Human beings are thin-skinned. It varies from about 0.0197 inches thick on your eyelids to about 0.157 inches on the (uncalloused) heels of your feet.

But that thin covering mounts a powerful defense against disease, environmental toxins, and aging. Totaling around 22 square feet, your skin contains 20 trillion immune cells and 1,000 types of friendly bacteria. (You have a skin biome, just like you have a gut biome.)

A new study reveals that your skin also contains hemoglobin, the protein in your red blood cells that binds oxygen. In your skin, it appears to function as an antioxidant that helps control inflammation and may protect against the sun's rays and other external hazards.

With such protective powers, how does skin get damaged and wrinkly? And what happens inside your body when your skin loses some of its protective powers?

Overexposure to the sun and a diet loaded with inflammatory foods weaken the skin, so wrinkles and discoloration appear. In addition, such skin damage allows the release of harmful chemicals into your bloodstream.

To protect your skin and your overall health, wear a micronized zinc-based 35 SPF sunscreen year-round; wash your face with pH-neutral cleansers to protect your skin's natural oils (they are part of the effective barrier); enjoy an anti-inflammatory diet of fruits, vegetables, and healthy fats; and avoid added sugars and syrups. They trigger inflammation and erode the skin's collagen.