The Thyroid Diet: Everything You Need to Know

Thyroid disease affects an estimated 30 million Americans, mostly women. Women are five to eight times more likely than men to be affected by hypothyroidism; recent statistics say that as many as one in eight women is likely to develop hypothyroidism in her lifetime. Hashimoto’s, an autoimmune condition is by far the most prevalent form.

Having hypothyroidism can cause troublesome, and for some women even debilitating symptoms including depression, anxiety, problems with memory and focus, insomnia, and fatigue. It can also cause weight gain, constipation, dry skin, and more. What's more, hypothyroidism is often under-diagnosed and, when finally diagnosed, is often inadequately treated. I've written more on what you need to know about women and thyroid health here – if you suspect you might be dealing with possible thyroid issues, that piece is a must-read. 

Why Your Thyroid Matters

A healthy thyroid is crucial for thousands of important functions in your body, including:

• Metabolism and weight regulation
• Helping keep cholesterol levels within a healthy range
• Supporting mental clarity
• Regulating sleep patterns
• Heart function
• Digestion and assimilation
• Hormonal balance – which includes maintaining healthy menstrual cycles, fertility, and pregnancy

When you think about the importance of thyroid hormone for every cell, tissue and organ in the body, it's clear that widespread thyroid disease is something we need to address. My preferred approach is through an appropriate combination of conventional medicine with nutrition and supportive botanicals. In other words, and integrative approach. 

Importance of Diagnosis and Proper Testing

Before you begin any type of thyroid treatment plan it’s important to get properly tested and diagnosed. For one, hypothyroidism is indeed very common, but a number of conditions can cause similar symptoms, such as:

• Iron deficiency anemia and other nutritional deficiencies, especially if your diet is limited or restrictive (vegan, low-carb, cleanses and fasting)
• Adrenal/stress response symptoms, stress, overwhelm
• Viral infection
• Lyme disease
• Depression

Secondly, untreated hypothyroidism long-term, can eventually lead to cognitive and even affect heart health.

Lastly, as much as missed diagnoses and under-treatment by conventional medicine can be a problem so can over-diagnosis and unnecessary treatment be in the integrative and functional medicine worlds. My book The Adrenal Thyroid Revolution promotes a sensible approach to healing your thyroid and includes clear guidelines on the use of thyroid medication, when needed. You can learn much more about thyroid testing here.

The Thyroid Diet: What You Need to Know

Perhaps you’ve been been hearing a lot about the “Thyroid Diet” lately. While there's really no single thyroid diet, there are some nutritional and dietary strategies that can help. I want to share some of the science behind nutrition for thyroid health.

I've been an advocate for sound nutrition and healthy eating and its impact on our health for over 30 years now. I’m excited to share that there is data supporting the benefit of certain nutrients specifically for the thyroid. For instance, there's strong evidence for sufficient but not excessive iodine intake to benefit thyroid health in general, as well as selenium supplementation. Aside from these, scientific data showing that dietary changes can really benefit hypo- or hyperthyroidism is more limited – but that doesn't mean they should be ignored. Possible nutritional approaches include supplementation with micronutrients, vitamins, and minerals, as well as reducing intake of certain foods or food groups, for example, gluten. 

In the next sections, I'll walk you through what I know about using diet for thyroid health and creating a “Thyroid Diet” that works for you.

All About Gluten: Celiac Disease & Leaky Gut

Celiac disease is another common autoimmune condition, also a frequently overlooked diagnosis by conventional doctors, and it is a common underlying cause of Hashimoto’s. The reason behind this is because the triggering of antibodies as a reaction to gluten can attack the thyroid, as well as thyroid receptors on cells around your body, which diminishes your thyroid hormone production or makes your body unable to use the thyroid hormone you are producing. Going off of gluten for as little as three months can not only improve digestion and mood, but also improve or even reverse Hashimoto's and reduce dependence on medication. I've seen this happen in my own practice!

Gluten intolerance, even without celiac disease, may also have an impact on thyroid health by causing intestinal hyperpermeability – commonly called ‘leaky gut.” Other triggers for this include lactose or dairy intolerance, antibiotic use, ibuprofen, and certain gluten cross reactive foods including corn, coffee, millet and oats.

