Hypothyroidism develops when the thyroid gland does not produce enough hormones, primarily thyroxine and triiodothyronine. According to MayoClinic.com, hypothyroidism has many causes, is more common in females and occurs in at least 15 percent of the U.S. population . Symptoms of hypothyroidism include profound fatigue, lethargy, weight gain, constipation, dry skin, depression and difficulty in keeping warm. Some forms of hypothyroidism are diet related and may be helped by eating certain nutrient-rich vegetables.
Iodine-Rich Vegetables
Iodine is an essential trace element the body needs to make thyroid hormones. Table salt has been iodized for decades in efforts to prevent goiter, or swelling of the thyroid gland, but some prefer to avoid the toxic effects of sodium chloride and obtain iodine more naturally. Kelp, or seaweed, is an excellent source of iodine and can be consumed raw or as capsules. Excessive amounts of kelp, more than 600mcg daily for many months, may upset the balance of the thyroid, so moderation is important, according to "Biochemical, Physiological and Molecular Aspects of Human Nutrition." Other vegetables that are a good source of iodine include Jerusalem artichokes, fennel, the skin of potatoes and spinach. Note that those with Hashimoto's Thyroiditis, a cause of spontaneous hypothyroidism, should avoid iodine as it has been shown to increase the severity of the disease.
Tyrosine-Rich Vegetables
Iodine combines with the amino acid tyrosine to make thyroxine hormone. Vegetables rich in tyrosine include avocado, lima beans and lentils. Some vegetables rich in tyrosine, such as mustard greens, soybeans, spinach and cabbage are considered goitrogens, which contain substances that interfere with the production of thyroid hormones. According to "Contemporary Nutrition," it is commonly believed that cooking these vegetables before consuming them inactivates their goitrogenic potential. However, soy products also contain isoflavones, such as genistein, which can reduce thyroid hormone production. Genistein blocks the activity of thyroid peroxidase, an enzyme needed for combining iodine into thyroid hormones. People with hypothyroidism should avoid soy products, regardless of other health benefits.
Vegetables Rich in Vitamin A and Beta-Carotene
Vitamin A, and its precursor beta-carotene, are excellent antioxidants that act to destroy free radicals capable of causing thyroid gland damage and degeneration. Yellow vegetables, such as winter squash and turnips, orange vegetables, such as carrots and sweet potatoes, and dark green, leafy vegetables all contain high amounts of vitamin A or beta-carotene.
Mineral-Rich Vegetables
Some vegetables improve hypothyroidism by supplying essential minerals, especially selenium and zinc, needed by the thyroid gland to function properly and produce hormones. Broccoli, spinach, kale and onions are rich in minerals, which are more bioavailable if eaten raw. However, all cruciferous vegetables, which includes broccoli, cauliflower, brussels sprouts, cabbage and turnips, contain isothiocyanates and are considered goitrogens. Cooking these vegetables makes the isothiocyanates less active, but decreases the bioavailability of the minerals and vitamins.
References
- MayoClinic.com: Hypothyroidism
- "Biochemical, Physiological and Molecular Aspects of Human Nutrition"; Martha Stipanuk; 2006
- "Contemporary Nutrition"; Gordon M. Wardlaw; 2010
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