How Eczema and Food Allergies Are Linked

Eggs, milk, and wheat, foods that can trigger ezcema

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There is a clear connection between atopic dermatitis (eczema) and food allergies. While eczema is known to be triggered or worsened by certain food allergies, there is evidence that eczema may be responsible for the development of these allergies in the first place. In some cases, allergy screening may be recommended if you or your child is newly diagnosed with eczema.

Prevalence

Eczema and food allergies are common in the developed world. Research suggests that eczema affects roughly 20% of children and up to 5% of adults. By comparison, around 7% of children and 6% of adults have at least one food allergy.

While a connection between allergic or atopic diseases long been recognized, a 2017 review published in The Lancet reported that up to 81% of people with eczema were also found to have some form of food allergy. According to the researchers, eczema appeared to precede the development of the allergy, suggesting that the former somehow triggered the latter.

It is a pattern identified in other studies, which scientists today refer to as the "atopic march." This describes a pattern of development in which eczema generally appears first, followed by food allergies, seasonal allergies, and asthma.

Food allergies are today recognized as a comorbidity (related health condition) of eczema along with allergic rhinitis (hay fever) and asthma.

Symptoms

Food allergies are more likely to cause eczema flares in infants and people with severe eczema. Symptoms can develop soon after eating an offending food or up to several days later, and may include:

  • Itching that tends to get worse at night
  • Increased dryness, redness, and swelling
  • Formation of tiny bumps that can ooze and crust over

Eczema symptoms can wax and wane, often for no apparent reason. Just because a flare occurs after eating doesn't mean that food was the cause. An extensive evaluation by an allergist may be the only way to determine if an allergy was, in fact, the cause.

Causes

Why eczema tends to precede a food allergy is still something of a mystery. Part of the explanation may be in the way in which each develops.

An allergy, by definition, is an abnormal immune response to an otherwise harmless allergen (such as food or pollen). By contrast, eczema is one of several atopic disorders in which a hypersensitive reaction occurs as a result of allergen exposure on another part of the body.

It has been hypothesized that eczema "landscapes" the body for allergy, in part, by diminishing the barrier function of the skin. As the structure of skin cells collapses, it not only causes the loss of moisture but allows allergens and irritants to infiltrate vulnerable tissues. This, in turn, triggers an immune response in the form of inflammation.

It is believed that this "hypersensitizes" the immune system to the various allergens it encountered on the skin, causing an exaggerated response when those allergens are later eaten or inhaled.

This may explain why kitchen workers with eczema are more likely to develop food allergies than people with eczema who don't work in kitchens. The increased exposure to food allergens appears to amplify the risk, suggesting that the environment plays as strong a role in the development of allergy as physiology.

Once the flip side, food allergies can trigger eczema by causing the itching and swelling. Scratching only makes things worse.

Itch-Scratch Cycle

Eczema flares are frequently triggered by the "itch-scratch cycle." This is when itching leads to scratching, which triggers the release of inflammatory compounds, which instigate a flare. Eczema symptoms, in turn, lead to more itching, perpetuating the cycle.

Risk in Children

Food allergies are also more common in people who develop eczema early in life compared to those who experienced a later onset of disease. Moreover, those who develop eczema as infants or in early childhood are more likely to experience severe food allergy symptoms.

A 2019 study published in Science Translational Medicine reported that children with both eczema and food allergies had significant differences in their skin at the molecular level when compared to children with eczema only. Not only was their skin more prone to moisture loss, but they were at a far greater risk of Staphylococcus aureus skin infections.

This suggests that eczema associated with food allergies may, in fact, be an entirely unique subtype of atopic dermatitis.

Common Food Triggers

Though food allergies don't cause eczema, they can trigger a worsening of existing eczema symptoms. The process by which flares are triggered can vary by the type of food eaten as well as the immunologic response of the individual.

IgE-Mediated Food Allergies

True food allergies are triggered by a reaction called an immunoglobulin E (IgE)-mediated immune system response. This involves the release of IgE by the immune system which stimulates the production of histamines that cause allergy symptoms.

The foods that are most likely to trigger an IgE response in people with eczema are also among the most common food allergens in the United States, namely:

  • Eggs (the allergy of which is six times more common in infants with eczema)
  • Milk (not to be confused with lactose intolerance)
  • Soy (not to be confused with soy-protein enterocolitis).
  • Wheat (not be confused with gluten intolerance)
  • Peanuts (the allergy of which is 11 times more common in infants with eczema)

IgE-associated food allergies can be difficult to diagnose and avoid as many of the offending foods are used as ingredients in other food and non-food products.

Non-IgE-Mediated Food Allergies

Non-IgE-mediated food allergies are those in which IgE is not involved. These are hypersensitivity reactions that mainly take place in the intestines after certain foods have been eaten. Among these are celiac disease, food-protein-induced enterocolitis, and allergic proctocolitis (primarily seen in infants).

