Chromium picolinate, which is marketed for blood sugar control and weight loss, also impairs the absorption of thyroid medications. If clients decide to take chromium picolinate, they should take it three to four hours apart from thyroid medications.23 Flavonoids in fruits, vegetables, and tea have been shown to have potential cardiovascular benefits. However, high-dose flavonoid supplements may suppress thyroid function.24 The Natural Standards Database provides an extensive list of supplements that have a potential impact on thyroid function, so taking precautions and coordinating patient care with a knowledgeable practitioner is prudent.
Thyroid disease presents unique challenges due to undesired weight changes, significant cardiovascular risks, and symptoms such as fatigue, mood changes, and gastrointestinal upset, which can hinder the development of healthful behaviors. It’s vital that dietitians focus on setting realistic goals for heart-healthy changes and regular exercise when counseling clients. With so many potential nutrient deficiencies and interactions with medications and supplements, it will be important for dietitians to coordinate with their clients’ healthcare team for optimal health outcomes.
l-Thyroxine monotherapy for athyreotic rats results in a high T4:T3 ratio at doses sufficient to normalize serum TSH levels (8). Yet, the brain, liver, and skeletal muscle tissues of these l-thyroxine–treated animals continue to exhibit markers of hypothyroidism (9), probably because of the inability of l-thyroxine monotherapy to restore tissue levels of T3 (8). This is probably a direct consequence of lower serum T3 levels and the relatively high T4 concentration in these tissues, which inactivates the type 2 iodothyronine deiodinase (D2). In the hypothalamus, loss of D2 is minimal in the presence of T4, which increases sensitivity to T4 levels and explains TSH normalization, despite relatively lower levels of serum T3. Only combination therapy with l-thyroxine plus l-triiodothyronine normalized all thyroid hormone–dependent measures (9), including serum and tissue T3 levels (8). Whether tissue-specific markers of hypothyroidism are restored with l-thyroxine monotherapy in humans remains to be determined, as does the ability of l-thyroxine plus l-triiodothyronine combination therapy to normalize the serum T4:T3 ratio without adverse events. The development of a novel drug delivery system for l-triiodothyronine would facilitate these studies (5).
The development of TSH assays led to a dramatic reduction in thyroid hormone replacement dosage and the ability to diagnose with certainty milder forms of hypothyroidism. Discovery of peripheral T4-to-T3 conversion gave a physiologic means to justify l-thyroxine monotherapy. In combination with the concerns over consistency and safety of natural thyroid preparations, synthetic l-thyroxine was perceived as a more reliable therapy. These findings laid the foundation for the clinical practice trend away from natural thyroid preparations and toward l-thyroxine monotherapy at doses to normalize the serum TSH. Later, a subpopulation of patients with residual symptoms of hypothyroidism was recognized. It remains to be determined whether this is due to a trend of attributing nonspecific symptoms to minimal thyroid dysfunction, relatively low serum T3 levels and/or high T4:T3 ratio, or the role of Thr92AlaD2 polymorphism, and whether combination therapy with l-thyroxine plus l-triiodothyronine will be beneficial.
Megan Casper, RDN, a dietitian based in New York City and the founder of Nourished Bite, points out that iodine deficiency is the leading cause of hypothyroidism worldwide. This mineral can’t be made by the body, so dietary sources like iodized salt, dairy products, seafood, seaweed, and fortified cereals are important. “Iodine is an essential nutrient in the body, and thyroid hormones are composed of iodine,” explains Rizzo. “Those lacking thyroid hormones may also be lacking iodine.”
Affiliate Disclosure: There are links on this site that can be defined as affiliate links. This means that I may receive a small commission (at no cost to you) if you purchase something when clicking on the links that take you through to a different website. By clicking on the links, you are in no way obligated to buy.
Please Note: The material on this site is provided for informational purposes only and is not medical advice. Always consult your physician before beginning any diet or exercise program.
Copyright © thembcookbook.com