Kale’s quandary!

Now, I know a lot of you are very sensibly onto the green smoothie trail at present. Well done, all those lovely fresh green enzymes being zapped and consumed. However, do bear in mind that too much raw kale can interfere with thyroid production.

Goitrogens are compounds found in many cruciferous vegetables such as broccoli, Brussels sprouts, cauliflower, cabbage, kale, bok choy, turnips (root and greens) etc.
Goitrogens can interfere with normal thyroid production as they prevent the uptake of iodine into the hormone the thyroid gland produces.

Progoitrins are precursors to goitrins. In order for the progoitrins to convert to the goitrins, they need to be converted by activation of an enzyme called myrosinase, found in the plant cell. If broccoli or the other crucifers are cooked, the myrosinase enzyme is destroyed and goitrins are not produced.

Raw kale is very high in progoitrins, increasing the risk of thyroid dysfunction. Juicing raw kale increases the risk of thyroid problems, particularly if dietary iodine is low (a common deficiency in Australia).

Brussels sprouts, kale, and several of the Asian vegetables, such as choy sum, pak choy, senposai and Chinese cabbage contain the highest percentage of progoitrins.

I would hate to ever discourage green veggie consumption! But please lightly steam these vegetables before consumption, and don’t over juice!