Mediterranean Diet and Thyroid: An Interesting Alliance

Obesity and Obesity-Related Thyroid Dysfunction: Any Potential Role for the Very Low-Calorie Ketogenic Diet (VLCKD)?

PURPOSE OF REVIEW

This review aims to explore in-depth the different aspects of the association between very low-calorie ketogenic diet (VLCKD), obesity and obesity-related thyroid dysfunction.

RECENT FINDINGS

The VLCKD, proposed as a non-pharmacological strategy for the management of certain chronic diseases, is becoming increasingly popular worldwide. Initially used to treat epilepsy, it has been shown to be effective in controlling body weight gain and addressing various pathophysiological conditions. Research has shown that a low-calorie, high-fat diet can affect thyroid hormone levels. Weight loss can also influence thyroid hormone levels. Studies have suggested that long-term use of VLCKD for refractory epilepsy may be related to the development of hypothyroidism, with an effect seen in various populations. In particular, women with obesity following VLCKD tend to have reduced T3 levels. We propose further research to unravel the underlying mechanisms linking VLCKD to obesity and obesity-related thyroid dysfunction.

Maternal plasma phospholipid polyunsaturated fatty acids in early pregnancy and thyroid function throughout pregnancy: a longitudinal study

BACKGROUND

Evidence has indicated that polyunsaturated fatty acids (PUFAs)-enriched diet could reduce inflammation because of thyroid autoimmunity in vivo, and therefore, enhance thyroid function.

OBJECTIVES

We investigated whether early pregnancy plasma phospholipid PUFAs could benefit maternal thyroid function across pregnancy, which is critical to fetal brain development and growth in pregnancy.

METHODS

Within the National Institute of Child Health and Human Development Fetal Growth Studies-Singleton Cohort, we collected plasma samples longitudinally from 214 subjects [107 with gestational diabetes mellitus (GDM) matched with 107 controls] with a singleton pregnancy. We measured 11 PUFAs at early pregnancy (10-14 wk) and 5 thyroid biomarkers at 10-14, 15-26, 23-31, and 33-39 wk, including free thyroxine (fT4), free triiodothyronine (fT3), thyroid-stimulating hormone, antithyroid peroxidase, and antithyroglobulin. Associations of PUFAs with thyroid function biomarkers and relative risk (RR) of gestational hypothyroidism (GHT) during pregnancy were assessed using generalized linear mixed models and modified Poisson regression, respectively.

RESULTS

After sample weighting because of subjects with GDM over-representing in the analytic sample with biomarkers, eicosapentaenoic acid (EPA) at early pregnancy was associated with a reduction of 0.24 pmol/L (95% confidence intervals: -0.31, -0.16) in fT3 across gestation per standard deviation (SD) increment, whereas docosahexaenoic acid (DHA) at early pregnancy was associated with an increment of 0.04 ng/dL (0.02, 0.05) in fT4 across gestation per SD increment. Furthermore, EPA and docosatetraenoic acid (DTA) were associated with lower risks of persistent GHT (EPA-RR: 0.13; 0.06, 0.28; DTA-RR: 0.24; 0.13, 0.44) per SD increment. All significant associations remained robust in sensitivity analysis and multiple testing.

CONCLUSIONS

Certain plasma phospholipid PUFAs were associated with optimal levels of thyroid biomarkers and even lower risk of GHT throughout pregnancy, which might be potentially targeted for maternal thyroid regulation in early pregnancy.

CLINICAL TRIAL REGISTRY

This trial was registered at https://beta.

CLINICALTRIALS

gov/study/NCT00912132?distance=50&term=NCT00912132&rank=1 as NCT00912132.

Progress in long non-coding RNAs as prognostic factors of papillary thyroid carcinoma

Papillary thyroid carcinoma (PTC) is generally recognized as a slow-growing tumor. However, a small subset of patients may still experience relapse or metastasis shortly after therapy, leading to a poor prognosis and raising concerns about excessive medical treatment. One major challenge lies in the inadequacy of effective biomarkers for accurate risk stratification. Long non-coding RNAs (lncRNAs), which are closely related to malignant characteristics and poor prognosis, play a significant role in the genesis and development of PTC through various pathways. The objective of this review is to provide a comprehensive summary of the biological functions of lncRNAs in PTC, identify prognosis-relevant lncRNAs, and explore their potential mechanisms in drug resistance to BRAF kinase inhibitors, tumor dedifferentiation, and lymph node metastasis. By doing so, this review aims to offer valuable references for both basic research and the prediction of PTC prognosis.

