Hashimoto’s Diet: The Link Between Gut and Thyroid Health

Hashimoto’s thyroiditis — often referred to as Hashimoto’s disease or Hashimoto’s — is a common thyroid disorder.

It causes a range of signs and symptoms, that even with medications, can be difficult to manage.

Fortunately, you may be able to alleviate your signs and symptoms by addressing the health of your gut since it plays a crucial role in thyroid health.

This article explains the connection between the thyroid and gut and how healing the gut may improve the signs and symptoms of Hashimoto’s.

What is Hashimoto’s?

Hashimoto’s thyroiditis is an autoimmune condition — like Graves’ disease — that gradually destroys thyroid tissue (1).

The thyroid is a butterfly-shaped gland in your neck that sits just above your collarbone. It secretes hormones that affect nearly every organ system in your body.

The primary hormones secreted by the thyroid are triiodothyronine (T3) and tetraiodothyronine or thyroxine (T4).

The thyroid gland also secretes calcitonin, a hormone that regulates calcium levels in your blood.

Damage to the thyroid cells eventually leads to insufficient production of thyroid hormones, resulting in underactive thyroid or hypothyroidism.

The signs and symptoms of Hashimoto’s depend on its severity and the organs affected but may include (1):

• swelling of the skin
• scaly and dry skin, especially on the palms and soles
• dry, dull, or brittle hair
• fatigue
• shortness of breath during exercise
• muscle weakness
• constipation
• brittle nails
• high blood pressure
• depression
• insomnia
• cold intolerance
• weight gain

Hashimoto’s affects both men and women, but women are 10 times more likely to be diagnosed. The risk of developing Hashimoto’s increases with age and most women are diagnosed between 30 and 50 years of age (1).

Causes

The development of Hashimoto’s is believed to be influenced by an interaction between genetics and environmental factors like diet, gut health, and infections.

More recently, alterations in the gut microbiota — the collection of organisms that colonize the gut — have been suggested to play a role in triggering Hashimoto’s (2).

The factors that lead to Hashimoto’s can lead to the development of other autoimmune conditions, including (3):

• type 1 diabetes
• anemia
• myasthenia gravis
• celiac disease
• rheumatoid arthritis
• systematic lupus erythematosus (SLE)

The primary treatment for Hashimoto’s is thyroid hormone replacement therapy. However, the symptoms of Hashimoto’s can persist even if you take thyroid medication (4).

However, you may be able to experience symptom relief or improvement by combining thyroid medication with dietary changes focused on gut health.

Thyroid-gut axis

There is growing evidence to suggest that there is a strong connection between the thyroid and gut — known as the thyroid-gut axis (2).

The gut microbiota — the collection of organisms that inhabit your intestines — supports thyroid health in several ways.

For example, the gut microbiota, when healthy, keeps the immune system from mistakenly attacking the proteins needed to make thyroid hormone (2).

A healthy gut microbiota allows for the absorption of certain minerals that are important for thyroid health, including iodine, selenium, zinc, and iron (5).

But just as much as a healthy gut is necessary for healthy thyroid function, healthy thyroid function is necessary for a healthy gut.

A healthy thyroid supports gut health by strengthening the cells that line the intestines to prevent inflammatory proteins, food antigens, and bacteria from passing to parts of the body where they can trigger an immune response and promote inflammation.

When harmful compounds from the gut cross the intestinal barrier or gut wall into the bloodstream, it’s known as increased intestinal permeability or leaky gut syndrome.

Leaky gut syndrome is associated with dysbiosis — an imbalance in the composition of the microbiota or a change in their activities — and small intestinal bacterial overgrowth (SIBO).

These gut issues tend to occur more frequently in people with Hashimoto’s compared to people without the condition and therefore may contribute to Hashimoto’s development (6, 7, 8, 9).

To this point, you may be able to alleviate some of your symptoms by addressing the gut through dietary changes in combination with thyroid medication (5, 10).

Identifying the root of your gut issues

If you are experiencing gut issues, the first step is always to figure out the cause.

