How Flavonoid-Rich Foods Affect Thyroid Health in Adults

Jim Crocker
22nd May, 2024

How Flavonoid-Rich Foods Affect Thyroid Health in Adults

Image Source: Natural Science News, 2024

Key Findings

  • The study from Shanxi Provincial People's Hospital, China, found that higher intake of dietary flavonoids is linked to lower levels of the thyroid hormone total thyroxine (TT4)
  • The relationship between flavonoid intake and another thyroid hormone, free triiodothyronine (FT3), is U-shaped, meaning both low and high intakes can affect FT3 levels differently
  • Socioeconomic factors, such as high annual family income and high poverty to income ratio, may influence how dietary flavonoids impact thyroid function
Thyroid hormones play a critical role in numerous bodily functions, including growth, neuronal development, reproduction, and energy metabolism. Dysfunctions such as hypothyroidism and hyperthyroidism are prevalent worldwide and can have severe health consequences[2]. Various factors, including iodine nutrition, genetic susceptibility, and environmental influences, impact thyroid function[2][3]. However, there has been limited large-scale epidemiological research on how dietary flavonoids, a group of plant-based compounds, affect thyroid function. A recent study conducted by Shanxi Provincial People's Hospital, China, aims to fill this gap by evaluating the relationship between dietary total flavonoids (TFs) intake and serum thyroid function[1]. The study included 4,949 adults from the National Health and Nutrition Examination Survey (NHANES) 2007-2010. Researchers employed multivariable linear regression, subgroup analyses, and restricted cubic splines (RCS) to explore these relationships. The primary focus was on two thyroid hormones: total thyroxine (TT4) and free triiodothyronine (FT3), which are essential markers of thyroid function. After adjusting for various covariates, the study found a significant negative association between dietary total flavonoids intake (log10-transformed, LgTFs) and total thyroxine (TT4). Specifically, higher flavonoid intake was linked to lower TT4 levels (β = -0.153, 95% CI = -0.222 to -0.084, P<0.001). This finding aligns with earlier studies that have shown environmental factors, including diet, can influence thyroid hormone levels[3]. The study further identified that this association was more pronounced in individuals with high annual family income and high poverty to income ratio (PIR), suggesting socioeconomic factors may modulate the impact of dietary flavonoids on thyroid function. Moreover, the study uncovered a U-shaped relationship between LgTFs and free triiodothyronine (FT3), with an inflection point at LgTFs: 2.063. This implies that both low and high intakes of flavonoids could affect FT3 levels differently, a complexity that underscores the need for personalized dietary guidelines for thyroid health. The findings from this study provide novel insights into how diet, specifically flavonoid intake, can influence thyroid function. This is particularly relevant given the earlier understanding that various lifestyle factors, such as smoking, BMI, and iodine intake, impact thyroid hormone levels[3]. The study's results also contribute to the broader epidemiological data on thyroid dysfunction, which has been highlighted as a pressing need, particularly in developing countries[2]. The use of multivariable linear regression and restricted cubic splines allowed the researchers to control for potential confounding factors and explore non-linear relationships, respectively. These methods enhance the robustness of the findings and provide a more nuanced understanding of how dietary flavonoids interact with thyroid function. In conclusion, the study from Shanxi Provincial People's Hospital underscores the importance of considering dietary flavonoid intake in managing thyroid health. The negative association between higher flavonoid intake and lower TT4 levels, along with the U-shaped relationship with FT3, offers valuable guidance for future dietary recommendations aimed at preventing thyroid dysfunction. This research adds a new dimension to our understanding of the complex interactions between diet and thyroid health, complementing earlier studies on environmental and genetic factors influencing thyroid function[2][3][4].



Main Study

1) The relationship between dietary total flavonoids and thyroid function in U.S.adults, NHANES 2007-2010.

Published 21st May, 2024

Related Studies

2) Global epidemiology of hyperthyroidism and hypothyroidism.

3) Environmental Factors Affecting Thyroid-Stimulating Hormone and Thyroid Hormone Levels.

4) Thyroid Function Characteristics and Determinants: The Rotterdam Study.

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