food allergy

Will This Trigger My Food Allergy?

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Peanuts

Peanuts

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They’re in lots of products, including baked goods and sauces. Always check the food label. Packages must say if they have peanuts. When you eat out, ask how the food is prepared and let servers know you’re allergic. You should also avoid tree nuts, like walnuts or almonds, if they bother you.

Dairy Foods

Dairy Foods

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Milk is one of the most common food allergy triggers for kids. Most outgrow it. In the meantime, your baby may need hypoallergenic or soy formula. Look at the label on packaged foods. Even things like tuna can have milk protein in it. Sometimes it shows up as the ingredient casein.

Eggs

Eggs

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It’s not just a problem with omelettes. Eggs are in many foods, including noodles, mayonnaise, and baked goods. They can also be in some surprising places, like the foam topping on drinks or the egg wash on pretzels. They’re used to make most flu vaccines, too, so check with your doctor before you get it.

Shellfish

Shellfish

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You can get a sudden seafood allergy as an adult. If you do, it’ll typically stick with you for life. Shrimp, crab, crawfish, and lobster can all cause serious reactions. Clams, mussels, scallops, escargot, octopuses, and squid can be triggers, too. If you’re allergic, avoid all shellfish.

Tree Nuts

Tree Nuts

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They can even be in lotions made from tree nut oils, like shea oil. Packaged foods must list them. But they’re harder to avoid in restaurants and bakeries. If you’re allergic, watch out for walnuts, almonds, pecans, hazelnuts, cashews, pistachios, Brazil nuts, and pine nuts. Nutmeg, water chestnuts, sunflower seeds, and sesame seeds aren’t nuts and should be OK.

Fish

Fish

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Some people are allergic to fresh salmon, tuna, or halibut. If you’re allergic to one type of fish, you may react to others, too. Be careful of the fish sauce in Thai and Chinese food. The same goes for Caesar dressing and Worcestershire sauce, which often have anchovies in them.

Soy

Soy

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Breads, cookies, canned soups, processed meats, and snack foods all can have soy in them. If you’re allergic, read food labels so you can steer clear. Also avoid the traditional soy foods: edamame, tofu, soy milk, miso, and soy sauce. Babies and children are more likely to have this allergy than adults.

Wheat

Wheat

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It’s in a lot of things, from bread to beer, and salad dressing to deli meats. Why? Wheat proteins help some processed foods stick together and give them texture. If you’re allergic to wheat, other grains — like barley, oats, rye, corn, and rice — may be safe. But you may need to avoid bulgur, couscous, and farina. It’s possible to have a wheat allergy but be OK to eat gluten.

Gluten Sensitivity?

Gluten Sensitivity?

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You can be sensitive to something but not allergic. Gluten is usually found in wheat, rye, and barley. If you’re allergic, your immune system reacts to any food that has it. And it can cause permanent damage to your intestines when you have Celiac disease. You may also find that gluten upsets your digestive system, without Celiac disease or an allergy. It doesn’t cause permanent damage, but you may want to avoid it.

How a Food Allergy Starts

How a Food Allergy Starts

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You eat or drink a trigger food and your immune system kicks into gear. You won’t notice any allergy symptoms like a rash or itching this first time, but your body will watch out for that item again. The next time you eat it, since your body thinks the food is bad, it’ll release the chemical histamine, which causes allergy symptoms such as rashes, itching, and swelling.

Know the Symptoms

Know the Symptoms

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If you eat something you’re allergic to, your symptoms will probably start pretty quickly. It could take just a few minutes to 2 hours. You could have: 

  • Hives or another skin rash
  • Tingling or itching in your mouth
  • Swelling of your face, tongue, or lips
  • Coughing or wheezing
  • Vomiting, diarrhea, or belly cramps
  • Swelling of throat and vocal cords
  • Trouble breathing
The Riskiest Reaction

The Riskiest Reaction

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Symptoms can sometimes be life-threatening. This is called anaphylaxis. When this happens, you may have trouble breathing and your blood pressure may drop. If you have food allergies, your doctor might prescribe epinephrine shots to always carry with you. If you have food allergies, your doctor might prescribe epinephrine shots to always carry with you. Call 911 and give yourself a shot at the first sign of symptoms. Children with a severe peanut allergy may also be prescribed the newly approved drug Palforzia to help lesson symptoms.

