I do all of the things I’m supposed to do in order to boost my immunity and nourish my bod. I drink a shot of apple cider vinegar every morning, try to include ginger in my diet whenever I can, and I load up on vitamin C (not just topically). But I’ve never really thought about the immunity of my skin, or that my complexion might be able to get malnourished, and as it happens that might be a mistake.

“The skin is your body’s largest organ and plays an important role in overall immunity by providing a barrier of protection to the body,” says Naomi Whittel, wellness expert and founder of OMI Skin Nutrition, a new line of skin care launching this month. “The skin also has its unique microbiome, and the beneficial bacteria that live in and on it contribute to the immunity of your skin.”

After all, skin is the first thing that pollution, chemicals, and all the crud from the environment touches. The outer layer is protecting your body from a ton of environmental aggressors, and that’s precisely why you want your skin to be well-functioning and strong. According to the pros, here’s how to strengthen the barrier function of skin for optimal skin immunity and nourishment.

How to tell if your skin’s malnourished

Essentially, your skin’s a reflection of what’s going on in your body. “When your body’s lacking key nutrition including water, collagen, omega-3 fats, vitamin A, zinc, selenium, probiotics, and polyphenols, the result is dull skin that often shows premature signs of aging, as well as inflammation,” explains Whittel. “Nourishing the body’s key nutrition can turn the skin around from the inside out, through detoxification and autophagy—your body’s cellular recycling and rejuvenation.”

That’s why more-and-more skin experts are talking with clients about diet and not just topical solutions for skin qualms. “Since your skin thrives off of the same nutrients, many skin issues steep from the same sources: imbalance and inflammation,” says April Gargiulo, founder of Vintner’s Daughter. “Imbalance and inflammation are majorly due to your diet and lifestyle, and then 20 percent is topical.”

And just how do you look for signs of this imbalance and inflammation? Your typical skin woes: “It’s red, it’s super reactive, it’s dry in some places and super oily in others,” explains Gargiulo, whose new Active Treatment Essence ($225) is meant to replenish skin with potent vitamins and nutrients. “A lot of the times the malnourishment is from being over-processed—too many products on the skin, and some that are harsh, so the skin’s microbiome is imbalanced.” This matters because once skin is aggravated and stripped of the things that it needs to make it happy, the barrier and immune function can become compromised.

“A lot of the times the malnourishment is from being over-processed—too many products on the skin, and some that are harsh, so the skin’s microbiome is imbalanced.” —April Gargiulo

Besides that, Whittel notes that your complexion will have an overall dullness to it. “You can likely tell [if your skin’s malnourished] if it’s lackluster, you notice an uneven skin tone, or if it’s overly dry or oily,” she says, adding that signs of inflammation point to it as well (like acne, rosacea, eczema, etc.). This all goes to say that your skin’s barrier has been compromised, so it can’t properly protect your skin from environmental factors.

How to boost your skin’s immunity

The important thing to remember is that your skin’s health is not only an outside job—it can’t be fixed with just a serum. “Skin malnutrition can never be solved via the surface alone—you need to give your skin the right nutrition from the inside and outside to maximize your skin’s potential,” says Whittel.

That being said, your diet is an influential factor in your skin’s immunity—so get in a variety of healthy fats, high-quality protein, colorful fruits and veggies, and fiber, according to Whittel. “Vegetables and herbs that provide antioxidants, polyphenols, and fiber are good, and include fermented foods like sauerkraut, yogurt, and kefir to help nourish the microbiome of the skin,” she says. “Supplemental polyphenols include resveratrol, curcumin, berberine, and EGCG from green tea.”

On a topical level, cut down on harsh ingredients and stick with a simple regimen. “When you use sulfates, you’re disrupting the natural barrier of your skin,” says Cybele Fishman, MD, a board-certified dermatologist in New York City. “The reason is that sulfates are alkaline, and your skin operates best in an acidic environment. And when you disrupt the acid mantle of the skin, one of the things you disrupt is the skin’s immune abilities—people don’t think of the skin as an immune organ, but it absolutely is.”

That healthy bacteria on your skin is important—so look for sulfate-free, vitamin-packed cleansers as your first step if you’re looking to replenish the barrier. “Good bacteria on your skin help fight bad bacteria, so if you kill good bacteria by using antibacterial cleansers, you’re harming your skin’s ability to protect itself,” says Dr. Fishman. Gargiulo also stresses that your skin basically needs all the vitamins and minerals that your body does via its diet—so look for everything from vitamins A to Z, your omegas, fatty acids, and amino acids.

Your lifestyle has an impact on your skin health as well (hello, stress skin). “Getting good sleep, moving the body, sweating and managing your stress also help increase your skin’s immunity,” says Whittel. So overall, a healthy you equates to a solid skin immune system that’s properly nourished and therefore protecting you from the outside world—don’t underestimate the power of your dermis.

Also, read up on your skin’s microbiome connection, AKA how your stools and your skin indicate an imbalance in the gut. And here are some gut-healthy, immunity-boosting recipes from Seamus Mullen.