Looking for an underactive thyroid diet?

I am a nutritionist with Hashimoto’s. Here are my eight tips for a happy thyroid.


Let me guess. You have just been diagnosed with an underactive thyroid, told it’s incurable and sent on your way with a prescription for a pill to take for life. Or you’ve been taking the pill for a while, your labs are normal, but your symptoms are still here. What the hell.

So, you start googling, quickly realising that although conventional medicine doesn’t have a solution, there is actually a lot you can do with your diet and lifestyle to give your thyroid a bit of a boost and reduce your symptoms. But there is so much conflicting information out there - go paleo, or vegan, ditch gluten, but eat carbs, broccoli is good for thyroid, or no actually it’s bad, supplement with iodine, don’t touch iodine ever again… etc, etc. It’s overwhelming and exhausting. 

But worry not. Thankfully your research has led you to this article, and I am here to cut through the nutrition noise out there and shed some light on the underactive thyroid diet conundrum.

First, the facts.

The thyroid is a small endocrine gland located in the front of your neck, producing two hormones thyroxine (T4) and triiodothyronine (T3). These hormones are released when stimulated by TSH (thyroid-stimulating hormone). Most of us wouldn’t be aware of its existence until of course, it starts malfunctioning. Despite its unimpressive size, it is involved in most body functions, with thyroid receptors in most tissues throughout the body, affecting virtually every organ system, including the heart, nervous system, bones, digestion and metabolism.

The most common type of thyroid disorder is hypothyroidism (affecting about 2% of the adult population in the UK), which is diagnosed when your body struggles to produce sufficient amounts of thyroxine. The key symptoms are fatigue, weight gain, constipation, bloating, cold hands and feet, ‘brain fog’, dry skin, low mood, aches and pains throughout the body and more.

Research, as well as multiple clinical case studies, show that autoimmunity can be successfully addressed via diet and lifestyle changes, minimising the symptoms and restoring your energy and zest for life. 

You would typically be diagnosed through a blood test, showing elevated TSH and low levels of T4. It’s treated with levothyroxine, a T4 hormone replacement, administered orally, for life.

It’s important to note that according to NICE, a whopping 20% of adults have subclinical hypothyroidism, where your TSH is slightly raised, but T4 stays within the range. A subclinical underactive thyroid can still produce symptoms! 

Annoyingly, when you are taking levothyroxine your lab results can often be within the norm, however, your symptoms persist. The reason for that phenomenon is fairly simple - the root cause of the imbalance has not been addressed.

The key causes of underactive thyroid

Hashimoto’s Thyroiditis

It is estimated that approximately 90% of underactive thyroid cases are due to an autoimmune condition called Hashimoto’s Thyroiditis. Yes, you read that right. Nine in 10. What does that mean for you? It simply shifts the focus from your thyroid to your immune system. It’s your own overactive immune system attacking the thyroid tissue that has caused it to malfunction.

The good news is, research, as well as multiple clinical case studies, show that autoimmunity can be successfully addressed via diet and lifestyle changes, minimising the symptoms and restoring your energy and zest for life. 

How would you know that Hashimoto’s is the culprit? Super simple. A thyroid blood antibody test (TPO, Tg) will reveal what is happening behind the scenes. You can either ask your GP to organise the test for you, have it done through your nutritionist, or through a private lab.

Other factors

Sometimes hypothyroidism can be caused by other factors, hence why it is incredibly important to get tested and get to the bottom of the imbalance. These factors include iodine deficiency, certain medicines, thyroid inflammation, problems with the pituitary gland and others.

Close up of woman's neck

Eight tips to boost your thyroid function

Thankfully, there are things you can do to give your thyroid a little boost

1. Increase the nutritional value of food that you consume 

Rather than following yet another fad restrictive diet out there, focus on eating real, unprocessed food and a balanced, wholesome diet. Make sure half of your plate consists of colourful veggies, complimented by complex carbs, high-quality protein with healthy fats, fibre and plenty of antioxidants.

2. Eat more quality protein

Protein is crucial for your body to make thyroid hormones and balance blood sugar levels well. Make sure to consume at least 1g of protein per kg of body weight. What to eat? Organic beef, pork, poultry, game. Don’t forget to include some organ meats, like liver! Fish, eggs, organic dairy, quinoa, legumes, nuts.

3. Consume foods rich in Zinc, Selenium and Magnesium

The main T4 hormone, Thyroxine, is inactive. Our body needs to convert it to an active form T3. In order to do that, it needs zinc, selenium and magnesium! What to eat? Brazil nuts, kale, spinach, chard.

4. Consume foods rich in vitamins A and D

As we’ve learnt above, we have hormone receptors throughout the body! In order to activate them, we must consume sufficient amounts of vitamin A and spend time in the sun to boost those vitamin D levels! What to eat? Eggs, oily fish, liver.

5. Cook cruciferous veggies

Cruciferous vegetables contain goitrogens that can interfere with thyroid function and hormone conversion. Thankfully there’s a solution - heat deactivates goitrogens so make sure you steam or boil your cruciferous veggies before eating them!

6. Avoid iodine if Hashimoto’s is the cause

Excessive intake of iodine has been linked with Hashimoto’s development. If you have determined that that’s the cause of your hypothyroidism, avoid any added iodine in your diet and in a supplemental form. Avoid seaweed, iodised salt, shrimp, and limit your whitefish and tuna intake.

7. Work on your stress levels and sleep quality

Thyroid and adrenal health go hand in hand, with high levels of stress hormone cortisol affecting thyroid hormone production and conversion. Both psychological and physical stress can be detrimental to your thyroid health.

Make sure you find time for relaxation, practise self-care and find time for gentle exercise daily. Breathing exercises, meditation, yoga and reflection time are great examples 

8. Eliminate irritants

Yes, I am going to talk about gluten now as you might have guessed! If your symptoms persist or are getting worse it is recommended to try an elimination diet, which removes common irritants and allergens (like dairy and gluten) allowing your body and gut (where autoimmunity usually starts!) to heal.

This is usually carried out under a supervision of a nutrition specialist with the aim to possibly re-introduce some of the product groups after the healing phase and make sure your nutritional needs are met throughout the programme.

If you ever need more tailored advice on how to co-create a thyroid-friendly, healing meal plan, feel free to send me a message for a free 30-minute chat to discuss your needs.

Nutritionist Resource is not responsible for the articles published by members. The views expressed are those of the member who wrote the article.

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London SE13 & N20
Written by Aggie McCabe, Specialising in Underactive Thyroid & Female Hormonal Health
London SE13 & N20

Hi, I’m Aggie, great to see you here! If you are looking for an advice on how to make positive changes to how you feel every day, you are in the right place.I am a Registered Nutritional Therapist (DipNT, mBANT, CNHC) and a Wellness Coach and I help women like you, reclaim their energy and liv...

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Find a nutritionist dealing with Hypothyroidism (underactive thyroid)

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