What damages collagen?
According to Medical News Today:
Some factors can deplete the levels of collagen within the body. Avoiding them could keep the skin healthy for longer.
High sugar consumption: A high-sugar diet increases the rate of glycation, a process where blood sugars attach to proteins to form new molecules called advanced glycation end products (AGEs).
AGEs damage nearby proteins and can make collagen dry, brittle, and weak.
Smoking: Many chemicals present in tobacco smoke damage both collagen and elastin in the skin.
Nicotine also narrows the blood vessels in the outer layers of the skin. This compromises skin health by reducing the delivery of nutrients and oxygen to the skin.
Sunlight: Ultraviolet rays in sunlight cause collagen to break down more rapidly, damaging collagen fibers and causing abnormal elastin to build up.
The UV rays in sunlight damage the collagen in the dermis, and the skin rebuilds incorrectly, forming wrinkles.
Autoimmune disorders: Some autoimmune disorders cause antibodies to target collagen.
Genetic changes can affect the extracellular matrix. The collagen that is produced can be lower, or it may be dysfunctional, mutated collagen.
The aging process causes collagen levels to deplete naturally over time. There is no way to prevent this.