From the looks of it, this essential protein certainly seems to be working its magic! The stars swear by this biological building-block, said to help make hair shinier, smooth skin, plump lips and strengthen nails. Besides the outward effects, studies of ingestible collagenOpens a New Window. — as opposed to the collagen that was used as a filler in years past — are starting to link it with feeling younger. (And who doesn’t want that!) Scroll through to shop these products that can help you boost your beauty from the inside out.