Hypothyroidism Diet Plan: Foods To Eat & Avoid (List)

Hypothyroidism is a medical condition characterized by insufficient secretion of thyroid hormone (thyroxine) by the follicular cells of the thyroid gland.  Common symptoms of hypothyroidism include: chronic fatigue, depression, memory deficits, and weight gain.  If you’ve been diagnosed with hypothyroidism, there’s a good chance you’re utilizing a thyroid replacement therapy such as Synthroid or Armour Thyroid.

These thyroid replacement therapies are regarded as first-line, clinically effective interventions for normalizing T4, T3, and TSH concentrations – thereby improving neurophysiological outcomes among those with hypothyroidism.  While thyroid replacement therapies are often highly therapeutic, evidence suggests that other lifestyle interventions may improve hypothyroidism symptoms.  One way in which you may be able to reverse abnormal concentrations of thyroid hormones is via dietary modifications.

Particularly, optimizing your dietary intake by eating certain foods (while simultaneously avoiding others) may enhance T4 and T3 levels.  Although strict adherence to a hypothyroidism diet is unlikely to “cure” hypothyroidism, it may reduce your need for medication.  Many people underestimate the degree to which their diet may affect their thyroid levels.

Is there such thing as an effective hypothyroidism diet plan?

Currently there is no evidence to suggest that dietary adjustments are clinically effective for the treatment of hypothyroidism.  While eating nutrient-dense foods, reducing sugar intake, and avoiding preservatives may prove beneficial for overall health – there’s no evidence to suggest that a specific diet can reverse hypothyroidism.  There is evidence from one study noting that adherents to a vegan diet may be at less risk of developing hypothyroidism; hypothetical reasons for this aren’t fully elucidated.

Cases of individuals claiming that dietary adjustments helped them overcome hypothyroidism should be examined with cautious skepticism.  There may be examples of select individuals with subclinical hypothyroidism (e.g. mild hypothyroidism) in which dietary tweaks improved thyroid functionality or hormonal biomarkers (T4, T3, TSH), thereby allowing them to manage hypothyroidism without medication.  Perhaps simple changes such as optimization of iodine intake, reducing soy consumption, and/or decreasing refined carbohydrates may be therapeutic for cases of subclinical hypothyroidism.

However, among individuals with severe hypothyroidism, symptomatic relief from diet is highly unlikely.  Among those who underwent a thyroidectomy, dietary changes should be considered useless for improving thyroid function because the thyroid was removed.  For this reason, it is important to avoid getting totally duped into pseudoscientific claims that a “hypothyroidism diet” served as some sort of utopian magic bullet.

Foods to Eat with Hypothyroidism (List)

If you’ve been diagnosed with hypothyroidism, your goal should be to consume nutrient-dense foods that reduce inflammation and support thyroid health. You may find that inclusion of: bone broth, fermented foods, fish, organ meats, etc. – provides significant benefit in thyroid function and/or hormonal biomarkers.  Understand that there are likely interindividual nuances in regards to the quantities and specific foods necessary to improve thyroid function.

Bone broth: Some have suggested that among the most effective foods for reducing hypothyroidism is bone broth.  Quality bone broth derived from humanely-raised, grass-fed cows can repair the lining of the gut – perhaps to a greater extent than fermented foods.  Bone broth is chock-full of minerals and nutrients that improve functioning of the gut and digestive system.

If you have hypothyroidism, bone broth may help with food sensitivities, energy level, immune function, and joint pain.  There’s a chance that it may even improve your thyroid function.  Consider adding bone broth to your diet and determining whether your overall health improves.  While it may not have a direct effect on your thyroid, it may help you better cope with hypothyroidism.

Carbohydrates (Selective): Eliminating carbs altogether may be problematic for those attempting to maintain sufficient levels of thyroid hormone.  Low carbohydrate diets stress the adrenal glands, cause increased production of cortisol, and can disrupt the HPA (hypothalamic pituitary adrenal axis).  If you engage in regular exercise, are highly stressed, don’t get enough sleep and you’ve been eating low carb – it may be normal to find that you’re in a state of hypothyroidism.

• Cassava
• Pumpkin
• Squash
• Sweet potatoes
• White rice
• Yams

To avoid excess cortisol associated with stressing your adrenals, you’ll want to consume some carbohydrates.  Obviously you’ll want to avoid processed carbohydrates and possibly gluten (especially if you’re sensitive and/or have celiac disease).  Inclusion of carbohydrates such as white rice, sweet potatoes, squash, and yams – should allow your body to correct low-carb induced HPA dysfunction and improve your thyroid.

Fermented foods: Many individuals with hypothyroidism struggle with autoimmune conditions, as well as “leaky gut syndrome.”  While removal of certain foods that caused leaky gut can be helpful, removal of these foods doesn’t automatically reverse damage that’s already occurred.  Some individuals find that restoration of healthy gut flora (microorganisms) significantly improves their hypothyroidism and/or health.

• Kimchi
• Kombucha
• Pickled cucumbers
• Sauerkraut

Consider adding fermented foods such as: kimchi, kombucha, sauerkraut, etc. to your diet and determine whether your thyroid function improves.  It may be that upon restoration of a healthy gut flora, inflammation is reduced, nutrient absorption (from other foods) improves, and hypothyroidism decreases.  While many people take a “probiotic” supplement, eating the actual foods is likely a more effective route.

Fish (Omega-3s): Consumption of wild-caught, fatty fish such as sockeye salmon may indirectly improve the function of your thyroid.  Regular consumption of fatty fish is known to bolster levels of omega-3 fatty acids – particularly DHA and EPA.  Most people are deficient in omega-3 fatty acids and have ingested abnormally high amounts of omega-6 fatty acids.

• Anchovies
• Herring
• Mackerel
• Salmon
• Sardines
• Sturgeon
• Trout
• Tuna
• Whitefish

While omega-6 fatty acids are helpful for many neurophysiological processes, when they are not kept in check with sufficient omega-3s, inflammation can occur.  As a result of this inflammation, the functionality of hypothalamic pituitary thyroid axis (HPTA) may become impaired.  Impairment of this axis can lead to suboptimal production and/or conversion of thyroid hormones.  Consider upping your intake of fish or utilizing a supplement such as krill oil or fish oil to improve omega-3 levels.

Fruits: Going overboard with fruit consumption is not advised for most individuals with hypothyroidism, but moderate consumption of fruits is likely beneficial for health.  Excessive fruit intake causes an insulin spike via the “fructose” which can alter endocrine function and possibly the thyroid.  Eat sufficient fruit to ensure that you’re getting necessary antioxidants and vitamins to help reduce inflammation and nourish the body.

• Blackberries
• Blueberries
• Coconuts
• Cranberries
• Limes
• Pineapples
• Raspberries
• Strawberries

Healthy fats: If your diet is lacking in healthy fats, you may want to consider increasing your intake.  One of the best ways to ensure that you’re getting enough fat in your diet is to eat more avocados.  Avocados contain mostly monounsaturated fat and some polyunsaturated fat – each of which are regarded as conducive to overall health.

• Avocados
• Coconut oil
• Dark chocolate
• Eggs
• Grass-fed butter
• Nuts & Seeds

Increasing intake of saturated fats may also provide significant functional benefit to those with hypothyroidism.  Particularly, addition of unrefined, virgin coconut oil to the diet of individuals with hypothyroidism may: decrease brain fog, enhance cognitive performance, and boost overall physical energy.  Coconut oil contains MCTs such as caprylic acid that modulate: blood sugar and metabolism, improve digestion, and reduce inflammatory responses.

Organ meats: Vitamin A is important for optimal thyroid health, yet many people are deficient.  Although a vitamin A deficiency may not severely compromise your thyroid function, ensuring that you’re getting enough vitamin A may improve your thyroid health.  Consider purchasing some grass-fed beef liver and including it in your diet once or twice a week.  After regularly consuming organ meats, reassess whether your thyroid has improved.

Vegetables: Many people don’t eat enough vegetables and expect their body (and thyroid) to remain optimally functioning.  You may want to consider ramping up your intake of veggies, but beware of the fact that excess raw, cruciferous veggies (e.g. broccoli, kale, spinach) may be of detriment to your thyroid (as they contain goitrogens).  Steam all cruciferous vegetables prior to consumption to reduce goitrogenic compounds.

The antioxidants, minerals, and vitamins within vegetables can decrease inflammation, which in turn could improve your thyroid function.  Don’t go days without vegetables and expect your thyroid health to improve.  Try to eat at least several servings of different vegetables throughout the day.

Foods with Iodine: Adequate iodine intake is extremely important for thyroid health.  Without proper iodine intake, your thyroid may have a difficult time manufacturing adequate T4 and T3.  That said, it is important to evaluate your existing iodine levels (via a blood test) to determine the degree to which you are deficient.

• Dried seaweed
• Eggs
• Oysters
• Kelp

If you’ve gotten your iodine levels tested and were found to be deficient, your thyroid will likely benefit from consumption of iodine-rich foods.  You should be cautious of the fact that overconsumption of iodine may be equally problematic for the thyroid as underconsumption.  Aim to optimize your iodine levels with quality food sources, but don’t get too carried away.

Foods to Avoid for Hypothyroidism (List)

If you have hypothyroidism, it is important to be cognizant of the fact that certain foods may interfere with normative, healthy thyroid function.  Avoidance of specific foods may enhance the functionality of your thyroid, allowing it to manufacture adequate T4 and T3, while maintaining a lower level of TSH (thyroid stimulating hormone).  You may not need to avoid all of the foods listed below, as certain ones may be more problematic for your thyroid than others.

