Kale is not the Problem, Pollution is

Does kale contain thallium, and is it a health risk?

The internet has gone crazy recently over the news that kale may contain high amounts of thallium, a heavy metal. This has caused a lot of distress, and more than its fair share of comments from people frustrated and wondering if their healthy diet – which included kale – was ruining their health instead of improving it.

Let’s go over what you need to know about kale and thallium, and then let’s talk about what this situation should really teach us.

Where this Story Started

Mother Jones published an article titled, Sorry, Foodies: We’re about to Ruin Kale. In it, they discussed the clinical experience of a Californian alternative researcher and molecular biologist who discovered that some of his patients dealing with issues such as hair and skin issues, neurological issues, fatigue and brain fog, had elevated levels of thallium. This was even more puzzling as the people with these symptoms were very health conscience and ate a great diet, including lots of dark greens and cruciferous vegetables.

He then found research noting that plants in the cruciferous family, including kale, cabbage, radishes, turnips and watercress, were effective in pulling out the heavy metal from soil.

He felt it wasn’t hard to connect the dots, and when some of his patients improved and their thallium levels dropped once cutting cruciferous vegetables out of their diet, it seemed to confirm the connection.

What we don’t know

Obviously, that thallium levels appear to become elevated for his patients when eating cruciferous vegetables is distressing news. But we also need to keep in mind what we don’t know. It’s possible that this is an isolated incidence geographically, or that there were other causes to blame in the above situation, or that his conclusion was flawed.

Why Pollution is to Blame, not Kale

Plus, I think that the kale haters showing up in droves over this story are missing the point. Kale is not the problem. But pollution is. I read another study talking about how pollution in seafood is distressing high. Considering that seafood and the cruciferous vegetables contain a lot of research behind them demonstrating their ability to improve health, this is depressing news.

But again, the problem is not that kale and seafood are bad for you, the problem is that our human-created pollution issues could be literally poisoning some of the most valuable and healthy foods we have.

And yes, that is distressing.

While trace of amounts of thallium are in the earth’s crust, elevated levels come from pollution, Mother Jones also reported. Cement plants, oil drilling, smelting, and ash from coal burning are all problematic. A local to me doctor also mentioned fracking as a source of thallium pollution.

So, if you are going to be upset at something, don’t blame kale. It’s still a wonderful source of many minerals and vitamins (and delicious to boot), but do get upset about the pollution that may be causing our most valuable, health-producing foods to become poisonous. That’s something worth being angry about.

His Conclusions May Be Flawed

Vox published a damning rebuttal to this story, criticizing the lack of science behind his conclusions. I personally never throw out clinical observations, but we should recognize their limitations, and his lab hopping is questionable. As reported in the Vox article, it appears that yes, kale does have the ability to accumulate thallium. But, to cause a problem for humans you’d have to plant it in heavily poisoned soils, and they’d have to accumulate it in their leaves (which doesn’t always happen). Thankfully, it sounds like researchers don’t believe that most soil contains high amounts of thallium. Generally, it would be nearly impossible to poison yourself with kale (or cabbage). But yes, not eating kale grown in soil with large amounts of thallium would be advised.

Is it possible that his 20 patients were eating kale from heavily poisoned soil? Perhaps, but researchers don’t believe that this should be an issue for the vast majority of kale. And if you are worried about thallium, kale is hardly the only vegetable that is an issue. A lot of vegetables pull it from the ground. Not eating vegetables seems like a poor route to good health.

Yes, I’m Still Eating Kale

If you think that the agriculture areas you are getting food from contain a lot of heavy metals from pollution, then you have cause for concern for a variety of reasons. But there doesn’t seem to be a lot of evidence that we should be greatly concerned about this issue. In fact, with so many studies demonstrating health benefits to kale and cruciferous vegetables, science seems to point us towards eating plenty of it.

Really, the drama about this issue simply reminded me of how little kale I’ve eaten lately, and why I should remedy that, and also why it’s important that we don’t allow our country to become heavily polluted.

Related: Should we fear and avoid goitrogenic foods such as cabbage?

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I love beautiful and simple food that is nourishing to the body and the soul. I wrote Fresh: Nourishing Salads for All Seasons and Ladled: Nourishing Soups for All Seasons as another outlet of sharing this love of mine. I also love sharing practical tips on how to make a real food diet work on a real life budget. Find me online elsewhere by clicking on the icons below!

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  1. says

    More likely a case of thyroid dysfunction caused by too many goitrogens. These are a natural toxins found in cruciferous vegetables, and can block iodine absorption. This is only a problem if you are eating heaps of cruciferous vegetables, which may be the case for people who like blending them up.
    The high levels of Thallium are probably an indicator they are eating lots, but thallium is likely still well below toxic levels (if it even can be toxic?).

    The point that should be made is this: cruciferous vegetables are extremely nourishing, but like many vegetables should be eaten in the amounts that you would eat naturally if you weren’t trying to go all ‘superfoody’!

  2. says

    That was my first thought when i saw the article. Kale or pesticides? Great article. I’ll continue to eat kale and crucifers along with practicing detoxification methods of sweating, consuming chlorella and taxing Epsom salt baths.

    Thanks for the article!

  3. Sandra says

    Simply another argument for eating a variety of foods. People who are on a fad diet, no matter how healthy the food, which makes up a substantial amount of their calories can not only be effected by something like arsenic in kale, but you can develop food allergies. Eat a variety of healthy foods and “don’t put all your eggs in one basket.”

  4. Lauren says

    Those patients may be sensitive to greens & antioxidants like I am. Greens & large doses of vitamin B’s make me very tired/sleepy.

  5. f nord says

    I just did a bit of research. Thallium is highly toxic (it used to be used as a rodenticide), and can be absorbed through skin, by breathing air, and from food and water. Body load levels are tested in urine and/or hair. Smokers urine’ dontains high levels compared to non-smokers’. The research I found relating to kale is from the UK which burns a *lot* of coal.

    Since a common sources of thallium toxicity are coal-burning, various kinds of manufacture (cement plants, sulfuric acid production, various kinds of smelting, and a few other), and particles settle into soil and leech into water supplies.

    Thallium is highly stable (i.e., it doesn’t degrade or form harmless complexes), and also highly bio-accumulative.

    Sea plants absorb it readily, and it bioaccumulates in fish and other seafood. So now our formerly pristine oceans and their provender can kill us with mercury, thallium or radioactivity. Hallellujah.

    I thought for a bit I had a problem with sulfur — problems from eating brassicas — but I found cauliflower is an exception. Now I wonder if the actual problem has been thallium.

    Re the folks offering alternative diagnoses: the good doctor apparently based his diagnosis on urine levels; if the alternative diagnoses would explain that, please post how?

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