Kale might be bad for you in some cases — here’s when you should be careful about eating it

  • Kale is packed full of things that are good for you like protein, vitamin A, and vitamin K.
  • But if you have an underactive thyroid, it might be a good idea not to eat too much of it.
  • Certain compounds in the vegetable can interfere with thyroid hormone synthesis and essentially block the iodine your thyroid needs to function.
  • You probably would have to eat an excessive amount for this to happen, though.
  • Kale also lists highly in the US for being contaminated with pesticides, so you should wash it thoroughly before eating it raw.

There’s no doubt that kale is an excellent health food. Just one cup can give you more than 200% of your vitamin A for the day, and nearly 700% of your vitamin K. It also contains certain plant compounds that can help protect against certain cancers.

But in some cases, eating kale might not be as healthy as you think. For example, it can interact with thyroid function if it’s eaten in very high amounts. It contains something called progoitrin, which can interfere with thyroid hormone synthesis and essentially block the iodine your thyroid needs to function. This can result in fluctuating blood sugar levels and weight.

However, it’s probably not something to worry about as you would have to eat an excessive amount of raw kale to experience these negative effects — a lot more then you’re likely to have in one sitting. If you’re unsure, or you have an underactive thyroid (hypothyroidism) already, ask your doctor or a dietitian.

Read more: Bubble tea is a whole lot worse for you than regular tea. Here’s why.

If you regularly eat kale, it might also be a good idea to make sure you wash it thoroughly. The Environmental Working Group just released its “Dirty Dozen” list for the year, which is a guide to the products that are covered in the most pesticides.

It found that kale had the highest pesticide residues compared to nearly all other produce found on supermarket shelves in the US.

About 60% of the kale samples tested positive for Dacthal, which is listed as a Group C human carcinogen according to the National Library of Medicine — meaning there is suggestive evidence of carcinogenic potential but more research is needed.

“We were surprised kale had so many pesticides on it, but the test results were unequivocal,” said EWG toxicologist Alexis Temkin. “Fruits and vegetables are an important part of everyone’s diet, and when it comes to some conventionally grown produce items, such as kale, choosing organic may be a better option.”

The Dirty Deets

Kale is a warrior that fights against heart disease, cancer, inflammation and toxins. To make the most of all it has to offer, chow down on 1 1/2 cups a few times a week. At 33 calories a cup, that is a really strong nutritional investment. There are some other things you may not know:

  • Kale has 134 percent of your daily vitamin C needs (twice as much as an orange), 206 percent of your vitamin A recs and 684 percent of your daily vitamin K. It has more calcium per serving than milk and is loaded with ALA, an important omega 3 fatty acid that keeps your brain sharp and heart throbby. Bonus: All of the nutrition in this catwalk wonder is super easy for the human bod to absorb.
  • I’ve implied kale is a supermodel and called it a natural wonder, but sadly it is linked to some legit bad press. The Environmental Working Grouphas found a spot for this leafy green on it’s dirty dozen list because the pesticide residues found on kale are toxic to our nervous systems. There is no sugar-coating this one, we actually don’t know how much of this residue can be washed off and how much becomes systemic to the leaf. Buy organic when possible.
  • Detox. D-whaaat? Yeah. You don’t need a pill, liquids or an enema. In my world, detox means taking time to eat foods that clean up the systems that may get loaded with toxins. Enter kale. It helps take a scrub brush to the liver, kidneys, colon, skin, lungs and lymph. Flush that, toxins!

The problem is not eating kale per se, but eating so much of it that you may be giving yourself low-level poisoning of the toxic heavy metal thallium. That can’t be good.

The issue is raised in an article in Craftsmanship magazine that was picked up by Mother Jones. The piece tells the story of a natural medicine researcher in the kale-loving San Francisco Bay Area whose patients complained of vague, similar problems like fatigue, foggy thinking, and digestive issues. The researcher, Ernie Hubbard, realized many of them had unusually high levels of thallium in their blood. Looking to find the cause, he turned up academic articles that showed how kale and its veggie relatives, such as cabbage and cauliflower, are particularly adept at taking up thallium from the soil. His patients were showing symptoms of “mild” thallium poisoning. When one patient stopped eating so much cabbage, her favorite food, she started to feel better as her thallium levels dropped.

This isn’t cause to toss away your kale chips, kale soda, and kale popsicles. There’s still work to do in showing what’s going on: Hubbard hasn’t actually established that excess greens consumption is actually causing his small group of patients to feel ill or how thallium is getting into the soil where kale grows. Also, as Mother Jones writer Tom Philpott points out, you’d have to be eating very high quantities for these kinds of health problems to become an issue.