Dietary Patterns and Hypothyroidism in U.S. Adult Population

The thyroid gland produces hormones that are essential for various body functions. Hypothyroidism is defined as insufficient thyroid hormone production. Several studies have found associations between specific micronutrients and overall thyroid function; however, the amount of evidence regarding the relationship between dietary patterns and hypothyroidism among the U.S. population is limited. Data from three cycles of National Health and Nutrition Examination Surveys (NHANES), 2007-2008, 2009-2010, and 2011-2012, were used (n = 8317). Subjects with serum thyroid stimulating hormone >4.5 mIU/L or on levothyroxine were considered to have hypothyroidism. Age, sex, race/ethnicity, body mass index, and several lifestyle factors were considered as covariates. Three patterns were extracted using factor analysis. These were labeled as fat-processed grains-sugars-meats (FPSM), oils-nuts-potatoes-low-fat meats (ONPL), and fruits-whole grains-vegetables-dairy (FWVD) patterns. In a weighted multiple logistic regression, FPSM and ONPL were inversely associated with hypothyroidism (OR, 0.75; 95% CI, 0.57-1; p = 0.049 and OR, 0.81; 95% CI, 0.67-0.97; p = 0.025, respectively). However, FWVD demonstrated no association with hypothyroidism (p = 0.63). In conclusion, FPSM and ONPL patterns but not FWVD patterns were associated with hypothyroidism in U.S. adults. Nutrient deficiencies and their interactions may be linked to hypothyroidism.

Cherries with Different Geographical Origins Regulate Neuroprotection in a Photoperiod-Dependent Manner in F344 Rats

The photoperiod is the main environmental cue that drives seasonal adaptive responses in reproduction, behavior, and metabolism in seasonal animals. Increasing evidence suggests that (poly)phenols contained in fruits can also modulate seasonal rhythms. (Poly)phenol-rich diets are associated with an improvement in cognitive function and neuroprotection due to their anti-inflammatory and antioxidative properties. However, it is unknown whether cherries affect neuroprotection in a photoperiod-dependent manner. To test this, F344 rats were exposed to L6 (6 h light/day), L12 (12 h light/day) and L18 (18 h light/day) photoperiods and fed a standard chow diet supplemented with either a control, lyophilized cherry 1 or cherry 2 with distinctive phenolic hallmarks. Physiological parameters (body weight, eating pattern index (EPI), testosterone, T4/T3) and hypothalamic key genes (Dio2, Dio3, Raldh1 and Ghrh) were strongly regulated by the photoperiod and/or fruit consumption. Importantly, we show for the first time that neurotrophs (Bdnf, Sod1 and Gpx1) in the hippocampus are also regulated by the photoperiod. Furthermore, the consumption of cherry 2, which was richer in total flavonols, but not cherry 1, which was richer in total anthocyanins and flavanols, enhanced neuroprotection in the hippocampus. Our results show that the seasonal consumption of cherry with a specific phenolic composition plays an important role in the hippocampal activation of neuroprotection in a photoperiod-dependent manner.

Role of Mediterranean diet in endocrine diseases: a joint overview by the endocrinologist and the nutritionist

PURPOSE

The purpose of this review is to examine the current evidence on the potential role of Mediterranean diet (MD) in the prevention and management of endocrine disorders and to highlight the importance of interdisciplinary collaboration between endocrinologists and nutritionists.

METHODS

A literature search was conducted using PubMed and Google Scholar databases to identify relevant studies published in English. Studies were selected based on their relevance to the role of MD in the prevention and management of endocrine disorders. The search terms included "Mediterranean diet," "endocrine disorders," "thyroid disorders," "gonadal disorders," and "neuroendocrine tumors".

RESULTS

The studies reviewed suggest that MD may have a beneficial effect in the prevention and management of various endocrine disorders, including thyroid disorders, gonadal disorders, and neuroendocrine tumors. MD has been associated with decreased risk of nodular thyroid disease and thyroid cancer, improved male and female reproductive health, and a potential role in the management of neuroendocrine tumors. MD's anti-inflammatory and antioxidant properties, as well as its high levels of phytochemicals, may play a role in its beneficial effects.

CONCLUSION

Interdisciplinary collaboration between endocrinologists and nutritionists is essential for the optimal management of endocrine disorders, including the potential role of MD in their prevention and management. While further research is needed, the current evidence suggests that MD may have a protective effect against endocrine disorders, and its incorporation into dietary recommendations may be beneficial.

