Effects of vitamin D supplements on frequency of CD4+ T-cell subsets in women with Hashimoto's thyroiditis: a double-blind placebo-controlled study

Vitamin D: An Essential Nutrient in the Dual Relationship between Autoimmune Thyroid Diseases and Celiac Disease-A Comprehensive Review

Autoimmune thyroid diseases (AITD) are among the most frequent autoimmune disorders, with a multifactorial etiology in which both genetic and environmental determinants are probably involved. Celiac disease (CeD) also represents a public concern, given its increasing prevalence due to the recent improvement of screening programs, leading to the detection of silent subtypes. The two conditions may be closely associated due to common risk factors, including genetic setting, changes in the composition and diversity of the gut microbiota, and deficiency of nutrients like vitamin D. This comprehensive review discussed the current evidence on the pivotal role of vitamin D in modulating both gut microbiota dysbiosis and immune system dysfunction, shedding light on the possible relevance of an adequate intake of this nutrient in the primary prevention of AITD and CeD. While future technology-based strategies for proper vitamin D supplementation could be attractive in the context of personalized medicine, several issues remain to be defined, including standardized assays for vitamin D determination, timely recommendations on vitamin D intake for immune system functioning, and longitudinal studies and randomized controlled trials to definitely establish a causal relationship between serum vitamin D levels and the onset of AITD and CeD.

Effects of vitamin D supplementation on autoantibodies and thyroid function in patients with Hashimoto's thyroiditis: A systematic review and meta-analysis

BACKGROUND

Hashimoto's thyroiditis (HT) is the prevailing form of autoimmune thyroiditis and the leading cause of hypothyroidism in iodine-sufficient regions worldwide. This study aims to evaluate the efficacy of vitamin D supplementation on HT through a meta-analysis of randomized controlled trials (RCTs).

METHODS

The databases searched included PubMed, and others. We included RCTs that the treatment group received vitamin D, while the control group received either a placebo or no treatment. The studies measured the baseline and endpoint levels of 25-hydroxyvitamin D [25(OH)D], thyroid-stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), anti-thyroid peroxidase antibody (TPO-Ab), and thyroglobulin antibody (TG-Ab). We performed a meta-analysis to calculate the standardized mean difference (SMD) and 95% confidence interval (CI).

RESULTS

A total of 12 studies involving 862 individuals were included. Vitamin D supplementation has a significant impact on reducing the titers of TPO-Ab (SMD = -1.084, 95% CI = -1.624 to -0.545) and TG-Ab (SMD = -0.996, 95% CI = -1.579 to -0.413) in patients with HT, and it also improves thyroid function by decreasing TSH level (SMD = -0.167, 95% CI = -0.302 to 0.031) and increasing FT3 (SMD = 0.549, 95% CI = 0.077-1.020) and FT4 (SMD = 0.734, 95% CI = 0.184-1.285) levels. Active vitamin D (calcitriol) significantly reduces the titer of TPO-Ab compared to naive forms of vitamin D (vitamin D2 or D3); treatment durations > 12 weeks result in a more effective reduction of TPO-Ab levels and a more significant increase in FT4 and FT3 levels in patients with HT (meta-regression P < .05).

CONCLUSION

Vitamin D supplementation may have beneficial effects on HT patients by modulating immune responses and improving thyroid function.

Mapping the path towards novel treatment strategies: a bibliometric analysis of Hashimoto's thyroiditis research from 1990 to 2023

Background

Hashimoto's thyroiditis (HT), a common form of thyroid autoimmunity, is strongly associated with deteriorating clinical status and impaired quality of life. The escalating global prevalence, coupled with the complexity of disease mechanisms, necessitates a comprehensive, bibliometric analysis to elucidate the trajectory, hotspots, and future trends in HT research.

Objective

This study aims to illuminate the development, hotspots, and future directions in HT research through systematic analysis of publications, institutions, authors, journals, references, and keywords. Particular emphasis is placed on novel treatment strategies for HT and its complications, highlighting the potential role of genetic profiling and immunomodulatory therapies.

Methods

We retrieved 8,726 relevant documents from the Web of Science Core Collection database spanning from 1 January 1990 to 7 March 2023. Following the selection of document type, 7,624 articles were included for bibliometric analysis using CiteSpace, VOSviewer, and R software.

