So much of being a mother is ensuring the health of our children, and sometimes, it seems we can go overboard. Allergies have been a hot topic since the number of children who suffer from them has been alarmingly on the rise. Are we perhaps overprotecting our children, so that they’re increasingly susceptible to developing immunologic responses to things they ordinarily shouldn’t? Or are we overexposing them to potential allergens that should be avoided?
Here, Bay Area allergist Allyson Tevrizian, M.D. weighs in.
A Mother’s Day Health Blog: Allergies, the Ultimate Imbalance with Nature
The New Pandemic
We have all heard the story: The prevalence of allergic disease has dramatically increased over the past generation. In the United States, allergic disease (atopic dermatitis, food allergy, allergic rhinitis or “hay fever,” and allergic asthma) affects 20% of the population. As mothers we want to know why and what do we do for our generation of children afflicted with these conditions. I want to share with you some of the medical and scientific communities’ latest research regarding these issues. It is an exciting time of discovery but the answers are still unfolding for some of the specific questions. Fortunately, as the prevalence of these diseases rise, so does the support network and information sources for mothers of children with allergic disease.
So many of my patients’ moms tell me when they were children they knew of one or two kids with nut allergies and now there are one or two if not more children per class with nut allergies. Allergic asthma runs rampant among school-age children, especially those living in inner city environments. Allergic nasal symptoms not only contribute to persistent upper airway congestion, increased risk of sinus and ear infections but also can contribute to poor sleep and poor school or work performance. Studies from the last decade estimate a total of 3.5 billion dollars per year spent on prescription drugs, over the counter allergy medication, and allergy related health care provider visits. Allergies affect cost in other ways with billions of lost dollars resulting from absenteeism from work or school. Clearly the effects of allergic disease go beyond the nose, lung and skin. So the big question is “what is going on?” In order to understand the current theories, it is imperative to note that allergic disease results from a complex interaction between genetics and environmental factors.
Eat Dirt, the Wonderful World of Microbes
The leading theory for the increase in allergic disease is referred to as the “hygiene hypothesis.” The crux of this theory is that our current society’s “clean practices” (smaller family size, less early life exposure to farm animals and dirt in general, and increased use of antibiotics) is skewing the infant’s immunologic development toward allergy. It appears that an individual’s immunologic fate is highly influenced in the first year of life. The big player in this fate is the infant’s gut. The gut is the largest immune organ in humans and in the first several months of life undergoes enormous change including population with bacteria. Everything from the route of birth (vaginal versus C-section), feeding practice, antibiotic exposure, home environment, and early life animal exposure, especially livestock exposure, influences the number and species of resulting gut bacterial colonies. The gut microbial flora’s mingling with outside world’s ingested substances is thought to shape early immune development. We have all observed our infants happily mouthing objects in the outside world. The infant’s gut is thought to be the first place where the body either ignores things or makes immune responses against them. The consequence from the hygiene hypothesis’ viewpoint is that the microbial equation necessary for tolerance to innocuous substances (food or environmental pollens), has been violated.
Pollution, Dust mites, and Cockroaches, Oh My!
Additionally, other outside influences may also turn on the genes for allergy. Elevated levels of certain airborne allergens such as dust mites and cockroaches are associated with increased risk of nasal allergies, atopic dermatitis, and asthma. Furthermore, some air pollution components, namely diesel exhaust particles, have also been associated with elevated rates of allergic disease and asthma. Feeding practices among various cultures differ and it is hypothesized that this may also influence the development of food allergy. As an example, peanuts in the United States tend to be dry roasted. This type of preparation may enhance the “allergic-ness” or as we say in the business, the “immunogenicity,” of peanuts. Peanuts in some cultures with lower peanut allergy rates are boiled or introduced as a powdered ingredient in a first baby food. Finally, there are some preliminary studies looking at the pollen consequences of increased temperatures and environmental CO2 levels. These studies have demonstrated increased growth of allergic trees towards polar latitudes, earlier tree pollination, and increased amounts and immunogenicity of specific pollens.