You Can't Always Predict It

You Can’t Always Predict It

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One bite of seafood went down OK last time. Does that mean that much is fine for you? Not necessarily, if you’re allergic. In general, the size of your allergic reaction you’ll have depends on how bad the allergy is and how much of the trigger food you eat. But reactions can surprise you. Yours could be more severe next time.

Intolerance or Allergy?

Intolerance or Allergy?

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Even if you have trouble digesting something, like milk or gluten, it may not be an allergy. Your body may not handle that food well, and have bloating, cramps, and diarrhea. But if it doesn’t involve your immune system, it’s not an allergy.  For instance, lactose intolerance happens when your body can’t break down lactose, the sugar in milk and dairy products.

What About Food Additives?

What About Food Additives?

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You can have a reaction to them without being allergic. MSG (monosodium glutamate) can cause flushing, warmth, headache, and chest discomfort. Sulfites, which are found in some dried fruits, wine, and other foods, can cause breathing problems for people with asthma. Food labels must list sulfites.

What Is Oral Allergy Syndrome?

What Is Oral Allergy Syndrome?

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Some people who have hay fever, especially triggered by birch or ragweed pollen, react to uncooked apples, cherries, kiwis, celery, tomatoes, and green peppers. They feel tingling, itching, or swelling of the lips, tongue, or throat. And they can get watery or itchy eyes, and a runny, sneezy nose.

When Exercise Triggers It

When Exercise Triggers It

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This problem happens only in some people when they eat something they’re allergic to right before they exercise. Their body temperature rises and the food can cause an allergic reaction, such as itching, hives, lightheadedness, or even anaphylaxis. The items most likely to trigger this type of allergy are shellfish, alcohol, tomatoes, cheese, and celery. Avoid your trigger foods for a couple of hours before you exercise.

Should You Try an Elimination Diet?

Should You Try an Elimination Diet?

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If you’re not sure what caused an allergic reaction, write down what you eat and how you feel. It can show possible triggers. Or ask your doctor about going on an elimination diet. On this plan, you stop eating one suspicious food at a time. This may help you figure out which food causes your allergy.

How to Tell for Sure

How to Tell for Sure

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You may need tests to find out if you have a food allergy.

Skin prick test — This is the most common one. An allergist puts a drop of liquid on your skin, then pricks the skin to allow it to soak in. No reaction means you’re not allergic.

Blood test — Your doctor takes a sample of your blood to see if it reacts to certain triggers.

Supervised food challenge — While a doctor watches, you eat foods to see if you react.

Will Your Child Outgrow It?

Will Your Child Outgrow It?

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Kids are likely to outgrow allergies to milk, eggs, wheat, and soy. But children with peanut, tree nut, fish, and shellfish allergies usually have them for life. If you want to see whether your kid has outgrown their allergy, your doctor can do a blood test. Do not feed your child a possible trigger food on your own to check. Even a small amount could cause a life-threatening reaction.

Tips to Manage Your Food Allergy

Tips to Manage Your Food Allergy

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You’ll need to avoid your trigger foods and read labels to check ingredients. Make a plan for what you need to do if you or your child accidentally eats something off-limits. At the first sign of anaphylaxis, (wheezing, trouble breathing, dizziness) call 911 and use an epinephrine shot. Give yourself another shot if your symptoms don’t get better. It’s wise to wear a medical ID bracelet, or carry something that says you have the allergy.

No association found between mode of birth, risk for food allergy

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Whether infants were born via vaginal or cesarean delivery did not lead to meaningful differences in likelihood of food allergy at age 12 months, according to a study published in The Journal of Allergy and Clinical Immunology.

The lack of likelihood persisted regardless of onset of labor or whether cesarean deliveries were elected or emergent, Anne Currell, MEpi, a researcher in population health at Murdoch Children’s Research Institute in Parkville, Victoria, Australia, and colleagues wrote.

