I’ve been involved in the health field for a long time and have seen a few fads come and go—oat bran, carrot juice, and macrobiotic diets have all had their day. One fad food that has been around for a while is kale—mostly consumed as chips or raw in juice.
Aficionados hale kale as a superfood, rich in antioxidants, folate, biotin, vitamin C, calcium, and magnesium. But kale has a dark side because it is also rich in something else: anti-nutrients.
Goitrogens in Kale
The main anti-nutrient in kale is a goitrogen called thiocyanate. Goitrogens block the uptake of iodine by the thyroid gland, making it difficult for the thyroid gland to produce thyroid hormones. The result can be a condition called hypothyroidism, characterized by fatigue, low body temperature, constipation, weight gain, muscle weakness, hoarseness, and memory loss. At high levels and in sensitive people, goitrogens can lead to outright “goiter”—swelling of the neck and thyroid gland….