Since that’s pretty much true of any food that has components that can be bad in large quantities (think: carrots, fish, and even water), this isn’t necessarily a huge worry. However, given how Jake Gyllenhaal fared on his all-kale diet, I wouldn’t recommend trying that soon.

LOOKING to clean up your diet and eat nothing but healthy food?

You’re going to want to keep scrolling.

10 Eating healthy food in high doses can be bad for you

It is possible to overdo it on some healthy foods, including spinach, kidney beans, canned tuna, brown rice and even nuts.

But don’t go throwing your healthy eating plan in the bin just yet.

Overdoing it on these foods is rare and most would require a person to eat or drink a lot in one sitting – but consuming them regularly over time can cause issues, Kate Morin writes on The Fix.

Here are nine foods you shouldn’t eat in large quantities…

Spinach, beet greens and swiss chard

10 Credit: www.fix.com

Dark, leafy greens are a nutritional powerhouse, packed with essential nutrients including vitamins A and C, iron, and folate, Kate says.

But some – namely spinach, beet greens, and Swiss chard – are also high in oxalic acid, the compound that gives hearty greens their signature earthy, slightly bitter taste.

Consume too much and you may be in for unpleasant symptoms such as kidney stones, abdominal pain, low blood pressure, tremors or convulsions, vomiting, and weak pulse.

But don’t think this means dark, leafy greens aren’t part of a healthy diet. In moderation, they’re perfectly fine.

Some research shows it would take about 25 grams of oxalic acid to cause death in a 145-pound person, which would equate to about 7.3 pounds of spinach.

Brazil nuts

10 Credit: www.fix.com

Eating too many Brazil nuts can cause selenosis, or an overdose of the mineral selenium.

Symptoms can include an upset stomach, hair loss, fatigue, irritability, diarrhoea, brittle hair or nails, discoloured teeth, nervous system issues, a metallic taste in the mouth, and a garlic-like odour in the breath.

Untreated, selenosis can even lead to difficulty breathing, tremors, kidney failure, heart attack, or heart failure.

Don’t go avoiding selenium completely, though, writes Kate.

Selenium is an essential mineral needed to produce selenoproteins, which function as antioxidants.

It also plays an important role in reproduction, thyroid function, and DNA production.

So just how many Brazil nuts is too many?

One Brazil nut contains 68 to 91 micrograms of selenium, and the upper limit of consumption for adults is 400 micrograms – so try to keep your daily dose to four or five nuts.

Keep your intake below this level and you shouldn’t have any problems.

Canned tuna

10 Credit: www.fix.com

Tuna contains more mercury than many other fish, and excessive mercury can cause some alarming side effects, including vision, hearing and speech problems, lack of coordination, and muscle weakness.

So just how does mercury contaminate fish?

First, industrial sources such as power plants release mercury into the environment. The molecules then make their way into clouds, where they stay until they return to the ground when it rains.

Canned tuna can still be part of a healthy diet.

Stick to “light” varieties, which are made from smaller skipjack tuna that typically have lower levels of mercury than larger albacore tuna and keep consumption to no more than three to five cans per week, and you should be safe.

Tomato plants

10 Credit: www.fix.com

Tomatoes themselves are perfectly safe to eat.

Stay away from the leaves and stems, though.

Tomato leaves contain an alkaloid toxin called tomatine.

While studies have not shown any apparent toxic effects on humans, too much of the compound can lead to digestive issues.

And definitely keep all parts of the tomato plant away from pets.

Tomatine has a much stronger impact on dogs and can lead to a host of dangerous side effects, including digestive and nervous system issues.


10 Credit: www.fix.com

Nutmeg contains a compound called myristicin, which can lead to myristicin poisoning in large doses, explains Kate.

It would take commitment to consume enough nutmeg to make a human sick.

Throwing a pinch into a quiche or baked good isn’t going to hurt, but consuming too much (think tablespoons) can lead to not-so-great side effects, including headaches, nausea, dizziness, and even hallucinations.


10 Credit: www.fix.com

There’s a reason rhubarb makes its way to grocery store shelves without leaves.

While rhubarb stalks are fine to eat, the leaves contain oxalic acid, a compound that’s used in bleach and antirust products.

Eating rhubarb leaves can cause a burning sensation in the mouth and throat, and lead to vomiting, nausea, convulsions, and even death, says Kate.

Just how many leaves would you have to chow down to get sick?

One study determined that a 130-pound woman would have to eat about 10 pounds of rhubarb leaves to show symptoms of oxalic acid poisoning.


10 Credit: www.fix.com

Kate says if you ever come across a green potato, especially one that has started to sprout, toss it.

Green potatoes contain solanine, a natural pesticide that is toxic to humans when consumed in large quantities.

Too much of this compound can cause vomiting, diarrhea, and cardiac arrest.

Luckily, it would be nearly impossible for an adult to consume enough green potatoes to get sick.