Clearly both individual and global factors are occurring. The hope is that future studies will be able to shed light on a primary prevention strategy for allergic disease.
The First year: Pregnancy, Breastfeeding, Formulas, Solid Food Introduction, and Pre/Probiotics
Infants are considered to be at risk of allergic disease if at least one parent or sibling has any form of allergy (atopic dermatitis, food allergy, allergic asthma, allergic rhinitis). There have been studies done looking at the effect of maternal avoidance of cow’s milk, egg, or peanut during pregnancy and breastfeeding. The take home message from these studies is that single food maternal restriction of cow’s milk, egg, or peanut in pregnancy and breastfeeding does not reduce risk for future development of allergic rhinitis, asthma or food allergy in the infant. There is one further piece of data worth mentioning. There are a couple of small studies looking at more intense allergen avoidance strategies for mothers. These studies look at maternal dietary restriction of several foods during pregnancy and breastfeeding, such as cow’s milk, egg, and nuts (and fish and soy in some studies). These studies also included environmental dust mite avoidance strategies. The more intense diet avoidance paired with the dust mite environmental control measures seem to have a more pronounced effect on the prevention of atopic dermatitis, asthma and allergic rhinitis and a trend towards reduction in food allergy in the infants. This approach has to be undertaken with caution to ensure the mother’s diet is nutritionally complete and would need further discussion with an allergy specialist to determine if it is worthwhile to pursue.
Several questions regarding infant feeding practices have also emerged. Breast milk is the ideal source of nutrition for the first four to six months of an infant’s life. Breast milk may have a protective effect on the development of certain food allergies and is associated with decreased wheezing in children during the first two years of life. When exclusive breast feeding is not possible or preferred, the infant is given formula. There are a variety of formulas out there including cows milk formula, soy formula, and more pre-digested (called hydrolyzed) cow’s milk formulas. At the extreme predigested end are amino acid based formulas. Current studies suggest that if breastfeeding is not an option or if formula supplementation is done in high-risk infants, a partially or extensively predigested formula is preferred over regular cow’s milk formulas or soy formulas. Amino acid formulas are reserved for infants with several already established food allergies. In addition, several moms have questions regarding when to introduce solid foods. The window of opportunity appears to be between four to six months, even in infants at high risk for allergic disease. The practice of delaying introduction of solid food beyond six months has not been effective at prevention of allergic disease. Introduction of rice cereal, fruit, vegetables and meat constitute the usual first solid foods in an infant’s diet.
Finally there is a lot of buzz out there about prebiotics and probiotics. Prebiotics are nondigestable carbohydrates that stimulate the growth of one or a limited number of beneficial gut bacteria. Probiotics refer to a specific strain or groups of strains of beneficial gut bacteria. Prebiotics and probiotics are found in breast milk, can be added to infant formulas, are available as over the counter supplements, or are ingredients in specific foods such as yogurt. The idea is that populating the infants gut with beneficial bacteria may steer the future immune development away from a food or environmental allergic response. While this approach certainly holds promise, the exact way of how to do this, when to do this(again, there may be a limited window of time), and what is the best combination of administered bacteria is unknown.
I want to emphasize that the above information applies only to infants at risk of allergic disease rather than those with established allergic disease such as atopic dermatitis. The specific feeding practices in those infants differ and require consultation with a medical professional. Also all the data mentioned above refer to population-based studies rather than to individual cases. The best approach to your specific situation will depend on you, your family, your living practices, and an informed discussion with your health care provider.
