Vc
Strong evidence

Vitamin C for Sun Damage (Photoaging)

Brightens dull skin and helps fade dark spots. Also defends against everyday UV and pollution damage when worn under sunscreen.

Why it works for Sun Damage (Photoaging)

Your skin needs vitamin C to build collagen, and it is the skin's main water-based antioxidant, mopping up the damaging molecules that UV light creates. Darr et al. (1992, PMID:1390143) showed topical vitamin C cuts UV redness and reduces sunburn-damaged cells. L-ascorbic acid at 10 to 20 percent in a low-pH formula soaks in well and adds extra sun protection on top of sunscreen when used in the morning. It also blocks the enzyme that makes pigment, so it fades sun spots. It works even better alongside ferulic acid and vitamin E.

How Vitamin C works

Donates electrons to neutralize free radicals and cofactors collagen-synthesis enzymes.