Everything in moderation—except green juice loaded with kale, right? We’re not too sure about that anymore.

An article in Craftsmanship Magazine by Todd Openheimer raises the question of whether eating too much kale—and related cruciferous vegetables like cabbage—could lead to negative side effects. The report tells the story of Ernie Hubbard, a doctor in Marin County, CA who began to find detectable levels of a thallium, a toxic-heavy metal, in patients’ blood samples at higher-than-normal levels. Hubbard also found thallium in kale leaves from the region.

He had health-fanatic patients who had been experiencing symptoms like fatigue, brain fog, digestive troubles, nausea, and skin and hair issues—all symptoms of low-level thallium poisoning. One patient’s thallium levels measured at .7 parts per million (ppm), which is seven times higher than what’s considered the “threshold” limit. That same patient was a big cabbage eater, and her hair had been recently falling out in large clumps. When she cut way down on her cabbage consumption (which she now calls “getting off the sauce,” according to Oppenheimer), her symptoms got better.

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We know you’re thinking: That was cabbage, not kale. The link between the two veggies—and other crucifers like broccoli, cauliflower, mustard, and collard greens—is that they’re “hyperaccumulators” of thallium, which means they are capable of growing in soil with very high levels of the toxic heavy metal. Oppenheimer writes that Hubbard began pulling up more and more concerning information on thallium:

It turns out thallium was once a common ingredient in rat poison. It was also Saddam Hussein’s favorite poison to use on his enemies. (The metal works exquisitely for poison because it is tasteless, odorless, and nearly colorless.) While none of Hubbard’s test subjects had been consuming doses even close to poisonous levels, the medical and scientific literature linked low-level doses to many of the complaints brought to his clinic: fatigue, heart arrhythmia, and—in more extreme cases—nausea, neurological problems, and hair loss.

Okay, so we should all just be wary of our kale intake, right? While that may sound easy, it’s safe to say a certain subset of yuppie Americans in coastal cities are addicted to the leafy green. “In the last five years, the number of restaurants serving kale has reportedly risen by some 400 percent,” Oppenheimer points out. At least the first “death by kale overconsumption” has yet to occur.


[via Craftsmanship Magazine, Mother Jones]