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The Influence of Nutritional Intervention in the Treatment of Hashimoto's Thyroiditis-A Systematic Review.
Osowiecka, K, Myszkowska-Ryciak, J
Nutrients. 2023;15(4)
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Hashimoto’s thyroiditis is an autoimmune disorder characterized by the presence of antibodies in the thyroid gland such as thyroid peroxidase (TPO) and thyroglobulin (TG) antibodies. Immune-mediated inflammatory responses eventually lead to the progressive destruction of the gland and impaired thyroid function. The disease has a strong genetic disposition but is also influenced by environmental factors, including diet. Hence diet has been considered a complementary tool to manage thyroid function and disease progression by harnessing the benefits of certain nutrients and anti-inflammatory properties. This systematic review examined the effects of nutrients and dietary interventions on Hashimoto’s disease in current literature. Using antibody levels, thyroid hormone levels and body weight to measure outcomes. The review included 9 studies, all of which compared the intervention group to the control groups. The trials included looked at gluten-free, lactose-free and energy-restricted diets, with or without selected nutrients and foods supplements (ie. Nigella sativa, iodine). The intervention duration ranged from 3 weeks to 12 months. Despite the small number of trials, the data from those studies included in this review showed promising results. Improvements in disease parameters were observed in diets that were energy deficient, eliminated gluten, lactose and goitrogens or added Nigella sativa. Iodine restrictions did not show any improvements. In the discussion section, the authors presented the results in the wider context and the findings from other studies. Ultimately there appears to be a wide variance in outcomes, usually ranging from beneficial to neutral. The authors contributed to such variability due to the complexity of the condition and many influencing factors. Often participants in trials have highly variable thyroid status and function, and differences in regular dietary intakes of nutrients critical to thyroid health can easily distort the results. Hence much more specific research is needed to make firmer conclusions. Whereby no clear conclusions in larger groups could be drawn, potential benefits of dietary interventions in Hashimoto's disease may be much more apparent in clinical settings with personalized approaches that account for such individual variances.
Abstract
Diet can be a complementary treatment for Hashimoto's disease by affecting thyroid function and anti-inflammatory properties. It is still unclear which dietary strategy would be the most beneficial. The aim of this systematic review is to examine all the data currently available in the literature on the effects of nutritional intervention on biochemical parameters (anti-thyroid antibody and thyroid hormones levels) and characteristic symptoms in the course of Hashimoto's thyroiditis. This systematic review was prepared based on PRISMA guidelines. Articles in PubMed and Scopus databases published up to November 2022 were searched. As a result of the selection, out of 1350 publications, 9 were included for further analysis. The nutritional interventions included the following: elimination of gluten (3 articles) or lactose (1 article), energy restriction with or without excluding selected foods (n = 2), consumption of Nigella sativa (n = 2), or dietary iodine restriction (n = 1). The intervention duration ranged from 21 days to 12 months and included individuals with various thyroid function. Of the nine studies, three studies were female only. An improvement was observed during an energy deficit and after the elimination of selected ingredients (e.g., gluten, lactose, or goitrogens), as well as after the intervention of Nigella sativa. These interventions improved antibody levels against peroxidase (anti-TPO), (thyrotropin) TSH, and free thyroxine (fT4). No improvement was seen on the iodine-restricted diet. Varied outcomes of analyzed dietary interventions may be due to the heterogeneous thyroid condition, high variability between patients, and differences in habitual intake of critical nutrients (e.g., iodine, selenium, and iron) in different populations. Therefore, there is a great need for further experimental studies to determine whether any nutritional interventions are beneficial in Hashimoto's disease.
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Associations between Dynamic Vitamin D Level and Thyroid Function during Pregnancy.
Wang, H, Wang, HJ, Jiao, M, Han, N, Xu, J, Bao, H, Liu, Z, Ji, Y
Nutrients. 2022;14(18)
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Thyroid hormones play a vital role in regulating metabolism. Adequate thyroid hormone levels are also critical during pregnancy for optimal fetal growth and development. The foetus is dependent on maternal thyroid hormones until its own thyroid gland matured in the second half of pregnancy. Furthermore, pregnancy impacts thyroid function leading to an increased demand for thyroid hormones. Thyroid disease has been associated with Vitamin D deficiency. During pregnancy, both thyroid disorders and Vitamin D deficiency can have adverse effects on pregnancy and pregnancy outcomes, hence a potential link between Vitamin D status and thyroid function has been postulated. To fill the gaps in previous research, this retrospective cohort study aimed to explore the associations between Vitamin D status and thyroid function throughout the pregnancy, in each trimester. The analysis of hospital data collected in Beijing demonstrated an association between Vitamin D levels and thyroid function throughout pregnancy. Such interlink appeared to be dynamic and changed depending on the stage of pregnancy. The author's findings affirmed that maintenance of adequate Vitamin D levels supports normal thyroid function which is an important nutritional strategy for a healthy pregnancy.
Abstract
Optimal Vitamin D (VitD) status and thyroid function are essential for pregnant women. This study aimed to explore associations between dynamic VitD status and thyroid function parameters in each trimester and throughout the pregnancy period. Information on all 8828 eligible participants was extracted from the Peking University Retrospective Birth Cohort in Tongzhou. Dynamic VitD status was represented as a combination of deficiency/sufficiency in the first and second trimesters. Thyroid function was assessed in three trimesters. The associations between VitD and thyroid function were assessed by multiple linear regression and generalized estimating equation models in each trimester and throughout the pregnancy period, respectively. The results indicated that both free thyroxine (fT4; β = 0.004; 95%CI: 0.003, 0.006; p < 0.001) and free triiodothyronine (fT3; β = 0.009; 95%CI: 0.004, 0.015; p = 0.001) had positive associations with VitD status in the first trimester. A VitD status that was sufficient in the first trimester and deficient in the second trimester had a lower TSH (β = -0.370; 95%CI: -0.710, -0.031; p = 0.033) compared with the group with sufficient VitD for both first and second trimesters. In conclusion, the associations between VitD and thyroid parameters existed throughout the pregnancy. Maintaining an adequate concentration of VitD is critical to support optimal thyroid function during pregnancy.
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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.