13.2% of infants born via vaginal delivery and 12.7% of infants born via cesarean delivery had developed a food allergy by at 12 months.
Data were derived from Currell A, et al. J Allergy Clin Immunol. 2022;doi:10.1016/j.jaip.2022.03.031.

The researchers examined 2,045 infants born between September 2007 and August 2011 in the Melbourne area from the HealthNuts population-based longitudinal study, where parents completed questionnaires and infants underwent skin prick testing, oral food challenges and blood collection.

Of the included infants, 70% were delivered vaginally, 12.5% were born by cesarean section after the onset of labor and 17.5% were born by cesarean section before the onset of labor. Also, 14.9% of births were emergency cesarean sections, and 15.2% were elective cesarean sections.

Overall, 13% of infants were sensitized to food and 18.7% had food allergy.

Food allergy occurred among 12.7% of infants born via cesarean delivery and 13.2% of those born vaginally, indicating no evidence of an association between type of delivery and risk for any food allergy (adjusted OR = 0.95; 95% CI, 0.7-1.3), including to egg (aOR = 0.8; 95% CI, 0.57-1.13) or peanut (aOR = 1.11; 95% CI, 0.69-1.91).

However, food allergy occurred among more children born by cesarean section after labor had started (14.2%) than those born vaginally (13.3%) or via cesarean without labor (11%), but adjusted models showed no association between labor and risk for any food allergy, including egg or peanut allergy.

Fewer infants born via emergency cesarean section experienced food allergy (11.2%) than those born via elective cesarean section (13.4%) or vaginal delivery (13.3%), but adjusted models indicating no risk for any food allergy — egg or peanut included — based on these qualifications.

The researchers additionally found no evidence for increased risks for food allergy based on breastfeeding, older siblings, a pet dog or maternal history of allergy, with similar results for egg and peanut allergies.

Similarly, the researchers continued, there was no evidence of an association between mode of cesarean birth (with or without labor, or elective or emergency cesarean) and risk for food, egg or peanut sensitization compared with vaginal delivery.

The researchers noted the microbial exposure hypothesis, which proposes that altered exposure to microbes and infections early in life could predispose infants to allergic disease, with mode of delivery potentially influencing the microbiome.

However, the researchers wrote, their results suggest that gut colonization may begin in utero and have an impact on the infant’s microbiome and on risks for allergic disease, not just mode of delivery.

Caregivers can consider these findings, the researchers continued, in advising patients about the benefits and risks that come with cesarean delivery and in reassuring them that their infants are not likely to be at increased risk for food allergy.

Reference:

PERSPECTIVE

BACK TO TOP Tetsuhiro Sakihara, MD)

Tetsuhiro Sakihara, MD

The authors demonstrated that elective or emergency cesarean delivery with or without labor was not associated with the risk for food allergy development at age 12 months in HealthNuts cohort participants. One of the strengths of this study was its use of OFC tests to confirm food allergies.

Although there was no significant difference, infants born through vaginal delivery had a higher proportion of egg allergy development compared with those born through cesarean delivery in this study. On the other hand, the proportion of peanut allergy development was higher in those born through cesarean delivery compared with those born through vaginal delivery.

Our nested case-control trial of SPADE study participants also demonstrated that only a proportion of hen’s egg sensitization development at 6 months of age was higher among infants born through vaginal delivery compared with those born through cesarean delivery. The effect of delivery mode on the development of food allergy might differ between food allergens.

In addition, although there were no significant differences, the authors demonstrated that cesarean delivery with labor had higher proportions of egg allergy and peanut allergy development compared with cesarean delivery without labor. Our analysis revealed that participants who developed food sensitization had longer labor durations than those without food sensitization. Furthermore, longer labor durations were significantly associated with a higher proportion of participants with food sensitization.

Several reports have indicated that cesarean delivery can elevate the risk for food sensitization and food allergy compared with vaginal delivery. However, our study and Currell and colleagues showed that cesarean delivery might not elevate the risk for food sensitization and food allergy.

