Advanced glycation endproducts, also known as AGEs, are caused by the body's major fuel source, namely glucose. This simple sugar is essential for energy, yet it also can bind strongly to proteins (the body's fundamental building blocks) and form abnormal structures (AGEs) that progressively damage skin's appearance of firmness. The glucose itself isn’t damaging, it’s what happens when glucose transforms into AGEs that’s the problem. Refined sugar from our diets is a major source of AGEs, and more research is revealing a diet high in sugar causes the body to age faster.
AGEs and environmental damage may be inextricably linked, but none of this has been shown to have relevance when it comes to topical application of these substances when they are included in cosmetics.
It is possible in the future that skincare products will be formulated with ingredients proven to effect the formation of AGEs when applied topically. For now, eating a low sugar diet rich in antioxidants and ingredients is the best approach.
References for this information:
Cosmetics & Toiletries, June 2011, pages 438–444
European Journal of Neuroscience, December 2001, issue 12, page 1961
Neuroscience Letters, October 2001, issue 1, pages 29-32