Alcohol: If you have hypothyroidism, you may want to completely rid alcohol from your diet.  Alcohol can detrimentally impair function of the thyroid gland and simultaneously lower concentrations of thyroid hormones (T4 and T3) throughout the body.  Regular drinking of alcohol may also interfere with the body’s natural ability to use thyroid hormones for important functions, so even when thyroid is produced, it isn’t properly utilized.

Cruciferous vegetables (Raw): Consuming copious amounts of raw, cruciferous vegetables may prove disastrous for your thyroid function.  Veggies from the Cruciferae family are understood to contain goitrogenic compounds that interfere with thyroid peroxidase (TPO).  Thyroid peroxidase (TPO) is an enzyme that aids in the production of thyroid hormone and conversion of T4 to T3.

• Arugula
• Bok choy
• Broccoli
• Brussels sprouts
• Cabbage
• Cauliflower
• Collard greens
• Kale
• Spinach

It is important to understand that steaming most of these vegetables prior to consumption should eliminate most of the goitrogenic compounds capable of inducing thyroid dysfunction.  If you’ve been eating large portions of raw, cruciferous veggies – it could increase your risk of thyroid abnormalities.  Individuals at greatest risk of experiencing thyroid dysfunction from overconsumption of cruciferous veggies are those with preexisting iodine deficiencies.

Dairy products: Elimination of dairy products may be especially beneficial for those with an unknown dairy sensitivity or allergy.  Many individuals are allergic to A1 casein, a protein within cow’s milk.  If you’re consuming any products with A1 casein, yet have an underlying sensitivity, there’s a chance it could be contributing to your hypothyroidism.

Like those with gluten allergies, individuals with A1 casein allergies may be prone to substantial inflammation.  The inflammatory response alters functionality of the HPTA (hypothalamic pituitary thyroid axis) and causes thyroid dysfunction; less T4 is converted to T3.  Even if you don’t have a know dairy allergy, you may want to eliminate dairy altogether and assess whether thyroid function improves.

Gluten: Gluten is a component of all barley, wheat, and rye products; if you’re eating carbohydrates – you’re probably eating gluten.  Many individuals diagnosed with hypothyroidism have comorbid gluten sensitivities and/or celiac disease.  While gluten is often overly-demonized by mainstream health gurus, and going gluten-free has become a blatant dietary-fad, some individuals find that thyroid function improves upon elimination of gluten from their diets.

• Beer
• Bread
• Cakes
• Cookies
• Couscous
• Crackers
• Flour
• Muffins
• Oats
• Pasta
• Pastries
• Tortillas

Listed above are some of the more common gluten-containing foods.  Realize that many of these foods are now sold in “gluten-free” formats.  You could consider going gluten free for awhile and assess whether your thyroid biomarkers improve as a result of the dietary change.  Understand that upon going gluten-free, you may experience some uncomfortable (albeit transient) gluten withdrawal symptoms.

If you do have celiac disease and/or gluten sensitivity along with hypothyroidism, it may be even more important to remain gluten-free.  Consumption of gluten among those with sensitivities can trigger an increase in inflammation, which in turn disrupts function of the hypothalamic pituitary thyroid axis (HPTA).  Disruption of the hypothalamic pituitary thyroid axis decreases conversion of T4 to T3, thereby altering concentrations of thyroid hormones.

Junk food: If you have hypothyroidism and regularly consume processed food, artificial sweeteners, unhealthy fats, or foods with chemical additives – you’ll want to eliminate them from your diet.  Replace junk food with organic, whole foods with ingredients that you can pronounce.  The long-term implications of consuming processed food with artificial ingredients and additives aren’t fully understood, however, it could be speculated that many of these foods could interfere with thyroid functionality and levels.  Fully detoxifying from junk food may be difficult (because many are addictive), but it may be necessary to improve your thyroid.

• Artificial sweeteners
• BPA-encapsulated foods
• Chemical additives
• Processed foods

Soy products: If you’ve been eating a high-soy diet, realize that it may have played a role in your development of hypothyroidism.  It is understood that soy products contain phytoestrogens (which increase estrogen).  Increases in estrogen via the phytoestrogens in soy can decrease the efficiency by which the body is able to utilize thyroid hormone.

In addition, soy is understood to contain goitrogenic compounds which can disrupt and/or damage the thyroid gland.  Countless studies have linked soy products to digestive stress, malnourishment, and immune dysfunction – each of which may also affect thyroid function.  Medical professionals that have read the literature linking soy to thyroid dysfunction may advise individuals with hypothyroidism to eliminate dietary soy products.

However, since no studies are able to state that soy products cause hypothyroidism, some doctors don’t bother mentioning the links between soy and hypothyroidism to patients; correlation does not equal causation.  Even if you are skeptical that soy products may cause hypothyroidism, you may want to eliminate them for awhile and assess whether your thyroid function improves.

