole grain diet in comparison with a refined grain diet on the immune system, levels of inflammation and gut bacteria. 81 men and women aged between 40 and 60 were randomly assigned to either a whole grain or a refined grain diet for a period of 6 weeks. All other dietary components were kept the same and calorie levels were controlled to maintain weight levels. The study findings showed a positive effect on stool frequency and stool weight with the whole grain diet in comparison to the refined grain diet. The whole grain diet also showed modest positive effects on gut bacteria profiles and aspects of immunity. The whole grain diet showed no effects on markers of inflammation.
Abstract
Background: Observational studies suggest an inverse association between whole-grain (WG) consumption and inflammation. However, evidence from interventional studies is limited, and few studies have included measurements of cell-mediated immunity.Objective: We assessed the effects of diets rich in WGs compared with refined grains (RGs) on immune and inflammatory responses, gut microbiota, and microbial products in healthy adults while maintaining subject body weights.Design: After a 2-wk provided-food run-in period of consuming a Western-style diet, 49 men and 32 postmenopausal women [age range: 40-65 y, body mass index (in kg/m2) <35] were assigned to consume 1 of 2 provided-food weight-maintenance diets for 6 wk.Results: Compared with the RG group, the WG group had increased plasma total alkyresorcinols (a measure of WG intake) (P < 0.0001), stool weight (P < 0.0001), stool frequency (P = 0.02), and short-chain fatty acid (SCFA) producer Lachnospira [false-discovery rate (FDR)-corrected P = 0.25] but decreased pro-inflammatory Enterobacteriaceae (FDR-corrected P = 0.25). Changes in stool acetate (P = 0.02) and total SCFAs (P = 0.05) were higher in the WG group than in the RG group. A positive association was shown between Lachnospira and acetate (FDR-corrected P = 0.002) or butyrate (FDR-corrected P = 0.005). We also showed that there was a higher percentage of terminal effector memory T cells (P = 0.03) and LPS-stimulated ex vivo production of tumor necrosis factor-α (P = 0.04) in the WG group than in the RG group, which were positively associated with plasma alkylresorcinol concentrations.Conclusion: The short-term consumption of WGs in a weight-maintenance diet increases stool weight and frequency and has modest positive effects on gut microbiota, SCFAs, effector memory T cells, and the acute innate immune response and no effect on other markers of cell-mediated immunity or systemic and gut inflammation. This trial was registered at clinicaltrials.gov as NCT01902394.