It is so much better to listen to what people say and do. It means that the person thinks that it is easy to either predict or see by your facial or body expressions what you are thinking or what you will do next. Think of poker players and how they hide their reactions to their cards.
This doesn't mean you can take vitamins or apply topical vitamin C and then bake safely in the sun, but you can help keep your skin healthy and supple by making sure you get enough of this antioxidant vitamin [source: Bouchez].
Yes if they are delivered in a specific manner. That is, you probably won't get the benefits of topical Vitamin A by rubbing some carrots on your skin. (And carrots contain b-carotene, which must be converted to retinol by the body to gain benefits for skin). There are different nutrients that get absorbed into skin and have positive benefits for some skin conditions: