Curcumin
Curcumin is the bright yellow substance in turmeric that may help protect cells from harm.
Think of it this way
Curcumin is like a yellow powder you stir into a glass of water. Some of the powder clumps near the surface and some sinks to the bottom. As it sits, the powder coats the inside walls of the glass. In the same way, curcumin moves through the body and coats surfaces.
Explaining curcumin by grade level
Turmeric is a yellow spice used in cooking. The part that makes it yellow is called curcumin. It may help guard tiny living things from bad stuff in the water. That is why some tests add turmeric to see if it helps.