Results

The temporal evolution of HT research is categorized into three distinct phases: exploration (1990-1999), rapid development (1999-2000), and steady growth (2000-present). Notably, the United States, China, Italy, and Japan collectively contributed over half (54.77%) of global publications. Among the top 10 research institutions, four were from Italy (4/10), followed by China (2/10) and the United States (2/10). Recent hotspots, such as the roles of gut microbiota, genetic profiling, and nutritional factors in HT management, the diagnostic dilemmas between HT and Grave's disease, as well as the challenges in managing HT complicated by papillary thyroid carcinoma and type 1 diabetes mellitus, are discussed.

Conclusion

Although North America and Europe have a considerable academic impact, institutions from emerging countries like China are demonstrating promising potential in HT research. Future studies are anticipated to delve deeper into the differential diagnosis of HT and Grave's disease, the intricate relationship between gut microbiota and HT pathogenesis, clinical management of HT with papillary thyroid carcinoma or type 1 diabetes, and the beneficial effects of dietary modifications and micronutrients supplementation in HT. Furthermore, the advent of genetic profiling and advanced immunotherapies for managing HT offers promising avenues for future research.

Hypovitaminosis D in persons with Down syndrome and autism spectrum disorder

BACKGROUND

Plasma levels of vitamin D have been reported to be low in persons with Down syndrome (DS) and existing data is limited to small and homogenous cohorts. This is of particular importance in persons with DS given the high rates of autoimmune disease in this population and the known relationship between vitamin D and immune function. This study sought to investigate vitamin D status in a multi-center cohort of individuals with DS and compare them to individuals with autism spectrum disorder (ASD) and neurotypical (NT) controls.

METHODS

A retrospective, multi-center review was performed. The three sites were located at latitudes of 42.361145, 37.44466, and 34.05349. Patients were identified by the International Classification of Diseases (ICD)-9 or ICD-10 codes for DS, ASD, or well-child check visits for NT individuals. The first vitamin D 25-OH level recorded in the electronic medical record (EMR) was used in this study as it was felt to be the most reflective of a natural and non-supplemented state. Vitamin D 25-OH levels below 30 ng/mL were considered deficient.

RESULTS

In total, 1624 individuals with DS, 5208 with ASD, and 30,775 NT controls were identified. Individuals with DS had the lowest mean level of vitamin D 25-OH at 20.67 ng/mL, compared to those with ASD (23.48 ng/mL) and NT controls (29.20 ng/mL) (p < 0.001, 95% CI: -8.97 to -6.44). A total of 399 (24.6%) individuals with DS were considered vitamin D deficient compared to 1472 (28.3%) with ASD and 12,397 (40.3%) NT controls (p < 0.001, 95% CI: -5.43 to -2.36). Individuals with DS with higher body mass index (BMI) were found to be more likely to have lower levels of vitamin D (p < 0.001, 95% CI: -0.3849 to -0.1509). Additionally, having both DS and a neurologic diagnosis increased the likelihood of having lower vitamin D levels (p < 0.001, 95% CI: -5.02 to -1.28). Individuals with DS and autoimmune disease were much more likely to have lower vitamin D levels (p < 0.001, 95% CI: -6.22 to -1.55). Similarly, a history of autoimmunity in a first-degree relative also increased the likelihood of having lower levels of vitamin D in persons with DS (p = 0.01, 95% CI: -2.45 to -0.63).

CONCLUSIONS

Individuals with DS were noted to have hypovitaminosis D in comparison to individuals with ASD and NT controls. Associations between vitamin D deficiency and high BMI, personal autoimmunity, and familial autoimmunity were present in individuals with DS.

Do Dietary Supplements Affect Inflammation, Oxidative Stress, and Antioxidant Status in Adults with Hypothyroidism or Hashimoto's Disease?-A Systematic Review of Controlled Trials

