Gluten-Free for Hashimoto's: Does It Help?

For most people with Hashimoto's, going gluten-free has not been shown to change thyroid antibodies, thyroid function or the need for medication. The exception is coeliac disease, which is more common in people with Hashimoto's and can stop levothyroxine absorbing properly. So the useful first step is not cutting gluten. It is asking your doctor to test for coeliac disease while you are still eating it.

If you have Hashimoto's or an underactive thyroid, you have probably seen someone online say that going gluten-free changed everything. This guide sets out what the research actually shows, where gluten genuinely matters, and how to find out whether it matters for you.

Why gluten and Hashimoto's get linked

There is a real connection, and it runs through coeliac disease. Coeliac disease is an autoimmune condition triggered by gluten, and autoimmune conditions tend to cluster. A 2016 review of more than 6,000 people with autoimmune thyroid disease found about 2.7% of adults had biopsy-confirmed coeliac disease, roughly 1 in 37, compared with about 1 in 70 Australians overall.

The link runs both ways. A Swedish study of 14,000 people with coeliac disease found they were about four times as likely to develop an underactive thyroid. That points to shared genetic risk, not to gluten causing Hashimoto's.

You may see a figure of 5 to 7% quoted online. That number is for people with a positive coeliac antibody test, not people with diagnosed coeliac disease. A positive antibody test is the start of an investigation, not the end of one.

Test first, while you are still eating gluten

This is the single most important point in this guide. Coeliac tests look for the body's reaction to gluten. If you cut gluten before you are tested, the results can come back falsely normal.

• healthdirect lists thyroid problems as a reason to ask your GP about coeliac testing, and is clear: do not stop eating gluten until you have been tested.
• Coeliac Australia advises that if you have already cut gluten, you will need to eat it again, around four slices of wheat bread a day, for at least six weeks before testing, with your doctor's guidance.
• A gene test does not need gluten. If it is negative, coeliac disease is very unlikely.

European coeliac guidelines updated in 2025 list Hashimoto's among the conditions where people should be tested, and the UK's NICE guidance recommends offering testing to people with autoimmune thyroid disease at diagnosis.

Where gluten really matters: coeliac disease and your medication

Untreated coeliac disease damages the lining of the small intestine, which is where levothyroxine is absorbed. In people with both Hashimoto's and coeliac disease, an Italian study found levothyroxine needs were about 50% higher when the coeliac disease was not being managed, and came back into line once a gluten-free diet was followed. A small US study saw doses fall after people's coeliac disease was treated.

Two practical points follow:

• If your levothyroxine dose keeps creeping up, or your results stay unsettled even though you take it correctly, it is reasonable to ask whether coeliac disease has been checked.
• If you are diagnosed with coeliac disease and start a gluten-free diet, ask your doctor when to recheck your thyroid tests, because your dose needs may change. Do not change your dose yourself.

A 2022 review in the Endocrine Society's journal summed it up: cutting gluten helps thyroid treatment mainly in people who actually have a problem with gluten, probably because it lets levothyroxine absorb properly.

What the trials show without coeliac disease

For people with Hashimoto's who do not have coeliac disease, the evidence is thin and does not support going gluten-free to change the condition:

• The longest randomised trial followed 62 people with Hashimoto's for a year. Thyroid antibodies were no different between those who went gluten-free and those who did not.
• The first pooled analysis, of four small studies and 87 people, found antibody changes that were not statistically significant, and concluded the evidence was not enough to recommend a gluten-free diet to everyone with Hashimoto's.
• A 2025 review that included only randomised trials found three small studies with 110 people and rated the evidence "very uncertain". Thyroid function did not change, and one antibody measure went up rather than down.

The small study most often quoted online did see antibodies fall on a gluten-free diet. But every one of its 34 participants already had positive coeliac antibodies, which is exactly why testing comes first.

The Australian Thyroid Foundation's answer to whether a gluten-free diet helps autoimmune thyroid disease is simply "no", unless you also have coeliac disease or a gluten intolerance.

