Your thyroid is responsible for regulating the metabolism of every single cell in your body. It influences how efficiently you burn fuel, how regularly your bowels move, and how much get-up-and-go you have, just to name a few!
This clever little gland is influenced by thyroid stimulating hormone (TSH), and in turn produces the thyroid hormones thyroxine (T4) and triiodothyronine (T3).
An underactive thyroid, known as hypothyroidism, is the most common pathological hormone deficiency — far more common than an overactive thyroid (hyperthyroidism).
Because your endocrine system works in a delicate balance, a problem in one area can ripple out and affect others. That’s why low thyroid function can impact reproductive health, with symptoms such as low libido, infertility, menstrual irregularities, and heavy bleeding.
Other common signs and symptoms of hypothyroidism include:
Fatigue, lethargy, brain fog
Feeling unusually cold
Unexplained weight gain
Constipation, bloating, wind
Frequent infections or poor immunity
Dry skin and dry mucous membranes
Hair loss, thin or brittle nails
Around 90% of hypothyroid cases are autoimmune in origin – known as Hashimoto’s disease – where the immune system mistakenly attacks the thyroid gland, producing thyroid antibodies and disrupting normal function.
It’s worth noting that thyroid hormone levels can fluctuate, so blood tests don’t always give the full picture and should be monitored over time if problems persist.
The best way to keep your thyroid functioning well is to supply it with the key nutrients it needs, including:
Selenium
Selenium is vital for the enzymes that convert T4 to the active hormone T3. It also acts as a powerful antioxidant, reducing free radical damage and supporting healthy immune function.
Vitamin D
Low vitamin D is linked with thyroid antibodies and poor thyroid function. Vitamin D supports a balanced immune system. Aim for safe sun exposure (about 10–15 minutes daily) or supplement if your levels are low.
Iodine
Iodine is essential for thyroid hormone production, but must be used cautiously if an autoimmune thyroid condition is present, as too much iodine can worsen the problem. Beyond the thyroid, iodine also plays a role in immune cell function and supports breast tissue health, protecting against oestrogen-dominant cancers.
Tyrosine
This amino acid is a building block for thyroid hormones. A wholefood diet rich in green leafy vegetables, whole grains, lean meats (chicken, salmon) and eggs will help supply enough tyrosine.
Iron
Iron is needed to convert the amino acid phenylalanine to tyrosine, making it crucial for healthy thyroid hormone production. Iron supplements should be guided by blood tests, as absorption can vary, and gut health may influence iron levels. Combining iron-rich foods with vitamin C-rich foods (citrus fruits, broccoli) will help improve absorption.
Some dietary and lifestyle factors can make thyroid conditions worse:
Brassica vegetables – broccoli, kale, cabbage, Brussels sprouts, cauliflower – contain goitrogens that can reduce iodine uptake if eaten raw in very large amounts. However, cooking these vegetables breaks down most goitrogens, so they’re fine to enjoy cooked.
Gluten – people with autoimmune thyroid conditions (positive thyroid antibodies) may benefit from avoiding gluten, as it can trigger the immune system.
Stress – chronic stress raises cortisol, which can disrupt thyroid balance. Identifying and reducing stress is vital for thyroid health. Try to carve out time for enjoyable activities, reduce caffeine, and practise calming breathing techniques, like taking ten slow belly breaths when stress hits.
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