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The thyroid gland — a small butterfly-shaped gland in the front of your neck — produces hormones that regulate the speed of virtually every cell in your body. Thyroid hormones (T3 and T4) control your metabolic rate, heart rate, body temperature, energy production, cholesterol levels, menstrual cycle, brain function, and mood. When the thyroid underperforms (hypothyroidism), the effects are pervasive and often mistaken for other conditions.
Key Signs and Symptoms
- Persistent fatigue despite adequate sleep
- Unexplained weight gain or difficulty losing weight despite diet and exercise
- Feeling cold all the time (low body temperature)
- Constipation and slow digestion
- Hair loss or thinning (including the outer third of eyebrows — a classic sign)
- Dry skin and brittle nails
- Brain fog, slow thinking, memory problems
- Depression or low mood
- Slow heart rate
- Swelling in the neck (goitre) — in some cases
- High cholesterol not responding to diet
- Muscle weakness and joint pain
- Heavy or irregular periods (in women)
Evidence-Based Strategies
- Get the right tests: standard TSH testing often misses subclinical hypothyroidism; request: TSH + free T3 + free T4 + anti-TPO antibodies (for Hashimoto's) + reverse T3
- Selenium: selenium is essential for converting T4 to active T3; Brazil nuts (2 per day = full daily requirement), or supplement 200mcg selenomethionine
- Zinc: zinc supports thyroid hormone production; pumpkin seeds, oysters, beef, legumes; supplement 15-30mg if dietary intake is low
- Iodine (with caution): iodine is required for thyroid hormone synthesis; most people get adequate iodine from iodised salt and dairy; excess supplementation can worsen Hashimoto's
- Ashwagandha: KSM-66 ashwagandha has shown evidence for increasing T3 and T4 in subclinical hypothyroidism — see our ashwagandha benefits guide
- Avoid goitrogens in raw form: cruciferous vegetables (broccoli, cauliflower, kale, cabbage) contain goitrogens that can inhibit thyroid function when eaten raw in large quantities; cooking deactivates most goitrogenic compounds
- Address Hashimoto's with anti-inflammatory diet: Hashimoto's thyroiditis is the most common cause of hypothyroidism and is an autoimmune condition; the seed cycling approach reduces the autoimmune inflammatory burden
- Work with a doctor: thyroid hormone replacement (levothyroxine) is necessary for significant hypothyroidism; natural support is complementary, not a replacement for appropriate medical treatment
The Bottom Line
Understanding and addressing thyroid health requires a comprehensive, evidence-based approach that combines dietary optimisation, targeted supplementation, lifestyle changes, and appropriate medical care. The strategies outlined here represent the current best evidence — always individualise your approach and work with healthcare professionals for personalised guidance.
