Underactive Thyroid

Underactive Thyroid

Thyroid hormones regulate the body's metabolism, so an under-active thyroid gland (hypothyroidism) has far-reaching physical effects, even if the under-secretion of thyroid hormones is so minor that it is undetectable in blood tests. More severe thyroid dysfunction can result in severe and even life-threatening health problems.


  • The symptoms of thyroid under-activity reflect the associated under-production of the hormones thyroxine (also known as T4) and tri-iodothyronine (T3). They may include:
  • Fatigue and weakness
  • Depression
  • Memory problems, poor concentration, impaired cognition
  • Weight gain (or trouble losing weight)
  • Loss of appetite, sluggish digestion, Constipation
  • Periods may be heavy and/or irregular
  • Slow heart rate
  • Susceptibility to recurrent infections, especially respiratory infections
  • Muscle cramps, headaches
  • Poor tolerance of cold temperatures
  • Dry scaly skin, brittle nails and hair, hair loss
  • Persistent hoarseness
  • Sweating may be reduced or excessive
  • Joints may be swollen and painful
  • Goitre (enlarged thyroid), swollen face and/or drooping, swollen eyes sometimes occur


  • One of the most common causes of hypothyroidism is Hashimoto's disease, an auto-immune disease in which the immune system attacks the thyroid gland, inhibiting its function, reducing its secretion of hormones, and destroying thyroid tissue
  • Other factors that can inhibit thyroid function include:
  • Iodine deficiency (once considered rare in Australia and New Zealand, but increasingly recognised as a major nutritional issue) may play a significant contribution in thyroid underactivity because iodine is required for thyroid hormone production. Other nutritional deficiencies may also be involved, including zinc, selenium, copper, and vitamins A, C, and E
  • Poor diet (e.g. excessive consumption of saturated fats)
  • Food allergy and/or intolerance
  • Stress
  • Sedentary lifestyle
  • Exposure to radiation from x-rays, especially around the throat area
  • Exposure to toxins (e.g. alcohol, pesticides)
  • Treatment for over-activity of the thyroid gland (hyperthyroidism) and thyroid cancer
  • Some prescribed medicines (e.g. lithium)
  • Pituitary gland or hypothalamus dysfunction, which can interfere with the signals that tell the thyroid to produce T3 and T4

Nutritional & Herbal Support

  • Iodine is the key nutrient for thyroid function, and is involved in the manufacture of T3 and T4. Kelp is a natural source of iodine
  • To safeguard against nutritional deficiency, take a high potency multivitamin that provides a broad spectrum of nutrients. A formula that also includes Korean ginseng may be particularly beneficial for men, because this herb has traditionally been used to raise energy levels and improve the ability to withstand Stress. Siberian ginseng has similar properties, and is an ideal inclusion in a multivitamin supplement for women
  • Other important ingredients to look for you in your multivitamin supplement include vitamins A and E, and the minerals selenium, copper and zinc, which are involved in the production and utilisation of thyroid hormones
  • Omega-3 fatty acids from fish oil, salmon oil or flax seed oil help to maintain the integrity and fluidity of cell membranes, including those in the thyroid gland

Diet & Lifestyle advice

  • Underactivity of the thyroid is a complex condition, but often responds well to natural therapies. Consult your healthcare professional, who can develop an appropriate treatment plan for your individual circumstances
  • In many cases they will recommend you stick to a low glycaemic index (GI) diet that includes slow-burning carbohydrates (such as oats and legumes) to help you manage your weight, energy and blood sugar levels. At the same time, you will be advised to avoid high GI carbohydrates such as sugars, wheat products (e.g. bread), and potatoes, which are metabolised quickly, leading to energy slumps and blood sugar fluctuations
  • Include plenty of fresh fruit and vegetables in your diet. Choose organic where possible to avoid exposure to pesticides and other toxins, which may be implicated in thyroid problems by interfering with the body's detoxification mechanisms and/or triggering auto-immune problems
  • Eating seafood, seaweed and small quantities of iodised salt will help to ensure you obtain iodine in your diet. Other important foods to include in your diet include Brazil nuts (an excellent source of selenium), sesame seeds and tahini (which provide zinc, copper, tyrosine and vitamin E) and other nuts and seeds, including pumpkin seeds and cashews
  • Some foods contain compounds called goitrogens, which bind to iodine and interfere with the production of thyroid hormones. These foods include broccoli, cauliflower, turnips, cabbage, mustard greens, spinach, radish, Brussels sprouts, kohlrabi, and horseradish. It is advisable to avoid eating these foods raw, however small quantities of cooked goitrogen-containing foods should not pose a significant problem, as the goitrogens are inactivated by heat
  • Limit your consumption of apples, walnuts and almonds too, as these contain thiocyanates, which impair iodine concentration
  • Regular exercise and activity are important for energy levels, and can also help to improve Stress levels, low moods, Depression, and weight problems. Exercise stimulates thyroid hormone secretion, increases tissue sensitivity to thyroid hormone, and prevents decline in metabolic rate in response to weight loss diets. Even a brisk 30-minute walk has health benefits, but other options include swimming and going to the gym. Yoga may have particularly beneficial effects via increased circulation and stimulation of the thyroid gland, and due to its Stress-reducing actions
  • Many natural therapists encourage those who suffer from thyroid underactivity to avoid fluoride, believing that it may inhibit the release of thyroid hormones. Although controversial, this is worth trying. Key sources of fluoride to avoid include tap water and fluoridated toothpaste
  • Stress may contribute to suboptimal thyroid function. Learn and practice meditation or relaxation techniques in order to improve your ability to cope with Stress
  • Don't smoke - it decreases the secretion of thyroid hormones as well as their actions in the body. Alcohol and recreational drugs should also be avoided

If symptoms persist consult your healthcare professional. Information provided is of a general nature and should not replace that of your healthcare professional.

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