Sugar:  It is understood that most people with hypothyroidism (and even euthyroid adults) consume far too much sugar for optimal health.  If you’re eating nothing but candies, cookies, and cupcakes all day – there’s a chance that the excessive sugar intake may detrimentally affect your endocrine function.  Sugar is understood to contribute to “leaky gut syndrome,” often a precursor to autoimmune disease and is capable of causing inflammation.

The combination of inflammation and insulin spikes may contribute to thyroid dysfunction in certain individuals.  Anecdotal reports from formerly hypothyroid patients have documented that elimination of sugar was able to completely reverse hypothyroidism.  It may be difficult to give up sugar though for a number of reasons: it is highly-additive (Read: Oreos as addictive as cocaine) and individuals often face disconcerting sugar withdrawal symptoms.

If you are serious about improving hypothyroidism via diet, eliminating sugar is a necessary sacrifice.  Elimination of sugar for a short-term period (e.g. days) is unlikely to significantly improve thyroid function.  However, sustained elimination of sugar over a long-term (e.g. months) may noticeably improve hormonal biomarkers and thyroid function.

Tap water: If you have hypothyroidism, you may find it beneficial to invest in a water filtration system to rid your tap water of fluoride.  Although concentrations of fluoride in tap water are relatively low and are considered “safe” for human consumption, some speculate that regular fluoride ingestion may have deleterious long-term neurological and hormonal implications.  There is clear evidence that, when ingested at high doses, fluoride causes neurotoxicity.

While the extent of neurological and hormonal dysfunction resulting from fluoride in tap water may be minor, sensitive individuals or those at risk for hypothyroidism may benefit from its removal.  Fluoride also is understood to interfere with the absorption of iodine, possibly leading to an iodine deficiency and ultimately hypothyroid function.  You may want to test whether hormonal biomarkers improve with a water filtration system.

Unhealthy fats: While the inclusion of healthy fats in the diet from food sources such as avocados may be helpful for reducing hypothyroidism, elimination of unhealthy fats may be of greater importance.  Unhealthy fats (e.g. trans fats) are known to interfere with many biochemical processes (including those related to the thyroid) and are detrimental to overall health.  If you’re consuming trans fats and/or excessive quantities of unhealthy saturated fats – you’ll want to cease consumption as soon as possible for the sake of your thyroid.

How diet may affect thyroid replacement medications

If you’re using thyroid replacement therapy such as Synthroid (levothyroxine) or a Armour Thyroid (desiccated thyroid extract), consumption of certain foods can affect how well your body is able to absorb the treatment.  For this reason, dosing instructions for your thyroid replacement therapy will likely recommend taking your medication on an empty stomach at least 60 minutes prior to breakfast (or food consumption).  Consumption of foods and/or certain drinks (e.g. coffee) along with your medication can interfere with its normative pharmacokinetics and substantially alter your thyroid levels.

Coffee: Many patients with hypothyroidism understand that they cannot eat food with their medication, but often aren’t informed that they should avoid caffeinated beverages such as coffee.  If you’re taking thyroid medication (e.g. levothyroxine) and are a heavy coffee drinker, you may want to cut back on your consumption or avoid coffee altogether.  The caffeine content within coffee inhibits absorption of thyroid replacement hormone, possibly causing you to remain stuck in a hypothyroid state even when you’ve been taking your medication.

Most professionals recommend avoiding coffee and other caffeinated beverages for at least 1 hour after taking your thyroid medication.  By waiting an hour, you can be sure that the coffee won’t interfere with its absorption.  You may also want to consider that if you drink a lot of coffee and/or require high doses of caffeine in the morning, it may be that the excess caffeine is taxing your adrenals.

While low or moderate doses of caffeine may not affect your thyroid health, large doses could influence HPTA dysfunction and ultimately thyroid function.  Additionally, when caffeine is coupled with high stress, lack of sleep, poor dietary choices – some degree of thyroid dysfunction is likely to occur.  Try cutting back on coffee (and caffeine sources) for awhile to determine whether your thyroid function improves.  If you quit altogether, be wary of caffeine withdrawal symptoms.

Gluten: Gluten is ubiquitous in grains such as: barley, wheat, and rye – and is a blend of starch and 2 proteins (gliadin and glutenin).  In any regard, gluten may irritate the small intestine and impair absorption of thyroid hormone replacement therapies.  For this reason, some experts recommend that those taking thyroid medication should limit and/or avoid gluten.

If you consume gluten and are taking a thyroid medication, you may want to decrease gluten intake for awhile to determine whether you notice any benefit.  Anecdotal reports have suggested that eliminating gluten from the diet decreased need for thyroid medication and/or enhanced its efficacy; this could be due to improved absorption.

High fiber: While consuming sufficient dietary fiber is healthy, excessive fiber consumption may affect hypothyroidism treatment.  Adults consuming over 40 grams of fiber per day may find that high fiber intake inhibits absorption of thyroid replacement medications.  If you’ve gone on a high fiber diet and noticed that your thyroid medication wasn’t working as well and/or your dosage needed to be increased – it could’ve been from the fiber.