Leaky gut can cause proteins to get into your intestinal immune system or even your bloodstream and trigger the production of antibodies, which much like celiac disease can trigger an autoimmune reaction in your thyroid. To identify and treat a leaky gut, head over here. The concept of increased intestinal permeability leading to various diseases such as hypothyroidism is why gluten-free diets, sugar-free diets, and probiotics are often recommended for promoting thyroid health.

Intestinal hyperpermeability (leaky gut) and another problem called dysbiosis (imbalance in your gut microbiome) have both been associated with autoimmune disease through mechanisms that involve the GALT, or gut-associated lymphoid tissue, the immune system located in your gut, as well as translocation of proteins and particles from gut bacteria called LPS (lipopolysaccharide) in the intestines, to trigger the antibodies that can later attack our own tissue.

Common dietary causes of both leaky gut and dysbiosis include hidden food intolerances, processed foods, artificial sweeteners, as well as gluten intolerance – which is far more commonplace than was previously known and is now recognized as a major trigger for autoimmune conditions. In my 28-Day Gut Reset program I walk you through recognizing common gut imbalances and repairing them with diet tweaks along with herbs and supplements to restore gut health. You can also learn more about how to do this in my book, The Adrenal Thyroid Revolution.

What About Coffee?

I know how important that cuppa’ joe can be – so I don’t want to take your coffee away from you. But do note that coffee can decrease the absorption of levothyroxine in some individuals being treated for hypothyroidism – so you might need to adjust your medication dose  if you’re finding you’re not getting the results you expect, and you might, might, might just need to kick the coffee habit to get your thyroid hormone levels to stabilize.

Fluoride, Bromide, Mercury, and Other Offenders

The addition of fluoride to our drinking water was considered a major public health innovation, intended to cut down on children's dental cavities, but it turns out that fluoride might be a player in hypothyroidism. The chemical structure of fluoride is very similar to that of iodine, thus fluoride can displace iodine and sneak into its place,  blocking thyroid hormone from getting formed! Other heavy metals can do this too, such as bromide found in many types of bread and baked goods made with brominated flour, and mercury which is high in many fish, including tuna. Heavy metals can bind to your thyroid and thyroid hormone receptors, and interfere with thyroid function.

So one thing we can do diet-wise to reduce our risk of developing thyroid problems is reduce heavy metal exposure, particularly to these avoidable triggers, by filtering tap water at home, avoiding bread and baked goods made with gluten-containing ingredients or brominated flour, and avoiding mercury-heavy fish (tuna, mackerel (King), marlin, orange roughy, shark, swordfish, and tilefish).

What About Iodine?

The production of thyroid hormone requires that we get enough iodide from the diet. The US Recommended Dietary Allowance (RDA) for iodine is 150 µg/day in adults, and 220 µg/day for pregnant women and 290 µg/day during breastfeeding. Iodine is not required to be labeled on food packaging, which may make dietary sources hard to identify.

Iodine nutrition in the United States is usually adequate, but only slightly so. Studies have found women to be at just par but not optimal levels of this nutrient which is so important for thyroid function. While eating a regular diet should meet nutritional iodine needs, some women might need to supplement to reach RDA goals, particularly if you don’t eat seafood and don’t use iodinated salt (i.e., Himalayan and earth salts are not iodine-rich).

Rich dietary sources of iodine include dulse and kelp (seaweeds), turkey breast, cod (fish), cranberries, and yogurt (from animal dairy). I recommend taking a whole foods approach to iodine, to avoid getting too much at once. For instance, the American Thyroid Association recommends avoiding supplements that contain >500 µg/day of iodine, and many of the iodine supplements on the market contain even more than this – even seemingly safe and natural seaweed extracts, for example, can contain dangerously high levels of iodine.

Trace Minerals: Zinc and Selenium

The important role of iodine in thyroid health is well understood. In contrast, data on other trace minerals and their effects on thyroid health are harder to come by – but that doesn't mean there is no benefit. After all, the thyroid gland needs to be nourished with specific vitamins and minerals to function well. These include, aside from iodine, the trace minerals zinc and selenium – which many of us are getting in too minuscule amounts in our diets in order to support optimal thyroid function.

