Some of the best food can be found at street vendors or hole-in-the-wall restaurants in China, but the secret ingredient in the food might just kill you.

Many of these products contain “gutter oil,” an oil illegally made by reprocessing waste and leftovers from restaurants. It's then marketed and sold to use as cooking oil for many lower market restaurants and street vendors. The process will terrify you:

So if you are heading to China for a visit, just be careful what you eat. Fortunately, Chinese authorities are cracking down on the use of gutter oil. Ten men were recently jailed for producing and selling it. One of the men, Zhu Chuanfeng, was sentenced to death while his two brothers were sentenced to life in prison. The seven others were given 5 to 15 years in jail with steep fines for each.