Non-IgE food allergies can manifest with both gastrointestinal symptoms (such as vomiting, diarrhea, gas, and stomach pain) and a flare of eczema symptoms. Non-IgE food allergies are different from IgE food allergies in that the symptoms tend to be delayed until food passes into the intestines, making them harder to diagnose.

The most common non-IgE mediated food allergens associated with eczema include:

  • Milk
  • Eggs
  • Wheat
  • Soy

The good news is that most children with non-IgE-mediated allergies will outgrow them by the time they reach adulthood.

Food Sensitivities

Many people with eczema will report reactions to food even though there are no actual allergies involved. These can be aptly described as food sensitivities or intolerances.

With food sensitivities, there is no immune response but the gastrointestinal symptoms caused by them can trigger eczema in some people. Intestinal inflammation is believed to be the key instigator.

Non-celiac gluten intolerance is a common food sensitivity. It is neither an allergy nor does it trigger an immune reaction. Gluten has also been closely linked to an eczema-like rash called dermatitis herpetiformis.

Other examples of food sensitivity include lactose intolerance and intolerance to fermentable carbohydrates called FODMAPS. Some of the other foods linked to food sensitivities and eczema are:

  • Sugar
  • Citrus
  • Tomatoes
  • Apples
  • Kiwi
  • Tree nuts
  • Spices
  • Vanilla
  • Caffeine

Diagnosis

There is no consensus as to who should be tested for food allergies and who should not. Some physicians recommend screening for food allergies in anyone with eczema, whereas others believe that testing should be performed if flares are severe or frequent.

Some doctors are reluctant to test due to the high rate of false-positive results. A false positive could very well motivate for changes in diet that are simply not needed.

Still, there are times when testing are appropriate. Food allergy testing is typically recommended when:

  • Moderate to severe eczema does not improve with treatment.
  • Eczema symptoms are worsening despite treatment.
  • A food allergy is suspected.

The American Academy of Dermatology recommends food allergy testing for all children younger than 5 whose eczema is not being controlled with treatment.

Labs and Procedures

A doctor or allergist can determine if food allergy testing is necessary and what forms of testing are appropriate. Among the options:

  • A food diary involves taking notes of the foods you eat and any symptoms you may experience. By identifying food triggers, you can better avoid them.
  • Skin prick testing involves the introduction of food allergens under the skin to see if you react to any of them.
  • Allergy blood tests measure the level of IgE in blood and, while far less sensitive than skin prick tests, may help support a diagnosis.
  • Food challenges involve the consumption of suspect foods under controlled conditions to see if a reaction occurs.
  • Elimination diets involve the removal of suspect foods from the diet for around two weeks. If symptoms improve, the foods will be added back to the diet one-by-one to determine which are causing symptoms.

All of these tests have their limitations. A positive result does not inherently mean that food is the cause of an eczema flare. Clinical expertise is often needed to interpret the results and, even so, there can be a high level of uncertainty.

Treatment

The treatment of eczema and food allergies is multifaceted and not only involves avoiding certain foods but treating eczema or allergy symptoms when they occur. In the end, neither eczema nor food allergies can be cured, but they can be treated.

The elimination of foods from your diet should be done under the supervision of a doctor or nutritionist. Avoiding certain foods or food groups (like dairy or wheat) can have serious consequences, depriving you of the nutrients and fiber you need to remain healthy.

Sadly, allergy shots used to treat seasonal allergies or hay fever are not effective for food allergies.

Probiotics

While there are no foods or dietary supplements known to treat eczema, some studies suggest that probiotics, prebiotics, and synbiotics (a combination of probiotics and prebiotics) may help. These work by supporting the bacterial flora in the gut and may help reduce the underlying inflammation that drives eczema symptoms. Foods rich in probiotics include yogurt, miso, and kefir.

According to a review of studies published in JAMA Pediatrics, the use of synbiotics for at least eight weeks improved eczemas symptoms in children one year of age and older. The effect was not seen in children under one.

Synbiotics containing multiple bacterial strains proved far more effective than single-strain probiotics in relieving symptoms.

Vitamin D

There is evidence that sun exposure can relieve eczema symptoms by increasing vitamin D production in the skin. While it is unclear whether an increased intake of vitamin-D-rich foods (like dairy, orange, and egg yolks) can do the same, it is certainly beneficial to bone health and the overall immune function.

People with lactose intolerance or a milk allergy can increase their intake of vitamin D with a daily supplement if needed. Overuse should be avoided as it can lead to vitamin D toxicity.

Anti-Inflammatory Diet

An anti-inflammatory diet involves the exclusion of foods known to promote inflammation (such as saturated fats) and the increased intake of foods with anti-inflammatory effects (such as those rich in omega-3-fatty acids).