Adults may want to keep their fiber intake between 20 and 30 grams per day.  Additionally, it may be best to refrain from fiber consumption for at least several hours after administration of thyroid medication.  Though it is not recommended to eliminate all fiber from your diet, it is recommended that you remain cognizant of your fiber intake.

Processed foods: If you’re taking medication to treat hypothyroidism, you should avoid processed foods.  Not only do processed foods contain artificial chemicals and preservatives which could detrimentally affect thyroid function, but they are often loaded with sodium.  Excessive sodium intake can increase risk of hypertension, a condition many people with hypothyroidism are already known to have.

Soy: If you’re consuming soy while taking a thyroid medication, it is important to realize that it may irritate the lining of your gastrointestinal tract.  This irritation may interfere with the absorption of your thyroid medication, thereby leaving you stuck in a state of hypothyroidism.  If you regularly consume soy products, understand that they could prevent your medication from working as intended.

Hypothyroidism & Diet: The Research

Included below is a synopsis of scientific studies investigating the link between dietary intake and hypothyroidism.  It is relatively difficult to determine whether one particular dietary subtype may increase propensity to develop hypothyroidism.  Additionally, specific foods associated with hypothyroidism haven’t been fully elucidated.

2013: Vegan diets and hypothyroidism.

A report by Tonstad et al. (2013) investigated whether vegan diets are associated with hypothyroidism.  Tonstad and other researchers stated that diets eliminating animal products are rarely associated with hypothyroidism, but are associated with protection against autoimmune disorders.  That said, they sought to determine the risk of hypothyroidism development among individuals adhering to an array of dietary subtypes.

Data was reviewed from a study that took place from 2002 through 2008, examining dietary intake as well as whether individuals were more (or less) likely to develop hypothyroidism.  Researchers discovered that several factors outside of diet were associated with increased risk of hypothyroidism including: overweight/obese (high BMI), female (sex), Caucasian (ethnicity), and higher education.  Upon examination of diet, vegan diets were associated with decreased risk of hypothyroidism.

On the other hand, lacto-ovo vegetarian diets were associated with increased risk of hypothyroidism.  Standard omnivorous diets were not associated as having increased risk of hypothyroidism, but were considered slightly riskier than vegan diets.  Based on this report, researchers concluded that vegan diets may be protective against hypothyroidism.

• Source: http://www.ncbi.nlm.nih.gov/pubmed/24264226

2006: Effects of soy protein and soybean isoflavones on thyroid function in healthy adults and hypothyroid patients: a review of the relevant literature.

A report published by Messina and Redmond (2006) analyzed the effects of soy protein and soybean isoflavones on thyroid function in both euthyroid (healthy) adults, as well as adults diagnosed with hypothyroidism.  Researchers highlighted the fact that ingestion of soy products, particularly soybeans, are known to alter hormone function.

They noted that there is concern over the fact that soy intake may impair thyroid function and possibly detrimentally affect the pharmacokinetics of synthetic thyroid hormone (e.g. synthroid).  Specifically, it is thought that soy intake may inhibit absorption of synthetic thyroid replacement therapies.  A total of 14 trials were identified and assessed in which the effects of soy products were assessed for effects on thyroid function.

In 13 of the 14 trials, soy products appeared to have no effect (or very modest effects) on thyroid function.  Researchers noted that there is no evidence to suggest that soy products adversely affect thyroid function among healthy, euthyroid individuals.  There was evidence to support the idea that soy products may interfere with the absorption of synthetic thyroid medication.

Although it was mentioned that soy products can be safely consumed among adults with hypothyroidism, researchers suggested caution.  Soy products may be contraindicated among those with either: compromised thyroid function and/or inadequate iodine intake.  The overarching conclusion made by the researchers is that if you’re consuming soy, and are at risk for hypothyroidism, be sure you’re ingesting sufficient iodine.

• Source: http://www.ncbi.nlm.nih.gov/pubmed/16571087

2004: Nutrition, evolution and thyroid hormone levels – a link to iodine deficiency disorders?

A report by Kopp (2004) indicated that many individuals are deficient in iodine due to adoption of high-carbohydrate diets.  Kopp believes that the main cause of iodine deficiency disorders (IDD) is a result of recent adoption of high-carbohydrate diets compared to the low carbohydrate/high protein diets of our Paleolithic ancestors.  The report notes that adherence to a high-carbohydrate diet increases serum T3 (triiodothyronine) levels.

When serum T3 concentrations increase as a result of high-carbohydrate consumption, dietary needs of iodine increase.  As a result, most individuals on high-carbohydrate diets suffer from iodine deficiencies.  Iodine deficiencies are known to deleteriously effect function of the thyroid, potentially contributing to certain cases of hypothyroidism.

If you’re eating a high-carbohydrate diet, you may want to consider reducing the carbohydrates and eating foods rich in iodine.  While too much iodine can be problematic for thyroid function, most individuals are eating too many carbs and likely are deficient.  Making adjustments in carbohydrate intake and iodine consumption may prove beneficial for your hypothyroidism.

• Source: http://www.ncbi.nlm.nih.gov/pubmed/15142639

2002: Thyroid-related autoantibodies and celiac disease: a role for a gluten-free diet?

A report published by Mainardi et al. (2002) examined the effect of gluten on thyroid function.  Previous research has noted a link between celiac disease (gluten intolerance) and autoimmune conditions.  This particular study sought to determine whether there was a relationship between celiac disease among 100 individuals diagnosed with autoimmune thyroid disease.

Among individuals with autoimmune thyroid disease, only 2% had celiac disease.  Upon adoption of a gluten-free diet, no significant changes in thyroid autoantibodies was observed.  This suggests that consumption of gluten is unlikely to trigger autoimmune thyroid dysfunction.

• Source: http://www.ncbi.nlm.nih.gov/pubmed/12192201

2001: Commercial diet induced hypothyroidism due to high iodine. A histological and radiological analysis.

A study published by Castillo et al. (2001) investigated whether a commercial diet may provoke hypothyroidism as a result of high-iodine content.  While it is understood that suboptimal iodine intake may detrimentally affect thyroid function, excessive iodine intake may be of equal detriment.  To better understand the effects of iodine on thyroid function, researchers recruited 3 groups of puppies from the School Hospital of the Faculty of Veterinary Science-UBA.

Among the 3 groups of puppies, different diets were administered including: a home-prepared diet, a commercial diet (with 5.6 mg/kg potassium iodide), and a home-based diet (supplemented with 5.6 mg/kg potassium iodide).  The groups fed diets with potassium iodide developed hypothyroidism, whereas the first group eating the home-prepared diet did not.  Researchers suggested that high-iodine, commercial diets may increase risk of hypothyroidism.

• Source: http://www.ncbi.nlm.nih.gov/pubmed/11765244

1979: Dietary-induced alterations in thyroid hormone metabolism during overnutrition.

A publication from 1979 by Danforth et al. analyzed the effects of dietary alterations on thyroid hormone metabolism among those experiencing overnutrition.  Researchers noted that since thyroid hormones enhance thermogenesis, dietary-induced alterations of thyroid hormones may explain increases in thermogenesis that occur among those experiencing overnutrition.  It was reported that overfeeding elevates serum concentrations of T3 (triiodothyronine) while simultaneously expediting its metabolic clearance and production.

That said, serum concentrations, clearance, and production of T4 (thyroxine) remain unaltered as a result of exceed food intake.  Regardless of whether diets were primarily carbohydrates, protein, or fat – overfeeding increased serum T3 concentrations.  Researchers speculated that in cases of overfeeding, elevated serum T3 results from accelerated conversion of T4 (thyroxine) to T3, rather than increased production of T3 from the thyroid gland.

Due to these findings, it was noted that caloric intake plays an important role in regulation of serum concentrations and peripheral metabolism of thyroid hormones.  In cases of starvation, serum concentrations of T3 are reduced, and conversion of T4 to T3 is slowed.  In addition to overnutrition and undernutrition affecting speed of T4 metabolism (to T3), each may elicit specific effects upon function of the hypothalamic pituitary thyroid axis (HPTA), thereby determining availability of T3.

The findings from this early research indicate that the number of calories you consume per day can affect peripheral metabolism of T4 to T3, and overall T3 concentrations.  If you’re deficient in T3, boosting overall caloric intake may be helpful.  It seems as if undernutrition (such as observed in fasted states) is associated with low T3.

• Source: http://www.ncbi.nlm.nih.gov/pubmed/500814

What can we conclude from this research?

The above literature indicates that dietary intake may increase risk for hypothyroidism for certain individuals.  Failure to optimize intake of iodine, insufficient consumption of calories, and excessive soy intake may reduce thyroid concentrations.  Additionally, there is some evidence to suggest that vegan diets may decrease risk of hypothyroidism.