The symptoms of gut issues may include diarrhea, constipation, bloating, and excess gas, but may also include less obvious symptoms like weight loss, chronic fatigue, and brain fog.

Hashimoto’s is one cause of gut issues, but other factors may play a more significant role.

Other causes of gut dysfunction may include (10):

• following a pro-inflammatory diet, such as the standard American diet (SAD) or Western diet
• unidentified food allergies and intolerances, such as dairy, gluten, or other wheat protein like amylase-trypsin inhibitors (ATIs)
• gastritis as a result of a Helicobacter pylori (H. pylori) infection
• viral infections, such as hepatitis C or Epstein-Barr virus

Following an elimination-style diet can help you identify foods or ingredients to which you may allergic or intolerant.

For example, a small study found the autoimmune protocol (AIP) diet beneficial for relieving Hashimoto’s symptoms in women.

The AIP diet eliminates foods that are thought to trigger inflammation in people with autoimmune diseases like Hashimoto’s.

For the study, 16 women with Hashimoto’s disease who followed the AIP diet reported significant improvements in various quality-of-life measures, disease symptoms, and high-sensitivity C-reactive protein (hs-CRP), a measure of inflammation (11).

However, elimination diets like the AIP diet are difficult to follow correctly so you may need support from a dietitian who specializes in autoimmune conditions like Hashimoto’s.

You may also need support from other healthcare providers to rule out other potential medical issues that may be causing your gut issues.

Once you identify the issue, you can turn your focus to healing the gut.

Foods to eat and avoid

The foods you eat strongly influence the composition of your gut microbiota and the strength of the gut barrier (12).

Certain foods and nutrients can increase gut inflammation and permeability, allowing bacteria and antigens — molecules recognized by the immune system as potential threats — to pass from the gut to the bloodstream where they can damage the thyroid and other organs.

Conversely, other foods and nutrients can decrease gut inflammation and strengthen the integrity of the intestinal barrier.

Foods to eat

Foods rich in fiber and beneficial plant compounds called polyphenols like fruits, vegetables, and wheat-free whole grains are especially helpful for promoting gut health.

In addition to these foods, include plenty of healthy proteins in your diet.

Eat these foods to support gut health (13, 14, 15):

• Fruits: apples, bananas, berries, cherries, grapes, kiwis, mango, melons, oranges, pears, pineapples, etc.
• Vegetables: artichokes, asparagus, broccoli, brussels sprouts, cauliflower, kale, okra, potatoes, spinach, squash, etc.
• Wheat-free grains: amaranth, brown rice, buckwheat, corn, oats (certified gluten-free), millet, quinoa, sorghum, teff
• Animal proteins: eggs, fish and shellfish, lean cuts of beef and pork, and skinless poultry
• Dairy alternatives: calcium-fortified almond, coconut, and soy milk
• Seeds and nuts: almonds, brazil nuts, flaxseeds, pistachios, pumpkin seeds, walnuts, etc.
• Legumes: beans, lentils, and peas
• Beverages: coffee, tea, water

You may need to avoid or limit some of these foods as part of an elimination diet.

Foods to limit or avoid

Limit or avoid these foods as they can promote dysbiosis and leaky gut (16, 17):

• Added sugars: candy, cakes, cookies, flavored yogurt, ice cream, sugar-sweetened drinks, like regular soda, energy and sports drinks
• Fried food: chicken strips, cheese sticks, fish, french fries, etc.
• Refined grains: bakery items, breakfast cereals, desserts, and white flour, rice, bread, and pasta
• Processed meats: beef jerky, bologna, deli meats, ham, hot dogs, pepperoni, sausage
• Gluten-containing grains: barley, rye, triticale, and wheat, including all varieties like spelt, kamut, farro, and durum, and products like bulgur and semolina
• Alcohol

The bottom line

Hashimoto’s disease is an autoimmune disorder of inadequate thyroid hormone production.

Gut problems like leaky gut and dysbiosis are common in people with Hashimoto’s and may contribute to symptoms, like constipation, diarrhea, bloating, fatigue, and brain fog.

Identifying and correcting any gut problem and eating to promote gut health may help improve thyroid function and alleviate your symptoms.