About a 2 years ago, there were headlines that you can get sick from eating too much kale because it contains thallium, a heavy metal that occurs in the soil. Like most breaking news headlines, it was not true.
It even made it to SNOPES
https://www.snopes.com/fact-check/kale-not-safe/While I didn't see the comment, as we know, Dr McDougall recommends a starch based diet and is always cautioning about focusing too much on veggies and not getting in enough starch, and so his comments may have been tongue in cheek or off the cuff. especially considering the positions he has taken on arsenic, organic, GMO, acylamides, etc
In Health
Jeff