This is a common "ruse" used by marketers of the modern "snake oils". Just because collagen is such a critically important component of skin and skin support, doesn't mean you can eat it and have an effect on your skin. Otherwise eating a steak (it is part collagen) should improve your skin! Even putting collagen on your skin will not help--the molecule is simply too large and complex to penetrate the skin and have any effect.
So, back to basics...rest, sunblock, moisturize, healthy diet, and judicious use of medically proven effective products/techniques, ie, retin-A, laser therapies, etc.
The better treatments for dark circles and bags are discussed elsewhere on this site.