Written by Claire Thomas, Eve Biology’s consultant nutritionist.
Eve Biology Summary
What should you eat for thyroid health?
There is no single proven thyroid diet. A balanced, varied diet with enough protein and appropriate sources of iodine, selenium, iron and other essential nutrients supports your nutritional needs, but does not replace thyroid testing or treatment. If your thyroid is underactive, focus on nutritional adequacy, bowel health and consistent medication timing. If it is overactive, getting enough energy, protein and supporting bone health may need extra attention. More is not always better: avoid high-dose iodine, kelp or “thyroid support” supplements without professional advice. If you take thyroid medicine, check food and supplement timing with your GP, pharmacist or healthcare provider.
Your energy has changed. Your concentration is not what it was. Your sleep, weight, digestion, mood or periods may feel different too. In midlife, it can be difficult to know whether these changes are linked to perimenopause, thyroid function or something else.
The thyroid is a small, butterfly-shaped gland at the front of the neck. It mainly produces thyroxine, known as T4, and a smaller amount of triiodothyronine, or T3. These hormones reach tissues throughout the body and help regulate how you use energy, generate heat and support your heart, brain, gut, muscles, bones and
reproductive system.
Food cannot diagnose or cure a thyroid condition. A varied, balanced diet can, however, provide the nutrients needed to make and use thyroid hormones and support your wider health alongside appropriate testing and medical treatment.
This guide explains the basics, the difference between an underactive and overactive thyroid, and practical nutritional steps.
How thyroid function is regulated
The pituitary gland in the brain makes thyroid-stimulating hormone (TSH). Think of TSH as a thermostat signal: when the body detects too little circulating thyroid hormone, TSH usually rises to ask the thyroid to produce more; when there is too much, TSH usually falls.
The thyroid releases mostly T4, which tissues then convert into the more active T3 hormone. Blood-test patterns must be interpreted alongside symptoms, medical history, medicines, pregnancy status and laboratory reference ranges. A single result is not a diagnosis.
Common blood-test patterns
| Pattern | TSH | Free T4 / free T3 | What it can suggest |
|---|---|---|---|
| Typical thyroid function | Within range | Within range | Results are within the laboratory reference range. |
| Primary hypothyroidism | High | Free T4 low | The thyroid may not be producing enough hormone. |
| Subclinical hypothyroidism | High | Free T4 within range | An early or mild pattern that may need repeat testing and clinical review. |
| Primary hyperthyroidism | Low | Free T4 and/or free T3 high | The thyroid may be producing too much hormone. |
| Subclinical hyperthyroidism | Low | Free T4 and free T3 within range | An early or mild pattern that may need repeat testing and clinical review. |
Why thyroid health matters in midlife
Perimenopause and thyroid conditions can share symptoms, including fatigue, sleep disruption, anxiety, low mood, changes in weight, palpitations, brain fog, altered bowel habits and changes to menstrual bleeding.
Menopause does not cause thyroid disease, and not every midlife symptom comes from the thyroid. Because the overlap is real, blood testing is useful when symptoms are new, persistent, worsening or difficult to explain.[1–4]
Autoimmune thyroid conditions are common in women. Hashimoto’s disease is a frequent cause of an underactive thyroid, while Graves’ disease is a common cause of an overactive thyroid. A family or personal history of autoimmune disease may be relevant when discussing symptoms with your GP.
