What to eat and what to avoid when you have an underactive thyroid or Hashimoto’s Thyroiditis.

Our thyroid hormones regulate metabolism, growth and development, affecting almost every cell in the body.
They control energy production, temperature, heart rate and brain function, playing a vital role in overall health and well-being. This means that symptoms of an underactive thyroid are widespread and can be seen in any organ of the body.

What’s the difference between Hypothyroid (under active thyroid) and Hashimoto’s Thyroiditis?

Hypothyroidism is a condition where the thyroid gland does not produce enough thyroid hormone to meet the body’s needs. Hashimoto’s Thyroiditis (Hashimoto’s) is the most common cause of hypothyroidism and is an autoimmune disease where the body’s immune system mistakenly attacks the thyroid gland, leading to inflammation and ultimately the destruction of the gland itself.

Some common symptoms:

  • Fatigue
  • Depression
  • Weight gain and/or difficulty losing weight
  • Cold hands and feet
  • Constipation
  • High cholesterol
  • Insulin resistance
  • Heavy menstrual periods
  • Muscle and joint pain
  • Dry skin
  • Brain fog, poor concentration, and memory
  • Hair loss
  • Food sensitivities and increased allergies
  • Heart palpitations

Common risk factors

As Hashimoto’s is an autoimmune condition, it develops from a dysfunctional immune system, not a dysfunctional thyroid gland.
The gradual increase of stress and inflammation on the body eventually leads to immune dysregulation and the onset of Hashimoto’s.

The major risk factors are:
  • Under or overconsumption of iodine
  • Overconsumption of raw goitrogenic foods such as broccoli, cabbage, and kale
  • Overconsumption of soy products
  • Hormonal imbalances
  • Chronic stress
  • Chronic inflammation
  • Gluten intolerance
  • Coeliac disease
  • Autoimmune disease
  • Insulin resistance
  • Chronic blood sugar dysregulation
  • Nutrient deficiencies
  • Low vitamin D
  • Low Iron and/or Vitamin B12
  • Leaky gut and gut dysbiosis
  • Exposure to environmental toxins
  • Impaired detoxification

Getting a Diagnosis

Getting a diagnosis can be difficult because the most common test undertaken is Thyroid Stimulating Hormone (TSH). While this test can give some insights, it is a very small piece of a much larger puzzle and further testing is necessary to obtain the full picture.

Further testing must include:
  • Free T4 (the inactive form of thyroid hormone)
  • Free T3 (the active form of thyroid hormone)
  • RT3 (Reverse T3)
  • Thyroid Antibodies (anti-thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb)
  • Iodine

It’s also worth assessing other autoimmune condition markers and food allergies.

The role of nutrition in thyroid conditions

Nutrition plays a vital role in supporting thyroid health, managing symptoms of hypothyroidism and Hashimoto’s, and reducing the damage done to the gland itself if antibodies are present.

Some key nutrient considerations are:

Essential for the production of thyroid hormone and often deficient in the diet. Because both deficiency and excess can lead to thyroid dysfunction testing is recommended before supplementation. Food sources include seafood, and sea vegetables such as nori, kelp, and dulce.


A potent antioxidant providing essential protection against damage to the thyroid gland and assisting to reduce inflammation. It is also crucial to the conversion of T4 to T3. Food sources include Brazil nuts, seafood, and eggs.


A mineral that is involved in various processes within the body, including thyroid hormone production, immune modulation, and gut health. Foods sources include lean meats, shellfish, legumes, nuts, and seeds.

Vitamin D

A key modulator of the immune system. Food sources include salmon, cod liver oil, and a smaller amount in shiitake mushrooms.

Omega 3 Fatty Acids

These help to reduce inflammation associated with autoimmune conditions. Food sources include fatty fish (salmon, mackerel, and sardines), flaxseeds, chia seeds, and walnuts.

Antioxidant-rich foods

These help to protect the thyroid gland from damage caused by oxidative stress and inflammation. Food sources include a variety of brightly coloured fruits and vegetables such as berries, leafy greens, bell peppers, and citrus fruits.

Reduce goitrogen intake

Goitrogens are compounds that interfere with thyroid function and are found in foods such as cruciferous vegetables (broccoli, cabbage, cauliflower, kale). These are still an important part of a balanced diet however and provide much needed fibre to help reduce the common symptom of constipation in an underactive thyroid.
As such, consuming them in moderation and in a cooked state is best.


Triggers an inflammatory response and exacerbate an autoimmune condition.
Gluten-free alternatives such as brown rice, quinoa, and buckwheat provide high nutritional value and can help to reduce gluten associated inflammatory conditions.

Where to from here?

While hypothyroidism and Hashimoto’s Thyroiditis present many challenges, obtaining as much information as possible through testing and having the results reviewed thoroughly, ensures all the pieces of the puzzle are identified.
From here, we can formulate an appropriate and personalised treatment plan. Adopting a thyroid-friendly, nutrient dense diet can help to support thyroid function, reduce inflammation, and potentially prevent further progression of thyroid disease.

If you need more support with Thyroid conditions such as Hypothyroidism or Hashimoto’s Thyroiditis or are wanting to get further testing done to discover if a thyroid condition is causing your symptoms, book an appointment with our clinical nutritionist Kylie.

Kylie is an Adelaide based, degree qualified Clinical Nutritionist who is passionate about ensuring your treatment is based on an individualised and holistic approach. Meaning she empowers clients to be in control of their own wellbeing and looks for the root cause of any health concerns, believing this will help achieve and maintain results over the long term.
All treatment plans have a focus on food as medicine and are formulated with you in mind, with changes you are prepared to make. This may include functional testing, supplementation if necessary, dietary advice and health and wellbeing advice.

Kylie is passionate about thyroid function and correct testing to ensure an accurate treatment plan. If you suspect your thyroid is causing you to gain weight, feel exhausted and lose your hair, Kylie is the practitioner for you – even if you’ve been told previously that your thyroid is ‘fine’.

Body Institute Google Reviews

We pride ourselves on delivering a top notch service at Body Institute.
Below are few of our realtime reviews direct from Google.

A lovely tranquil and caring environment with highly knowledgeable naturopaths and health care providers. Their treatments really work, and I am especially impressed with the meal plan Georgia set out for me. Couldn't reccomend them highly enough !

Sarah Dallwitz Avatar Sarah Dallwitz
December 14, 2021

Karina has been wonderful helping me work through my digestion and skin concerns over the past few moths. She is a warm, kind and gentle soul who instantly make you feel at ease. There is no judgement or disapproval in discussions with her and I always leave feeling relaxed, revived and inspired to make positive changes. The rooms are beautiful, clean and relaxing. I would highly recommend seeing Karina as a naturopath or for amazing facial treatments!

Leah Nolan Avatar Leah Nolan
December 21, 2022

I have been seeing Emily at Body Institute after being diagnosed with type two diabetes right before Christmas. I have never seen a naturopath before so I didn't know what to expect but I have been blown away. Emily is outstanding! She is professional, kind, hard working, makes health terms easy to understand and her willingness to work with the other health professionals in my life has been truly amazing. I can't wait to see what we achieve on this health journey together ✨️

Chelsea McCarthy Avatar Chelsea McCarthy
January 28, 2023
Ready to Book or Shop Online?

Our Online Booking is the quickest most convenient way to secure the time you want. Plus our Online Shop is full of high quality, responsibly sourced products you will love!