Causes of an underactive thyroid

* Iodine deficiency. This was the most common cause of hypothyroidism in the past, as the thyroid gland adds iodine to the amino acid tyrosine to create thyroid hormones. This has become rare nowadays due to iodised table salt. Yet, it can still be caused by an excessive consumption of foods that block iodine utilisation such as turnips, cabbage, mustard, cassava root, soybean, peanuts, pinenuts and millet. However, cooking usually inactivates this blocking mechanism.

* Drugs, including lithium, dopamine, steroids, some cough mixtures, sulphonamide and even radiographic contrast agents can adversely affect the function of the thyroid.

* Mega-doses of vitamin C or of glutathione can alter thyroid function.

* Prolonged use of medicinal herbs such as bladder kelp (Nereocystis luetkeana), bladderwrack (Fucus vesiculosus), bugleweed (Lycopus virginicus), dulse (Rhodymenia palmetto) and sea tangle (Laminaria digitata) may bring about iodine-induced thyroid deficiency.

* Multivitamin preparations containing more than 100 mg (0.1 g) of iodine per capsule/tablet will eventually do the same thing (Nutr Health Rev, 1996, 75: 4).

* Iron supplements can bring on symptoms of hypothyroidism because iron binds to thyroxine, making it insoluble (Ann Intern Med, 1992; 117: 1010-3). And if you think taking iron will give you more energy (which you lack in hypothyroidism), you’re wrong.

* The medicinal herb ma huang (Ephedra sinica) is contraindicated in hyperthyroidism, also known as ‘thyrotoxicosis’.

Tests that work
Perhaps the best test to discover if you have an underfunctioning thyroid is the naturopathic basal body temperature (BBT) test. As soon as you wake up, place a thermometer under your armpit for 10 minutes. Supposedly normal readings are 36.6-36.8°C (97.8-98.2°F). Anything lower could be an underactive thyroid and anything higher, an overactive one. If you’re a premenopausal woman, the most accurate measurement is on the second or third day of your menstrual cycle. Remember, the BBT will slightly rise and fall just before and after ovulation.

One of the best diagnostic tools is infrared thermography - which measures temperature as infrared radiation - both for early diagnosis and control during treatment. As the thyroids lie just below the skin (on each side of the throat), they are readily visualised by thermography.

Nutritional medicine

* Supplement with zinc, and vitamins A and E, which work together to make the thyroid hormones. A deficiency in any one of these nutrients will reduce the amount of active hormones produced. Low zinc is common in the elderly, as is hypothyroidism. Supplementing with zinc reestablishes normal thyroid function in zinc-deficient hypothyroid patients (Alt Ther Health Med, 1997; 3: 78-81). Riboflavin, niacin and pyridoxine (vitamins B2, B3 and B6, respectively), and vitamin C are also necessary for hormone synthesis, and copper, selenium and zinc are necessary for enzyme conversion of T4 to T3 (Clin Sci, 1995; 89: 637-42; Bio Trace Elem Res, 1992; 33: 155-6).

* Avoid eating too much bran or bioflavonoids, both of which lower levels of circulating thyroid hormones (J Clin Endocr Metab, 1996; 80: 857-9).

* Essential fatty acids are needed for the smooth functioning of thyroid cells, and the amino-acid tyrosine (200 mg/day) is also vital for the formation of thyroid hormones, and has been used successfully to treat some cases of hypothyroidism (Alt Ther Health Med, 1997; 3: 78-81).

Alternative medicine

* The homoeopathic remedy Iodum (low potency) taken twice daily, has shown success. In one study, circulating T3 and T4 hormone levels were increased by 20 per cent and 5 per cent, respectively, in those given the remedy (Br Hom J, 1988; 77: 152-60).

* Traditional Chinese medicinal herbs have also proven effective. In one study, 32 hypothyroid patients were treated for a year with the Chinese herbal preparation Shen Lu, and compared with 34 healthy controls. Following the herbal treatment, the patients’ symptoms markedly improved, with levels of T3 and T4 nearly doubled (Chung Kuo Chung His I Chieh Ho Tsa Chih, 1993; 13: 202-4).

* Try Thyrejuv, a combination remedy of nettles, Damiana, Siberian ginseng, parsley, Irish moss, mistletoe and kelp, produced and marketed by Nutriscene UK Ltd. Although there have been no controlled clinical trials of this medication, I have found it to be effective for T3 deficiencies.

Harald Gaier

Harald Gaier is a registered naturopath, osteopath, homoeopath and herbalist based at The Health Equation, 11 Harley Street, London W1G 9PF; tel: 020 7612 9800/07917 662 042.