Several important potential confounders such as indication of cesarean delivery, labor duration, levels of stress hormone and microbiota should be considered in future research.

Caesarean births not linked to increased risk of food allergy during infancy

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Caesarean births are not linked to an increased risk of food allergy during the first year of life, according to a new study.

The research, led by the Murdoch Children’s Research Institute (MCRI) and published in the Journal of Allergy and Clinical Immunology: In Practice, found caesarean delivery, either with or without labour, or elective or emergency, compared to vaginal birth does not impact on the likelihood of food allergy at 12 months of age.

Murdoch Children’s Associate Professor Rachel Peters said the association between mode of delivery and the risk of food allergy had remained unclear prior to this study due to the lack of studies linking accurate food challenge outcomes to detailed information on the type of caesarean delivery.

The study involved 2045 infants from the HealthNuts study, with data linked to the Victorian Perinatal Data Collection to source detailed information on birth factors.

The study found of the 30 per cent born by caesarean, 12.7 per cent had a food allergy compared to 13.2 per cent born vaginally.

“We found no meaningful differences in food allergy for infants born by caesarean delivery compared to those born by vaginal delivery,” Associate Professor Peters said. Additionally, there was no difference in likelihood of food allergy if the caesarean was performed before or after the onset of labour, or whether it was an emergency or elective caesarean.”

Associate Professor Peters said it was thought a potential link between caesarean birth and allergy could reflect differences in early microbial exposure (bacteria from the mother’s vagina) during delivery.

“The infant immune system undergoes rapid development during the neonatal period,” she said. Mode of delivery may interfere with the normal development of the immune system. Babies born by caesarean have less exposure to the bacteria from the mother’s gut and vagina, which influences the composition of the baby’s microbiome and immune system development. However, this doesn’t appear to play a major role in the development of food allergy.”

Associate Professor Peters said the findings would assist caregivers in evaluating the risks and benefits of caesarean delivery and provide reassurance for mothers who require such interventions that there was little evidence that their baby was at an increased risk of food allergy.

Australia has the highest rates of childhood food allergy in the world, with about one in 10 infants and one in 20 children over five years of age having an allergy to food.

The findings come as new research, led by the Murdoch Children’s, also found that 30 per cent of peanut allergy and 90 per cent of egg allergy naturally resolves by six years of age.

Associate Professor Peters said the resolution rates were great news for families and even a little higher than what was previously thought.

The results, published in the Journal of Allergy and Clinical Immunology, found infants with early-onset and severe eczema and multiple allergies were less likely to outgrow their egg and peanut allergies.

Associate Professor Peters said these infants should be targeted for early intervention trials that evaluate new treatments for food allergies such as oral immunotherapy.

“Prioritising research of these and future interventions for infants less likely to naturally outgrow their allergy would yield the most benefit for healthcare resources and research funding,” she said.

Nicole McEvoy’s daughter Moira, 3, was diagnosed with an egg allergy six months after having a life-threatening allergic reaction to a tiny amount of scrambled eggs. 

“She stopped breathing and we thought she was choking but after undergoing several tests we learnt it was anaphylaxis,” she said. We don’t have a family history of allergies so it never crossed our mind that any of our children would have food allergies.”

Nicole said the family always had to remain vigilant around food.

“It was easier to control when Moira was a baby but now that she is attending kindergarten, playdates and birthday parties it’s always in the back of your mind that she could accidentally be given something containing egg,” she said. We have had to drill into her that she only takes food from mum and dad.” 

Nicole, who is expecting her fourth child, said the latest research from the Murdoch Children’s comes as a welcome relief to her family.

“When you’re pregnant there is a lot you need to consider but knowing that if I must have a caesarean it won’t increase the risk of food allergy is one less thing I need to worry about it,” she said.

“Knowing that 90 per cent of egg allergy resolves by six years old age offers us a lot of hope for Moira and is hugely encouraging. It would be an enormous relief that if by the time Moira started school, the allergy had resolved and she wouldn’t have to worry about avoiding egg for the rest of her life.”

