Written By: Jessica Frey, Dietetic Intern

Functional Foods: Not Another Gimmick

You’re probably wondering…  aren’t ALL foods functional?? You’re right, of course! All foods have nutrients and give energy to our bodies that help keep us alive. So, what in the world is a “functional food” then? Surely, you’ve heard the saying, “an apple a day keeps the doctor away!” That may not just be an old wives’ tale, but instead an example of a functional food!

 A functional food is broadly defined as a food that beneficially affects target functions—beyond adequate nutritional needs—in the human body to improve overall health and wellness. These foods can include the following: conventionally or organically grown; some whole food supplements; and fortified, enriched, or enhanced foods. So, it shouldn’t come as a surprise that you’re probably already eating them on a regular basis! Check out the list highlighted in green for some examples and some of their target functions!

Functional Foods to Fight Your Hypothyroidism Symptoms

In scientific studies, the following functional foods and their micronutrients, like iodine, iron, selenium, or zinc, have been shown to improve thyroid function. If you have hypothyroidism symptoms like fatigue, weight gain, brain fog, or constipation, it may due to your thyroid, and its hormones, being underactive. For gut health, a sluggish thyroid contributes to constipation because it has been shown to slow down digestion. Not surprisingly, if you have a gut flora imbalance, it will also negatively affect your thyroid health!

Special note—Although positive effects have been reported in research, these functional foods will not cure your hypothyroidism or alleviate all your symptoms. They are simply options, with known beneficial target functions, to help thyroid hormones and gut health, which might help you feel better in a noticeable way!



Seaweed – Iodine

If you’re like me, you may have switched out your table salt for non-iodized sea salt, or maybe you’ve cut down on salt altogether, which might lower your iodine intake. Iodine is a critical mineral for optimal thyroid development and function. Therefore, a diet supplemented with seaweed, which is a good source of iodine, has been shown in studies to improve thyroid hormone production in post-menopausal females. Seaweed is also chock full of other minerals and health benefits.

  • Aim for 1 mg of iodine a day for healthy thyroid function. Sprinkle some dulse (red seaweed flakes) on your meals or wrap some veggies in nori to get your daily dose! Seaweed is naturally salty, so you can even lessen your salt intake at the same time!

Brazil nuts – Selenium

This trace element has a profound amount of functions in your body, including a direct relationship with iodine and thyroid hormones.

  • You only have to eat about three brazil nuts a day to get the recommended amount of 200 mg.

Pumpkin seeds – Zinc

A zinc deficiency has been found to suppress thyroid hormone production, which means your hypothyroidism symptoms may worsen.

  • With only two small handfuls of these dynamic seeds, you’ll meet the 20 mg of zinc suggested for healthy thyroid function.


Fermentable fibers – Prebiotics

Prebiotics are considered an ingredient that promote the growth of probiotics to aid in healthy digestion. Additionally, your gut microbiome uses fermentable fibers to make short-chain fatty acids (SFCA), which may enhance cellular signals to improve thyroid function.

  • The following foods can be added to your daily diet to potentially improve your digestion and thyroid function: artichokes, garlic, leeks, onions, asparagus, cassava, sweet potato, or plantains.


Fermented foods – Probiotics

Fueled by prebiotics, some probiotics (Lactobacillus reuteri) have been shown to improve thyroid health. In general, probiotics stimulate the growth of healthy bacteria in the gut to counterbalance any disease-promoting pathogens.

  • Although probiotics can be taken in supplement form, whole food options are always better. Specifically, fermented vegetables are great choices, such as sauerkraut and kimchi. If you can tolerate dairy products, yogurt and kefir will do the trick!

Be a Smart Advocate for Your Health

No one cares about your health more than you! So, it is always important to do your own research but be smart about it! There is no magical pill or cure-all functional food that will alleviate your hypothyroidism symptoms. If you come across an article with these claims, check the author’s credentials and verify any provided references for truthful content. Your health is too important to believe unfounded and sensational claims!

As the Academy of Nutrition and Dietetics urges, functional foods should be eaten as part of a varied diet on a regular basis. Do not eat an excess of any particular food without consulting an integrative registered dietitian nutritionist (RDN) first. An integrative RDN can perform the necessary lab tests to check for mineral deficiencies and your thyroid function. If you do have a deficiency, then try a functional food, instead of supplementation! As Hippocrates famously said, “Let Food Be Thy Medicine…”

Reference List

Collins, S.C. (2014). Entering the World of Prebiotics — Are They a Precursor to Good Gut Health? Today’s Dietitian, 16(12), 12.

 Crowe, K., & Francis, C. (2013). Position of the Academy of Nutrition and Dietetics: Functional Foods. Journal of the Academy of Nutrition and Dietetics, 113(8), 1096-1103. DOI: https://doi.org/10.1016/j.jand.2013.06.002

 Gersh, F.L. (2017). Subclinical Hypothyroidism—Controversial Treatment Recommendations Made Clear. The Integrative RDN Fall 2017, 20(2), 46-47.

 Goetzke, B., Nitzko, S., & Spiller, A. (2014). Consumption of organic and functional food. A matter of well-being and health? Appetite, 77, 96-105. DOI: 10.1016/j.appet.2014.02.012

 Institute of Food Technologists. (2017, October 9). Introduction to Functional Food. Retrieved from http://www.ift.org/Knowledge-Center/Read-IFT-Publications/Science-Reports/Scientific-Status-Summaries/Functional-Foods/Introduction-to-Functional-Food.aspx

 Kresser, C. (2019). Your Gut Microbes and Your Thyroid: What’s the Connection? Retrieved from https://chriskresser.com/your-gut-microbes-and-your-thyroid-whats-the-connection/

 Mohamed, S., Hashim, S.N., & Rahman, H.A. (2012). Seaweeds: A sustainable functional food for complementary and alternative therapy. Trends in Food Science & Technology, 23(2), 83-96. DOI: https://doi-org.csulb.idm.oclc.org/10.1016/j.tifs.2011.09.001

 MyFoodData. (2018, February 23). The 10 Best Foods High in Zinc + Printable One Page Sheet. Retrieved from https://www.myfooddata.com/articles/zinc.php

 Rostami, R., Beiranvand, A., & Nourooz-Zadeh, J. (2011). Effect of zinc deficiency on thyroid hormone synthesis and thyroid antibodies. Clinical Biochemistry, 44(13), S108. DOI: 10.1016/j.clinbiochem.2011.08.258

 Stuss, M., Michalska-Kasiczak, M., & Sewerynek, E. (2017). The role of selenium in thyroid gland pathophysiology. Endokrynologia Polska, 68(4), 455-465. DOI: 10.5603/EP.2017.0051

 Victor, B. (2014, May 1). Health benefits of functional foods. Retrieved from http://bonvictor.blogspot.com/2014/05/health-benefits-of-functional-foods.html