A 100-pound adult would have to eat a full pound of completely green potatoes before showing symptoms.

Red Kidney Beans

10 Credit: www.fix.com

Raw red kidney beans contain a toxin called phytohaemagglutinin, explains Kate.

To remove it, the beans have to be boiled for at least 10 minutes before consuming.

And don’t try to simmer them for a longer period of time in place of boiling.

Cooking the beans at temperatures below boiling multiplies their toxicity.

Fail to remove the toxin before eating and symptoms could include severe nausea and vomiting.


10 Credit: www.fix.com

Surely not?

But believe it or not, there is such thing as consuming too much water, writes Kate.

Overconsumption can lead to water intoxication, a condition that occurs when extreme water intake dilutes the sodium in the blood, which can then lead to impaired brain function and even death.

Don’t let this be a deterrent to drinking enough water every day.

Hyponatremia is usually only a problem for ultra marathon runners and people who force themselves to drink too much water.

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Rhubarb and Swiss chard – they’re both leafy red stalks of vegetables. So, what’s the difference?

Although I don’t set out to make the Difference Between posts a competition, inevitably sometimes there’s a winner. And this is one of those times.


  • Rhubarb: any of several plants belonging to the genus Rheum, of the buckwheat family, as R. officianle, having a medicinal rhizome, and R. rhabarbarum, having edible leafstalks; the edible, fleshy leafstalks of R. rhabarbarum, used in making pies, preserves, etc.
  • Swiss chard (redirected to chard): a variety of beet, Beta vulgaris cicla, having leaves and leafstalks that are used as a vegetable; also called Swiss chard, leaf beat.

From the definitions we don’t learn too much, other than rhubarb is often utilized as a fruit, while Swiss chard is more vegetable-like, related to the beet family. Although not specified above, Swiss chard is also often compared to spinach.

In fact, there are several different varieties of Swiss chard, two of which could be confused for rhubarb: rainbow and ruby red. Rainbow Swiss chard is sometimes red, and ruby red Swiss chard is always red; ruby red is also called (appropriately) rhubarb Swiss chard.

Swiss chard has a darker, more vein-y leaf. It fits into the spinach and other greens category.

Rhubarb’s leaves are not as vibrant of a green, and furthermore, they cannot be eaten. Although both rhubarb and Swiss chard contain oxalic acid, the leaves of rhubarb contain significant enough amounts that it can be fatal.

Taste-wise, rhubarb is highly tart and acidic, which is why it’s typically combined with a sweet fruit, such as strawberries, in a pie. Swiss chard is compared to spinach, as mentioned before, but it’s generally considered to be better tasting, with a meaty, earthy flavor, according to Vegetables Revised.

Nutrition-wise, Swiss chard by far comes out on top. World’s Healthiest Foods (which does not even include rhubarb in their extensive list) explains that: “Calorie for calorie Swiss chard is one of the most nutritious vegetables around.”

Moreover, Swiss chard contains high levels of vitamins and minerals, including vitamins A, C, E, and K; outstanding phytonutrient antioxidants; anti-inflammatory enzymes; calcium; and magnesium.

Comparatively, rhubarb, as described by RhubarbInfo.com, contains a decent amount of potassium, small amounts of vitamins, and is rich in calcium, vitamin C, and dietary fiber. Although, the calcium is combined with the oxalic acid and is therefore not as easily absorbed by the body.

Clearly, we have our winner. Swiss chard is more flavorful and significantly more nutritious than rhubarb. Unless you’re making a pie, go with the Swiss chard.

Side note: While researching this post, I came across more than one person who had bought rhubarb instead of Swiss chard, or vice versa. In addition, there was a seed company who used the same picture for both vegetables.

Keeping Greens Fresh

Question: I am trying to get back into juicing and eating salads. It’s a start. I have a hard time keeping my greens from going bad before I can eat/juice them. Kale, celery, parsley are the most troublesome. Do you have info on your website or is there a good book on how to store veggies? Sometimes I don’t eat or juice every day. Can you eat veggies when they are starting to turn yellow especially kale and parsley? Thanks for a great website. I have been trying some new recipes.

Sassy Sez: Very cool that you are getting more salads and fresh juices into your diet. These two ideas are very easy, effective ways to supercharge your nutrition! Awesome!

Firstly, I would buy less produce more often. It sounds like you are buying way more than you can use and it is sitting there getting old and yucky on you. Unless you are picking them fresh from a garden, fruits and veggies are already on their way to “old” when we buy them in the store; by the time it is picked and shipped and put into a display in the store – well, let’s just say it is BEST to eat your fruits and veggies as soon after purchase as possible.

So the best advice I can give is to buy less produce more often. Jeff and I shop once every week or two for non-produce items, but we head to the store twice/week to pick up fruits and veggies that will last us the next few days.

