Cruciferous Vegetables (Brassicas) and Thyroid
Cruciferous vegetables, also called brassicas, are a family of plants containing goitrogenic compounds (glucosinolates and their derivatives, including isothiocyanates and thiocyanates) that can interfere with thyroid iodine uptake and hormone synthesis.
Examples
- Bok choy
- Broccoli
- Brussels sprouts
- Cabbage
- Cauliflower
- Kale
- Kohlrabi
- Watercress
Effects on the Thyroid
In Hyperthyroidism (Potentially Beneficial)
Cruciferous vegetables may reduce thyroid hormone production and decrease iodine uptake by the thyroid — both desirable effects for someone with hyperthyroidism. They are a recommended food group in some hyperthyroid dietary protocols.
In Hypothyroidism / Healthy Thyroid (Generally Safe at Normal Intake)
Consumption would need to be very high before goitrogen content becomes a real concern. Under normal UK/US dietary conditions, brassica consumption does not pose a risk to thyroid function. Cooking largely deactivates goitrogens.
Goitre
In theory, extremely high brassica consumption could contribute to a goitre (thyroid enlargement). This is not a practical concern at typical dietary amounts.
Also Rich in Calcium
Broccoli and kale are also good sources of calcium — useful for protecting bone-mineral-density in hyperthyroid patients, and with lower iodine content than dairy, making them suitable on a low-iodine-diet.