Like plants, humans need sunlight to grow—but we need to balance this with protecting our skin from the sun’s fearsome strength.
Like a stretchy covering of solar panels, the outermost layer of your skin harnesses the sun’s ultraviolet (UV) rays to create the life-essential vitamin D.
Unfortunately, this type of UV ray called UVB has the same skin-burning frequency that causes skin cancer, wrinkles, and eye damage. Sunscreen offers some protection, but it also blunts vitamin D production. Like any medicine, some sunlight is good—but not too much, especially if you’re fair-skinned. Our skin tone comes from melanin, a substance that acts like a biological bulletproof vest to shield our skin’s precious DNA by absorbing slugs of UV light and dissipating its powerful punch as harmless warmth.The darker your skin, the more UV-blocking melanin you have, so you need more sunlight than a fairer-skinned person to produce enough vitamin D. Darker-skinned people living in latitudes where the sun is weaker should consider taking vitamin D supplements, especially in winter.
There is a sweet spot of safe sun exposure—too little and you risk vitamin D deficiency; too much and you risk skin damage. Those with darker skin—and more melanin—can spend longer in the sun, but melanin can’t protect you indefinitely.