Selenium, for example, is a micronutrient important for thyroid hormone metabolism. I always recommend “food first” to optimize thyroid function – rich sources of zinc include oysters, red meat, poultry, seafood such as crab and lobsters, beans, nuts, whole grains, and dairy products, while rich sources of selenium include Brazil nuts, tuna, halibut, sardines, ham, and shrimp.

While the data in the medical literature on supplementing selenium for thyroid function is mixed, because of the significant effects I've observed on antibody levels time and again in my practice, I do supplement 200 mcg selenium daily (this dose shouldn't be exceeded in supplements, so if you're taking for example, a multivitamin, check the amount of selenium in there before supplementing, and check any other supplements you're taking as well – you don't want to get too much), along with 800 mg of the fatty acid inositol, the combination of which has been found beneficial for reducing antibodies and improving thyroid hormone levels in small studies. The authors of a Cochrane review of hypothyroidism interventions during pregnancy concluded, based on a trial that administered supplements containing 200 mcg selenium as selenomethionine daily to 151 pregnant women with thyroid peroxidase antibodies, that selenomethionine supplementation in this population is a promising strategy, especially for reducing postpartum thyroiditis

Soy & Leafy Green Veggies – The Goitrogens Debate

The term “goitrogen” refers to any substance that can produce goiter, which is enlargement of the thyroid gland. This usually happens through effects that decrease thyroidal iodine, but goitrogenic compounds can also act by disrupting other components of normal thyroid hormone production. The most common dietary goitrogens include Brassicacae (a.k.a.cruciferous) veggies (yes, like kale) and soy products.

Brassicacae vegetables include broccoli, cabbage, Brussels sprouts, kale, turnips, cauliflower, collard greens, bok choy, and cabbage including red, green, and Nappa, for example. They are rich in a compound called glucosinolates which are important for are health, but which also includes a compound called thiocyanate – and this is the troublesome compound responsible for inhibiting thyroid hormone synthesis.

That is why, though these vegetables offer significant health benefits, their frequent consumption in large quantities (like what you find in a raw green juice) may induce or worsen hypothyroidism. Green leafies are still important for your health, and no rigorous clinical studies exist to support the need to stop eating them altogether. However, I recommend a well-balanced diet that includes cruciferous vegetables in reasonable amounts, but if you have Hashimoto’s, it’s best to keep concentrated sources like green drinks to 1-2 times/week at most just to be extra careful. Instead, simply eat your greens cooked – sauteed, steamed, or roasted are all delicious options.

What about soy? Dietary soy products – including soymilk, tofu, tempeh, and miso – contain isoflavones. Because isoflavones can inhibit the action of thyroid peroxidase, which is required for thyroid hormone synthesis, some worry that dietary soy intake may boost the risk for hypothyroidism. However, no studies show that in otherwise healthy individuals, soy poses any risk to thyroid function, though those taking thyroid medication may need to slightly increase their dose if consuming soy more than occasionally – though this need was only seen in newborns with congenital hypothyroidism being fed soy formula.

What About Supplements?

While not everyone with Hashimoto’s has nutritional deficiencies, many do – in fact, most Americans do – and healthy thyroid function requires specific nutrients. The most important thyroid nutrients and their doses (for adults) are zinc (30 mg/day), selenium (200 mcg/day), iodine (150 mcg), and iron (18 mg). Additionally, low vitamin D levels have been found in association with hypothyroidism in several studies.

Most nutrients (zinc, selenium, iodine, iron, B vitamins) can be obtained directly from food, and the risk of over-supplementing can actually be harmful. Working with a nutrition savvy practitioner can help you to identify your unique needs, and the best way to meet them. In general, supplementing in the above doses is safe for most women (but avoid iodine supplements if you have a true iodine allergy!). Read my supplement recommendations for Hashimoto's in my blog post here.

Eat Whole for Thyroid Health

With a healthy diet that avoids a few possible triggers (i.e., gluten) and the right nutrients to support thyroid health, we should be able to reduce thyroid disease – and help women to improve thyroid health. For some women this leads to lower thyroid antibodies and a need for less medication. A well-balanced “Thyroid Diet” does work! I have seen patients’ antibodies go from well into the thousands down to close to normal – and the the ability to lower medication doses. While there’s a time and place for thyroid medication, which I also prescribe in my medical practice, giving the thyroid diet a try could be a great start to reclaiming your health and vitality – and to feeling like yourself again.