Thus far, we’ve looked at why getting some sun is actually good for you, how to wisely choose and apply sunblock, and how to time your sun exposure to allow the maximum number of hours outside.

Today, however, we’ll be working from the inside out, starting with Polypodium leucotomos, a green leafy fern found in the wilds of Central and South America. Polypodium initially evolved as an aquatic plant, before a changing environment forced it to adapt to life on land. Unable to leverage the sun-blocking effects of water-cover as it had when it lived underwater, the fern instead evolved to produce powerful antioxidants that offset the free-radical damage of all-day above-water sun.

As recent research has shown, those fern antioxidants work nearly as well inside of you, too. By taking pills that contain Polypodium leucotomos extracts, like Heliocare or Solaricare, you can triple or quadruple your natural resistance to burns. In other words, if it might normally take you 15-20 minutes to scorch at a given UV intensity, you could instead hold out for a full hour.

And while, in most cases, that’s not enough to supplant sunscreen, given how quickly sunscreen sweats and washes off (as previously discussed, ‘waterproof’ sunscreens are designed to weather just 40 minutes of swimming and sweating), a belt-and-suspenders approach seems like reasonable insurance.

Pick up some Heliocare or Solaricare, pop one in the morning, and another before and every few hours during your time in the sun. If nothing else, you can offset the $20 cost of a bottle by the money you’ll save on aloe vera. (Which, as we’ll see in the next installment, doesn’t really do much of anything anyway.)