阅读理解
Over the last week, a "poisonous kale（甘蓝菜）" theory has been going widespread after an article warned that the vegetable was associated with a variety of medical conditions. It's time to separate fear from fact on the health benefits of kale.
As a member of the cabbage family, kale is low in calories and rich in nutrients and minerals, especially vitamin A,C and K. Consumed for thousands of years, it's been a health plus for millions of eaters throughout the world.
However, numerous web articles have reported on some evidence offered by a medicine researcher. The researcher found that thallium（铊）was detected in a few people who were heavy consumers of kale. Thallium is a heavy metal often found in trace amounts（微量）in soil and minerals. His conclusion was that these medical conditions were connected to the impact that trace amounts of thallium detected in some kale samples had on the body.
I don't think the conclusion is based on a strict scientific basis. It's essential to point out that the original report was in a web magazine, not a scientific journal which is subject to peer review by other scientists. A scientific review includes a careful evaluation of how the findings and conclusions were made. Certain factors are critical before an evidence-based conclusion can be made, such as: how many people were in a study; how well controlled were other factors; how much kale was consumed and for how long; how much thallium was in the kale.
It is a fact that kale and other vegetables can absorb thallium from the soil. But the ability for a plant to absorb traces of a chemical does not automatically make it harmful to your health. And even finding measurable amounts of thallium in someone's body doesn't imply that the thallium is causing an ill health effect, according to the CDC.
But we can still learn a lesson from this. Plants grow in soil. Growers must continue to be careful in monitoring the quality of their soil. And what about consumers? Eat your kale—and include lots of other colorful fruits and vegetables. As with all things in nature, variety is key for good health.
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