Vitamin C has been the IT ingredient for quite some time. If you take a look at any brightening product, you are most likely to find L-Ascorbic Acid listed at the top of the list. L-Ascorbic Acid (Vitamin C). In addition to its brightening properties, is an excellent choice for fighting oxidative stress, which is at the root of rapid collagen degradation, and which in turn causes the skin to lose its firmness and elasticity.
Vitamin C has so many properties, it can be labeled as a "miracle ingredient". Unfortunately, some people, like myself, may find Vitamin C to be cause skin irritation, redness and possibly breakouts, and will therefore choose to avoid it entirely.