This systematic review aims to summarise the results of controlled trials on dietary supplements (DS) usage and inflammation, oxidative stress, antioxidant status, and thyroid parameter improvement in hypothyroidism (HT)/Hashimoto's thyroiditis (AIT) patients. The study protocol was registered with PROSPERO (no. CRD42022365149). A comprehensive search of the PubMed, Scopus, and Web of Science databases resulted in the identification of nineteen randomised controlled trials and three non-randomised studies for the review; three studies examined the effect of supplementation with vitamin D, twelve studies-with selenium, and seven studies-with other DS. Based on very limited evidence, the lack of influence of vitamin D supplementation on inflammatory parameters was found, while no studies have examined oxidative stress and antioxidant status parameters, and only one provided results for a single thyroid parameter after an intervention. Some evidence was found proving that selenium supplementation may decrease inflammation and improve thyroid parameters, but reaching a conclusion about its influence on oxidative stress and antioxidant status is not possible because of the insufficient number of studies. Additionally, due to examining other DS (e.g., multicomponent, Nigella sativa, and genistein) only in single studies, conclusions cannot be drawn. Further long-term, high-quality randomised controlled trials are necessary to better understand the influence of DS on inflammation, oxidative stress, and antioxidant status, as well as their potential to improve thyroid gland function in HT/AIT patients.

Impact of Vitamin D on Immunopathology of Hashimoto's Thyroiditis: From Theory to Practice

Hashimoto's thyroiditis (HT) is a common autoimmune disease affecting the thyroid gland, characterized by lymphocytic infiltration, damage to thyroid cells, and hypothyroidism, and often requires lifetime treatment with levothyroxine. The disease has a complex etiology, with genetic and environmental factors contributing to its development. Vitamin D deficiency has been linked to a higher prevalence of thyroid autoimmunity in certain populations, including children, adolescents, and obese individuals. Moreover, vitamin D supplementation has shown promise in reducing antithyroid antibody levels, improving thyroid function, and improving other markers of autoimmunity, such as cytokines, e.g., IP10, TNF-α, and IL-10, and the ratio of T-cell subsets, such as Th17 and Tr1. Studies suggest that by impacting various immunological mechanisms, vitamin D may help control autoimmunity and improve thyroid function and, potentially, clinical outcomes of HT patients. The article discusses the potential impact of vitamin D on various immune pathways in HT. Overall, current evidence supports the potential role of vitamin D in the prevention and management of HT, although further studies are needed to fully understand its mechanisms of action and potential therapeutic benefits.

How does Hashimoto's thyroiditis affect bone metabolism?

Bone marrow contains resident cellular components that are not only involved in bone maintenance but also regulate hematopoiesis and immune responses. The immune system and bone interact with each other, coined osteoimmunology. Hashimoto's thyroiditis (HT) is one of the most common chronic autoimmune diseases which is accompanied by lymphocytic infiltration. It shows elevating thyroid autoantibody levels at an early stage and progresses to thyroid dysfunction ultimately. Different effects exert on bone metabolism during different phases of HT. In this review, we summarized the mechanisms of the long-term effects of HT on bone and the relationship between thyroid autoimmunity and osteoimmunology. For patients with HT, the bone is affected not only by thyroid function and the value of TSH, but also by the setting of the autoimmune background. The autoimmune background implies a breakdown of the mechanisms that control self-reactive system, featuring abnormal immune activation and presence of autoantibodies. The etiology of thyroid autoimmunity and osteoimmunology is complex and involves a number of immune cells, cytokines and chemokines, which regulate the pathogenesis of HT and osteoporosis at the same time, and have potential to affect each other. In addition, vitamin D works as a potent immunomodulator to influence both thyroid immunity and osteoimmunology. We conclude that HT affects bone metabolism at least through endocrine and immune pathways.

Vitamin D and the Thyroid: A Critical Review of the Current Evidence

Vitamin D is necessary for the normal functioning of many organs, including the thyroid gland. It is, therefore, not surprising that vitamin D deficiency is considered a risk factor for the development of many thyroid disorders, including autoimmune thyroid diseases and thyroid cancer. However, the interaction between vitamin D and thyroid function is still not fully understood. This review discusses studies involving human subjects that (1) compared vitamin D status (primarily determined by serum calcidiol (25-hydroxyvitamin D [25(OH)D]) levels) with thyroid function assessed by thyroid stimulating hormone (TSH), thyroid hormones, and anti-thyroid antibody levels; and (2) evaluated the effect of vitamin D supplementation on thyroid function. Due to the many inconsistencies in the results between the studies, it is still difficult to draw a definite conclusion on how vitamin D status affects thyroid function. Studies in healthy participants observed either a negative correlation or no association between TSH and 25(OH)D levels, while the results for thyroid hormones showed high variability. Many studies have observed a negative association between anti-thyroid antibodies and 25(OH)D levels, but equally many studies have failed to observe such an association. Regarding the studies that examined the effect of vitamin D supplementation on thyroid function, almost all observed a decrease in anti-thyroid antibody levels after vitamin D supplementation. Factors that could contribute to the high variability between the studies are the use of different assays for the measurement of serum 25(OH)D levels and the confounding effects of sex, age, body-mass index, dietary habits, smoking, and the time of year when the samples were collected. In conclusion, additional studies with larger numbers of participants are needed to fully understand the effect of vitamin D on thyroid function.

