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Collagen protects the skin from UV radiation from the sun. These rays can cause skin cancer, sunburn, and acne, again by mutating the cells and creating free radicals. However, you also need UV rays to make vitamin D, a nutrient that’s critical for controlling inflammation and preventing insulin resistance. And actually, you can’t just avoid sunlight all your life and neither would you want to. You wouldn’t be able to get a tan, you wouldn’t be able to surf and sunbathe at the beach, and you couldn’t even go to waterpark without getting inflammatory acne.
Collagen has been shown repeatedly to increase your skin cells’ resistance to UV light:
This study fed patients a collagen peptide formulated to dramatically increase collagen production in the skin. The patients’ skin became highly resistance to ultraviolet-B rays, with a smaller decrease in skin hydration and less hyperplasia (proliferation) of skin cells. The scientists concluded that “these results suggest that collagen peptide is beneficial as a dietary supplement to suppress UV-B-induced skin damage and photoaging”.
Additionally, elderly people are notoriously more prone to skin cancer, and the fact that collagen plummets after age 25 is a big reason why. You can get the same benefits from the special hydrolyzed peptide supplement the scientists used, by eating more protein or vitamin C that increases collagen.