It is presumed that by reducing inflammation in the gut, the risk of eczema may also be alleviated. To date, there is little solid evidence that this can improve eczema symptoms, particularly since it doesn't address allergy or other causes of inflammation.

With that said, the anti-inflammatory effects of omega-3s (found in fatty fish such as salmon, mackerel, sardines, and herring) are known to be beneficial to the heart and circulatory system.

Coping

If you or your child has been diagnosed with a food allergy, avoiding food allergens may help improve eczema symptoms but may not be the "magic bullet" you had hoped for. Even if an allergen is found, the impact that it has on eczema can vary from one person to the next. In some cases, the benefits may be minimal.

Eczema is a multifaceted disease with many interlinked causes and triggers. Ensuring long-term remission typically requires a multi-faceted approach. Among some of the self-care tips that can help:

  • Read ingredient labels. Food allergens (like wheat fillers and whey) are not only found in foods but also in supplements, cosmetics, and skincare products. By learning how to read labels—and learning the alternate names for food allergens—you can better avoid accidental exposure.
  • Take an antihistamine. There is no evidence that antihistamines can prevent eczema, but they may reduce itching and swelling if an allergy occurs. By doing so, you will be less likely to scratch and make things worse.
  • Reduce the itch. In an itch is driving you mad, rather than scratching, apply a moist, cool towel to the skin. Some people also keep moisturizing lotion in the refrigerator for an immediate cooling effect.
  • Meet with a nutritionist. If certain foods need to avoided (like milk or wheat), a nutritionist can help you find ways to replace lost nutrients and teach you how to read food labels to avoid accidental exposure.
  • Deal with food cravings. Being told you can't eat certain foods can often increase your cravings for those foods. Prepare for this by stocking up on snacks you can nibble whenever cravings strike or drink plenty of water until the cravings pass.
  • Exercise regularly. Exercise not only reduces stress (a major risk factor of eczema but also boosts serotonin levels that suppress hunger cravings.
  • Eliminate other triggers. People with food allergies tend to have other hypersensitivities. These may common eczema triggers like dust mites, pollen, heavy fragrances, cigarette smoke, and extreme hot or cold temperatures.
  • Dine out safely. Check the restaurant menu online if you plan to dine out, and don't hesitate to call the restaurant in advance to check if a dish is safe for you to eat.

When to Call a Doctor

As the recognition of eczema and food allergies has increased, so, too, has awareness about the serious health risks associated with the comorbid conditions.

Chief among these is anaphylaxis, a potentially life-threatening, whole-body allergy that may pose a risk to certain people with eczema. The risk appears greatest in those who undergo an elimination diet and are later reintroduced to a trigger food.

According to a 2016 study published in the Journal of Allergy and Clinical Immunology, 18.9% of children with eczema but no previous history of food sensitivity experienced an allergic reaction after the initiation of an elimination diet. Of these, 30% experienced anaphylaxis.

To this end, any allergy in a child with eczema should be reported immediately. Severe allergic reactions should be treated as a medical emergency even if the initial symptoms appear to be waning.

Anaphylaxis Symptoms

  • Severe rashes and hives
  • Swelling of the lips, tongue, or throat.
  • Shortness of breath
  • Wheezing
  • Dizziness or fainting
  • Rapid heart rate
  • Nausea or vomiting
  • Diarrhea
  • Confusion
  • A feeling of impending doom

If left untreated, anaphylaxis can lead to coma, shock, respiratory or heart failure, and death.

Prevention

While there is no real way to prevent eczema, there is increasing evidence that the appropriate introduction of food to infants and children may reduce the risk of certain food allergies. In fact, most research today suggests that gradually exposing a child to common food allergens can help reduce the risk of allergies compared to the avoidance of allergens.

The American Academy of Pediatrics currently recommends exclusive breastfeeding for four to six months, followed by breastfeeding in combination with the introduction of complementary foods until the child is at least 12 months of age. This includes the early introduction of peanuts to reduce the risk of peanut allergy.

Children with mild to moderate eczema should be introduced to peanuts starting at six months. Children with severe eczema, an egg allergy, or both should first undergo a skin prick and IgE test to ensure they do not already have a peanut allergy.

Other studies have looked into the early introduction of cow's milk and eggs, but there is not enough research yet to conclude if the same strategy might prevent milk or egg allergies.

A Word From Verywell

Eczema is a serious condition that can diminish the quality of life of individuals as well as their families. The uncomfortable and often unsightly rash can be distressing enough without the added burden of a comorbid allergy.

Fortunately, there are ways to manage both conditions. While a solution may take time, by working with the appropriate specialists—including a dermatologist, allergist, and nutritionist—you are more likely to restore your quality of life and improve your overall health. Patience and persistence are key to obtaining an informed diagnosis and effective treatment.

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Article Sources

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