Researchers from the University of Melbourne, The Royal Children’s Hospital and The Florey Institute for Neuroscience and Mental Health also contributed to the findings.  

Genetics, environment, lifestyle influence risks for food allergy early in life

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Genetic, environmental and lifestyle factors influence the risk for food sensitization and food allergies during the first thousand days of life, according to a literature review published in Annals of Allergy, Asthma & Immunology.

Erin C. Davis, PhD, postdoctoral fellow in the department of pediatrics’ division of allergy and immunology at the University of Rochester School of Medicine and Dentistry and the Center for Food Allergy at Golisano Children’s Hospital, University of Rochester Medical Center, in Rochester, N.Y., based their findings on a PubMed search of articles in English on food allergy (FA) and food sensitization (FS), prioritizing studies published after 2015.

Asian baby with bottle
Source: Adobe Stock

The review explored the genetic risks for food allergy, links between atopic dermatitis (AD) and food allergy, dietary allergen exposures in early life, maternal antigen consumption during pregnancy and lactation, breastfeeding and formula feeding, introduction to solid foods, lifestyle and environmental exposures, the gut microbiome and metabolome in food allergy and potential early immune biomarkers of food allergy.

Genetic risks for food allergy include the number of parents or siblings with a history of allergic disease, although the researchers caution that some of this association may be due to the family’s practice of prolonged avoidance or late introduction of the allergen.

Specifically, researchers have found connections between the major histocompatibility complex genes, which encode the human leukocyte antigen complex, and FA development including sensitization to peanut, cow’s milk and egg.

The review also found that approximately one of every three children with AD are prone to immediate-type IgE-mediated FA. One hypothesis suggests the impaired skin barrier that patients with AD experience allows epicutaneous sensitization to foods before oral ingestion.

Noting that infants may be exposed to allergens early in life, the researchers said that the mechanisms behind sensitization or tolerance likely vary based on how that exposure occurred.

For example, the researchers said, infants may be exposed to allergens in utero or through human milk or infant formula before they begin solid foods. Environmental or household exposures to allergens are plausible as well.

However, the researchers found scarce and contradictory findings about the relationship between maternal intake of allergenic foods and infant FA risks, even though major food allergens have been detected in amniotic fluid and human milk. The American Academy of Pediatrics does not recommend maternal dietary restrictions to prevent atopic disease.

Studies that have evaluated the protective effect of breastfeeding against FA have been mixed, the researchers continued. Human milk includes immunomodulatory components that shape the early life microbiome and immune system, but variations between women influence the risk for disease.

Early introduction to solid foods appears to have a significant impact, as the researchers cited the Learning Early About Peanut trial, which demonstrated how the early and sustained intake of peanut could be protective against peanut allergy. Also, the Enquiring About Tolerance Study found a 67% lower risk for FA with early introduction when children are aged 1 to 3 years.

The growing adoption of a Westernized lifestyle that limits less industrialized exposures to microbial influences may contribute to increasing rates of FA and FS as part of the hygiene hypothesis, the researchers further found.

For instance, larger family sizes are related to lower incidences of AD and hay fever. Exposure to pets and vaginal delivery also are associated with lower risks for allergic diseases. Farming lifestyles can be protective as well.

Such early exposures to diverse populations of microorganisms may train the immune system to mount tolerogenic responses during exposures later in life to environmental or food allergens, the researchers said.

The gut microbiome, meanwhile, also is a factor mediating the association between increases in the prevalence of allergic disease and industrialization. There may be an association between FA and FS development and less mature microbiomes, the researchers said, although studies have provided limited data.

Finally, the researchers found studies demonstrating associations between a differential infant immune profile and FS and FA. The loss of immune cell populations and potential hyper-responsive profiles could increase risks for aberrant responses including sensitization, the researchers said.

Multiple factors drive disease pathogenesis, including genetics as well as maternal and infant allergen exposure, human milk composition and other environmental factors, the researchers concluded, with tolerance or sensitization likely depending on the route of first exposures and possibly genetic risk.

