Here are some studies about the role of dietary healthy fats in photodamage prevention:
Note: Comprehensive article explaining the mechanisms through which fish-source omega-3 and omega-6 fatty acids support skin repair and photoprotection by increasing ceramide production (the glue that holds your skin cells together), inhibiting expression of matrix metalloproteinases (UV-stimulated enzymes the break down skin collagen), reducing inflammation, increasing people’s minum erythemal dose (sunburning threshold), improving skin hydration, improving skin wound healing, and deterring skin cancer development.
Association Between Dietary Intake of N-3 Polyunsaturated Fatty Acids and Severity of Skin Photoaging in a Middle-Aged Caucasian Population. (2013)
Conclusion: To investigate a possible link between photoprotection and omega-3 fatty acid intake, nearly three-thousand middle aged people were evaluated for facial photodamage severity and also had their diets evaluated over a 2.5 year period. Researchers found that those who consumed higher amounts of ALA omega-3 fats (plant/nut/seed sources) and EPA omega-3’s (fish/seafood source) demonstrated less facial photodamage compared to those with a lower intake of omega-3’s.
Note: Very good, easy-to-read overview on the role of healthy fats in skin health, repair, and photoprotection.
Effects of High-Fat Diets Rich in Either Omega-3 or Omega-6 Fatty Acids on UVB-Induced Skin Carcinogenesis in SKH-1 Mice (2011)
Conclusion: Two groups of hairless mice were fed different quality high-fat diets to test for an association with skin cancer. One group was given a diet very rich in healthy, high-quality fish oil omega-3 fats the other group was given a high fat diet rich in unhealthy fats very high in omega-6’s (soybean oil, corn oil) to simulate the typical American’s fat intake. The mice were blasted with intense UVB light adequate to induce skin cancer, twice a week, for 10 months. The mice were then euthanized and their skin examined. By the end of the study, the unhealthy fat group had more than double the amount of skin tumors as the healthy fat group. The healthy fat group also demonstrated physically smaller tumors. “Our results indicate that omega-3 fatty acids in an HFFO [high-fat fish oil] diet have beneficial effects against UVB-induced skin carcinogenesis in mice and these effects may be associated with an inhibition on UVB-induced inflammatory response.”
Effect of Eicosapentaenoic Acid, An Omega-3 Polyunsaturated Fatty Acid, on UVR-Related Cancer Risk in Humans. An Assessment of Early Genotoxic Markers (2003)
Conclusion: Randomized control trial found that daily supplementation with EPA omega-3 increased subjects MED, aka sunburn threshold.
Dietary Fish-Oil Supplementation in Humans Reduces UVB-Erythemal Sensitivity but Increases Epidermal Lipid Peroxidation (1994)
Conclusion: To test the effect of fish oil on reducing and preventing sunburn, 15 subjects took 10g fish oil supplement daily for 6 months. Their skin sensitivity to UVB light was measured throughout the study and even 2.5 months after stopping supplementation. Their minimum erythemal dose (MED – aka sunburn threshold) more than doubled over the 6-month period meaning that at the end of the study it took more than double the amount of UVB light to produce sunburn than it did at the start of the study.