Overview of gene expression techniques with an emphasis on vitamin D related studies

Each cell controls when and how its genes must be expressed for proper function. Every function in a cell is driven by signaling molecules through various regulatory cascades. Different cells in a multicellular organism may express very different sets of genes, even though they contain the same DNA. The set of genes expressed in a cell determines the set of proteins and functional RNAs it contains, giving it its unique properties. Malfunction in gene expression harms the cell and can lead to the development of various disease conditions. The use of rapid high-throughput gene expression profiling unravels the complexity of human disease at various levels. Peripheral blood mononuclear cells (PBMC) have been used frequently to understand gene expression homeostasis in various disease conditions. However, more studies are required to validate whether PBMC gene expression patterns accurately reflect the expression of other cells or tissues. Vitamin D, which is responsible for a multitude of health consequences, is also an immune modulatory hormone with major biological activities in the innate and adaptive immune systems. Vitamin D exerts its diverse biological effects in target tissues by regulating gene expression and its deficiency, is recognized as a public health problem worldwide. Understanding the genetic factors that affect vitamin D has the potential benefit that it will make it easier to identify individuals who require supplementation. Different technological advances in gene expression can be used to identify and assess the severity of disease and aid in the development of novel therapeutic interventions. This review focuses on different gene expression approaches and various clinical studies of vitamin D to investigate the role of gene expression in identifying the molecular signature of the disease.

Assessment of the reporting quality of randomised controlled trials for vitamin D supplementation in autoimmune thyroid disorders based on the CONSORT statement

BACKGROUND-PURPOSE

Randomized controlled trials (RCTs) are the cornerstone of evidence-based medicine, yet their quality is often suboptimal. The Consolidated Standards of Reporting Trials (CONSORT) statement is a list of advice to upgrade the quality of RCTs. The aim of this study was the assessment of the quality of RCTs for vitamin D supplements in thyroid autoimmunity according to the revised CONSORT 2010 checklist.

METHODS

Databases were searched for RCTs involving patients with autoimmune thyroid disorders (AITDs) who received vitamin D supplements published from 2011 to 2021. A list of 37-items was used and adherence ≥75% was considered of optimal quality. The primary outcome was the mean CONSORT adherence of studies. Secondary outcomes were the estimation of compliance per CONSORT item and the examination for possible determinants of the reporting quality.

RESULTS

Thirteen eligible trials were finally included. The mean compliance was 61.15% ± 14.86%. Only threeof the studies (23%) achieved a good reporting quality (≥75%), while ten (77%) were presented with inadequate reporting (<75%). Randomization and blinding were mainly poorly reported. Impact Factor (IF) of journal was associated with the reporting quality in the univariate analysis [p = 0.033, OR = 1.65, 95%CI = (1316, 1773)]. Sample size (p = 0.067), number of authors (p = 0.118) and number of citations (p = 0.125) were marginally not significant. None of the factors showed significant results in multivariate analysis. Reporting quality and IF were strongly positively correlated [Pearson's r = 0.740, p = 0.04].

CONCLUSION

This study shows that mean CONSORT adherence of RCTs for Vitamin D supplementation in AITDs is moderate, reflecting that study quality and transparency could be improved with better adherence to CONSORT rules.

