Your thyroid gland uses iodine to produce hormones that regulate your body's metabolism. Without proper levels of thyroid hormones, your body will not be able to use fat and energy stores, nutrients or oxygen efficiently. Certain foods, including radishes, contain chemicals classified as goitrogens that suppress your thyroid gland's function when eaten raw. Eating radishes in moderation is unlikely to have any noticeable effect in a healthy person. However, people with existing thyroid disease should limit radishes in their diet and talk to their doctors about overall dietary guidelines.
Thyroid Gland
Your thyroid is a small gland that sits on the front of your neck, wrapping around your windpipe. Your thyroid gland stores iodine and uses it to produce thyroid hormones. These thyroid hormones --- triiodothyronine, or T3, and tetraiodothyronine, or T4 --- control how your body uses and stores energy and nutrients. You are constantly taking in new nutrients from food and using energy from your body's stores, such as fat. Without thyroid hormones, this process will be unbalanced and your body will not function properly.
Hypothyroidism
When your body does not produce enough thyroid hormones, you develop a condition called hypothyroidism. Signs of hypothyroidism can include fatigue, weakness, muscle pain, low body temperature, brittle hair and nails, frequent infections, poor wound healing, depression and unexplained weight gain. Do not assume you have hypothyroidism if you gain weight or have trouble losing weight. See your doctor for diagnostic tests and proper treatment.
Iodine
Iodine is a trace mineral found in meats, dairy, seafood and in small amounts in most fruits and vegetables, although levels vary with soil conditions. Iodine is also added to table salt, making iodine deficiency rare in developed countries. The daily recommendation for adults is 150 mcg of iodine per day. One-third of a tablespoon of salt --- 2,000 mg --- contains your daily intake of iodine.
Goitrogens
Goitrogens are chemicals that prevent you from absorbing iodine or otherwise interfere with the production of thyroid hormones. They are named because of their association with goiter, a swollen thyroid gland that accompanies thyroid hormone deficiency. Goitrogens are almost completely broken down during cooking. Many foods naturally contain chemicals that are goitrogens: In addition to radishes, soybeans, cruciferous vegetables and greens also contain goitrogenic chemicals. Though they have undetectable effects in healthy people, goitrogens can be detrimental to those with a weakened thyroid.
Dietary Recommendations
Avoid eating large amounts of raw radishes if you have pre-existing thyroid disease, such as hypothyroidism. Goitrogen intake was correlated --- albeit weakly --- with thyroid function in children with thyroid disease, according to a 2006 study in the journal "Clinical Chemistry and Laboratory Medicine." Goitrogenic foods should also be avoided if you have been diagnosed with iodine deficiency or have a low iodine intake, as goitrogens may interfere with your ability to absorb iodine.
References
- "Clinical Chemistry and Laboratory Medicine"; Actual Levels of Soy Phytoestrogens in Children Correlate with Thyroid Laboratory Parameters; Milerová et al.; 2006
- "Progress in Clinical Biology Research"; Mechanisms of Chemical Injury of Thyroid Gland; Capen; 1994
- "Thyroid"; Risk Factors for Goiter and Thyroid Nodules; Knudsen et al.; 2002
- American Association of Endocrince Surgeons: Function of the Thyroid Gland
- Oregon State University: Linus Pauling Institute: Micronutrient Information Center: Iodine
- Pubmed Health: Hypothyroidism
