3. Conventional Kale
Kale is a leafy green that is often hailed as a superfood, due to its high nutritive value and purported healing properties.
Kale is packed with calcium, vitamin A, vitamin K, and iron. Unfortunately, the non-organic version is contaminated with organophosphates that are known to be toxic to a human’s nervous system.
It also contains oxalates, so even the organic version should be avoided by people with kidney or gallbladder issues. Finally, kale is a goitrogenic food that can cause goiters in people with an unhealthy thyroid.