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.
"This stuff bioaccumulates," he added. "Down the road, it's going to kick you in the ass one way or another." Okay, so we don't have to panic—yet.
That said, is THIS the new kale? It's twice as healthy, and kind of tastes like bacon...
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FAQs
Right now, there is no published, peer-reviewed research on low-dose thallium-induced disease or the adverse effects in humans from eating kale. We've simply seen no credible evidence to back up this viral idea, and at this point, there is no reason that anyone should take these warnings about kale seriously.
Why do people say kale is unhealthy? ›
According to research, kale contains "progoitrin, a compound that can interfere with thyroid hormone synthesis, and thiocyanate ions, which can crowd out the iodine your thyroid needs." When consumed in large quantities, "one could experience a swelling of the thyroid, often called a goiter."
Can kale cause sickness? ›
Kale is loaded with soluble fiber that can cause nausea and insoluble fiber that can cause diarrhea. It also belongs to a complex sugar family — called the raffinose family of oligosaccharides (RFOs) — that can cause bloating.
Why do I feel bad after eating kale? ›
Fiber from kale leaves can get stuck in the intestines. As a result, you will feel bloated and pass gas more often. Not only that, kale leaves also contain a sugar called raffinose. This type of sugar is difficult to digest by the stomach.
Is kale high in cadmium? ›
Hoagland's team's results showed kale accumulated higher levels of cadmium than basil under the same soil conditions, but symptoms of cadmium stress were stronger in basil. They also discovered that the plants only showed cadmium stress in early development.
Why can't you eat kale everyday? ›
Plus, eating too much fiber (like what you find in kale) could wreck havoc on your GI system, causing bloating, diarrhea, gas, constipation, and even improper absorption of nutrients. Of course, you'd have to be eating a lot of kale to suffer these effects, says Manganiello, but it's still something to keep in mind.
Who should avoid eating kale? ›
These vegetables offer health benefits, including supporting the immune system, regulating blood pressure and potentially reducing the risk of various types of cancer. People who may need to avoid or limit kale intake are those who form oxalate-containing kidney stones or take the blood thinners Coumadin or warfarin.
Can kale be inflammatory? ›
Kale contains phytochemicals, sulfur-containing indolic glucosinolates, and aliphatic glucosinolates that have demonstrated anti-inflammatory activity [18].
How to tell if kale is bad? ›
Texture changes: Fresh kale should be crisp. If it feels slimy or overly wilted, it's time to discard it. Smell: Kale that's starting to spoil will have a sour or unpleasant odor. Trust your nose; if it smells off, it's best not to eat it.
Is bagged kale safe? ›
Different microorganisms can contaminate those leafy greens inside packaged salads, including pathogenic E. coli, norovirus, Salmonella, Listeria, and Cyclospora.
Kale and other greens (such as swiss chard, arugula, spinach, etc) are also loaded with oxalates, a compound that can promote kidney stones and severe pain in the body organs and tissues.
Is kale bad for gut health? ›
Leafy greens, such as spinach or kale, are excellent sources of fiber, as well as nutrients like folate, vitamin C, vitamin K and vitamin A. Research shows that leafy greens also contain a specific type of sugar that helps fuel growth of healthy gut bacteria.
Why shouldn't you blend kale? ›
Oxalic acid overload
Are green smoothies bad for kidneys? The answer may be yes if you overdo it on leafy green vegetables – Swiss chard, spinach, kale and beet greens – that all contain high levels of oxalic acid, a naturally occurring compound that forms oxalate crystals in the body.
Is kale anti carcinogenic? ›
These defenses help stop free radicals from damaging DNA that can lead to cancer. The vitamin C in kale is also a powerful antioxidant, and helps to inhibit formation of carcinogens.
Is coffee high in cadmium? ›
Coffee brews usually contain smaller concentrations of elements than the corresponding roasted coffees from which the brews were prepared [38]. To sum up, the content of Cd and Pb in the analysed coffee beverages and coffee substitutes was low; thus, drinking such beverages is safe for consumers.
Is there estrogen in kale? ›
Vegetables like broccoli, Brussel sprouts, and kale contain phytoestrogens with anti-cancer and anti-inflammatory properties. Diets rich in cruciferous vegetables are also associated with lower risk of many chronic diseases, including heart problems.
Why is kale controversial? ›
Kale is Dangerous!
“Seven out of eight US kale samples recently tested for toxic PFAS “forever chemicals” contained high levels of the compounds.
Is kale one of the Dirty Dozen? ›
A new report identifies the fruits and vegetables with the most pesticides.
Is kale as good as people say? ›
But does the science really back up its reputation? Is kale packed with nutrients? You bet. One serving of kale — a cup of raw greens or half a cup of cooked ones — only has 35 calories, but is a very good source of vitamins A, C, and K, and also contains calcium, iron and folate.
How to tell if purple kale is bad? ›
Kale leaves should be firm. If leaves look wilted, or wet and mushy, the kale has gone bad. Keep them dry. The key to keeping kale fresher, longer, is keeping the vegetable dry.
