It makes sense that Kale would be dangerous given it evolved in an evolutionary war against those that dare to eat its leaves from aurochs to insects. One powerful weapon it possesses is lectins, which many of you recognize as a serious danger to human health, implicated in manyautoimmune illnesses and other inflammatory disorders. The lectins in kale and other related species are very similar to the equally dangerous wheat germ agglutinin lectin.
Some people think that kale and other related vegetables prevent cancer, but large-scale epidemiological studies have shown no such effect and their phytochemicals may even cause cancer. For example, indole and its derivatives have been shown to promote many types of cancer, possibly by causing hormone imbalances or by stimulating the cyt-P450 pathway that produces genotoxic metabolites. If you already have cancer, it can promote further growth and the so-called “antioxidants” which people think are so healthy can prevent your body from fighting the cancer effectively.