While it is said that a cup of coffee a day is good for anti-aging, looking at it differently, it can also be a major culprit in dehydrating the skin. In particular, polyphenols, which are abundant in coffee, are known to have a positive effect on the skin as a type of antioxidant; however, excessive consumption can accelerate skin aging. This is because caffeine draws moisture from the body, causing the skin to become dry and look tired.