Underactive and overactive thyroid: a quick comparison
| Comparison point | Hypothyroidism — underactive | Hyperthyroidism — overactive |
|---|---|---|
| What is happening? | The thyroid does not produce enough hormone, so many body processes slow down. | The thyroid produces too much hormone, so many body processes speed up. |
| Common causes | Hashimoto’s disease; previous thyroid surgery or radioiodine; some medicines; iodine imbalance; pituitary disease is less common. | Graves’ disease; thyroid nodules; thyroid inflammation; excess iodine or excess thyroid medicine. |
| Possible symptoms | Fatigue, feeling cold, constipation, dry skin, hair changes, low mood, slower thinking, muscle aches, heavier or irregular periods, and weight gain. | Heat intolerance, sweating, tremor, anxiety, palpitations, frequent bowel movements, muscle weakness, sleep disturbance, lighter or irregular periods, and unplanned weight loss. |
| Usual medical approach | Levothyroxine replaces the hormone the body is not making. Dosing and blood monitoring are individual. | Treatment may include antithyroid medicine, radioiodine or surgery, depending on the cause and clinical circumstances. |
| Nutrition focus | Adequate protein and micronutrients, regular meals, bowel support and a consistent routine around levothyroxine. | Enough energy and protein to reduce unintended weight and muscle loss, with attention to bone health. |
Nutrition and thyroid health: the foundations
There is no single proven thyroid diet. For most people, the same foundations support both underactive and overactive thyroid conditions. The emphasis changes according to symptoms, appetite, treatment, deficiencies and overall health.[10]
Claire’s nutritional foundations are:
- Eat regular, balanced meals that provide steady energy.
- Include a useful source of protein at each main meal.
- Choose a varied range of plant foods: vegetables, fruit, pulses, wholegrains, nuts and seeds.
- Include appropriate sources of iodine, selenium, iron, zinc and B vitamins, without assuming that more is better.
- Support muscle and bone health with enough protein, calcium, vitamin D and suitable resistance or weight-bearing activity.
- Use symptoms and test results to personalise your diet, avoiding unnecessary restriction.
- Take thyroid medicine consistently, checking timing or interactions with your prescriber or pharmacist.
How this connects to the Menopause Diet
These foundations also run through Eve Biology’s Menopause Diet.
Protein, fibre, varied plant foods and attention to muscle and bone health remain relevant whether you are navigating menopause, managing a thyroid condition or both.
The additional considerations are individual: your diagnosis, medication, symptoms and whether you have a nutrient deficiency. You can build on a familiar way of eating while making the adjustments relevant to you.
| Nutrient | Why it is relevant | Food-first sources |
|---|---|---|
| Protein and tyrosine | Tyrosine is an amino acid used to make thyroid hormone. Most people obtain enough by eating a varied diet with adequate protein. | Fish, eggs, poultry, meat, dairy foods, tofu, tempeh, beans, lentils, nuts and seeds. |
| Iodine | Iodine is built into T4 and T3. Both deficiency and excess can disrupt thyroid function, so high-dose or concentrated sources are not a shortcut.[5,7] | Milk and dairy foods, eggs and seafood. Some plant drinks are fortified; check the label. Seaweed content is highly variable. |
| Iron | Iron supports thyroid-peroxidase activity and oxygen transport. Low iron may contribute to fatigue, but supplements should be based on clinical need.[13] | Red meat, poultry, shellfish, beans, lentils, tofu, seeds and fortified cereals. Add vitamin C to plant sources to improve absorption. |
| Selenium | Selenium-containing enzymes help convert T4 to T3 and protect cells from oxidative damage. Soil content varies, and excessive supplemental intake can be harmful.[6] | Fish, shellfish, eggs, meat, poultry, dairy foods, grains, nuts and seeds. Brazil-nut content is especially variable. |
| Zinc | Zinc is involved in thyroid-hormone metabolism, immune function and tissue repair. | Meat, shellfish, dairy foods, eggs, beans, lentils, nuts, seeds and wholegrains. |
| B vitamins | B vitamins support energy metabolism, blood-cell production and the nervous system. Vitamin B12 is especially relevant when pernicious anaemia or other autoimmune disease is present.[14] | Meat, fish, eggs, dairy foods, legumes, leafy greens, wholegrains and fortified foods. Reliable B12-fortified foods or supplements are needed on a vegan diet. |
| Calcium and vitamin D | These are central to bone health. They deserve particular attention when an overactive thyroid has been prolonged or after menopause.[3,11] | Calcium: dairy foods, calcium-set tofu, fortified plant drinks, tinned fish with edible bones and some greens. Vitamin D: sunlight, oily fish, egg yolk and fortified foods. |
| Glutathione and antioxidant defence | The body makes glutathione from amino acids. A varied, plant-rich diet supports antioxidant systems, but individual foods do not detox or repair the thyroid. | Protein foods plus vegetables and fruit, including brassicas, onions, garlic, peppers, citrus fruit and berries. |
| Magnesium | Magnesium supports muscle, nerve, bone and energy metabolism. It is important for general health but is not a thyroid treatment. | Nuts, seeds, beans, lentils, wholegrains, leafy greens and cocoa. |
A food-first note
Iodine, selenium and iron are essential, but excessive intakes can be harmful. More is not automatically better, particularly with an autoimmune thyroid condition.
If you are concerned about a deficiency, ask for an appropriate assessment rather than building a high-dose supplement stack.
Thyroid UK: Why vitamins and minerals deserve attention
Vitamins and minerals are involved in thyroid hormone production and metabolism, as well as the health of your muscles, bones, blood and nervous system.
That makes nutritional adequacy an important part of looking after yourself. Thyroid UK also highlights the importance of vitamins and minerals in its discussion of Dr Ridha Arem’s The Thyroid Solution. Dr. Arem is also the author of over 40 peer reviewed articles in the fields of thyroid disease, endocrinology, and metabolism.
The practical question is whether your meals are providing enough of the nutrients you need. This can be particularly relevant if you regularly miss meals, eat a restricted range of foods or exclude food groups without replacing the nutrients they provide.
Some deficiencies can also contribute to symptoms such as fatigue, alongside a thyroid condition. Identifying and addressing a deficiency is different from taking extra nutrients when you already have enough.
Putting the nutritional foundations into an everyday meal
Getting enough protein, vitamins and minerals matters. Busy days can make that harder to put into practice. Eve Biology’s Rebalancing Shake can help you to meet your everyday nutritional needs.
| Nutrient | Per serving | % NRV* |
|---|---|---|
| Selenium | 19.5 µg | 36% |
| Iodine | 58.5 µg | 39% |
| Zinc | 5.9 mg | 59% |
| Iron | 11.1 mg | 79% |
| Vitamin B12 | 1.0 µg | 41% |
| Vitamin D | 1.8 µg | 35% |
| Calcium | 246.3 mg | 31% |
| Magnesium | 116.5 mg | 31% |
*NRV = Nutrient Reference Value.
Used in place of a meal, it offers a convenient way to include protein, fibre and a range of micronutrients when time is short.
If you have a thyroid condition or take thyroid medication, speak to your doctor or pharmacist before using Eve. Each serving contains 165mg of KSM-66 ashwagandha. Share the full ingredient and nutritional information so they can advise on suitability and timing.
That reflects the approach running through our Menopause Diet: adequate protein, fibre and a varied nutrient intake, alongside movement and meals you enjoy.
Foods women often worry about
Do I need to avoid soy?
Soy isoflavones can affect thyroid-related enzymes in laboratory studies, but human evidence does not show a meaningful effect on thyroid hormones when iodine intake is adequate.[8]
Most people do not need to avoid ordinary portions of soy for this reason.
Medication timing is a separate consideration: soy can reduce levothyroxine absorption when taken too close to the dose. Follow your medicine instructions and ask your pharmacist about an appropriate interval. Cooking or fermenting soy does not remove the need to consider timing.
What about broccoli, cabbage and kale?
Raw brassicas contain compounds that can affect iodine use in experimental settings. Normal food portions have not been shown to cause thyroid disease in people with adequate iodine intake.[4,10,15]
Broccoli, cabbage, kale and cauliflower are nutritious foods and usually do not need to be restricted. Cooking reduces the activity of some of these compounds.
Should I stop eating gluten?
A gluten-free diet is required for diagnosed coeliac disease. It is not a routine treatment for Hashimoto’s disease or other thyroid conditions.[10]
Do not remove gluten solely because you have a thyroid condition. If coeliac disease is suspected, speak to your GP and continue eating gluten until testing is complete, unless advised otherwise.
Do I need to avoid dairy?
Dairy foods can provide iodine, protein and calcium. They do not need to be removed for thyroid health unless there is an allergy, intolerance or another clinical reason.
If you avoid dairy, choose alternatives fortified with calcium, vitamin D and ideally iodine.
Calcium-rich foods may need to be separated from levothyroxine according to your medicine instructions.
