Kale isn't oxalate-free. Oxalates bind calcium to form kidney stones, which account for about 70% of cases, not meat and beer as commonly believed. Lacy kale has more oxalates than dino kale, and they're also in spinach, raspberries, and coffee. Moderation and choosing lower-oxalate options helps.
Some people like to say kale doesn't have oxalates in it, and that is not true. According to all the research I can find. Oxalates are a compound that's much more common in spinach, actually in raspberries, and it is found in kale, especially the lacy kale, the dino kale I've been recommending for 10 years. If you have to eat kale, you could eat dino kale. But the lacy kale, really, really not good for you. About 33 milligrams of oxalate. Oxalate binds to calcium in your blood and it forms tiny crystals that can get in your vulva if you have them and can get in your brain. But it's a major cause. Like 70% of kidney stones are caused by calcium oxalate from plants, not from meat and beer like they tell you. So there you go. You are eating some plants that are causing problems. Some people handle more than others. Coffee does have low levels of oxalate in it, and if you're worried about it, you can add a little bit of calcium, which is why people put milk in their coffee. Except milk takes away the polyphenols. So there is no need to go on a zero oxalate diet. You just need to be on a low to mid oxalate diet, which means cut out the big offenders. Lots of foods have small amounts of oxalate. They're probably. I can hurt you.
