Goitrogens

What slows things down

Compounds of crucifers, soy and a few roots that hinder the uptake of iodine by the thyroid.

Effects

Compounds in cabbages, soy and cassava hinder the thyroid in capturing iodine, the raw material of its hormones. Poorly prepared cassava is the extreme example; on an ordinary plate, the effect is weak.

Cut cabbages release thiocyanates and goitrin, which compete with iodine at the entrance of the thyroid; soy isoflavones curb an enzyme that makes the hormones. Lacking raw material, the gland swells to compensate: that is goiter, hence their name.

In one trial, adults ate 150 g of Brussels sprouts every day for four weeks with no change in thyroid function (McMillan et al., 1986). The extreme case is poorly prepared bitter cassava, whose cyanides give thiocyanates: in Central Africa, combined with iodine shortage, it sustained endemic goiters (Delange et al., 1982).

By sex and age: pregnancy raises iodine needs by a third, from 150 to 200 µg a day (EFSA, 2014); that is when a brake on iodine matters most.

Sources: McMillan et al., 1986 · Delange et al., 1982 · EFSA, 2014

The remedy

Cooking reduces a good part of them, and the problem only really arises if iodine is otherwise lacking — which is why this signal is read next to the “Iodine” line.

Goitrogens

Effects

The remedy

Where to find it (40)