• Iodine optimization is important: Studies indicate that excessive intake of iodine can cause hypothyroidism, whereas insufficient iodine may be equally as problematic. For this reason, if you suffer from hypothyroidism and/or at risk for hypothyroidism, you may want to check your iodine levels.  Optimizing your iodine intake with certain foods and/or supplementation may improve thyroid function.
• Caloric intake affects T3: Individuals that are chronically overfed or experiencing nutritional affluence may have high serum concentrations of T3. Increased caloric intake enhances conversion speed of T4 (thyroxine) to T3 and boosts total T3 levels throughout the body.  On the other hand, individuals who are underfed or malnourished may experience hypothyroid function as a result of inadequate caloric intake.  Consider that if you’re not eating enough calories, your T3 levels may be low.
• Carbohydrates affect iodine requirements: As was already mentioned, optimizing your iodine is important to ensure healthy thyroid function; too much/little will be of detriment to your thyroid. Research suggests that if you’re eating a high-carbohydrate (non-Paleolithic) diet, your iodine needs will increase.  Due to these increased iodine needs, you may be more likely to end up deficient; this deficiency could lead to hypothyroidism.
• Soy products may raise risk: Among euthyroid, healthy adults, intake of soy products is not associated with a significant change in thyroid function. However, among adults with hypothyroidism and/or those at risk for the condition, soy products may have a modest detrimental effect on thyroid levels.  Additionally, soy products may interfere with absorption of thyroid medications, thereby requiring individuals to administer higher doses for thyroid optimization.  It is also necessary to consider that soy products yield an estrogenic response, which may be unwanted for men. (Read: Foods high in estrogen).  Although soy may not significantly affect thyroid function, those at risk for hypothyroidism may want to avoid it altogether to eliminate risk.
• Vegan diets may reduce risk: Evidence from a large-scale study indicated that individuals consuming vegan diets appear to have a reduced risk of hypothyroidism. It is unclear as to why adherents to a vegan diet are at less risk for thyroid dysfunction, but reasons can be hypothesized.  Perhaps those ingesting vegan diets are more conscientious of foods that they eat and are less likely to consume artificial sweeteners, sugars, preservatives, etc. – all of which may disrupt thyroid function.  Additionally, those consuming vegan diets may have lower BMIs (a risk factor for hypothyroidism) and have reduced risk for other health conditions (which may indirectly induce hypothyroidism).

Hypothyroidism & Diet: Future Research Is Warranted

It is relatively difficult to fully elucidate how dietary intake affects risk of hypothyroidism.  There aren’t many large-scale studies comparing various diets and accounting for potential confounding factors.  Furthermore, among adherents to specific diets (e.g. high fat diets), there may be differences in the quality/types of fats consumed – which could affect onset of hypothyroidism.  Moreover, whenever considering how dietary intake could affect hypothyroidism, genetics should be considered.

• Genetics: We are on the cusp of understanding how genetics (and epigenetics) affect how individuals respond to food. It could be that among a subset of individuals with a particular gene or system of genes, that intake of a high fat diet increases risk of hypothyroidism.  For other individuals with different genes, a high fat diet may reduce risk of hypothyroidism.  It may be necessary to explore interindividual differences at the genetic level for determining optimal diet for hypothyroidism correction and/or prevention.
• Fat intake: There is some evidence to suggest that the type of fat consumed may affect thyroid function. Individuals consuming saturated fat may be at different risk for hypothyroidism than those consuming monounsaturated fat.  In addition, the specific source of fat within a particular subtype (e.g. saturated fat) may affect hypothyroidism risk.  For example, consumption of coconut oil may be less risky than consuming peanut oil or corn oil.  Additionally, the specific quality of the source of fat (e.g. virgin coconut oil vs. refined coconut oil) may necessitate consideration – further complicating the research.
• Sugars and artificial sweeteners: It is unclear as to whether a high-sugar, high-aspartame, or high-HFCS diet may have deleterious effects upon thyroid function. In the future, researchers may want to explore the effects of a high-sugar, moderate-sugar, and low-sugar diet on thyroid function.  It may be that restriction of sugars and/or even other sweeteners (e.g. high-fructose corn syrup) may improve thyroid among those with dysfunction.
• Preservatives: Little research has explored the possibility that preservatives within foods may cause hypothyroidism. Individuals that consume foods with preservatives and/or artificial colorings may be at increased risk of hypothyroidism (or possibly even decreased risk – albeit this is unlikely).  Since preservatives and other chemical additives have become increasingly common in foods – these should be considered as a potential cause of (or contributor to) thyroid dysfunction.

How long does a hypothyroidism diet take to work?

Assuming you’ve made numerous dietary changes in attempt to ameliorate symptoms of hypothyroidism, it may take awhile (e.g. 3+ months) before the cumulative effect of these changes yields benefit.  That said, some individuals may notice immediate benefits within a day or two of making changes.  For example, someone who regularly drank coffee with their thyroid medication may have been oblivious to the fact that the caffeine affected absorption.

By eliminating coffee consumption altogether or postponing it to a time later in the day, this individual may report that his/her medication is working much better than in the past.  In other cases, elimination of gluten, soy, and excessive fiber may provide similarly instantaneous benefit because they are no longer interfering with absorption of the thyroid medication.  However, if you’re looking to heal your thyroid function with a diet, it’ll likely take a much longer duration.

If diet caused or contributed significantly to your underlying hypothyroidism, chances are that it wasn’t overnight.  For this reason, if you’ve adopted a new hypothyroidism diet in attempt to normalize thyroid function, you shouldn’t expect a healthy thyroid (or even improvements) overnight.  It’ll likely take at least several months before you notice any changes resulting from elimination of foods (e.g. alcohol, gluten, soy) and/or addition of foods (e.g. bone broth, fish, fruits, veggies, healthy carbs).

