Eek! Why it Might Be Time to Step Away from the Kale

By Lauren Le Vine, REDBOOK.

For the past few years, kale has enjoyed a meteoric rise in the superfood world akin to Jennifer Lawrence's ascendency in Hollywood. Just when we'd resolved that this is the year we make healthy, nutritious green juices every morning; however, total buzzkill The New York Times published an essay in which writer Jennifer Berman says kale--with which she juiced every morning-was to blame for her hypothyroidism. Plus, thanks to all the fruit-and-vegetable-based juices she drank, she had five new cavities during a recent trip to the dentist.

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Apparently, researchers have known about the deleterious effects of very high intakes of cruciferous vegetables like kale, cabbage, and turnips for years. And it's easier to slip into "very high intake" level than you think. "It's the dose that makes a poison," Teresa Fung, a nutrition professor at Harvard, told WBUR's CommonHealth blog. "Reasonable amounts shouldn't be a problem. Now, if people have a tall glass of kale juice every single day, then it gets into the unknown territory."

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Do not take this as a sign you should forsake kale entirely, though. Studies have found that cooking cruciferous vegetables dramatically reduces their "goitrogenic properties" (read: ability to enlarge your thyroid). Plus, kale alone doesn't increase your risk of developing thyroid problems, there have to be other factors, such as iodine deficiency. She recommends eating foods like seaweed, a good source of iodine, to counteract this.

Fung also recommends eating foods that contain selenium, like Brazil nuts, which support normal iodine levels, in turn aiding your thyroid. You should also keep a lot of variety in your choice of greens. If you eat kale one day, "choose a non-cruciferous, non-goitrogenic veggie dish the next, like a simple cucumber and tomato salad, or beets," Fung says. Other non-goitrogenic veggies include parsley, zucchini, carrots, and celery.

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As for the cavities, Berman's dentist said to always wait half an hour after eating or drinking anything before brushing her teeth. Also, there's no need to brush more than two times a day. If you really want to spare your choppers, eat fruits and vegetables in solid form. The natural sugars in juices can lead to decay, and the acid can erode enamel. In conclusion, there's no need to turn your back on kale just yet.

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