Once you hit around your mid-20s (the exact age varies from person to person), your collagen production decreases by about 1% each year. So, yes, it’s a great idea to maintain the balance of production and degradation through supplementation, but this requires your body to absorb the collagen you’re feeding it.
Here’s the thing: In order for collagen-infused skin care products to work, the collagen molecules have to be able to actually enter the skin—which is where problem No. 1 comes into play. “Collagen is a huge molecule that sits on the surface of the skin and cannot be absorbed into the dermis," board-certified dermatologist Dendy Engelman, M.D. once told mbg.
Engelman further explains that this is a common marketing tactic in the skin care industry and confirms that any topical product with collagen in it will likely not provide the claimed benefits. Some topical active ingredients can stimulate your natural collagen production, but not by the same mechanism as layering collagen onto the skin.
According to research, retinoids (including retinol, retinaldehyde, etc.) stimulate fibroblasts to synthesize collagen fibers and promote skin elasticity by removing degenerated elastin fibers and enhancing the production of new fibers. For this reason, it makes sense that retinol products often claim to stimulate collagen production, without promising to inject the skin with new collagen itself.