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pregnant woman holding eggs

How does diet during pregnancy impact allergies in offspring?

pregnant woman holding eggs

A small percentage of women said they consumed fewer allergens during pregnancy to stave off food allergies in their newborns, according to preliminary research Karen Robbins, M.D., presented during the American College of Asthma Allergy and Immunology 2018 Annual Scientific Meeting.

Pregnant women routinely swear off alcohol and tobacco to boost their chances of having a healthy baby. What about common food allergens like nuts and milk?

There are scant data that describe how often pregnant women deliberately stop eating a specific food item in order to prevent future food allergies in their newborns. As a first step toward addressing this data gap, a research team led by Karen Robbins, M.D., an allergist at Children’s National Health System, pored through a longitudinal study conducted by the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention.

About 4,900 pregnant women completed the Infant Feeding Practices Study II prenatal questionnaire from May 2005 to June 2007. The study tracked 2,000 pregnant women from the third trimester of pregnancy and their infants through the first year of life. A small percentage of women said they had consumed fewer allergens during pregnancy to stave off food allergies in their newborns, according to a poster Dr. Robbins presented during the American College of Asthma Allergy and Immunology 2018 Annual Scientific Meeting. While their numbers were small, most of these women reported giving up major allergens like nuts, milk or eggs during pregnancy, including:

  • 144 (2.9 percent) reported restricting their diet in some way to prevent future food allergies in their offspring
  • 84 women (1.7 percent) ate fewer nuts
  • 15 women (.3 percent) ate fewer eggs and
  • 2 women (.04 percent) ate/drank consumed less dairy/milk.

“At the time the survey was conducted, few pregnant women in this large data set said they gave up certain foods with the express aim of avoiding a food allergy in their babies,” Dr. Robbins says. “However, mothers who had an older child with a food allergy or who had food allergies themselves had significantly higher odds of trying this food avoidance strategy.”

Despite the diet changes, infants born to these expectant mothers were twice as likely to experience problems with food at age 4 months – though not at age 9 months or 12 months. And these infants were no more likely to be diagnosed with a food allergy.

According to the FDA, millions of Americans suffer a food allergy each year. Reactions can range from mild to life-threatening and can begin soon after eating a problematic food item or an ingredient from that food. Among the most common allergenic foods are milk, eggs, fish, shellfish, tree nuts, peanuts, wheat and soybeans.

“We really need to know more about how often targeted food avoidance occurs among U.S. pregnant women who have a family history of food allergies,” Dr. Robbins adds. “We hope to learn what factors into these women’s decision-making as well as why many of them settled on food avoidance as a potential strategy to try to prevent food allergy in their infants.”

American College of Asthma Allergy and Immunology 2018 Annual Scientific Meeting presentation

  • “Prenatal food allergen avoidance practices for food allergy prevention.”

Karen Robbins M.D., lead author; Ashley Ramos Ph.D., co-author; Marni Jacobs, Ph.D., co-author; Kate Balas BS, co-author; and Linda Herbert, Ph.D., director of Children’s Division of Allergy and Immunology’s psychosocial clinical program, and senior author.

Adora Lin

Funding will help uncover immune system differences that trigger food allergies

Adora Lin

“When it comes to food allergies, we really don’t know how they develop. We don’t know how to best differentiate between a child who can safely eat a potential allergen, like peanuts, compared with a child who cannot safely eat peanuts.” says Adora A. Lin, M.D., Ph.D.

Adora A. Lin, M.D., Ph.D., an attending physician in Children’s department of Allergy and Immunology, was awarded $240,000 to improve understanding of how children’s immune systems tolerate or react to certain food allergens – sometimes triggering a cascade of side effects that can be fatal.

The three-year American Academy of Allergy, Asthma & Immunology (AAAAI) Foundation award will underwrite Dr. Lin’s ongoing research into the regulation of the antibody Immunoglobulin E (IgE), which plays a pivotal role in these allergic responses.

“Our immune system maintains a delicate balance, working just enough to ward off potential invaders and pathogens, but not so much that it triggers problems of its own making,” Dr. Lin says. “When it comes to food allergies, we really don’t know how they develop. We don’t know how to best differentiate between a child who can safely eat a potential allergen, like peanuts, compared with a child who cannot safely eat peanuts.”

Food allergies have become a growing problem and affect about 1 in 13 U.S. children, or about two per classroom. Food items such as eggs, milk, peanuts, tree nuts, soy and wheat trigger allergic reactions that can include itching, swelling, hives and difficulty breathing. As children’s immune systems react to exposure to such allergens, their B-cells produce IgE antibodies.

Apart from avoiding these foods and carrying rescue medications, which must be used immediately after accidental exposure, there is no way to treat food allergies effectively. That makes it essential to better understand how the immune system works in order to innovate new and better food allergy treatments and diagnostics.

