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12 Things That May Be Impacting Your Thyroid, According To A Functional Medicine Expert

William Cole, IFMCP, DNM, D.C.
Author: Medical reviewer:
Updated on March 31, 2021
William Cole, IFMCP, DNM, D.C.
Functional Medicine Practitioner
By William Cole, IFMCP, DNM, D.C.
Functional Medicine Practitioner
Will Cole, IFMCP, DNM, D.C., is a leading functional medicine practitioner with a certification in natural medicine and a doctor of chiropractic degree.
Sheeva Talebian, M.D.
Medical review by
Sheeva Talebian, M.D.
Reproductive Endocrinologist
Sheeva Talebian, M.D., is a board-certified reproductive endocrinologist. She graduated from Columbia University and obtained her medical degree from Mount Sinai School of Medicine.
Last updated on March 31, 2021

Your thyroid hormones determine the function of every single cell of your body: The hair on your head, mood, immune system, energy levels, digestion, metabolism, and sex drive all hinge on the delicate balance of the queen of all hormones. For this reason, these same areas of your health suffer when your thyroid hormones are out of balance. There are many underlying reasons for thyroid problems, but the two I see most often in my patients are:

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  1. Autoimmune thyroid problems (Hashimoto's or Graves disease): when your immune system attacks your thyroid.
  2. Low T3 syndrome: when your body isn't converting the inactive T4 hormone to the active, usable T3.

Almost all thyroid cases are due to variations of one or both of these problems. And the shocker here is that neither of these two issues are inherently thyroid problems. In autoimmune thyroid problems, your thyroid wants to work but falls victim to the immune system, and in low T3 syndrome, your thyroid is working like a champ, but it is not being activated in your liver or gut.

How to manage your thyroid problems.

To manage both of these hidden thyroid problems, mainstream medicine recommends a synthetic T4 hormone such as Synthroid or Levothyroxine. But does this get to the root cause of why there's an issue in the first place? Hardly. So let's dig deeper and discover potential root causes for these two very common thyroid problems, and what to do about each:

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1. Stress

Stress can mess with your health in many different ways, and one of them is impairing thyroid function1. Your main stress hormone, cortisol, can block conversion to the active T3 and also increase the unusable reverse T3 (rT3), a Hormones and Behavior study says.

Anecdotally, many of my patients found their thyroid problems started after a stressful time in their lives. Research validates this stress-thyroid connection—one Clinical Endocrinology study says, compared to control groups, autoimmune thyroid patients had a higher rate of stressful life events prior to their diagnosis.

What to do: Be consistent with activities of calm, like mindfulness, meditation, and yoga. These activate your body's parasympathetic nervous system, which can make you feel more zen.

2. Low vitamin A

Low vitamin A can spell trouble for your thyroid because this fat-soluble vitamin has been shown to boost T3 levels and normalize TSH2 in premenopausal women, according to one study.

What to do: True vitamin A, called retinol, is only found in animal products like fish, shellfish, fermented cod liver oil, liver, and butterfat from grass-fed cows. Plant carotenes, a precursor to vitamin A, are found in sweet potatoes and carrots, but the conversion rate to the usable retinol is very weak. In fact, research suggests that just 3% of beta-carotene gets converted3 in a healthy adult. So, be sure to eat some of these animal-based sources, if possible.

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3. Low selenium

Selenium is essential to convert T4 to T34 in the liver. Selenium also protects against autoimmune thyroid problems5, according to some research.

What to do: Eat a variety of nuts and seeds like Brazil nuts, as well as oysters.

4. Viral infections

A study in the Central European Journal of Immunology, low-grade reactivations of viruses such as Epstein-Barr virus (EBV) have been linked to autoimmune thyroid problems6, like Hashimoto's.

What to do: Consider taking with supplements and vitamins with known antiviral properties, like astragalus7, bee propolis8, L-lysine9, zinc10, or vitamin C11. Always consult with your doctor before taking new supplements.

