Kale-troversy: Is America’s Favorite Green Making People Sick?

Recent stories suggest that residents of Marin County, California, are getting a heavy dose of heavy metals in their brassicas.

(Photo: Flickr)

Aug 5, 2015· 3 MIN READ
Jane Lear is a regular contributor to TakePart and the executive editor of CURED, a magazine devoted to the art and craft of food preservation. She was on staff at 'Gourmet' for almost 20 years.

Ive heard that kalethe be-all, end-all nutritional powerhouseis actually toxic! Do I need to worry?

Lindsay Franklin

It was inevitable, I suppose, that there’d be a kale takedown. The higher you rise, the harder you fall, as they say, and kale—which has a magnificent abundance of vitamins, minerals, antioxidants, and fiber—is the king of greens, the first breakthrough brassica. People don’t just cook it; they turn it into salads, juices, smoothies, chips, and other snacks—even birthday cake. Can a kale vape pen be far behind?

Don’t get me wrong—as a transplanted Southerner, I love my greens, kale included. But if you’re familiar with this column, you know I swear by eating a variety of foods, and all in moderation, even when it comes to antioxidants.

The flap over kale has to do with the idea that it may be a so-called hyper-accumulator—that is, it takes up and stores poisonous heavy metals such as thallium from contaminated soil. It stems from a July 7 piece by Todd Oppenheimer in Craftsmanship magazine about Ernie Hubbard, on staff at the Preventive Medical Center of Marin as “vitality researcher, business consultant, biochemist and geneticist researcher.” Hubbard noticed that patients complaining of chronic fatigue, skin and hair issues, arrhythmias, neurological disorders, and foggy thinking had elevated levels of thallium—and ate copious amounts of kale or other brassicas, such as cabbage. The Craftsmanship story got additional play in a July 15 piece by the levelheaded Tom Philpott in Mother Jones that ran under the unfortunate headline “Sorry, Foodies: We’re About to Ruin Kale.”

“Now, just because kale and other brassicas can effectively take up thallium from soil doesn’t mean that they always contain thallium,” Philpott explained. “The metal has to find its way into soil first. It exists at low levels in the Earth’s crust, and the main way it gets concentrated at high enough levels to cause worry is through ‘nearby cement plants, oil drilling, smelting, and, most of all, in the ash that results from coal burning,’ Oppenheimer reports.” Coal fly ash is a common soil amendment, but so far, Hubbard hasn’t pinned down the source of the thallium he’s found in his kale samples.

The topic made it to Snopes two days later, with the claim “A recent study proved that kale is making people ‘seriously sick’ and everyone should stop eating it,” categorized as “unproven.”

But what I found most interesting was what the on-it-like-white-on-rice watchdog blog Health News Review had to say. “To its credit, Mother Jones does note that there’s no ‘definitive link between heavy kale consumption and any health problem,’ ” wrote managing editor Kevin Lomangino.

“But it doesn’t note that extreme intake of cruciferous vegetables like kale might theoretically, in very rare cases, be related to hypothyroidism—a condition with a list of symptoms very similar to those reported by Hubbard’s patients,” he added. “In addition, the piece is light on any details that might make a thallium connection plausible. For instance, how many people are we talking about? How much kale did they eat? How high were their thallium levels, and what were the levels in the kale plants? Were alternate sources of thallium ruled out?” Inquiring minds want to know.

“We also hear from Dr. David Quig, a scientist at Doctors Data, Inc., which performed the thallium testing for Hubbard’s inquiries,” Lomangino continued. “According to Craftsmanship, Quig says that consumers should be concerned about the potential for poisoning from toxic metals—even when their test readings come back at levels not considered poisonous. He argues that the interaction of various toxins can lead to synergistic effects in the body, and that this compounds their negative impact. ‘If you get a little thallium, and a little lead, and a little cadmium in your system, you’ve got one plus one plus one equals five or six, not just three,’ he says. But a quick Internet search raises serious questions about Quig’s credibility. His employer has apparently been sued multiple times for promoting a variety of tests, including urine tests that purportedly indicate elevated levels of heavy metals. The tests are then used as the basis for prescribing ‘detoxification’ treatments like those touted by Hubbard’s clinic.”

There is no scientific evidence whatsoever, by the way, to support the theory that detox diets or cleanses flush out toxins.

If you, like me, are wondering how this research into kale toxicity got started in the first place, the folks at Health News Review are one step ahead. “As Craftsmanship points out, Hubbard’s clinic started its testing at the request of the makers of ZNatural, a chelating supplement that’s designed to remove toxic heavy metals like thallium from the body.” It’s unclear whether the clinic was paid to do the testing by ZNatural, but there is clearly some bias.

“Despite these questions and red flags, the prospect of toxic kale seems to have struck a chord in some corners of the Internet,” Lomangino added. He appended this list of headlines that are all based on the Mother JonesCraftsmanship coverage:

• “People Are Getting Seriously Sick From Eating Kale: Find out why this superfood is actually super-poisoning

• “Could Kale Be Poisoning You?

• “Hidden Health Dangers of Kale: Traces of Rat Poison Found in Popular Superfood

• “Eating too much kale may result in thallium poisoning

• “Is kale making people sick?: The dark side of everyone’s favorite superfood

• “The Shocking (and Scary) Truth About Kale

“In my view, the real victims here are unwitting health news consumers who may now be needlessly frightened of a nutritious vegetable,” he concluded. Amen to that. And I’ll continue to blame my foggy thinking on the fact that I just switched to decaf.