Polypodium supplementation can increase the minimal erythema dose of UV exposure.

“polypodium is a fern from the Amazon rainforest that was discovered when they studied an indigenous population that would eat this Fern before they would go on their fishing Expeditions on the Amazon and they'd be gone for 3 Days they'd eat this Fern and come back not burned so a lot of studies were done on this Fern in the last 5 10 years that showed it increases your Skin's minimal athema dose the amount of redness your skin gets from UV exposure that's our general barometer for Effectiveness without any topicals it's taken or ingested orally”