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5. Too much iodine

While iodine is needed for thyroid hormone production, several studies have found that increased iodine intake is associated with flare-ups of Hashimoto's disease12. This goes to show that even with natural remedies, what works for one person may not be right for the next.

What to do: Continue getting iodine in your diet, but pay attention to how much you're consuming (the recommended daily allowance for adults is 150 mcg13). Sea vegetables, like dulse, nori, kombu, and arame are all rich in iodine. Getting your iodine levels tested is a good idea to know where your starting point is.

6. Low iron

According to research, iron is necessary for the production of thyroid peroxidase14, which is the enzyme used to make your thyroid hormones.

What to do: Check with your doctor and get a blood test to find out if you have iron deficiency. Make sure you're getting plenty of iron-rich foods and pairing them with vitamin C when necessary. If that's not enough, consider adding an iron supplement as well.

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7. Low copper

A 2014 study in the Biological Trace Element Research journal found healthy copper levels could increase total T3 and T4 levels15 in men and women.

What to do: The best way to get bioavailable copper16 is by eating grass-fed liver and oysters. Sesame seeds, mushrooms, potatoes, and even baking chocolate, are other good sources.

8. Hormone imbalances

Your hormones are all connected, and the ripple effect of one hormone problem can negatively affect your thyroid. For example, low estrogen, insulin resistance, and low testosterone have all been found to inhibit proper thyroid function.

What to do: Depending on your individual hormone problems, solutions will vary. Talk to your doctor and get blood and lab work done to find your personalized course of action.

9. Artificial sweeteners

Artificial sweeteners, like saccharine, sucralose, or aspartame are in many sugar-free, diet, or zero-calorie drinks and foods. One small-scale study found that people were able to reverse their Hashimoto's disease after removing artificial sweeteners17 from their diets.

What to do: Avoid artificial sweeteners and opt for natural sugar substitutes, like raw honey, fresh fruit, or maple syrup.


Microbiome problems

Like most things, the gut is intertwined with hormones—specifically, thyroid hormones through the thyroid-gut-axis. 18Gastrointestinal issues like candida overgrowth and small intestine bacterial overgrowth (SIBO) are all associated with autoimmune thyroid problems via this axis. In fact, 20% of your T4 is converted to T3 in the gut19, which can be inhibited with an imbalanced, unhealthy microbiome, one study says.

What to do: Talk to a doctor or gastroenterologist to find out the best plan of action for supporting your gut. Eating a high-fiber diet, taking a quality probiotic, getting plenty of sleep, and reducing stress are just a few ways to promote a healthy gut.



Gluten is a protein found in wheat, rye, oats, barley, and spelt. The inflammatory effects of gluten in people with autoimmune diseases20 have been shown to last for up to six months. People who are intolerant to gluten likely have celiac disease, and a test would need to be run to find out for sure.

What to do: Go to the doctor and get tested if you think you may have a gluten allergy. In the meantime, consider eliminating grains with gluten from your diet, and instead opt for gluten-free options.



Smoking isn't healthy for anyone, but in people genetically susceptible to thyroid issues it may be especially dangerous. One study found an association between cigarette smoking and an increase in Grave's disease21, but more research is needed22 to prove the link.

What to do: Work with a doctor or addiction specialist who can help you quit smoking.

William Cole, IFMCP, DNM, D.C.
William Cole, IFMCP, DNM, D.C.

Will Cole, IFMCP, DNM, D.C., is a leading functional medicine expert who consults people around the globe, starting one of the first functional medicine telehealth centers in the world. Named one of the top 50 functional and integrative doctors in the nation, Dr. Will Cole provides a functional medicine approach for thyroid issues, autoimmune conditions, hormonal imbalances, digestive disorders, and brain problems. He is the host of the popular The Art Of Being Well podcast and the New York Times bestselling author of Intuitive Fasting, Ketotarian,The Inflammation Spectrum, and the brand new book Gut Feelings: Healing the Shame-Fueled Relationship Between What You Eat and How You Feel.

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