While this is a best-case scenario (short of growing your own food!), I realize this isn’t always do-able for everyone. So simply do the very best you can to eat whatever you buy as soon as possible. It’s better to eat all your produce up while it’s fresh, then to have it sitting in your fridge waiting for you to get around to eating it as the nutrients slowly but surely say goodbye.

By the way, you might invest in some Vejibags — oh, they are AMAZING! Also, Debbie Myers Green Bags keep your produce until you can eat it – these bags seem to be available everywhere. I also like Tupperware’s Fridgesmart Containers which work beautifully, especially to keep my just-cleaned lettuces crisp.

Hope this helps. xo

More Thoughts On The Topic:

Clean As You Go
By Rachel Assuncao

I’d add to Sassy’s comments to say – don’t clean your greens until just before you eat them. I find that if I wash them and any moisture remains on them (which, with greens is near impossible to avoid) that they spoil much more quickly than if I wash them just before I eat them.

Good luck in finding what works for you!

Paper Towels

By Cindy

You can actually wrap the veggies in paper towels (try to dab dry them first) than put them in plastic bag. Normally they will last for 2 weeks or so.

E.g.g.s for Vegans…really!
By Memory

I use a product called E.g.g. to keep my veg fresh. They are a colorful plastic egg which contains a packet of E-Ethylene Gas absorber inside. The packet is replaceable at the end of a few months. (Depends on how much veg you keep) They really, really work. I got mine at Community Health, but I just went into my fridge and looked inside the egg.

The packet says that they have a website called www.4theegg.com. They are fairly in-expensive and they prolong the life of my veg by easily a few weeks.

E-Ethylene is the gas that builds up in your veg drawer that causes food to age more quickly. The eggs remove that gas. When the packet is old and I replace it, I cut open the old packet and put it into my Hoi plant pot. It acts as a bit of a fertilizer.

Oh, and I had my hubby, who is a chemical engineer, read the blurb on the Egg website. He’s pretty cynical and skeptical about most products and is a man of few words. After he read it, he just said “Yep, that’s right” and then left the room. For him, that’s high praise indeed.

What I Do

I get a shipment of fruits and vegetables every 2 weeks. I used to struggle with the same thing. I found if I wash and prep the veggies right away, seal them in plastic bags by push out as much air as possible. I place them in a storage bin I keep in the fridge. Leafy greens including kale I first wash then roll in paper towels then tear in bite size pieces and place in ziplock bag. Press out air and voila it keeps for up to 2 weeks without any issues. Hope this helps someone.

Cloth Bags
By SarahG

Hi, I shop for my produce with cloth bags and store them in there too. Cloth really prolongs the life of my fruit and vegetables.

Keeping Vegetables Fresh
By Dr. Jeanette

A thought: When you wash vegetables and you will not be eating immediately or wish to put them back into the refrigerator for a period of time and this works for cut vegetables too: Place them in a large bowl with cold water, no ice, and open a pack of Emergen C and dissolve in the water. Let them soak for about five minutes, gently rinse for two or three seconds and then lay to dry on a towel. They are now ready for the refrigerator. Healthy and safe.

Didn’t respond to the part of question that would help me…
By Richard

Why no comment about eating leafy vegetables that turn yellow? I know they are not as fresh but should I throw them out or still cook?

Pretty Old
By Sassy

Hi Richard! That would be your call, for sures. If your greens are turning yellow? They must be pretty old and the nutrients have likely pretty much left the building.

If you’re like hubby Jeff who REFUSES to waste anything, then you might consider adding them to soups/stews, or maybe smoothies. Couldn’t hurt! 🙂

Keeping Celery Fresh

I wrap celery in aluminum foil and it lasts for weeks that way. It’s amazing!

Save The Veggies!
By Charles

There are proactive ways to Save the Veggies! I could write a really long description of the basic processes I use to increase vegetabilian longevity.

Short version: In the ’70’s I lived in a raw foods community in eastern Arizona, and then began an organic produce distribution out of Phoenix, so I guess I learned a bit then.

I call the process Rehydration and it applies to most vegetables. My belief is that food loses moisture content from the field to the fridge; rehydrating restores that, and makes them last longer. It makes rooties & stalkies crisp & crunchy, and wilted kale to stand up! It makes gardens in the fridge, too.

BTW, recent research says that wilted veggies retain most of their nutritional goodies. Who knew? So, to me personally, wilted veggies are perfect for smoothies!

I am able to eat veggies further along in their lifespan because I look at their condition as a spectrum: from growth thru digestion it’s all the same (entropy?), so pick your point on the spectrum to ingest. As an example, I drink about a half-gallon of carrot juice a week, and we all know how lovely & viscous it can become when aging, and yet I can drink it far past others’ tolerance.

