Here’s the thing: You can get vitamin D from sunlight, but for many, sun exposure alone is not enough to provide all the vitamin D that your body needs. 

Even if you’re outside in the heat all day long, you still may be vitamin D deficient. “In one study, [researchers] followed migrant farmworkers in Florida, as well as farmworkers in Hawaii,” Hu says on a recent episode of Clean Beauty School. “They found significant vitamin D deficiency in farmworkers who don’t use sunscreen. So even if you work outside on the field eight hours a day in various sunny [conditions], you can still be vitamin D deficient.” 

What’s more, attempting to get enough vitamin D from sunlight risks exposing you to unsafe skin practices. Excess sun exposure, after all, is the source of about 80% of visible signs of skin aging1 and a major cause of serious skin issues (the most notable being melanoma). And even if you ignore these risks, you still might wind up vitamin D deficient!