Up to 6% of adults have atopic dermatitis

 A chronic, severe form of eczema that causes skin to become dry, red, itchy, and cracked. If you have it, you’re probably eager to find out if changing your diet might help.
“It’s a reasonable question, considering that many people, including health care practitioners, promote the idea that food is the root cause of eczema,” says Peter Lio, MD, founder and director of the Chicago Integrative Eczema Center.

The bottom line: It’s not.
In reality, eczema seems to be the result of an inherited defect in the skin’s ability to act as a barrier and keep in things that are beneficial (like moisture) and keep out things that are harmful (such as irritants, allergens, and germs).
While food allergies do not cause eczema, there is a link, especially with young children.
Research shows that moisturizing the skin of babies at high risk for atopic dermatitis and food allergies appears to prevent the development of both.

The Link Between Food Allergies and Eczema Flares
There’s not a lot of research on the link between adult eczema and food. Researchers know people with atopic dermatitis are more likely to have food allergies than the rest of us. That’s most true in children: Thirty-five percent of kids with moderate-to-severe eczema have a food allergy that can trigger a flare-up, with eggs topping the list.

Hard data aren't available, but experts agree that adults with eczema are far less likely to have food allergies. Even better: When they do have them, those allergies usually don’t lead to more -- or worse -- symptoms, Silverberg says. Still, there are cases when food allergies have a powerful effect, resulting in everything from hives to anaphylaxis, a life-threatening response.
“Eating the food triggers a reaction that then triggers an eczema flare-up,” Lio says.
You don’t have to be allergic to a food for it to cause a flare-up, though.
“Certain foods can fuel inflammation in the body in a less-specific manner,” Lio says. This is called a food sensitivity or a food intolerance. The good news about these is that they tend to stop wreaking havoc when atopic dermatitis becomes better controlled.
Once atopic dermatitis is adequately treated with medication and proper skin care, studies show people are usually able to eat some foods they couldn’t before.

“When [atopic dermatitis] is poorly controlled, food sensitivity tends to go through the roof,” Lio says. “Once it’s properly managed, everything settles down and borderline foods end up being OK.”
Diagnosing Food Allergies
When should you be tested for food allergies? Experts say you should see an allergist in two cases:
When your eczema consistently flares after you eat certain foods. That usually means you’ll see a reaction on the lips and around the mouth. Rarely, your skin symptoms get worse.
When you feel like you’re doing everything else correctly and the disease isn’t responding. If you take care of your skin and use medicines as instructed and things aren’t getting better, you should probably get tested.
It’s important to know that diagnosing food allergies is difficult. A positive blood test reflects a food allergy in only up to 65% of cases. A positive skin test is accurate only about 20% of the time. At best, positive tests provide a clue to a possible allergy but shouldn’t be accepted as the last word.
“On the one hand, we certainly wouldn’t want to ignore a potentially relevant allergen that might cause serious consequences,” Silverberg says. “On the other hand, it might simply be a false positive and much ado about nothing.”
The surest way to diagnose an allergy is if your eczema gets worse after you eat a specific food. Sometimes this is only a coincidence, though. Even so, it would need to be verified with something called a food challenge. That’s where the food in question is removed from the diet and then brought back in at the doctor’s office.

Experts differ about having patients conduct food challenges on their own.
“It’s totally reasonable to stop eating a suspicious food for a month or two, and then try adding it back,” Lio says. If a bad flare-up occurs, you can say this is a contributing food and then continue to avoid it. If nothing out of the ordinary happens, you can resume eating it.
The danger can be when people eliminate several foods at once. Such “elimination diets” can be extreme and very challenging. For example, some try to exclude all of the foods people tend to be allergic to -- dairy, eggs, soy, gluten, peanuts, tree nuts, fish, shellfish, and wheat.
Besides rarely being helpful, these types of diets can cause malnutrition and other problems. They should only be tried under the supervision of your doctor.
What About Gluten?
There’s been more focus on gluten-free diets recently, even for those who don’t have a proven allergy or sensitivity to it. Some think gluten, a protein naturally in wheat, barley, and rye, ups inflammation that can worsen eczema.
The attention seems warranted. One study looked at more than 1,000 patients with celiac disease (where gluten causes an immune-system reaction) and found that atopic dermatitis was about three times more common in these people. Unfortunately, one year on a gluten-free diet didn’t change the amount of atopic dermatitis or allergies in them.
Still, there are many people, virtually none of whom have celiac disease, who are convinced that gluten made their atopic dermatitis worse and that eliminating it improved their skin, Silverberg says. He suspects these cases are likely some form of gluten intolerance. That’s almost impossible to prove or disprove with the limited testing available today.
If you’re thinking about going gluten-free, be careful. A gluten-free diet can lack vitamins, minerals, and fiber, and sometimes the gluten is replaced with sugar and saturated fat to add flavor. Talk to a nutritionist before trying one.

More Food For Thought
There aren’t any miracle foods that keep eczema at bay. But eating a healthy, balanced diet with lots of vegetables and minimal junk food may be helpful, says Silverberg, who notes one study associated atopic dermatitis with a Western-style diet.
Another option is the Paleo diet, which consists chiefly of meat, fish, vegetables, and fruit and excludes dairy, grain products, and processed food.
“It’s a very smart, anti-inflammatory diet that’s very hard to argue against,” Lio says. “It’s gluten-free, dairy-free, and processed-food-free. It’s vegetable-rich and has complete nutrition.” If you opt to try the Paleo diet, Lio recommends eating fish, particularly fatty fish like salmon, as your primary protein source to get the most anti-inflammatory benefits.