The potential role of reprogrammed glucose metabolism: an emerging actionable codependent target in thyroid cancer

Although the incidence of thyroid cancer is increasing year by year, most patients, especially those with differentiated thyroid cancer, can usually be cured with surgery, radioactive iodine, and thyroid-stimulating hormone suppression. However, treatment options for patients with poorly differentiated thyroid cancers or radioiodine-refractory thyroid cancer have historically been limited. Altered energy metabolism is one of the hallmarks of cancer and a well-documented feature in thyroid cancer. In a hypoxic environment with extreme nutrient deficiencies resulting from uncontrolled growth, thyroid cancer cells utilize "metabolic reprogramming" to satisfy their energy demand and support malignant behaviors such as metastasis. This review summarizes past and recent advances in our understanding of the reprogramming of glucose metabolism in thyroid cancer cells, which we expect will yield new therapeutic approaches for patients with special pathological types of thyroid cancer by targeting reprogrammed glucose metabolism.

Intermittent fasting: A promising dietary intervention for autoimmune diseases

Intermittent fasting, which includes periods of fasting and nutrition, has been considered a dietary approach for weight loss and metabolic health improvement. However, its potential benefits in autoimmune diseases have not been widely studied. This study aims to review the existing studies on the role and effects of intermittent fasting on autoimmune diseases. A comprehensive search was conducted on electronic databases such as PubMed, Scopus, Embase, and Web of Science, and relevant studies were included based on inclusion criteria. Studies show that intermittent fasting may have beneficial effects on various autoimmune diseases, such as type 1 diabetes, rheumatoid arthritis, and systemic lupus erythematosus, by reducing inflammatory markers, modulating the immune system, altering and improving gut microbiota, and enhancing cellular repair mechanisms through autophagy. However, evidence regarding the effects of intermittent fasting on other autoimmune diseases such as multiple sclerosis, systemic lupus erythematosus, thyroid diseases, and psoriasis is limited and inconclusive. Nevertheless, further research is needed to determine optimal intermittent fasting guidelines and its long-term effects on autoimmune diseases. Overall, this literature review proves intermittent fasting may be a promising dietary intervention for managing autoimmune diseases.

Interactions between Polygenetic Variants and Lifestyle Factors in Hypothyroidism: A Hospital-Based Cohort Study

Hypothyroidism is a prevalent endocrine disorder and is associated with a variety of metabolic disturbances. This study aimed to investigate the polygenic variants associated with hypothyroidism risk and the interaction of polygenic risk scores (PRS) with dietary patterns in influencing disease risk in 56,664 participants aged >40 in a hospital-based cohort. The participants were classified as having hypothyroidism (n = 870) diagnosed by a physician and no hypothyroidism (n = 55,794). Genetic variants associated with hypothyroidism were identified using a genome-wide association study (GWAS). Genetic variants interacting with each other were selected using a generalized multifactor dimensionality reduction analysis, and the PRS generated was evaluated for interaction with lifestyle parameters. Coffee, alcohol, meat intake, and a Korean balanced diet were inversely associated with hypothyroidism risk, as were selenium, copper, and manganese intakes. White blood cell (WBC) counts and serum alkaline phosphatase and triglyceride concentrations were positively associated with hypothyroidism risk, as were osteoporosis and thyroid cancer. The GMDR analysis generated a three-single nucleotide polymorphism (SNP) model comprising dual oxidase-1 (DUOX1)_rs1648314; thyroid-stimulating hormone receptor (TSHR)_rs75664963; and major histocompatibility complex, class-II, DQ Alpha-1 (HLA-DQA1)_rs17426593. The PRS derived from the three- and seven-SNP models were associated with a 2.11- and 2.32-fold increase in hypothyroidism risk, respectively. Furthermore, the PRS from the three-SNP model showed interactions with WBC counts, wherein the positive association with hypothyroidism risk was more pronounced in participants with low WBC counts than those with high WBC counts (≥4 × 109 /L). Dietary patterns, such as the plant-based diet (PBD) and the Western-style diet (WSD), along with smoking status, exhibited interactions with the PRS, influencing hypothyroidism risk. In participants with a high PRS, those in the high-PBD, low-WSD, and smoker groups had a higher proportion of hypothyroidism than those in the low-PBD, high-WSD, and non-smoker groups. In conclusion, genetic variants related to immunity and thyroid hormone secretion were linked to hypothyroidism risk, and their PRS interacted with PBD and WSD intake and smoking status. These results contribute to a better understanding of hypothyroidism and its prevention strategies for precision medicine intervention.

Analysis of factors associated with abnormal thyroid function among medical staff in radiotherapy departments

Objective

To understand abnormal thyroid function and its associated factors among medical staff in radiotherapy departments.