But enough about me; here’s something for you when speaking to your adoring adherents: in order to ‘sell’ organic produce back in the day, I would tell folks that it is a “nutritional bargain” to justify its relatively high cost. I can proudly say that I was instrumental, a link in the chain, to ultimately bringing organic produce to Wal-Mart!!!! Yippee for unintended consequences.

By Sassy

Thanks for your comments. Maybe you can share with all of us exactly how you rehydrate your veggies?

Keeping Greens Fresh

I buy fresh kale. I clean some to use now for smoothies. I put a serving in a Mrs. Green Bag for my next smoothie and I freeze the rest in small servings for smoothies later in the week in my food saver bags. It is a little slimy so I only use in my smoothies. I guess you could use in a cooked dish but may not be good in a salad.

I put all my fresh produce in individual Mrs. Green Bags and it keeps it good for the week.

I love my Fridgemates
By Kathy TX

I invested in the Tupperware Fridgemates and LOVE them. They do keep my produce a lot long and it has help since I now buy from Bountiful Baskets.

By Sassy

Thanks for sharing, Kathy. I love them too. I think it’s always so good for others to hear what works out here in the trenches. 🙂

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If you’re a daily juicer and have a habit of throwing a certain leafy green superfood in your Vitamix, you might want to put down that leaf of kale. At least until after you read this.

A recent piece in the New York Times titled, “Kale? Juicing? Trouble Ahead,” has called some attention to a potential downside to eating large amounts of what’s become one of the health food world’s most en vogue items. As it turns out, eating (or drinking) kale on a daily basis can cause hypothyroidism, or underactive thyroid. And kale isn’t the only culprit.

See also: Juicy Battle: Juice Core vs. Original ChopShop Co.

The article, written by Jennifer Berman, explains how a Whole Foods junkie found her health comprised by one of the very foods she thought was doing her body good:

Imagine my shock, then, at my last physical, when my doctor told me I had hypothyroidism, common in women over 40. When I got home I looked up the condition on the Internet and found a list of foods to avoid. Kale, which I juiced every morning, tops the list, followed by broccoli, cauliflower, cabbage, Brussels sprouts and collard greens — the cruciferous vegetables I consumed in large quantities because they are thought to prevent cancer, which runs in my family. And flax — as in the seeds — high in omega 3’s, that I sprinkled on cereal and blended in strawberry almond milk smoothies. Also forbidden: almonds and strawberries, not to mention soy, peaches, peanuts, corn, radishes, rutabaga and spinach.

And it’s true, according to The Linus Pauling Institute Micronutrient Information Center, very high intakes of cruciferous vegetables (such as kale, broccoli, and brussel sprouts) can cause hypothyroidism. In one case, an 88-year-old woman developed severe hypothyroidism and coma after eating an estimated 1.0 to 1.5 kg a day of raw bok choy for several months.

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Teresa Fung, Sc.D., M.S.. an adjunct professor of nutrition at the Harvard School of Public Health and a professor at Simmons College in Boston, confirmed the link between kale and hypothyroidism. But she also pointed out that normal consumption shouldn’t be a problem — as in eating several servings a week, not a day.

“It’s the dose that makes a poison,” Fung told Common Health. “If people have hypothyroidism or they’re taking thyroid medication, then they should check with their doctor. But even in this case, 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.”

Symptoms of hypothyroidism include everything from fatigue, dry skin, weight gain and muscle weakness, to pain and stiffness in the joints, thinning hair, depression, and impaired memory.

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  • Wake Up Call

Consider the following: there are hundreds of objectively healthy foods out there for us to choose from: veggies rich in all manner of powerful antioxidants, fruits rich in potassium and vitamins, nuts and seeds rich in magnesium, fish and plant-based foods loaded with heart-healthy monounsaturated fats and omega-3’s, leafy greens and beans rich in folate, and herbs, spices and teas with known anti-inflammatory compounds.

Now, let’s say you have a friend who has an allergy to one of these healthy foods; we’ll choose nuts for the sake of this example. Does the fact of your friend’s nut allergy mean that nuts aren’t still an objectively healthy food for human beings in general? Should you encourage your friend to experience an allergic reaction because the nuts are a “superfood?” Are nuts a healthy food choice for your friend? Of course not. Can your friend obtain similar—if not the same—nutritional benefits from other foods that won’t endanger their life?

Most people considering the example of food allergy above would conclude that nuts can be both a nutritious food AND a food that happens to make this particular person feel “bad.” These two things can be true at once. We take it as a given that a person with a nut allergy should avoid nuts and replace them with something comparable but tolerable—like sunflower seed butter or roasted pumpkin seeds perhaps. It wouldn’t occur to us that the person should feel guilty for their allergy, as if the nut allergy were some sort of personal moral failing.