Metabolic Characteristics of Hashimoto's Thyroiditis Patients and the Role of Microelements and Diet in the Disease Management-An Overview

Hashimoto’s thyroiditis (HT) is the most common autoimmune disease and the leading cause of hypothyroidism, in which damage to the thyroid gland occurs due to the infiltration of lymphocytes. It is characterized by increased levels of antibodies against thyroid peroxidase and thyroglobulin. In this review, we present the metabolic profile, the effectiveness of micronutrient supplementation and the impact of dietary management in patients with HT. For this current literature review, the databases PubMed, Cochrane, Medline and Embase were reviewed from the last ten years until March 2022. This article provides a comprehensive overview of recent randomized controlled trials, meta-analyses, and clinical trials. Many patients with HT, even in the euthyroid state, have excess body weight, metabolic disorders, and reduced quality of life. Due to frequent concomitant nutritional deficiencies, the role of vitamin D, iodine, selenium, magnesium, iron and vitamin B12 is currently debated. Several studies have underlined the benefits of vitamin D and selenium supplementation. There is still no specific diet recommended for patients with HT, but a protective effect of an anti-inflammatory diet rich in vitamins and minerals and low in animal foods has been suggested. There is insufficient evidence to support a gluten-free diet for all HT patients. Pharmacotherapy, along with appropriate nutrition and supplementation, are important elements of medical care for patients with HT. The abovementioned factors may decrease autoantibody levels, improve thyroid function, slow down the inflammatory process, maintain proper body weight, relieve symptoms, and prevent nutritional deficiencies and the development of metabolic disorders in patients with HT.

Effects of vitamin D treatment on thyroid function and autoimmunity markers in patients with Hashimoto's thyroiditis-A meta-analysis of randomized controlled trials

Introduction

Recent evidence suggested that vitamin D deficiency was associated with Hashimoto's thyroiditis (HT) pathogenesis and thyroid hypofunction. This study aimed to investigate whether vitamin D supplementation would be effective in the prevention and progression of hypothyroidism in patients with HT.

Methods

PubMed, Embase and the Cochrane library were searched for randomized controlled trials (RCTs) and prospective cohort studies published from inception to August 2021.

Results

A total of 7 cohorts of patients from six clinical trials with 258 patients with HT were included. Significant difference was found (WMD = 19.00, 95% CI: 12.43, 25.58, p < 0.001; I² = 90.0%, p_{heterogeneity} < 0.001) between the vitamin D group and control group in serum 25‐hydroxyvitamin D level. And the combined results indicated vitamin D supplementation significantly reduced the level of thyroid peroxidase antibodies (TPO‐Ab) compared to the control group (WMD = −158.18, 95% CI: −301.92, −14.45, p = 0.031; I² = 68.8%, p_{heterogeneity} = 0.007). Whereas no significant differences were found on the levels of thyroid‐stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxine (FT4) compared to the control group (p > 0.05).

What is New and Conclusion

Our study demonstrated that vitamin D treatment might significantly increase the serum 25(OH)D levels and produce changes in TPO‐Ab titres.

No significant association was found between serum vitamin D treatment and the levels of TG‐Ab, TSH, FT3 and FT4, suggesting that vitamin D is not associated with the function of the thyroid in patients with HT.

Immunomodulatory Function of Vitamin D and Its Role in Autoimmune Thyroid Disease

Vitamin D is one of the most important nutrients required by the human body. It is a steroid hormone that plays an important role in regulating calcium and phosphorus metabolism, and bone health. Epidemiological studies have revealed a close correlation between vitamin D and many common chronic diseases. Additionally, vitamin D has recently been shown to act as an immunomodulatory hormone, and, accordingly, vitamin D deficiency was uncovered as a risk factor for autoimmune thyroid diseases, although the underlying mechanisms are still unknown. It is therefore necessary to disclose the role and mechanism of action of vitamin D in the occurrence and development of autoimmune thyroid diseases. This knowledge will help design intervention and early treatment strategies for patients with autoimmune thyroid diseases who present with low levels of vitamin D.

"Vitamin D Deficiency Is More Common in Women with Autoimmune Thyroiditis: A Retrospective Study"

BACKGROUND

Vitamin D is a hormone that is mainly produced in the skin upon ultraviolet B radiation exposure and has important influence on various organs. In recent years, data have been collected that vitamin D deficiency plays an important role in the development of various nonskeletal diseases, including autoimmune diseases. Chronic autoimmune thyroiditis (Hashimoto's thyroiditis) is one of the most common organ-specific autoimmune endocrine diseases. It is characterized by increased level of antithyroid peroxidase and/or antithyroglobulin antibodies in blood, which often leads to thyroid dysfunction and structural changes of the gland. There is an opinion that vitamin D deficiency may be considered as an important risk factor for development of chronic autoimmune thyroiditis, but data of various small studies are controversial. Despite the fact that Georgia is a sunny country, vitamin D deficiency is a widespread problem here. Thyroid diseases, including the chronic autoimmune thyroiditis, are also very common in Georgia. The aim of our research was to compare the level of vitamin D between the patients with chronic autoimmune thyroiditis and the healthy subjects.