Methods

Data related to medical staff in radiotherapy departments who met the inclusion and exclusion criteria were analyzed from September to December 2022 in Shenyang, Liaoning Province, including basic personal and lifestyle habits, work information, and scores on the Depression Self-Assessment Scale, Perception Stress Scale, and the Generalized Anxiety Scale. Data analysis was performed using the χ2 test and binary logistic regression.

Results

Among 484 medical staff in the radiotherapy department, 147 (30.4%) had abnormal thyroid function. Binary logistic regression analysis showed that age, years of work, smoking, occupational exposure, smoking, late-night snacking habits, depression, and stress perception were factors associated with abnormal thyroid function among medical staff in radiotherapy departments; on the other hand, physical exercise was a protective factor.

Conclusion

The positive rate of thyroid dysfunction among medical personnel in the radiology department is relatively high. It is necessary to strengthen health education and awareness among relevant practitioners and improve the coverage of occupational disease prevention and control education.

The Influence of Food Regimes on Oxidative Stress: A Permutation-Based Approach Using the NPC Test

(1) Background: This paper aims to assess the existence of significant differences between two dietary regimes (omnivorous vs. semi-vegetarian) with reference to some oxidative stress markers (SOD, GPx, TRxR, GR, AGEs, and AOPPs) using non-parametric combination methodology based on a permutation test. (2) Methods: At the endocrinology unit of Messina University Hospital, two hundred subjects were asked to fill out a questionnaire about their dietary habits. None were under any pharmacological treatment. Using the NPC test, all comparisons were performed stratifying patients according to gender, age (≤40 or >40 years), BMI (normal weight vs. overweight), physical activity (sedentary vs. active lifestyle), TSH, FT4 levels in quartiles, and diagnosis of Hashimoto's thyroiditis. We evaluated differences in oxidative stress parameters in relation to two examined dietary regimes (omnivorous vs. semi-vegetarian). (3) Results: The antioxidant parameters GPx and TRxR were significantly lower in subjects with an omnivorous diet than in semi-vegetarians, particularly in females, both age groups, subjects with normal weight, those not affected by Hashimoto's thyroiditis, and both the sedentary and active lifestyle groups. Finally, the AGE and AOPP markers were significantly lower in semi-vegetarians. (4) Conclusion: Thanks to the NPC methodology, we can state that dietary patterns exert a significant influence on some oxidative stress parameters.

Gut microbiota short-chain fatty acids and their impact on the host thyroid function and diseases

Thyroid disorders are clinically characterized by alterations of L-3,5,3',5'-tetraiodothyronine (T4), L-3,5,3'-triiodothyronine (T3), and/or thyroid-stimulating hormone (TSH) levels in the blood. The most frequent thyroid disorders are hypothyroidism, hyperthyroidism, and hypothyroxinemia. These conditions affect cell differentiation, function, and metabolism. It has been reported that 40% of the world's population suffers from some type of thyroid disorder and that several factors increase susceptibility to these diseases. Among them are iodine intake, environmental contamination, smoking, certain drugs, and genetic factors. Recently, the intestinal microbiota, composed of more than trillions of microbes, has emerged as a critical player in human health, and dysbiosis has been linked to thyroid diseases. The intestinal microbiota can affect host physiology by producing metabolites derived from dietary fiber, such as short-chain fatty acids (SCFAs). SCFAs have local actions in the intestine and can affect the central nervous system and immune system. Modulation of SCFAs-producing bacteria has also been connected to metabolic diseases, such as obesity and diabetes. In this review, we discuss how alterations in the production of SCFAs due to dysbiosis in patients could be related to thyroid disorders. The studies reviewed here may be of significant interest to endocrinology researchers and medical practitioners.

Hypothyroidism and non-alcoholic fatty liver disease: A coincidence or a causal relationship?

Non-alcoholic fatty liver disease (NAFLD) is a global problem. It may be caused by metabolic and hormonal disorders, including hypothyroidism. However, non-thyroid causes of NAFLD in people with hypothyroidism, including improper eating behavior and low physical activity, should be acknowledged. This study aimed to present the current literature on whether the development of NAFLD is related to hypothyroidism or a typical consequence of an unhealthy lifestyle in people with hypothyroidism. The results of previous studies do not allow for an unequivocal determination of the pathogenetic relationship between hypothyroidism and NAFLD. Important non-thyroid-initiating factors include providing too many calories in relation to requirements, consuming excessive amounts of monosaccharides and saturated fats, being overweight, and maintaining low physical activity levels. The recommended nutritional model for both hypothyroidism and NAFLD may be the Mediterranean diet, which is rich in fruits and vegetables, polyunsaturated fatty acids, and vitamin E.