Further, the researchers called for additional observational studies and clinical trials that span from early pregnancy through childhood so novel biomarkers and risk factors for predicting susceptibility for FS and FA could be uncovered.

New pediatric guidelines have slowed increase in food allergy anaphylaxis rate

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Although cases of pediatric food allergy anaphylaxis increased in Australia over the last 2 decades, the rate of increase slowed following the release of new guidelines, according to data in The Journal of Allergy and Clinical Immunology.

Doctors historically have advised parents to refrain from introducing their infants to common allergenic foods to prevent food sensitization. But in 2009, the Australasian Society for Clinical Immunology and Allergy (ASCIA) advised against these delays.

Food allergy anaphylaxis rates in children increased by 17.6% a year from 1998 to 2007, 6.2% a year from 2007 to 2015, and 3.9% a year from 2015 to 2019.
Data were derived from Mullins RJ, et al. J Allergy Clin Immunol. 2021;doi:10.1016/j.jaci.2021.12.795.

Subsequent studies then found that introducing infants to allergens reduced allergy development, prompting ASCIA to recommend early introduction of multiple allergenic foods in 2016.

Raymond James Mullins, MBBS, PhD, FRACP, FRCPA, consultant physician in clinical immunology and allergy at John James Medical Centre in Deakin, Australia, and colleagues examined data from the Australian Institute of Health and Welfare to determine whether the introduction of these guidelines affected food anaphylaxis admission rates.

The researchers compared food anaphylaxis admission rates between 1998 to 1999 and 2006 to 2007, when delayed introduction of allergenic food was recommended; between 2007 to 2008 and 2014 to 2015, when this recommendation was withdrawn; and between 2015 to 2016 and 2018 to 2019, when early introduction of allergens was recommended.

Anaphylaxis admission rates increased in all age groups during the 20-year period, with the highest overall increase among children aged younger than 1 year, increasing by a factor of five, from 14.8 per 105 population to 74.3 per 105 population. Food anaphylaxis admission rates increase by factors of 7.6 among children aged 1 to 4 years, 15.1 among children aged 5 to 9 years, 14.6 among those aged 9 to 14 years and 15.7 among 15- to 19-year-olds.

However, children aged 1 to 4 years and 5 to 9 years twice demonstrated significant reductions in year-on-year rates of increase in food anaphylaxis admissions, the first when delayed introduction recommendations were withdrawn and the second when early introduction of allergens was recommended.

Across the three time periods, the annual year-on-year rates of increase slowed after 2007 to 2008 among children aged 1 to 4 years (17.6%, 6.2%, 3.9% per year) and 5 to 9 years (22%, 13.9%, –2.4%) and after 2015 to 2016 in children aged 10 to 14 years (17.5%, 18%, 10.8%).

However, children aged younger than 1 year experienced accelerations in year-on-year rates of increase (5.2%, 8%, 18%), as did all children aged older than 15 years.

To determine whether the decrease in anaphylaxis admission among those aged 1 to 4 years led to an increase with earlier introduction in infants, researchers examined the year-on-year changes for the combined 0 to 4 years age group. They found that following the 2006 and 2015 guideline updates, year-on-year rates of food anaphylaxis admissions decreased overall for children aged 0 to 4 years, but there was a spike in year-on-year rates of admission for infants aged younger than 1 year.

“The acceleration in food anaphylaxis admissions amongst infants [younger than] 1 year of age is also consistent with the timing of 2016 guidelines to actively introduce allergenic solids in the first year of life, as this could result in earlier presentation of food allergy in those who already have established allergy,” the researchers wrote. “It is important to consider whether the acceleration in food anaphylaxis admissions amongst infants [younger than] 1 year of age, which could be the result of earlier introduction of allergenic food, may cause harm, especially given this population may not have access to weight-appropriate epinephrine autoinjectors. Although fatality from anaphylaxis in infancy is rare, this should be monitored closely to assess potential risks associated with earlier introduction of allergenic foods.”

Overall, the researchers noted the correlation between these changes in rates with the timing of guideline introductions. Although a causal relationship should not be assumed, the researchers continued, these findings indicate that recommendations for early introduction of allergenic foods may be slowing the rate of childhood food allergy.