While dietary changes may provide immediate benefit for a small percentage of individuals with hypothyroidism, it usually takes awhile (e.g. 6 to 18 months) for the neurophysiology to adjust to healthier nutritional choices.  To expedite the speed by which diet has an impact, you may want to consider getting blood work done to pinpoint nutritional deficits.  By specifically targeting underlying nutrient deficits, you may be able to improve your thyroid function quicker.

Will a hypothyroidism diet work for everyone?

No.  A hypothyroidism will NOT work for everyone.  Those that have had their thyroid removed (via a thyroidectomy) cannot improve thyroid function from dietary changes; in these cases, there is no thyroid to be improved.  On the other hand, if diet played a major role in your development of hypothyroidism, dietary changes may significantly improve functionality of your thyroid gland.

Individuals that are likely to derive most benefit from hypothyroidism diets are those that consumed an unhealthy diet and few nutrients.  For example, someone that eats zero omega-3s, zero veggies, and zero fruits – along with high sugar, high gluten, unhealthy fats/oils, and chemical preservatives – is likely at risk for poor overall health (and possibly thyroid problems) from diet.  Assuming this person reversed his/her poor dietary choices by eating things like: wild-caught fish, fruits, veggies – and minimizing sugar, gluten, and unhealthy fats/oils – he/she may notice significant improvement in thyroid function.

That said, consumption of a healthy, optimized “hypothyroid diet” is not a sure-fire guarantee to improve or normalize thyroid function.  In many cases, diet does not have any noticeable effect on thyroid function.  Furthermore, there is no scientific evidence to substantiate claims of individuals that reversed (or “cured”) their hypothyroidism with diet.

What are the potential benefits of a hypothyroidism diet?

There are many potential benefits associated with eating an optimal, healthy diet for hypothyroidism.  Perhaps the most significant benefit is that your thyroid replacement medication may be of greater efficacy at a lower dose.  In some cases, adopting a specific diet for hypothyroidism may reverse symptoms by targeting an underlying cause.

• Decreased medication needs: It is possible that by adopting a specific hypothyroidism diet, you may end up decreasing your dosing needs for certain medications (e.g. levothyroxine). By ridding your diet of foods that interfere with medication absorption (principally by causing GI distress) and increasing foods that support thyroid health, you may be able to reduce your dose.  Your goal in the first place should be to take the minimal effective dose of medication; lower doses tend to provoke fewer side effects.
• Enhanced medication efficacy: Efficacy of your current hypothyroidism medication may be enhanced when you eliminate certain foods from your diet such as: caffeine, gluten, soy, and unhealthy fats. As a result, if may feel as if your medication is more potent and/or “working better” than it was in the past.  The addition of certain foods may also augment the efficacy of your thyroid medication.
• Improved thyroid function: Certain individuals may notice that their thyroid function spontaneously improves within several months of adherence to a particular diet aimed to correct hypothyroidism. It may be difficult to know with 100% certainty whether dietary adjustments have improved your thyroid function.  However, if the only lifestyle changes you made were dietary ones, and your thyroid levels – it could be a sign that your thyroid function is better than in the past.
• Increased T4/T3 concentrations: Eating enough calories and the right kinds of foods can increase concentrations of T4 and T3 among those with hypothyroidism. Some foods and nutritional deficiencies may interfere with the synthesis of T4 and conversion of T4 to T3.  Upon correction of suboptimal nutrition, individuals may notice that concentrations of T3 (and possibly T4) are significantly improved.
• Targeting a causative factor: There are a multitude of potential factors that may cause hypothyroidism including: autoimmune disease, medications, thyroiditis, etc. Some speculate that hypothyroidism may also be caused by poor diet, particularly inadequate intake of iodine.  If upon making dietary changes you notice that it corrects your hypothyroidism, diet could’ve been a major causative factor in your thyroid dysfunction.

Have you tried a diet for hypothyroidism?

If you’ve tried a specific diet for hypothyroidism, share a comment mentioning whether you found it therapeutically effective for improving thyroid function and/or normalizing levels of T4, T3, and TSH.  To help others get a better understanding of your situation, discuss the specific dietary changes that you implemented and how long it took [after implementation] for you to notice improvement.  If you were already taking thyroid medication, did dietary changes reduce your need for medication and/or enhance the efficacy of your existing dosage?

Understand that when it comes to eating a particular diet to improve hypothyroidism, results will likely be subject to interindividual variation.  A dietary change that worked for you (e.g. eliminating soy) may differ from a dietary change that was efficacious for someone else (e.g. eliminating sugar).  Additionally, the duration to which you strictly adhere to the diet may also influence its overall efficacy.

Realize that there is currently no significant scientific evidence to indicate that adopting a certain diet or changing your diet will treat hypothyroidism.  That being said, absence of evidence does not mean evidence of absence – diet could affect thyroid function for certain individuals.  At the very least, adopting a healthy diet should improve your overall health, and if you’re lucky, it may also improve biomarkers and/or attenuate symptoms of hypothyroidism.

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