Ill see if I can find it. It was an article on HN yesterday about green smoothies. I think the concern with kale is thyroid problems and with spinach it’s kidney problems.

Edit: https://news.ycombinator.com/item?id=37168142

Not the most self-contained reference for what Im referring to but its what prompted my comment. There are more details in the comments and should provide plenty of fodder to follow up on.

And this one puts the upper limit at 2.2lbs of kale per day https://www.healthline.com/nutrition/can-you-eat-raw-kale

So I guess its still unlikely that youd reach that but seems like a lot lower threshold than dangerous aspartame levels.