PERSPECTIVE

 Bruce Roberts, PhD)

Bruce Roberts, PhD

The findings of this study are not surprising. There is a trend toward a reduced rate of anaphylactic reactions, with a flattening of the curve. But before we can assess significance, we also need to see more data. Will the trend continue, and will the rates continue to diverge?

Importantly, the authors point out that a true cause-and-effect relationship cannot be established. Therefore, we cannot categorically conclude that the introduction of guidelines is responsible for the trend in reduced anaphylactic reactions.

Still, the data suggest but do not prove that early dietary introduction of allergens may be beneficial as measured by reduced rates of food-induced anaphylactic reactions.

There is a need to continue to educate parents concerning the early dietary guidance. In addition, collection of more data will serve to determine whether rates of anaphylactic reactions will continue to decline as more and more parents heed guidance concerning early allergen dietary introduction.

The authors report an acceleration in food anaphylaxis admissions among infants aged younger than 1 year and speculate this could result in earlier presentation of food allergy in infants who already have established allergy. In other words, as parents introduce more allergens into the diet of infants to prevent food allergy, they may be discovering the child is already allergic.

Data from the Learning Early About Peanut Allergy study suggests there may be a window of opportunity for introduction of allergens, and, ideally, they should be introduced when children are aged 4 to 6 months. Thus, if a well-meaning parent introduces an allergen later — say, between 8 and 12 months — the allergy may have already developed. Hence, the child experiences a reaction.

The impact of timing of allergen introduction within the first year of life on allergy prevention and reduced anaphylactic events requires further investigation.

Why everybody with a food allergy should start eating more fiber immediately

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A high-fiber diet rich in vitamin A may alter gut bacteria in a way that could prevent or reverse food allergies. This is the finding of a new study published in the journal Cell Reports.

It is estimated that around 15 million people in the United States have food allergies, and this number is increasing.

 

According to the Centers for Disease Control and Prevention (CDC), between 1997-2007, the number of children and adolescents in the U.S. with food allergies rose by around 18 percent, though the reasons for this are unclear.

Eight food types account for around 90 percent of all food allergies. These are peanuts, tree nuts, egg, milk, wheat, soy, fish, and shellfish.

Allergic reactions to food vary from person to person, but they may include tingling or itching in the mouth, hives, nausea or vomiting, stomach pain, and diarrhea.

In more severe cases, a person with a food allergy may experience swelling of the lips, tongue, and/or throat, shortness of breath, trouble swallowing, chest pain, and a sudden drop in blood pressure.

Occurrence of severe symptoms – alone or alongside milder ones – could be indicators of anaphylaxis, a potentially life-threatening reaction that requires immediate medical attention.

Of course, the best way to avoid an allergic reaction to food is to avoid consuming the food that triggers it, though this can be easier said than done.

Now, a new study suggests there may be a simple way to prevent or reverse food allergies: a high-fiber diet, enriched with vitamin A.

Fiber Triggers Short-Chain Fatty Acid Production to Reduce Food Allergy

High+Fiber+Foods

Co-senior author Laurence Macia, of Monash University in Australia, and colleagues came to their conclusion after studying mice that were artificially bred to be allergic to peanuts.

The researchers fed some of the mice a high-fiber diet rich in vitamin A – found in many fruits and vegetables – while others were fed a diet with average fiber, sugar, and calorie content (the controls).

They found that the mice fed the high-fiber diet had less severe allergic reactions to peanuts than mice fed the control diet.

On closer analysis, the researchers found that the high-fiber diet altered the gut bacteria of mice, which protected them against allergic reactions to peanuts.

Next, the researchers took some altered gut bacteria from mice fed the high-fiber diet and transferred it to the guts of mice with a peanut allergy that were “germ-free” – that is, they had no gut microbes.

Even though these germ-free mice were not fed a high-fiber diet, the team found that the addition of the altered gut bacteria protected them against allergic reactions to peanuts.

Is food the cure for a food allergy?

