If you are taking important steps to support your thyroid health you may want to avoid consuming large quantities of cruciferous vegetables, especially in their raw state.
This includes putting fresh kale in your favourite green smoothie.
What are Cruciferous Vegetables?
Cruciferous vegetables are a group of vegetables that belong to the Cruciferae, or mustard family. They were originally named due to the shape of their flowers which have four equal sized petals in the shape of a crucifix.
The Most Common Cruciferous Vegetables
The most commonly consumed cruciferous vegetables includes; kale, broccoli, cauliflower, Brussels sprouts, bok choy, broccolini, Chinese cabbage, kohlrabi, radish, mustard greens, collard greens, choy sum, horseradish, turnips, rocket and wasabi.
Goitrogenic Foods Are Linked to Thyroid Dysfunction
Cruciferous vegetables are termed ‘goitrogens’ as they block proper thyroid function.
The word ‘goitrogen’ is derived from the word ‘goitre’, a condition in which the thyroid gland becomes enlarged.
Goitrogenic foods may not necessarily cause a goitre, but they do have the potential to block proper thyroid activity by interfering with iodine uptake in the thyroid. In addition, their goitrogenic effect is more significant when iodine stores are low.
The Kale Green Smoothie Fad
For health conscious people kale is a popular ingredient in green smoothies. The problem is, kale is a powerful thyroid-suppressor, especially when consumed raw. Consuming kale on a regular basis can therefore trigger a range of hypothyroid symptoms.
** IMPORTANT POST UPDATE March 2019: Kale is NOT a Superfood **
News in from the Environmental Working Group (EWG) raises serious new concerns regarding kale.
- The level, and type of pesticide residues on kale has expanded significantly in recent years.
- Conventional kale farming relies heavily on the use of several synthetic pesticides, including Dacthal. The Environmental Protection Agency (EPA) classified this pesticide as a possible cancer causing chemical back in 1995.
- All pesticides are potential thyroid disrupting chemicals (TDCs).
- Kale is now placed third on the EWGs Dirty Dozen™ 2019 annual ranking of the fruits and vegetables with the worst amount of pesticide residues.
Your Take Home Message? Mix It Up.
Once your thyroid hormones return to optimal levels a small amount of cooked, or lightly steamed cruciferous vegetables may be a healthy addition to your daily diet, especially when you also consume iodine rich foods to top up levels of this essential mineral.
There is one caveat…you should definitely avoid consuming kale!