1.
Thyroid-Gut-Axis: How Does the Microbiota Influence Thyroid Function?
Knezevic, J, Starchl, C, Tmava Berisha, A, Amrein, K
Nutrients. 2020;12(6)
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Thyroid and gut disease often coexist together. This literature review highlights the strong interplay between gut, microbiota and thyroid disease. In autoimmune thyroid disease (AITD) gut bacteria imbalances, bacterial overgrowth, Coeliac's disease or non-coeliacs wheat sensitivity, increased gut permeability and resulting deficiency of thyroid nutrients are not uncommon. Inflammation and intestinal wall damage that lead to increased permeability are thought to be one of the driving factors for autoimmune activity. Allergens, certain drugs, impaired gut flora and nutrient deficiencies are some of the contributors to heightened intestinal permeability. Furthermore, the gut walls host deiodinase enzymes that convert thyroid hormone to its active form. The gut microbiota however influence thyroid function in their own rights. The bacteria are crucial for nutrient synthesis, absorption and availability, including those essential for thyroid health. Gut bacteria and their metabolites also play a significant role in the regulation, development and training of immune cells, relevant to AITD. After all, the gut also houses a large proportion of the immune system known as gut-associated lymphatic tissue (GALT). Besides, some bacteria species seem to be capable of balancing fluctuating thyroid hormone levels in the blood. The writings further elaborate on thyroid-essential nutrients and the gut such as iodine, iron, zinc, selenium and Vitamin D. And the impact of bariatric surgery on thyroid function and the presence of certain gut bacteria in thyroid cancers. In summary, the authors concluded that the thyroid-gut axis seems to exhibit a strong connection. Limited evidence from human studies showed promising results of probiotics and synbiotics on thyroid function and targeting the microbiota as a novel strategies for the management of thyroid disease is encouraged to be explored further. This article may be of interest to those looking for an informative summary on the many ways in which the gut influences thyroid function in health and disease.
Abstract
A healthy gut microbiota not only has beneficial effects on the activity of the immune system, but also on thyroid function. Thyroid and intestinal diseases prevalently coexist-Hashimoto's thyroiditis (HT) and Graves' disease (GD) are the most common autoimmune thyroid diseases (AITD) and often co-occur with Celiac Disease (CD) and Non-celiac wheat sensitivity (NCWS). This can be explained by the damaged intestinal barrier and the following increase of intestinal permeability, allowing antigens to pass more easily and activate the immune system or cross-react with extraintestinal tissues, respectively. Dysbiosis has not only been found in AITDs, but has also been reported in thyroid carcinoma, in which an increased number of carcinogenic and inflammatory bacterial strains were observed. Additionally, the composition of the gut microbiota has an influence on the availability of essential micronutrients for the thyroid gland. Iodine, iron, and copper are crucial for thyroid hormone synthesis, selenium and zinc are needed for converting T4 to T3, and vitamin D assists in regulating the immune response. Those micronutrients are often found to be deficient in AITDs, resulting in malfunctioning of the thyroid. Bariatric surgery can lead to an inadequate absorption of these nutrients and further implicates changes in thyroid stimulating hormone (TSH) and T3 levels. Supplementation of probiotics showed beneficial effects on thyroid hormones and thyroid function in general. A literature research was performed to examine the interplay between gut microbiota and thyroid disorders that should be considered when treating patients suffering from thyroid diseases. Multifactorial therapeutic and preventive management strategies could be established and more specifically adjusted to patients, depending on their gut bacteria composition. Future well-powered human studies are warranted to evaluate the impact of alterations in gut microbiota on thyroid function and diseases.
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Psoriasis and Microbiota: A Systematic Review.
Benhadou, F, Mintoff, D, Schnebert, B, Thio, HB
Diseases (Basel, Switzerland). 2018;6(2)
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Psoriasis is an autoimmune inflammatory skin disease that causes red, itchy, flaky and scaly skin. Skin integrity and function are critically dependent on the microbial population on it. Based on this systematic review, the immune system's interaction with microbes on the skin was examined and its relationship to psoriasis. T-cell mediated inflammation is characteristic of psoriasis where interaction between type IV collagen and α1β1 integrin, a collagen receptor, occurs. In psoriatic skin lesions, Firmicutes were predominant, while Actinobacteria were less prevalent. Psoriasis exacerbations are also associated with an exacerbated number of fungi, Malassezia species, in skin lesions. As therapeutic strategies for psoriasis, this systematic review suggests adhering to a gluten-free diet and incorporating prebiotics and probiotics such as Lactobacillus. However, further research is needed to develop specific therapeutic and skin modulation strategies. Health care professionals can benefit from this systematic review by understanding the pathophysiology behind psoriasis and possible therapeutic strategies to consider.
Abstract
BACKGROUND Recent advances have highlighted the crucial role of microbiota in the pathophysiology of chronic inflammatory diseases as well as its impact on the efficacy of therapeutic agents. Psoriasis is a chronic, multifactorial inflammatory skin disorder, which has a microbiota distinct from healthy, unaffected skin. AIM: Through an extensive review of the literature, we aim to discuss the skin and gut microbiota and redefine their role in the pathogenesis of psoriasis. CONCLUSIONS Unfortunately, the direct link between the skin microbiota and the pathogenesis of psoriasis remains to be clearly established. Apart from improving the course of psoriasis, selective modulation of the microbiota may increase the efficacy of medical treatments as well as attenuate their side effects.
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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.