5. Rhubarb Leaves
Rhubarb is delicious in pies and desserts, but did you know when baking with this tasty plant, you should always make sure to use the stalk and never the leaves, as they can be lethal? Though the stalk is safe to consume, rhubarb leaves contain a highly toxic chemical compound, called oxalic acid, which is extremely poisonous, even if you only eat a small amount.
The oxalic acid contained in the leaves binds to calcium ions and produces calcium oxalate, which can build up in the kidneys and cause kidney stones. Studies have shown that broccoli contains oxalic acid as well, but as it’s in much lower quantities, it doesn’t pose a risk to health.
Symptoms of rhubarb leaf poisoning include nausea, eye pain, seizures, and kidney stones, as well as burning in the mouth and throat, and vomiting. Even eating a tiny amount of rhubarb leaves can bring on these symptoms, while research from the Journal of Occupational Medicine and Toxicology found that consuming a large quantity causes renal failure. As there’s no safe way to eat or prepare rhubarb leaves, we think it’s best to completely avoid them and just stick to using the stalk for those delicious crumbles, pies, and pastries instead!