What about gluten sensitivity?

Some people without coeliac disease feel better when they eat less wheat, and their symptoms are real. The question is whether gluten is the cause. When researchers in Melbourne retested people who believed gluten upset them, using hidden gluten or a placebo, only about 1 in 12 reacted to gluten specifically. Across ten blinded trials, about 1 in 6 did.

Other explanations often fit better. In a blinded Norwegian trial, fructans, a type of carbohydrate found in wheat, caused more bloating than gluten did. A 2024 international trial found that expecting to eat gluten affected people's symptoms about as much as actually eating it. None of this means the symptoms are imagined. It means the trigger is not always gluten, and a GP or dietitian can help you work out what it is.

The downsides of going gluten-free when you do not need to

• Nutrition. healthdirect notes a gluten-free diet is not automatically healthier and can lack nutrients if it is not well planned. Australian research found people who cut wheat without a diagnosis were often short on fibre and calcium.
• Fortified bread. Australian law adds folic acid and thiamin to wheat flour for bread, and gluten-free breads do not have to include them. Most bread, gluten-free included, must use iodised salt, so dropping bread altogether can also mean less iodine.
• Cost. In Australian supermarkets, gluten-free bread costs about three times as much as regular bread.
• Testing. Cutting gluten first makes coeliac disease harder to diagnose later.

If you do decide to go gluten-free, a dietitian can help you fill the gaps.

Questions to ask your doctor

1. Have I been tested for coeliac disease? Should I be, given my Hashimoto's?
2. Should I keep eating gluten until the test is done?
3. Could absorption be why my dose keeps changing?
4. If I am diagnosed with coeliac disease, when should my thyroid tests be rechecked?
5. Could a dietitian help me work out what is causing my gut symptoms?

Where ThyroBase fits

No nutrition product changes Hashimoto's. ThyroBase is a daily morning and evening nutrition powder for people living with Hashimoto's, an underactive thyroid or no thyroid, designed to sit alongside your thyroid medication, never instead of it. Here is who ThyroBase is, and is not, designed for. For the wider evidence on diet, see our guide to Hashimoto's and nutrition research.

Before you cut gluten, ask for a coeliac test.

It is the one step that tells you whether gluten matters for your thyroid.

Frequently asked questions

Should I go gluten-free if I have Hashimoto's?

Not without a reason. Trials in people with Hashimoto's who do not have coeliac disease have not shown that a gluten-free diet changes thyroid antibodies or thyroid function. Ask your doctor to test you for coeliac disease first, while you are still eating gluten.

Does a gluten-free diet lower thyroid antibodies?

Not reliably. A year-long randomised trial found no difference in antibodies, and the most recent review of randomised trials rated the evidence very uncertain. The small study often quoted online involved people who all had positive coeliac antibodies.

How are Hashimoto's and coeliac disease connected?

Both are autoimmune conditions that share genetic risk, so they often occur together. About 1 in 37 adults with autoimmune thyroid disease has biopsy-confirmed coeliac disease. Untreated coeliac disease can also reduce how well levothyroxine is absorbed.

Do I need to eat gluten before a coeliac test?

Yes. Coeliac Australia advises eating gluten, around four slices of wheat bread a day, for at least six weeks before testing if you have cut it out. A gene test does not need gluten and can rule coeliac disease out. Talk to your GP before changing your diet.

The honest takeaway

Gluten matters for your thyroid mainly if you have coeliac disease, and coeliac disease is common enough alongside Hashimoto's to be worth testing for. Get tested before you change anything. If the test is negative, the evidence does not support going gluten-free to change your thyroid, though a dietitian can help if wheat seems to upset your gut.

ThyroBase is a nutritional supplement and is not intended to diagnose, treat, cure, or prevent any disease. It is designed to sit alongside your thyroid medication, not replace it. This article is general information, not medical advice. Never start, stop or change a supplement, diet or prescription medication without speaking to your doctor or pharmacist first.

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