Generally, the raw materials of fried food are almost bad or have gone bad, and the oil used is unsanitary. Many unscrupulous traders use gutter oil or used old oil.
Fried food takes a short time to cook and is often undercooked, which not only does not kill pathogenic microorganisms carried by the food itself, but also causes intestinal parasites. Polymer dimers and trimers produced by repeated high-temperature heating of oil used in fried foods are highly toxic.
Fried food contains a lot of trans fatty acids and leavening agents.