METHODS

This retrospective study enrolled subjects, who were 18-70 years old and visited the clinics "Cortex" and "National Institute of Endocrinology" in 2018 or in 2019 from mid-spring to mid-summer. Data of thyroid-stimulating hormone, free thyroxine, antithyroid peroxidase antibodies, antithyroglobulin antibodies, thyroid ultrasonography, and 25(OH) vitamin D were retrospectively analysed based on medical history. In total, data of 1295 patients were collected. The statistical processing of data was performed through the SPSS 20 program.

RESULTS

The negative association between thyroid-stimulating hormone, antithyroid peroxidase antibodies, antithyroglobulin antibodies, heterogeneous parenchyma of thyroid gland, and vitamin D was found in women. Statistically significant association was not detected in men.

CONCLUSIONS

Serum vitamin D is lower in women with autoimmune thyroiditis and primary hypothyroidism. Further studies are needed to evaluate the influence of vitamin D supplementation on thyroid autoantibody positivity or primary hypothyroidism.

Vitamin D status and vitamin D receptor genotypes in celiac disease: a meta-analysis

BACKGROUND

There have been various articles reporting relationship between Vitamin D (VitD) and celiac disease (CeD), but results remain controversial. This study aimed to conduct a meta-analysis to systematically review and quantify the relationship between VitD and CeD. Moreover, difference in Vitamin D Receptor (VDR) genotypes between CeD patients and controls was also analyzed.

METHODS

Articles published until July 20, 2019 in the PubMed, MEDLINE, and EMBASE databases were searched. According to the inclusion and exclusion criteria, relevant statistical data were collated and extracted, which were finally analyzed by STATA15.1.

RESULTS

27 articles and 28 sets of data were included. It showed that average 25(OH)D level in CeD patients was 8.36 nmol/L lower than controls (Weighted Mean Difference (WMD) = -8.36, 95% CI = [-14.63, -2.09] nmol/L). After gluten-free diet treatment, we found that average 25(OH)D level in treated patients was 15.6 nmol/L higher than untreated patients (WMD = 15.6, 95% CI = [5.96, 25.23] nmol/L). In addition, 25(OH)D level in treated patients was close to healthy controls (WMD = -2.82, 95% CI = [-6.45, 0.73] nmol/L). However, genetic polymorphism analysis showed that there is no difference in VDR genotypes between CeD and control.

CONCLUSIONS

CeD had decreased serum 25(OH)D levels, which returned to normal after treatment, suggesting that VitD may play a role in the development of CeD. The directionality of this association cannot be confirmed from cross-sectional studies. Demonstration of a causal role of VitD deficiency in CeD development in future studies could have important therapeutic implications.

The exploration of Hashimoto's Thyroiditis related miscarriage for better treatment modalities

Hashimoto's thyroiditis (HT) is the most prevalent autoimmune thyroid disease (ATD) worldwide and is strongly associated with miscarriage and even recurrent miscarriage (RM). Moreover, with a deepening understanding, emerging evidence has shown that immune dysfunctions caused by HT conditions, including imbalanced subsets of CD4+ T-helper cells, B regulatory (Breg) cells, high expression levels of CD56dim natural killer (NK) cells, and cytokines, possibly play an important role in impairing maternal tolerance to the fetus. In recent years, unprecedented progress has been made in recognizing the specific changes in immune cells and molecules in patients with HT, which will be helpful in exploring the mechanism of HT-related miscarriage. Based on these findings, research investigating some potentially more effective treatments, such as selenium (Se), vitamin D3, and intravenous immunoglobulin (IVIG), has been well developed over the past few years. In this review, we highlight some of the latest advances in the possible immunological pathogenesis of HT-related miscarriage and focus on the efficacies of treatments that have been widely introduced to clinical trials or practice described in the most recent literature.