The Cat is Out of the Bag: No Pun Intended
Allergies happen and if they have happened to you, you number in the ranks of 20% of the US population. Allergies come in all shapes and sizes, many people have a few annoying weeks of hay fever during the spring that is readily treated with an over the counter antihistamine. On the other end of the spectrum is the individual with months of sinus symptoms, asthma, eczema, and life threatening food allergies. Allergies are a lifestyle issue and those with more severe disease or life threatening food allergies are impacted on a daily basis. The fear of accidental food exposure increases anxiety among patients and families, especially if there are multiple food allergies. One survey even found that one in four children had been taunted, bullied or harassed because of their food allergy. Education and preparedness are the best tools to combat these fears and fortunately there are a number of resources to help you. The first resource I wanted to point out is the Food Allergy and Anaphylaxis Network or FAAN (www.foodallergy.org). This nonprofit organization provides education on food avoidance, and offers programs to assist patients and families in matters of food shopping, food avoidance in the school and camp environment, vacation planning, dining out strategies, and emergency management plans for accidental food exposure. This organization has cookbooks, online recipes, and food substitution suggestions for the major food allergens. FAAN also has a number of instructional programs available on the website including The School Food Allergy Program and The Child Care and Preschool Guide to Managing Food Allergies. There are also food allergy apps for smart phones that help with food shopping and menu planning. The FAAN website reviews some of these apps. Other helpful resources (and this is by no means an exhaustive list)include The American Academy of Allergy, Asthma, and Immunology (www.aaaai.org), The American College of Allergy, Asthma, and Immunology (www.acaai.org), Asthma and Allergy Foundation of America (www.aafa.org), Mothers of Asthmatics (www.aanma.org), The American Lung Association (www.lung.org), the website UpToDate(R) (www.uptodate.com, click patient and search for food allergy, allergic rhinitis, and asthma), the National Eczema Association (www.nationalezcema.org), and the American Partnership for Eosinophilic Disorders (www.aphed.org).
Over the past several years the treatment for allergic disease has vastly improved. There are a number of safe and effective medications for allergic rhinitis, asthma, and atopic dermatitis. Allergy shots also remain a tried and true therapy for allergic rhinitis and asthma. Furthermore, the National Institute of Health created two nationwide programs to further study and improve asthma treatment. The Asthma Clinical Research Network (www.acrn.org) studies asthma treatment strategies for adults while the Childhood Asthma Research and Education or CARE network (www.asthma-carenet.org) focuses on asthma diagnosis and treatment in the pediatric population.
I would like to end the blog with some comments on the future direction of food allergy. At this time food allergen avoidance is the only means to prevent life threatening food reactions. A number of future studies are underway to see if there may be an alternative treatment strategy. Studies are currently being performed looking at oral immunotherapy for peanut, egg, and milk. Some of the results hold promise and as more studies are done this may be a potential future option for certain food allergic patients. Human studies are planned for engineered recombinant protein immunotherapy. This form of therapy looks at taking the allergic part of the peanut molecule and changing it so it does not cause an allergic reaction but instead causes a protective antibody to be formed. Finally there is a proprietary herbal formulation developed at the Jaffe Food Institute in New York that in mouse models has blocked food induced anaphylaxis. Human studies with the agent are underway. As the mystery of the human immune system is unraveled, more life changing therapies will be available for us and our children.
Allyson Tevrizian completed her undergraduate and medical school degrees at Duke University. She then went on to residency in Internal Medicine at the University of California San Francisco, followed by Allergy/Immunology Fellowship at the University of California San Francisco/Stanford combined training program. She served on faculty for 2 years at the University of California San Francisco as Clinical Instructor and Practice Chief of the Allergy/Immunology Clinic. Dr. Tevrizian is a member of the Amercian Academy of Allergy, Asthma, and Immunology and the American College of Allergy, Asthma, and Immunology. She has served on the Executive Board of the California Society of Allergy, Asthma, and Immunology from 2002-2006, and on the Executive Board for the Allergy, Asthma, and Immunology Foundation of Northern California from 2008-2012.
Dr. Tevrizian has been in Private Practice with Allergy and Asthma Medical Group of the Bay Area since 2005. Outside of medicine she enjoys the constant chaos of her two young children whose enthusiasm for life and energy level always keep things interesting.