But I’m amazed by the guilt that seems to drive my patients to force down foods that make them feel digestively awful because they feel they “should.”

There’s something amiss in our wellness culture when people feel so guilty about the fact that eating a bagel may feel infinitely better than eating a giant kale salad that they wind up in a clinician’s office essentially seeking “permission” to stop eating the kale salad.

I attribute this largely to a public dialogue about food and health that has appropriated such virtuosic language that it’s easy to see how feeling bloated, gassy, and miserable after eating a kale salad could seem like a moral failing to someone on a quest for better health. If kale salads are part of a “clean” diet and wheat flour is deemed “toxic” or “inflammatory,” then it’s not hard to imagine the impulse to seek a dispensation from a doctor or dietitian to eat a so-called ‘bad’ food that feels—well, good.

Social media messaging within the healthy eating and wellness community—particularly on Instagram—seems to fuel feelings of guilt associated with “failing” to tolerate the staples of “clean living,” like kale salads, smoothie bowls, raw date cacao energy balls, avocado chocolate “mousse” and entire heads of roasted cauliflower. (Not to mention those of us who are able to tolerate them digestively but simply dislike them.) One small study published in the European journal Eating and Weight Disorders surveyed hundreds of social media users who followed healthy-food-focused accounts. The researchers found that higher use of Instagram was associated with a person exhibiting more symptoms of an eating disorder called orthorexia nervosa. Orthorexia describes a fixation with “pure” or “clean” eating to the point of becoming unhealthily restricted. It can express itself in terms of extreme psychological preoccupation with the provenance of the food one eats; guilt over perceived dietary indiscretions; social isolation due to rigid, inflexible eating habits; and/or malnutrition from excessive restriction.

The increasingly narrow portrayal of what’s “healthy” as defined by fad diet books or social media influencers is often at odds with the wide variety of dietary patterns that actual scientific research tells us are healthy. And it can really do a number on your emotional wellbeing.

“Let’s find the healthiest diet you can comfortably tolerate.”

The first step in liberating yourself from unhealthfully-limiting beliefs about what you should be eating is to broaden your mindset around what constitutes a healthy diet. In the U.S. we are fortunate enough to live in a country where a dizzying variety of foods is available all year round (although food deserts and food swamps mean that we don’t all have equal access to all foods). Because of this, no single food in our diets needs to carry the weight of delivering the entire supply of a single nutrient, nor is there any single, essential “superfood” we all must eat… or else. Since many different foods provide similar nutrients, I try to help my patients identify nutritious foods they love—and that love them back—to replace others they feel obliged to eat but don’t actually feel so good.

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Research conducted in California by molecular biologist Ernie Hubbard connected complaints of fatigue, brain fogginess, nausea and other symptoms in patients at an integrative health clinic to their kale consumption. Hubbard found high levels of the mineral thallium in locally grown kale and in the clinic patients’ urine. He also reported finding traces of other heavy metals including cesium, cadmium, aluminum and arsenic in cabbage, broccoli, cauliflower and collard greens.

An account of Hubbard’s research was published in July 2015 in the magazine Craftmanship, which identifies itself as a publication created to explore the “ethos of craftsmanship in its widest sense.” It is not a scientific journal and Hubbard’s research has not been published in any scientific journal.

According to the Craftsmanship article, Hubbard’s tests of local kale and soil suggested to him that kale (and other crucifers) hyperaccumulate thallium. He also found that organically grown kale accumulates more of this heavy metal than conventionally grown kale. While Hubbard wasn’t able to determine the source of the thallium in the soil or the vegetable, he concluded that the complaints he was hearing from patients, their reported kale consumption, urine test results, and the thallium levels he found in local kale and soil all suggested low-level thallium poisoning.

One of Hubbard’s roles at the clinic was to recruit patients to evaluate a detoxification formula, which involved testing their urine. In several cases, he found unexpectedly high thallium levels.

Not surprisingly, the article attracted the attention of other publications that picked up the story and flagged it with alarming headlines such as “People Are Getting Seriously Sick from Eating Kale.” In fact, the magazine’s account of Hubbard’s research focused primarily on a single case (although a few other patients with similar complaints were mentioned). That case involved a 52-year-old woman, a vegetarian who reported eating kale almost every day; she complained that her hair was falling out and that she had occasional fatigue and brain fog. According to Hubbard, her urine tests showed especially high levels of thallium.

While a single study from Czechoslovakia published in 2006 found that kale accumulates thallium from the soil, my search of the medical literature found nothing to suggest that eating kale or other cruciferous vegetables leads to thallium poisoning. People have been eating these vegetables for centuries. If they routinely accumulated enough heavy metals to cause sickness, surely we would know it by now. In my view, the health benefits of including kale and related vegetables in your diet far outweigh any possible risk. I see no reason to avoid them.

