Skip the raw peanuts, pass on the coleslaw and hold the broccoli sprouts. After a lifetime of eating all I wanted of these and many otherwise-healthy foods, it came as a shock that they may have set me up to develop the same hypothyroid condition experienced by other members of my family.
Hypothyroidism (low thyroid function) is believed to be one of the most underdiagnosed health conditions in the United States. Many of its symptoms—lethargy, depression and weight gain—can be easily attributed to other factors, making hypothyroidism difficult to diagnose. Some reports estimate that around 15 percent of the population suffers from the condition; other reports estimate more than twice that. Risk increases with age, particularly in menopausal women. Hyperthyroidism (overactive thyroid), the opposite of hypothyroidism, is considerably less common and is characterized by extreme nervousness and restlessness.
A diet for hypothyroidism
Goitrogens are naturally occurring substances in certain foods that interfere with the production of thyroid hormones (the hormones that people with hypothyroidism lack). They include some of the most commonly consumed foods of the health-conscious community: broccoli, cauliflower, kale, spinach, radishes, soybeans, peanuts, pine nuts, peaches and millet. The good news is that many health professionals believe that cooking may inactivate goitrogens.
Although these foods provide many benefits for healthy people, goitrogenic potential should be considered by at-risk groups: people who have a family history of hypothyroidism, those who already have symptoms, and women approaching menopause.
Some goitrogens, such as soy isoflavones, pose a particular quandary for menopausal women—they can reduce certain menopausal symptoms, such as hot flashes, but are thought to aggravate hypothyroidism. Hypothyroidism could explain menopausal symptoms such as depression, weight gain, and lethargy. People with deficient thyroid function often feel cold, which might help differentiate the two conditions. It is unknown whether other phytoestrogenic foods are thought to affect thyroid functioning. While avoiding goitrogens may mitigate symptoms of hypothyroidism, many other dietary and nondietary factors are also involved.
At least a dozen vitamins and minerals are recommended for preventing low thyroid function—iodine, an essential trace element present in the thyroid gland, being the most widely recognized. Iodized table salt generally contributes enough iodine to the American diet to prevent goiter, a swelling of the thyroid gland visible around the Adam’s apple and associated with hypothyroidism; however, it may not be enough to counter other effects of low thyroid function. Iodine may be available in land-grown foods, but because the amount varies considerably depending on the minerals in the soil, seafood is a more reliable source. A significant amount of iodine is found in kelp, but excessive amounts (more than 600 mcg per day for prolonged periods) may actually trigger hypothyroidism, so moderation is the key.
Iodine combines with the amino acid tyrosine to produce thyroid hormones. Fish, dairy, oats, sesame seeds, bananas, avocados, and almonds are all good sources of tyrosine. Some goitrogenic foods such as mustard greens, soybeans, spinach, and cabbage are also high in tyrosine. Because current conventional wisdom says that cooking may inactivate goitrogenic potential, these foods may still have a place in a varied, balanced diet.
Zinc, vitamins B2, B3, B6, B12, and the antioxidant vitamins A, C, and E are also involved in improving thyroid function. Eggs, dairy, and shellfish and other seafood—key components of the protein-rich diets often recommended for weight maintenance for those with hypothyroidism—supply many of the above nutrients. The variety of vitamins and minerals involved in boosting thyroid function makes a balanced diet of whole foods particularly important for nourishing the thyroid.
Debbie Whittaker, the Herb Gourmet, lives in Denver, Colorado.