• Sarah Greenfield, RD

Kale. Friend of Foe?

There has been a lot of buzz around kale recently. The once touted “superfood” is now under fire for a slew of reported negative health attributes. Is it too soon to be demonizing this food, are people just jumping on the negative bandwagon without understanding the science? Lets take a look.

Like all plant foods, kale has a variety of nutrients tucked in to its leaves and stem.

Most dark leafy greens contain compounds called goitrogens, kale is no excepted. Goitrogens can negatively impact the health of the thyroid for those with hypo or hyperthyroidism by preventing the absorption of dietary iodine. However, when you steam or cook higher goitrogen foods, the amount of goitrogens are greatly decreased. There are no negative effects for those with a healthy thyroid. Rotating the greens you eat in your daily diet is always best, this gives your body a variety of nutrients, check out this video for a better explanation.

Take away: If you have a compromised thyroid, cooking kale will decrease goitrogen levels and rotating greens is always a great tactic.

A couple articles hit the internet related to heavy metals and kale’s ability to absorb and accumulate heavy metals from the soil. A study done by Ernie Hubbard in California linked many of his patients symptoms of feeling fatigue, light headed, nausea and brain fog to an increase in thallium levels in their system. He pointed the blame directly at kale and other vegetables in the brassica family. Without ruling out other causes and being set-up in a controlled and standardized environment, it becomes difficult to draw any scientific conclusions. While kale and brasiccas do have the ability to absorb heavy metals from the soil, you would have to eat 154 pounds of kale with high levels of lead, before there would be any negative health implications.

Take away: Buy a variety of greens and vegetables when food shopping, don’t just stick to the same thing every week. Mix it up! The bottom line is balance and variety. There is a tendency for extreme behaviors in a healthy lifestyle, if something is good than eating 10 times the normal amount must be better. Wrong! Health is about balance, don’t live off kale juice and almonds, it doesn’t make sense. Incorporate variety, rotate greens, eat kale, but do everything in moderation and your body will reap all the healthy benefits.

#Apples #HealthyEating #goitrogens #goitrogen #kale #friendorfoe #brasiccas


Sarah Greenfield RD, CSSD


16550 Riverside Drive


Studio City CA 91602 



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