Can seaweed, kelp or sea moss help?
Iodine content can be very high and unpredictable. Excess iodine can worsen both underactive and overactive thyroid problems in susceptible people.[5,7]
Avoid using concentrated seaweed products as a “thyroid booster”. Discuss iodine supplements with a qualified healthcare professional.
What should I know about coffee and caffeine?
Caffeine may worsen palpitations, tremor, anxiety or sleep problems.
Coffee can also interfere with levothyroxine absorption when taken too soon after the dose.
Adjust caffeine to your symptoms and follow the timing instructions for your medicine.
Does sugar affect thyroid health?
Sugar does not feed thyroid disease.
A diet dominated by highly processed foods can make it harder to meet nutrient and fibre needs. Focus on the overall pattern: regular meals, minimally processed foods most of the time, and flexibility rather than perfection.
How the nutrition emphasis may differ
If your thyroid is underactive
- Regular meals can help when appetite, energy or concentration are low.
- Include fibre and fluids to support constipation, increasing fibre gradually if needed.
- Correct confirmed iron, B12, folate or vitamin D deficiency with professional guidance.
- Avoid severe calorie restriction, which can worsen fatigue and make nutritional adequacy harder.
- Keep levothyroxine timing consistent, especially around coffee, calcium, iron and high-fibre supplements.
- Do not add high-dose iodine or selenium without a clear reason and professional advice.
If your thyroid is overactive
- Energy and protein needs may rise when metabolism is accelerated; aim to prevent unintended weight and muscle loss.
- Use smaller, more frequent meals if appetite or digestive symptoms make eating difficult.
- Give extra attention to calcium, vitamin D and protein, alongside suitable activity, to support bones and muscle.
- Reduce caffeine if it aggravates palpitations, tremor, anxiety or sleep problems.
- Seek medical support for ongoing weight loss, diarrhoea, marked weakness, palpitations or difficulty eating enough.
- Avoid iodine or seaweed supplements unless your specialist has specifically recommended them.
How thyroid changes can affect the whole body
Thyroid hormones reach tissues throughout the body, so symptoms can appear in more than one system at the same time.
Gut
An underactive thyroid can slow bowel movement and contribute to constipation. An overactive thyroid can speed it up and contribute to frequent stools or diarrhoea.
Useful support: regular meals, enough fluid and fibre adjusted to symptoms. Include varied plant foods where tolerated. Persistent bowel changes need assessment.
Liver and metabolism
The liver helps convert, transport and clear thyroid hormones. Thyroid conditions can also affect cholesterol, blood glucose and liver-enzyme results.
Useful support: a balanced eating pattern, adequate protein and fibre, limited alcohol and medical follow-up of abnormal blood results.
Nervous system and mind
Low thyroid hormone may be associated with slower thinking, low mood and fatigue. Excess hormone may be associated with anxiety, tremor, irritability and insomnia.
Useful support: regular meals, adequate protein and micronutrients, caffeine intake suited to your symptoms, sleep support and treatment of the thyroid condition.
Stress response
Stress can intensify symptoms and make self-care harder, but “adrenal fatigue” is not a recognised medical diagnosis.[9]
Useful support: a regular eating and sleeping rhythm, rest, appropriate movement and professional support for persistent anxiety, low mood or exhaustion.
Reproductive health and menopause
Both thyroid imbalance and perimenopause can affect periods, temperature regulation, mood, sleep and fertility.
Oral oestrogen can alter thyroid-hormone binding and may change levothyroxine requirements.[12]
Useful support: review persistent or changing symptoms with your GP. If you take levothyroxine and start or stop oral hormone therapy, ask whether follow-up thyroid testing is needed.
Muscle and bone
Both underactive and overactive thyroid conditions can affect muscle strength. Prolonged overactive thyroid function can accelerate bone loss.[3,11]
Useful support: adequate protein, calcium and vitamin D, plus suitable resistance and weight-bearing activity.
Heart and circulation
An underactive thyroid may raise cholesterol. An overactive thyroid may cause a fast or irregular heartbeat and increase cardiovascular risk.[1–3,11]
Useful support: medical treatment is central. Support it with a heart-healthy eating pattern, movement suited to your health and symptoms, and less caffeine if it triggers palpitations.