Andrew Weil, M.D.


Todd Oppenheimer, “The Vegetable Detective.” Craftmanship, July 7, 2015, http://craftsmanship.net/the-vegetable-detective/

Kale is heralded for its ample supplies of calcium, magnesium, potassium, Vitamin K, and various healthful phytochemicals and anti-oxidants. But the superfood is hiding a nasty secret: dangerous levels of heavy metals.

In a recent study, molecular biologist Ernie Hubbard found that kale—along with cabbage, broccoli, cauliflower, and collard greens—is a hyper-accumulator of heavy metals like thallium and cesium. What’s more, traces of nickel, lead, cadmium, aluminum, and arsenic are also common in greens, and this contamination affected both organic and standard produce samples.

The source? Its soil. “If it’s left in the ground, the leafy greens are going to take it up,” Hubbard told Craftmanship magazine.

This news gives us pause because kale has taken the culinary world by storm over the last few years: Back in 2007, the U.S. Department of Agriculture recorded 954 farms harvesting the green, but by 2012 the number of growers soared to 2,500. It’s become the “it” vegetable, getting juiced, sautéed, steamed, folded into smoothie bowls, baked into chips, and so much more.

Thallium has been a common ingredient in rat poison. It’s tasteless, odorless, and nearly colorless. While those who tested positive hadn’t consumed poisonous levels of the metal, it was enough to cause fatigue, heart arrhythmia, nausea, digestive trouble, neurological problems, and hair loss. The scariest part is that even after patients completed detoxification regiments, thallium continued to show up in their systems.

For example, the thallium levels of a 52-year-old female vegetarian, who both exercises for two hours and consumes kale on a daily basis, measured 0.7 parts per milligram—that’s seven times higher than what has been deemed the “threshold limit.”

And while toxins are nearly everywhere in our industrial-run world, it’s not an exaggeration to be concerned about these findings. “We now know that heavy metals are additive and synergistic,” says David Quid, the lead scientist at Doctors Data, who has an PhD in nutritional biochemistry. “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.” In other words, these metals do more damage when they’re combined.

That said, is THIS the new kale? It’s twice as healthy, and kind of tastes like bacon…

Delish: Eat Like Every Day’s the Weekend amazon.com $30.00 $17.99 (40% off)

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Are There Heavy Metals in Your Green Juice?

In recent years, green juices have become the poster child for the wellness movement. From casual health-conscious consumers to fitness buffs, everyone seems to be jumping on the green juice bandwagon. If you’re a green juice fan, your recipe probably includes a combination of green leafy vegetables, cruciferous vegetables, and grasses, among other ingredients. Those who prefer speed and convenience can find a diverse array of green powders to mix into water or other liquids. So you might be thinking — these are all healthy ingredients, so green juice must be healthy, right? Well, not necessarily. Some of the star superfoods in green drinks, like kale and broccoli, maybe hiding a dangerous secret: high levels of heavy metals, particularly thallium.

What is Thallium?

Thallium is a soft, malleable heavy metal discovered by Sir William Crookes in 1861. It is colorless, tasteless, and water-soluble; thus, it was once a favored homicidal poison.

Historically, thallium was once commonly used as a rodent or ant killer, but its use has been banned in the United States and many other countries due to accidental poisoning. Small amounts of thallium are still used industrially, for purposes such as:

  • Optical lenses
  • Green-colored fireworks
  • Semiconductors
  • Low-temperature thermometers
  • Imitation jewelry

Thallium can also be found naturally in the environment, although usually at low concentrations.

However, emissions from natural or human causes can lead to increased levels of the heavy metal in the environment, where it can eventually pose a major threat to terrestrial, aerial, and aquatic systems.

High concentrations of thallium in soil poses a unique threat due to possible uptake and storage by plants. As a result, thallium can enter the food chain and accumulate in our bodies, causing severe health problems and even death. Of particular concern is that high thallium concentrations have been found in drinking water and many green vegetables, some of which include those we’ve come to know as “superfoods,” such as:

  • Green cabbage1
  • Kale2
  • Broccoli
  • Cauliflower
  • Mustard
  • Collard greens
  • Brussels sprouts
  • Turnip (greens and roots)

The average human diet contains approximately 2 ppb thallium3, most of which is secreted in urine and feces. However, eating and juicing massive amount of kale day in and day out could contribute to thallium toxicity. This means that if you drink the same green juice or smoothie daily, you may want to reconsider your habit.

