There’s quite a bit of research on the topical application of nutrients to the skin and hair. Topically applied retinoids, carotenoids, nicotinamide, vitamin C, and vitamin E have all been studied for their effects on skin health.[1]
Topically applied caffeine, capsaicin, curcumin, garlic, melatonin, onion juice, and rosemary oil all show some promise for treating hair loss.[2]
Additionally, it’s advisable to use a broad-spectrum sunscreen, even if you aren’t spending much time in the sun.[3]