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Disturbances of Vaginal Microbiome Composition in Human Papillomavirus Infection and Cervical Carcinogenesis: A Qualitative Systematic Review.
Wu, M, Li, H, Yu, H, Yan, Y, Wang, C, Teng, F, Fan, A, Xue, F
Frontiers in oncology. 2022;12:941741
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Cervical cancer remains the fourth most prevalent cancer in women worldwide. The infection of certain strains of human papillomavirus (HPV)) are thought to have an important causative role in the development of cervical cancer. But since a vast majority of HPV infections clear naturally within a few months, this indicates other factors at play determine the progression of the disease and its cancerous developments. Recent findings indicate that there may be a close link between disruptions of the vaginal microbiome and HPV infection, cervical lesions, cervical cancer and other gynaecological diseases. However, the evidence thus far is quite varied. Hence this systematic review sought to gather the current evidence and integrate it to create up-to-date knowledge. Included were the 22 studies relating to vaginal microbiota, and women with HPV-associated cervical diseases. The studies were conducted in various countries around the world and contained a mixture of case-controlled, cross-sectional and longitudinal studies. The authors acknowledge the challenges of summarising the findings due to differences in how the studies have been conducted. The results of the review showed that vaginal disturbances in HPV infections and related cervical diseases, seem to manifest in decreases in Lactobacilli, and increases in aerobic and anaerobic bacteria. Lactobacillus iners seemed to have either protective or pathogenic effects. They also noted that there are geographical and ethnic differences and patterns, which made the consolidation of results more challenging. For future research, the authors deemed the role of the Lactobacillus family of particular interest.
Abstract
BACKGROUND Emerging evidence has demonstrated a close association between perturbations in vaginal microbiota composition in women and human papillomavirus (HPV) infection, cervical lesions, and cervical cancer (Ca); however, these findings are highly heterogeneous and inconclusive. AIM: To perform a comprehensive systematic review of the global disturbance in the vaginal microbiota, specifically in women with HPV-associated cervical diseases, and to further conduct within- and across-disease comparisons. METHOD Twenty-two records were identified in a systematic literature search of PubMed, Web of Science, and Embase up to February 28, 2022. We extracted microbial changes at the community (alpha and beta diversity) and taxonomic (relative abundance) levels. Within- and across-disease findings on the relative abundance of taxonomic assignments were qualitatively synthesized. RESULTS Generally, significantly higher alpha diversity was observed for HPV infection, cervical lesions, and/or cancer patients than in controls, and significant differences within beta diversity were observed for the overall microbial composition across samples. In within-disease comparisons, the genera Gardnerella, Megasphaera, Prevotella, Peptostreptococcus, and Streptococcus showed the greatest abundances with HPV infection; Sneathia and Atopobium showed inconsistent abundance with HPV infection, and Staphylococcus was observed in Ca. Across diseases, we find increased levels of Streptococcus and varying levels of Gardnerella were shared across HPV infections, high-grade squamous intraepithelial lesions, and Ca, whereas Lactobacillus iners varied depending on the HPV-related disease subtype. CONCLUSIONS This systematic review reports that vaginal microbiome disturbances are correlated to the depletion of Lactobacillus, enrichment of anaerobes, and increased abundance of aerobic bacteria in HPV infection and related cervical diseases. Moreover, L. iners may exert either protective or pathogenic effects on different HPV-related diseases.
2.
Yogurt, cultured fermented milk, and health: a systematic review.
Savaiano, DA, Hutkins, RW
Nutrition reviews. 2021;79(5):599-614
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Many fermented foods are associated with health benefits, including fermented dairy products. Whereby diary itself is part of many nutritional guidelines, the guidances rarely distinguish between dairy and fermented dairy. This qualitative, systematic review sought to capture how consumption of fermented milk products influences health. The review included 108 studies, with over 70% reporting beneficial health outcomes. A small number of studies reported insignificant or neutral results and four unfavourable ones. The aspects of health that were considered included lactose digestion and tolerance, gut health and disease, diarrhoea and constipation, irritable bowel syndrome, cardiovascular health and disease, hypertension, blood lipids, cancer risk, colorectal/breast/prostate cancer, weight and body composition, diabetes risk and metabolic syndrome and bone health. The authors concluded that eating fermented dairy products aided lactose digestion and showed a consistent link with reduced risk of breast and colorectal cancer, type 2 diabetes, and improved weight maintenance, cardiovascular, bone, and gastrointestinal health. As dairy appears to increase the risk for prostate cancer, fermented dairy seems to be no different here to unfermented dairy at increasing the risk. Some potential mechanisms are proposed in the discussion section, how fermented dairy may elicit its health benefits. Given the predominant health benefits of fermented dairy, the authors encouraged to include fermented dairy into national nutrition guidelines and stress distinction between dairy and fermented dairy products. This review captures current evidence of the widespread health benefits of fermented dairy consumption worthwhile considering in clinical practice. In the absence of more clear findings in relation to prostate cancer and prevention, a cautious approach to dairy and fermented dairy consumption may be warranted.