Symptoms of Thallium Poisoning

Needless to say, thallium is highly toxic. Its toxicity is known to be even higher than mercury, cadmium, and lead. Unfortunately, victims of thallium poisoning usually are not aware that they have consumed or have been exposed to the heavy metal. Furthermore, thallium poisoning is rare and published data is limited, which means it is often misdiagnosed until it is confirmed by urinary and blood tests, resulting in delay of treatment.4

What we do know is that thallium is quickly and almost completely absorbed via several pathways, including eyes, ingestion, inhalation, and skin exposure. Upon absorption, thallium spreads widely to multiple organs in a distribution pattern similar to that of potassium ions. Therefore, thallium deposition occurs in all tissues and is most highly concentrated in neuronal, heart, liver, kidney, and dermal tissues.5

Due to multiorgan involvement, the symptoms of thallium intoxication are nonspecific and variable, depending on the dose and route of exposure. Thallium poisoning commonly occurs in three stages.

Gastrointestinal phase:

Thallium and its salts are corrosive to the gastrointestinal mucosa, leading to the following symptoms:

  • Severe abdominal pain
  • Cramping
  • Nausea
  • Vomiting
  • Diarrhea, followed by constipation

This gastrointestinal phase may begin immediately after ingesting a large dose of thallium or 24 to 48 hours after smaller ingestions. These symptoms can last for 12 to 96 hours, and diarrhea is usually followed by several days of constipation. In some cases of chronic thallium poisoning, patients may experience few or no gastrointestinal symptoms.

Neurological phase:

This phase is characterized by painful, rapidly ascending sensory neuropathy. It may be accompanied by motor neuropathy. Patients commonly complain of the following:

  • Severe pain
  • Burning feet
  • Difficulty walking
  • Skeletal muscle cramps
  • “Stocking-glove” numbness and tingling
  • Vision changes due to dysfunction of cranial nerves
  • Nystagmus (involuntary eye movement in which the eyes move rapidly from side to side, causing reduced vision and depth perception)
  • Confusion
  • Anxiety
  • Tremor
  • Ataxia (impaired coordination)
  • Altered mental status
  • Seizures
  • Coma
  • Short-term memory and cognitive deficits

The neurological phase may begin 2 to 5 days after ingestion, although it may occur sooner after a massive exposure.

Alopecia phase:

Alopecia, or hair loss, is a hallmark of thallium poisoning and can occur 2 to 3 weeks after the other symptoms begin. Complete hair loss can occur within a month of exposure.

Other Symptoms of Thallium Poisoning

While alopecia and neuropathy may be the only symptoms present in some patients, others may also experience the following:

  • Pneumonitis
  • Acute respiratory distress syndrome (ARDS)
  • Pulmonary edema
  • Respiratory depression
  • High blood pressure
  • Abnormal heart rhythm
  • Rapid heart rate
  • Headaches
  • Loss of appetite
  • Dry and crusty scaling of skin
  • Inflammation of the mouth, lips, and gums

Severe cases of thallium poisoning can cause death in 5 to 7 days following exposure. The lethal dose of thallium in humans is reported to be 10 to 15 mg/kg, but deaths have been known to occur in adults with doses as low as 8 mg/kg.6,7

5 Ways to Minimize Thallium Exposure

  • Diversify your diet: The fact is, there is no “magic bullet” that prevents diseases and/or aging. Instead of sticking to just 2 or 3 vegetables, try to add some variety to your vegetable consumption.
  • Switch to stems and roots: The highest levels of thallium are found in plant leaves and seeds, while stems and roots have shown much lower levels. Switch out your kale and cabbage for radishes and wasabi (root) to minimize your thallium exposure.
  • Use soil rich in potassium: Heavy metals and nutrient minerals compete with one another for absorption. Therefore, if you grow your own vegetables, adding potassium to the soil can suppress uptake of thallium.8
  • Prioritize soil ecology: Potassium must first be solubilized before it can be taken up by plants, i.e., no amount of potassium supplementation will increase the uptake of the mineral without help. Potassium solubilizing microorganisms (KSMs) can help convert insoluble potassium to its soluble version.
  • Supplement your diet: Potassium supplementation has been shown to mobilize thallium from tissues in cases of severe thallium intoxication.9 If you feel that you are experiencing symptoms of thallium intoxication, talk to your doctor about adding a dietary potassium supplement. Selenium has also been shown to counteract the toxicity of heavy metals like thallium.10

Should You Stop Drinking Green Juice?

With that being said, should you stop drinking green juice? Green juices may not be as healthy as we may have believed, and I would not recommend anyone rely on them as the primary source of vegetables. Still, I think the bigger concern here is that too many Americans still don’t eat enough green leafy vegetables. Rotate and diversify your green superfoods, and you’ll be able to continue enjoying their health benefits.

Now it’s time to hear from you. Have you experienced any odd symptoms after consuming green juices or smoothies? Are you surprised by the presence of heavy metals in kale and other superfoods? Share your stories or thoughts in the comments below!

Kale is not good for you

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