Thyroid
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Videos
Physiology & Pathology:
Thyroid Reconnected with Dr. Kelly Eubanks
Target Organs of the Thyroid
Dr. Amy Myers - The Thyroid Connection
Restoration Thyroid: Body Temperature and Pulse
Nutritional Crash Course on Thyroid Function
7 Foods that Support Thyroid Health
The Best Diet for Thyroid Function Part 1
The Best Diet for Thyroid Function Part 2
How the Thyroid Works
Approaches to Thyroid Health with Natalie Douglas
Brain Chemistry's Impact on Thyroid Function
Thyroid Lymph Connection
Review of Thyroid Physiology
Thyroid Health is Dependent on the Liver
The Nutritional Approach For Your Thyroid Health
The Top Minerals & Nutrients for Thyroid Function
Natural Thyroid Treatment
Importance of Vitamin A
How diet and nutrition affect the thyroid
Food-Based Solutions for Your Thyroid
Intermittent Fasting and Your Thyroid
Thyroid Anatomy
Thyroid and Parathyroid Glands
Why You Should Know About Your Thyroid
The thyroid gland, or simply the thyroid is an endocrine gland in the neck, and consists of two lobes connected by an isthmus. It is found at the front of the neck, below the Adam's apple. The thyroid gland secretes thyroid hormones, which primarily influence the metabolic rate and protein synthesis. The hormones also have many other effects including those on development. The thyroid hormones T3 and T4 are synthesized from iodine and tyrosine. The thyroid also produces the hormone calcitonin, which plays a role in calcium homeostasis.
Hormonal output from the thyroid is regulated by thyroid-stimulating hormone (TSH) secreted from the anterior pituitary, which itself is regulated by thyrotropin-releasing hormone (TRH) produced by the hypothalamus
The thyroid may be affected by several diseases. Hyperthyroidism occurs when the gland produces excessive amounts of thyroid hormones, the most common cause being Graves' disease—an autoimmune disorder. In contrast, hypothyroidism is a state of insufficient thyroid hormone production. Worldwide, the most common cause is iodine deficiency. Thyroid hormones are important for development, and hypothyroidism secondary to iodine deficiency remains the leading cause of preventable intellectual disability. In iodine-sufficient regions, the most common cause of hypothyroidism is Hashimoto's thyroiditis—also an autoimmune disease. In addition, the thyroid gland may also develop several types of nodules and cancer.
Good thyroid function is necessary for resistance to bacterial infection, for regulation of blood sugar, neurotransmitters, and hormones related to mood, and for the formation of progesterone.
VITAMIN A & THE THYROID
Vitamin A deficiency affects thyroid gland function through several direct and indirect mechanisms, leading to structural changes and altered hormone metabolism. pmc.ncbi.nlm.nih+2
Impaired Thyroid Hormone Synthesis and Storage
- Vitamin A deficiency disrupts the synthesis of thyroglobulin, the precursor protein for thyroid hormones T4 (thyroxine) and T3 (triiodothyronine), impairing their production and storage in the thyroid.frontiersin+1
- Deficiency reduces the coupling of iodotyrosine residues necessary for forming T4 and T3, as well as overall thyroid iodine uptake, leading to lower intrathyroidal pools of these hormones.casi+2
- These alterations can result in thyroid hypertrophy, commonly visible as goiter.frontiersin+2
Disrupted Thyroid-Pituitary Axis Regulation
- Vitamin A deficiency increases pituitary secretion of thyroid-stimulating hormone (TSH) due to impaired negative feedback, resulting in elevated TSH levels and further thyroid gland stimulation.academic.oup+3
- Studies show that in vitamin A deficiency, TSH levels can rise despite normal or elevated thyroid hormone levels, indicating resistance or altered sensitivity in the feedback loop.pmc.ncbi.nlm.nih+1
Altered Peripheral Thyroid Hormone Conversion
- Vitamin A deficiency reduces the hepatic and tissue conversion of T4 to the biologically active T3, diminishing the availability of T3 in tissues.frontiersin+1
- This impaired conversion is mediated by changes in deiodinase enzymes, leading to increased T4 and decreased T3 in serum and tissues.pmc.ncbi.nlm.nih+1
Interaction with Iodine Status
- Vitamin A deficiency exacerbates the effects of iodine deficiency, with additive impacts observed on goiter prevalence and thyroid dysfunction when both deficiencies are present.casi+1
- Supplementing vitamin A in iodine-deficient individuals improves thyroid volume, lowers TSH, and increases thyroid iodine uptake.casi+1
Changes in Thyroid Hormone Binding and Transport
- Vitamin A deficiency may influence the binding of thyroid hormones to serum proteins (e.g., transthyretin), potentially affecting hormone circulation and tissue delivery.pmc.ncbi.nlm.nih
Vitamin A, therefore, is essential for thyroglobulin synthesis, hormone release and conversion, negative feedback regulation, and optimal thyroid structure. Deficiency may cause goiter, altered hormone levels, resistance to thyroid hormone, and increased risk of clinical or subclinical hypothyroidism, especially when combined with iodine deficiency.academic.oup+3
- https://pmc.ncbi.nlm.nih.gov/articles/PMC9592814/
- https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2023.1089315/full
- https://www.casi.org/vitamin-a-underappreciated-role-in-thyroid-health-0
- https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2022.824193/full
- https://academic.oup.com/jcem/article/89/11/5441/2844339
- https://thyroiduk.org/role-of-vitamins-and-minerals/
- https://www.palomahealth.com/supplements/vitamin-a-hypothyroidism
- https://pmc.ncbi.nlm.nih.gov/articles/PMC9596568/
- https://www.sciencedirect.com/science/article/abs/pii/0024320578904770
- https://academic.oup.com/endo/article-abstract/24/3/389/2772540
- https://www.conceivehealth.com/blog/how-vitamin-a-affects-thyroid-and-fertility/
- https://www.sciencedirect.com/science/article/pii/S0022316623189619
- https://www.sciencedirect.com/science/article/pii/S0002916523135246