Where is all the toxic kale coming from? An investigation of the “Vegetable Detective”

Update: This post has been revised to reflect input from Ernie Hubbard, the researcher profiled in the Craftsmanship piece that’s discussed in the post. See the editor’s note at the end for details.

Recent scare-mongering media reports have focused on killer kale smoothies.

Recent scare-mongering media reports have focused on killer kale smoothies.

In our diet-obsessed culture, we’re bombarded on a daily basis with messages about the dangers of food-based toxins — everything from gluten in our grains to plastic in our peaches (among many others). Now Mother Jones magazine has a surprising new suspect to add to the Most Wanted list of dietary villains: kale

That’s right, kale.

The cruciferous green is usually praised as a source of vitamins, minerals, and fiber. But now it’s under suspicion for harboring high levels of the poisonous heavy metal thallium.

Before you call for a toxic cleanup in your crisper, however, you may want to take a closer look at the so-called evidence on this latest food fright and who’s putting a spotlight on it. While there’s little sign of any public health concern, there are plenty of questions about who stands to benefit from scare-mongering media stories about toxic food.

Headlined “Sorry foodies, we’re about to ruin kale,” the Mother Jones piece is actually a summary of a longer investigation by Craftsmanship magazine called “The Vegetable Detective.” As Mother Jones explains, the “detective” here is an “alt-medicine researcher” named Ernie Hubbard who works at the Preventive Medical Center of Marin, an integrative health clinic that prominently features “heavy metals testing” in its suite of on-site patient services. According to Mother Jones, Hubbard first became suspicious of kale when he began to notice problems among his clientele of health-conscious northern Californians.

“Chronic fatigue. Skin and hair issues. Arrhythmias and other neurological disorders. Foggy thinking.”

Tests ordered by Hubbard showed these patients had elevated levels of thallium, as did samples of kale that he had analyzed, according to Mother Jones. Hubbard also found that patients “complaining of symptoms associated with low-level thallium poisoning—fatigue, brain fog, etc.—would also be heavy eaters of kale and related vegetables, like cabbage,” Mother Jones notes.

But wait a minute here. “Foggy thinking”? “Skin and hair issues”? “Arrythmias”? Those sound like symptoms that could be attributed to any number of physical or mental problems.

To its credit, Mother Jones does note that there’s no “definitive link between heavy kale consumption and any health problem.”  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 nonspecific symptoms very similar to those reported by Hubbard’s patients.

In addition, the piece is light on any details that might make a thallium connection seem 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 exposure ruled out?

The original Craftsmanship piece delves into the details of one woman’s test results and the results from one sample of kale. But single samples are hardly evidence of a widespread problem with the food supply.

We also hear from Dr. David Quig, a scientist at Doctors Data, Inc., which performed the thallium testing for Hubbard’s inquiries. 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 some 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.

Then there’s the question of how this research into kale toxicity got started in the first place. 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. While we don’t know if the clinic was paid to conduct the study, there’s clearly some industry involvement here. And while it’s possible for industry-involved research to be conducted to a high standard, the  ads that the company runs for ZNatural don’t project an image of responsible scientific inquiry.

Despite these questions and red flags, the prospect of toxic kale seems to have struck a chord in some corners of the Internet. Just look at these headlines that are all based on the Mother Jones/Craftmanship coverage:

In my view, the real victims here are unwitting health news consumers who may now be needlessly frightened of a nutritious vegetable.

Editor’s note: This article has been edited from its original version based on feedback from Ernie Hubbard, the researcher profiled in the Craftsmanship piece. Specifically, Hubbard objected to any suggestion that he was proposing a link between thallium in kale and either Lyme disease or gluten sensitivity. He says one of the implications of his research is that thallium in kale could be causing symptoms mistaken for other conditions. The terms “Lyme disease” and “gluten sensitivity” have been removed from the post. Hubbard also said that it was incorrect, as originally stated, that he sent kale samples to Doctors Data only after receiving initial test results from Curtis and Thompkins. That text has been removed from the post. Hubbard also objected to any suggestion that the kale tested was “from the region” and that he had drawn a “conclusion” regarding a link between kale and thallium-related disorders. Those statements have been removed from the post.

Kevin Lomangino is the managing editor of HealthNewsReview.org. He tweets as @KLomangino.

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Comments (4)

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Ernie Hubbard

July 22, 2015 at 12:55 am

Kevin, I am sorry that you did not see fit to contact me prior to publishing your post. It not only contains preventable inaccuracies, but it makes assertions that are simply false. I have issued an open invitation to writers, scientists and consumers to contact me about this work–I have nothing to sell and nothing to hide. My work stands on its own merits, about which you have not seen fit to inquire before you decided to offer your article to the public. Your readers would be well-served by better quality journalism, and I would be pleased to assist if you are interested. Thanks, Ernie

    Kevin Lomangino

    July 22, 2015 at 6:42 am

    Ernie, Thanks for your comment. My post is an evaluation and criticism of journalism that has already been offered to the public for consumption. That’s what this site is about — media criticism. I’m certainly not going to re-report every story that I comment on to see if the original reporter got their facts straight. If you have problems with the reporting about your work, I suggest that you take it up with Craftsmanship and/or Mother Jones, which is the basis for my commentary. I think both of those outlets, and the many others that have picked up this story, would have done well to investigate the issues and concerns that I raised in my post before publishing their pieces. And while you may not see the value in my post, I think our readers are well-served by the analysis. There’s nobody out there holding the media accountable like the bloggers and reviewers of HealthNewsReview.org, and I’m very proud of our work. Best regards, Kevin

Gabriela Thiecke, Naturopath

July 23, 2015 at 3:21 am

The only hesitation I’d have with regard to excessive use of RAW kale in smoothies, for example, is that kale, being a member of the cruciferous family of vegetables, releases substances called goitrogens during digestion that increase the need for iodine and can damage the thyroid gland when consumed in large amounts.
Steaming crucifers until they are fully cooked reduces the goitrogens to one-third the original value on average.
Fermentation does not neutralize the goitrogens in crucifers. When foods like sauerkraut are consumed as condiments, however, the small amount of goitrogens within them is not harmful if one’s diet is adequate in iodine.


    July 29, 2015 at 12:05 pm

    Please define “large amounts”. Also, please let us know where you studied chemistry.