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  • Writer's pictureMary Shackelton, MPH, ND

DARK SIDE OF KALE

Did you think I was going to write about how we should avoid kale if you have a thyroid problem? Nope. There’s a different issue with kale that many people don’t know about.


Meet Thallium - tall, dark, and handsome. Thallium has been showing up in Urine Heavy Metal tests for patients for many years, yet no one knew for a long time of its clinical significance or where it was coming from. Not much reliable information was available. So, we clinicians have been on our own detective hunt to figure it out.


Now, we know more. Thallium, which is odorless, tasteless, and colorless (as are most of our toxic exposures), was originally used as a rat and insect poison, but it was banned for use in households in the United States in 1965 after many unintentional poisonings. It was also banned in 1975 commercially but is still mainly obtained as a by-product from the smelting of copper, zinc, and lead ores. Its main entry into the environment is from coal-burning and smelting where it stays in the air, water, and soil for a long time. It is absorbed by plants and can build up in fish and shellfish.


Acute poisoning is really rare, but what I’m seeing is more chronic thallium exposure, which occurs over months or years of exposure to small doses of thallium. Thallium can be absorbed through the skin, respiratory, and gastrointestinal tracts and builds up to reach toxic levels.

Unfortunately, the way an elevated level of thallium looks clinically mimics many other problems, making it is difficult to be confident about these symptoms without a proper heavy metal urine test (specific companies that do these tests: Doctor’s Data or QuickSilver Scientific). Signs and symptoms of chronic poisoning include: tiredness, headaches, depression, hallucinations, psychosis, dementia, poor appetite, leg pains, hair loss, and vision disturbances. So, clearly it has negative impacts neurologically.

Digging deeper, I have come to understand that cruciferous veggies, e.g. Kale, Chard, Bok Choy, Watercress, Swiss Chard, have an increased uptake of thallium from the soil. Why? I’m not sure there is an answer for this, but this finally explains what I am seeing on tests that come back with high thallium levels.


Remember when kale hit the scene several years ago? This coincides with when I started seeing elevated levels of thallium in test results. Turns out the connection is correct. While the increase consumption has been overall great for increasing our intake of vegetables, especially antioxidants and fiber, whenever we make a major change in our diet there is bound to be some impact of that change.


So, should we stop eating kale? Not entirely. Rather, I am recommending that people mix up what is in their smoothies in the morning. Kale is not the only thing that is green that we should have in our diets; Consider alternating your kale intake with:


cilantro

parsley

romaine lettuce

spinach


These are also dark green leafy vegetables with high nutrient density. They will provide not only fiber but high amounts of vitamin A, vitamin C, and important minerals.

For some more recipes that are heavy with cilantro check out this website:


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