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Many plant foods contain flavone or other compounds which possess goitrogenic activity.  Thiocyanate is a thyroid-toxic compound found in the Brassicae plants cauliflower, cabbage, kale, rutabaga, kohrabi, brussels sprouts, Cruciferae plants such as broccoli, as well as tropical plants such as cassava, lima beans, linseed, bamboo shoots and sweet potatoes.  Additionally, peaches and strawberries, tea, buckwheat, flax, licorice, oregano, marjoram, cacao, fenugreek and corn, millet as well as soy contain goitrogens.  Millet is a critical staple food in parts of India, which contains glucosylvitexin, glycosylorientin and vitexin, three flavone compounds which may cause hypothyroidism via inhibition of thyroid peroxidase (TPO) with chronic intakes.  Many high-value food-flavone compounds such as fisetin, kaempferol, naringenin, myricetin, naringin, genistein, daidzein, and glycitein with enticing links to disease prevention and treatment are inhibitors of TPO.  Idiosyncratic TPO inhibition by these phytochemicals are dose related and may accumulate.  As opposed to a varied affluent diet, wherever a high level of chronic single source food dependence exists, such as in emerging populations beset with poverty, and even infant and enteral formulas, it is prudent to abrogate goitrogenic effect via variation and processing inasmuch as is possible.  Isoflavones can be reduced via ethanol solubilization to err on the side of caution in the production of infant and enteral formulas.  Some animal studies link high isoflavone intake with hypothyroidism caused by TPO inhibition.  Iodine has been added to soy-based formulas since the 1960's, however and there have been no reports of hypothyroidism in formula-fed infants since, nor in recent clinical trials on pre- and post-menopausal women with sufficient iodine intakes, nor do isoflavones result in clinically significant changes in circulating thyroid hormone levels.  A retrospective study of 811 men and women at 20-34 years of age found no differences in thyroid health outcomes between those fed soy-based versus cow's milk-based formula.  Despite reassurances in human data, it is still prudent to be mindful of soy isoflavone effects when chronic dosing/consumption is involved and attempt to vary the diet.