In his review of clinical studies, Dr. Dharmananda found “a clear pattern of herb selection” for hyperthyroidism. Heart palpitation, excessive perspiration, general hyperactivity, and other hyperthyroid symptoms are signs of yin deficiency. Consequently, yin nourishing and/or fire-purging herbs, such as raw rehmannia and scrophularia, are common ingredients in Chinese herbal formulas for hyperthyroidism. In cases with thyroid nodules or swelling, phlegm-resolving components, such as fritillaria and oyster shell, are added. Most patients gain symptomatic relief within 30 to 90 days of starting their herbal formula.
The inclusion of sea-derived ingredients, particularly iodine-containing seaweed, is controversial in the treatment of thyroid conditions. In his review, Dharmananda noted that oyster shell was used in 12 of 18 clinical trials using a basic formula. “Oyster shell and other shells not only resolve masses, but also help to calm liver wind, thought to be responsible for some hyperthyroid symptoms,” he explains. Also, sea materials, particularly seaweeds, have a long history of traditional use and would be particularly helpful in treating goiter, caused by iodine deficiency. However, we now have stresses, environmental toxins, and processed foods that were unheard of in earlier times, making thyroid disfunction etiology more complicated.
I found a few case reports in medical literature about iodine-induced thyrotoxicosis in people consuming kelp tablets or kelp-containing tea. B. Clair Eliason, MD, reports that four case reports of people developing hyperthyroidism while taking kelp were published in a 31-year MEDLINE search (1966 through 1997). Kelp, by far, has the highest iodine content of six common seaweeds, according to a 2006 Journal of General InternalMedicine article. Kelp/kombu iodine content measures 2650 micrograms/gram in one study and 1542 [mu]g/g in another. In contrast, nori’s iodine content is 43 [mu]g/g and 16 [mu]g/g; dulse’s is 44 [mu]g/g and 72 [mu]g/g; and wakame’s is 161 [mu]g/g and 66 [mu]g/g. A 1994 Japanese study that compares the incidence of thyroid dysfunction in 1061 coastal residents to the incidence found in 4110 inland residents concludes: ” … [thyroid autoantibody negative hypothyroidism] is more prevalent and marked in subjects consuming further excess amounts of iodine and … excessive intake of iodine should be considered an etiology of hypothyroidism in addition to chronic thyroiditis in these areas.”
As Dr. Dharmananda points out, Chinese studies have shown success without the use of seaweeds. “The continued use of surgical thyroidectomy and iodine-irradiation of the thyroid gland to remove thyroid activity in hyperthyroid patients,” says Dr. Dharmananda, “may be deemed a last resort rather than a standard method of therapy if Chinese medicine is incorporated into the health care system. This can reduce the health problems encountered by Grave’s disease patients and also reduce the cost of lifelong health care.”