Abstract
Consumption of yogurt and other fermented products is associated with improved health outcomes. Although dairy consumption is included in most dietary guidelines, there have been few specific recommendations for yogurt and cultured dairy products. A qualitative systematic review was conducted to determine the effect of consumption of fermented milk products on gastrointestinal and cardiovascular health, cancer risk, weight management, diabetes and metabolic health, and bone density using PRISMA guidelines. English language papers in PubMed were searched, with no date restrictions. In total, 1057 abstracts were screened, of which 602 were excluded owing to lack of appropriate controls, potential biases, and experimental design issues. The remaining 455 papers were independently reviewed by both authors and 108 studies were included in the final review. The authors met regularly to concur, through consensus, on relevance, methods, findings, quality, and conclusions. The included studies were published between 1979 and 2017. From the 108 included studies, 76 reported a favorable outcome of fermented milks on health and 67 of these were considered to be positive or neutral quality according to the Academy of Nutrition and Dietetics' Quality Criteria Checklist. Of the 32 remaining studies, the study outcomes were either not significant (28) or unfavorable (4), and most studies (18) were of neutral quality. A causal relationship exists between lactose digestion and tolerance and yogurt consumption, and consistent associations exist between fermented milk consumption and reduced risk of breast and colorectal cancer and type 2 diabetes, improved weight maintenance, and improved cardiovascular, bone, and gastrointestinal health. Further, an association exists between prostate cancer occurrence and dairy product consumption in general, with no difference between fermented and unfermented products. This article argues that yogurt and other fermented milk products provide favorable health outcomes beyond the milk from which these products are made and that consumption of these products should be encouraged as part of national dietary guidelines. Systematic review registration: PROSPERO registration no. CRD42017068953.
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Probiotics and oral health: A systematic review.
Seminario-Amez, M, López-López, J, Estrugo-Devesa, A, Ayuso-Montero, R, Jané-Salas, E
Medicina oral, patologia oral y cirugia bucal. 2017;22(3):e282-e288
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Oral cavity has its own microbiome. When the balance of the microbes living in the oral cavity is altered, e.g. due to poor oral hygiene, diet or the use of antimicrobial drugs, periodontal disease and dental caries can develop. Probiotics may provide a new approach for the prevention and management of these oral diseases. This review paper examined 12 published randomised clinical trials, 2 meta-analyses and 1 systematic review that assessed the effect of probiotics in the treatment and/or prevention of an infectious oral disease. Based on the reviewed studies, the authors concluded that the use of probiotics could be beneficial for the maintenance of oral health, due to its ability to decrease colony forming unit counts of oral pathogens. However, more clinical trials with longer-term follow-ups are needed to confirm the efficacy of probiotic therapy, identify specific probiotic strains and determine the correct dose, treatment time and delivery form required for each disease.
Abstract
BACKGROUND Probiotics are microorganisms, mainly bacteria, which benefit the host's health. Many studies support the role of probiotics as a contributor to gastrointestinal health, and nowadays many authors are trying to prove its influence in oral health maintenance. OBJECTIVES To review the published literature with the purpose of knowing the importance of using probiotics as a preventive and therapeutic method for oral infectious diseases management. MATERIAL AND METHODS An electronic search in PubMed database with the keywords "oral health AND probiotics AND dentistry" was conducted. The inclusion criteria were: randomized clinical trials (RCTs) that assess the action of any probiotic strain in the treatment and / or prevention of an infectious oral disease, RCTs that assess the action of any probiotic strain on counting colony forming units (CFU) of oral pathogens, systematic reviews and meta-analysis. The Jadad scale was used to assess the high quality of RCTs. RESULTS Fifteen articles were considered for this review. Of which, 12 were RCTs of good / high quality (Jadad scale), two meta-analysis and one systematic review. CONCLUSIONS The literature reviewed suggests probiotics usage could be beneficial for the maintenance of oral health, due to its ability to decrease the colony forming units (CFU) counts of the oral pathogens. However, randomized clinical trials with long-term follow-up periods are needed to confirm their efficacy in reducing the prevalence/incidence of oral infectious diseases. Furthermore, the recognition of specific strains with probiotic activity for each infectious oral disease is required, in order to determine exact dose, treatment time and ideal vehicles.