Dr. Lin’s work involves isolating immune cells from blood samples, culturing them and stimulating an immune response to known food allergy triggers. B-cells make IgE, but additional clarity is needed about what turns on the “make IgE” signal as well as which signals indicate it’s time to stop making IgE. Ultimately, the aim is to identify biomarkers that are akin to the “check engine” light that illuminates to warn of a potential problem long before a car stalls in traffic.

“I’m very excited about this funding,” Dr. Lin adds. “Our field has done an exceptional job with clinical work to help children with food allergies. This award recognizes the importance of the mechanistic side of the equation. I’m excited to help make that contribution to the research.”

As it stands now, blood tests are sensitive to food-related IgE, but are not specific. Only 30 to 55 percent of children who have IgE to common food allergens have an allergic reaction after eating the food, which means that 45 to 70 percent are merely sensitized and could tolerate eating the food. Current tests cannot distinguish between sensitized and allergic children.

“Our hope is to identify biomarkers that would serve as the ‘check engine’ light that tell us in advance which child’s immune system will react strongly to that food. Right now, there is no way to tell. This project will help uncover those differences,” she says.

Dr. Lin was one of three recipients of the AAAAI Foundation’s faculty development award, which was presented during a March 3, 2018, award ceremony held during the organization’s business meeting.

Training developing immune systems to prevent wheezing early in life

Stephen Teach does an asthma exam

Extensively engaging stakeholders such as parents, families and local service providers in the actual study design transformed a planned research project into a more patient-centered study.

For the small number of U.S. children who grow up on working farms, activities such as feeding the cows and clearing spent hay from the barn are little changed from a thousand years ago. Through such close contact with dirt and farm animals, rural kids’ immune systems develop more normally and better distinguish common bacteria from household allergens like dust, molds, pets, and pests. Rates of allergy and asthma continue to be lower in children who grow up in those conditions.

By contrast, rates of asthma have spiked among urban and disadvantaged kids, who have far less exposure to dirt and animals early in life. Today, leading pediatric institutions, such as Children’s National Health System, are “awash in emergency department (ED) visits for asthma” with each ED visit associated with 10 to 15 missed school days annually on a population basis, says Stephen J. Teach, MD, MPH, Director and Principal Investigator of IMPACT DC , a care, research, and advocacy program focused on under-resourced and largely minority children with asthma.

A paradigm-shifting multicenter clinical trial aims to reverse that trend by going old school and safely exposing very young infants to the type of immune system training they would have experienced if they grew up closer to the earth.

The five-year study, named “Oral Bacterial Extracts (ORBEX): Primary Prevention of Asthma and Wheezing in Children,” is funded by a $27 million cooperative agreement grant from the National Heart, Lung, and Blood Institute, which is part of the National Institutes of Health. Children’s National, one of eight participating sites across the nation, will enroll an estimated 150 children in the study and will receive at least $2.5 million of that grant.

“It is currently thought by many, including me, that asthma and allergic diseases are a result of disordered development of the immune system very early in life,” says Dr. Teach, who is also Chair of the Department of Pediatrics at George Washington University. The immune system development process begins to unfold in the last few months of pregnancy and continues through infancy, meaning “the die is cast, we think, at a very young age.”

According to the Centers for Disease Control and Prevention, 8.6 percent of children across the nation have asthma, but in the District of Columbia, a disproportionately higher number of children suffer from the respiratory ailment. Once children experience early wheezing, changes begin to occur in the architecture of their lungs, causing a thicker basement membrane, a thickening of the lining of the lungs, and resulting in a heightened tendency for the airways in the lungs to become inflamed and to excrete more mucous. As a result, the children’s poorly trained immune system becomes hyper vigilant, ready to recognize a multitude of things as potentially allergenic.

“We’ve got to do something to change the course of the disease and to make it less common and less severe,” Dr. Teach says.

The study will identify 1,000 babies who range in age from 6 months to 18 months who are the highest risk for asthma, either through family history, being diagnosed with eczema, or both. The infants will receive safe doses of the inactivated bacteria, which is marketed under the name Broncho-Vaxom®. The therapy comes in capsule form, which for two years will be sprinkled into bottles or onto food. The children will be followed to gauge whether infants randomly assigned to receive treatment suffer fewer respiratory symptoms than infants randomly assigned to receive placebo.

“The rationale if we can expose these very young children to the benefits, but not the risks, of early life bacterial exposure, they may reap the benefits of developing a more properly functioning and less allergic immune system,” Dr. Teach says.

He says the Children’s National research team has had “remarkable success” engaging young children and their parents in such long-term studies, losing few to attrition.

“Going for five years will be breaking new ground. But all of our experience suggests that we will succeed if we show the families we care, we stay in touch with them, and we form these therapeutic partnerships by saying: ‘We want to partner with you. We can do this safely with mutual benefit.’ Families will get on board,” he says.

Related resources: Learn more about the clinical trial | Research at a Glance