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http://edition.cnn.com/2016/04/07/health/feeding-to-prevent-food-allergy/index.html?sr=fbCNN040716feeding-to-prevent-food-allergy1243PMStoryLink&linkId=23176141

GUT BACTERIA THAT PROTECT AGAINST FOOD ALLERGIES IDENTIFIED

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The presence of Clostridia, a common class of gut bacteria, protects against food allergies, a new study in mice finds. By inducing immune responses that prevent food allergens from entering the bloodstream,Clostridia minimize allergen exposure and prevent sensitization — a key step in the development of food allergies. The discovery points toward probiotic therapies for this so-far untreatable condition, report scientists from the University of Chicago, Aug 25 in the Proceedings of the National Academy of Sciences.

140825152016-large (1)

Although the causes of food allergy — a sometimes deadly immune response to certain foods — are unknown, studies have hinted that modern hygienic or dietary practices may play a role by disturbing the body’s natural bacterial composition. In recent years, food allergy rates among children have risen sharply – increasing approximately 50 percent between 1997 and 2011 — and studies have shown a correlation to antibiotic and antimicrobial use.

“Environmental stimuli such as antibiotic overuse, high fat diets, caesarean birth, removal of common pathogens and even formula feeding have affected the microbiota with which we’ve co-evolved,” said study senior author Cathryn Nagler, PhD, Bunning Food Allergy Professor at the University of Chicago. “Our results suggest this could contribute to the increasing susceptibility to food allergies.”

To test how gut bacteria affect food allergies, Nagler and her team investigated the response to food allergens in mice. They exposed germ-free mice (born and raised in sterile conditions to have no resident microorganisms) and mice treated with antibiotics as newborns (which significantly reduces gut bacteria) to peanut allergens. Both groups of mice displayed a strong immunological response, producing significantly higher levels of antibodies against peanut allergens than mice with normal gut bacteria.

This sensitization to food allergens could be reversed, however, by reintroducing a mix of Clostridia bacteria back into the mice. Reintroduction of another major group of intestinal bacteria, Bacteroides, failed to alleviate sensitization, indicating that Clostridia have a unique, protective role against food allergens.

Closing the door

To identify this protective mechanism, Nagler and her team studied cellular and molecular immune responses to bacteria in the gut. Genetic analysis revealed that Clostridia caused innate immune cells to produce high levels of interleukin-22 (IL-22), a signaling molecule known to decrease the permeability of the intestinal lining.

Antibiotic-treated mice were either given IL-22 or were colonized withClostridia. When exposed to peanut allergens, mice in both conditions showed reduced allergen levels in their blood, compared to controls. Allergen levels significantly increased, however, after the mice were given antibodies that neutralized IL-22, indicating that Clostridia-induced IL-22 prevents allergens from entering the bloodstream.

“We’ve identified a bacterial population that protects against food allergen sensitization,” Nagler said. “The first step in getting sensitized to a food allergen is for it to get into your blood and be presented to your immune system. The presence of these bacteria regulates that process.” She cautions, however, that these findings likely apply at a population level, and that the cause-and-effect relationship in individuals requires further study.

While complex and largely undetermined factors such as genetics greatly affect whether individuals develop food allergies and how they manifest, the identification of a bacteria-induced barrier-protective response represents a new paradigm for preventing sensitization to food.Clostridia bacteria are common in humans and represent a clear target for potential therapeutics that prevent or treat food allergies. Nagler and her team are working to develop and test compositions that could be used for probiotic therapy and have filed a provisional patent.

“It’s exciting because we know what the bacteria are; we have a way to intervene,” Nagler said. “There are of course no guarantees, but this is absolutely testable as a therapeutic against a disease for which there’s nothing. As a mom, I can imagine how frightening it must be to worry every time your child takes a bite of food.”

“Food allergies affect 15 million Americans, including one in 13 children, who live with this potentially life-threatening disease that currently has no cure,” said Mary Jane Marchisotto, senior vice president of research at Food Allergy Research & Education. “We have been pleased to support the research that has been conducted by Dr. Nagler and her colleagues at the University of Chicago.”