What it is and why it’s important: Vitamin D is a hormone our bodies produce in response to sunlight, and it’s critical for healthy immune function. Some studies estimate that about two in five Americans are vitamin D deficient. Many studies link vitamin D deficiency with a higher risk of respiratory tract infections, and some draw a relationship between low vitamin D and certain autoimmune conditions. There are a few reasons why your body might not be making adequate vitamin D, like if you don’t spend much time in the sun, wear sunscreen religiously, or have dark skin.
How to get more of it: While it’s usually true that you can get the vitamins and minerals your body needs from a varied diet, it’s difficult—and, we have to admit, unrealistic—to get enough vitamin D from food alone. We recommend a supplement, like the capsule from Hum Nutrition or the oral spray from The Nue Co, to meet your daily goals. That said, if you want to work more vitamin D into the food you eat, there are a couple approaches to try. First up, you can eat more fatty fish, like salmon, mackerel, tuna, or swordfish. Baking your fish may retain vitamin D content better than frying does. (While you’re at it, leave the skin on to get the most out of their omega-3 fats).
Then, mushrooms: Mushrooms, like us, have the capacity to produce vitamin D in response to sunlight, but they’re typically grown in the dark and don’t get much exposure on their way from harvest to your kitchen. If you leave your mushrooms out in the midday sun for a while—we’re talking anywhere from fifteen minutes to a couple of hours—they can produce vitamin D. (How much exactly will vary depending on the type of mushroom, how long you leave it out, and what the weather’s like.) Egg yolks and fortified foods like cow’s milk or orange juice can be other sources.