Wear light colored clothing made of natural materials.

VOA: special.2010.07.27

It's usually colored because there's food dye in it, but it wouldn't be colored in its natural state.

通常是五颜六色的,因为其中含食用色素,但在自然情况下,它是无色的

耶鲁公开课 - 生物医学工程探索课程节选