Thyroid medicine and supplements
Keep treatment consistent
Take thyroid medicine exactly as prescribed.
Food, coffee, calcium, iron, antacids, fibre supplements and some other medicines can alter levothyroxine absorption. Use the same routine each day and follow the timing instructions supplied with your medicine.
If the routine is difficult, ask your pharmacist or prescriber for help rather than changing or stopping the dose yourself.
Some supplements can also interfere with blood tests. Tell the person arranging your thyroid tests what you take, including any biotin-containing hair, skin or nail supplements.
Check supplements with your GP, pharmacist or suitably qualified nutrition professional, especially if you take thyroid medicine, are pregnant or breastfeeding, have kidney or liver disease, or are under specialist care.
Persistent or worsening symptoms deserve medical review, even when you are already working on your diet.
Making nutrition work for you
The nutritional foundations are practical: eat enough, include protein regularly, choose a varied range of foods and give vitamins and minerals the attention they deserve.
Your symptoms, treatment and any confirmed deficiencies help determine where to focus. For some women, that means improving meal consistency. For others, it means replacing nutrients lost through unnecessary restriction or getting help with a specific deficiency.
Much of this is the same foundation we return to throughout Eve’s guidance on menopause and healthy ageing: food and movement that support your health and the life you want to lead.
Thyroid health and nutrition: common questions
Can thyroid symptoms be mistaken for menopause?
Thyroid conditions and perimenopause can share symptoms, including fatigue, changes in weight, disrupted sleep, anxiety and changes to periods. Symptoms alone cannot reliably distinguish them. Discuss new, persistent or worsening symptoms with your GP, who can assess whether thyroid testing is appropriate.
Is there a special diet for an underactive thyroid?
There is no single proven diet for an underactive thyroid. Focus on balanced meals, adequate protein, varied plant foods and appropriate sources of essential nutrients. Diet supports your nutritional needs but does not replace prescribed levothyroxine. If you take it, follow your medication instructions about food, drinks and supplements.
Can I use Eve Biology’s Rebalancing Shake if I have a thyroid condition?
Check with your doctor or pharmacist before using Eve if you have a thyroid condition or take thyroid medication. Each serving contains 165 mg of KSM-66® ashwagandha, alongside added vitamins and minerals. Share the full ingredient list and nutritional information so they can advise on suitability and medication timing. Eve is a meal replacement shake, not a treatment for thyroid disease.
References
- NICE. Thyroid disease: assessment and management, NG145.
- NHS. Underactive thyroid.
- NHS. Overactive thyroid.
- Larsen D, Singh S, Brito M. Thyroid, diet, and alternative approaches. Journal of Clinical Endocrinology & Metabolism. 2022;107(11):2973–2981.
- NIH Office of Dietary Supplements. Iodine: fact sheet for health professionals.
- NIH Office of Dietary Supplements. Selenium: fact sheet for health professionals.
- British Dietetic Association. Iodine.
- Otun J, et al. Systematic review and meta-analysis on the effect of soy on thyroid function. Scientific Reports. 2019;9:3964.
- Endocrine Society. Adrenal fatigue.
- British Thyroid Foundation. Diets and supplements for thyroid disorders.
- NHS. Overactive thyroid: complications.
- Arafah BM. Increased need for thyroxine in women with hypothyroidism during estrogen therapy. New England Journal of Medicine. 2001;344:1743–1749.
- Luo J, et al. Iron deficiency, a risk factor of thyroid disorders in reproductive-age and pregnant women: a systematic review and meta-analysis. Frontiers in Endocrinology. 2021;12:629831.
- Benites-Zapata VA, et al. Vitamin B12 levels in thyroid disorders: a systematic review and meta-analysis. Frontiers in Endocrinology. 2023;14:1070592.
- Felker P, Bunch R, Leung AM. Concentrations of thiocyanate and goitrin in human plasma, precursor concentrations in brassica vegetables, and associated potential risk for hypothyroidism. Nutrition Reviews. 2016;74(4):248–258..