Girl Planting seeds

Seasonal Allergies: Impact Of Our Environment

shutterstock_106241129By Lawrence Rosen, MD
Springtime brings us sunshine, flowers, and unfortunately for more than 35 million people in the United States, seasonal allergies.1 The cost to our society due to allergic rhinitis (irritation and inflammation of the nose) in the United States is estimated at greater than $6 billion.1 Allergic disorders, including asthma, allergic rhinitis and eczema, are widely considered to be rising in prevalence at epidemic rates.2,3 While genetics play a role in determining who’s at risk to develop allergies, the reasons for this tremendous increase in the prevalence of allergic disorders are clearly environmental. Simply defined by the U.S. Food and Drug Administration, “An allergy is the body's hypersensitivity to substances in the environment.”4

A New Paradigm: The Iceberg Model
The iceberg provides a useful metaphor to understanding how allergies develop. The tip of the iceberg represents the observable clinical traits seen in children, including skin rashes (eczema), vomiting (reflux), runny noses (rhinitis) and coughing (asthma). What lies beneath the surface is a complex matrix of genetic predisposition and resulting immune and metabolic dysregulation, all triggered under certain environmental conditions. These triggers include airborne, food and water contaminants (tobacco smoke, pesticides, heavy metals, pet and pest dander, food allergens), infectious agents (viruses, molds), and stress.5-10 Under these conditions, cracks in the ice develop, as certain immune cells are over stimulated relative to others, resulting in an imbalance between Th1 dominant and Th2 dominant immune responses.11 Even prenatal factors (mothers’ nutrition and other environmental exposures) can greatly affect this immune balance, making certain babies more likely to develop allergies than others.12,13 Perhaps, then, we can intervene pre-natally, or even pre-conceptually, to prevent the inevitable sequence of events. Th2 dominance leads to an immune dysregulation marked by a heightened allergic response and a proliferation of inflammatory cellular mediators (e.g. cytokines, interleukins, leukotrienes). Inflammation involves excess mucous production and other clinically-observable phenomena we call “allergies.”

The Hygiene Hypothesis and the Allergic March
The “hygiene hypothesis” is a popular current theory to explain why we are experiencing this great increase in allergy prevalence.14 According to this theory, our environments are now too “clean” – we are not exposed to as many infectious agents as previous generations. The reasons proposed for such a change include the eradication of infectious agents by vaccines, antibiotics, and “super-clean” living conditions. There is some evidence that children raised on a farm or exposed to certain livestock may in fact develop fewer atopic symptoms.15 Once the cascade of immune dysregulation is triggered, allergic symptoms often develop and multiply; this is known as the “allergic march” – once you develop one allergic trait (eczema), others are likely to follow (food allergies, asthma and allergic rhinitis).

Advice on Preventing Allergies

  • Our environment is loaded with potential allergy triggers. While avoiding the outdoors entirely in springtime is not feasible, one should aim to limit exposure to pollen and other common airborne triggers (e.g. tobacco smoke).
  • Keep windows and doors closed during high pollen count times and stay inside on the driest, windiest days to minimize exposure to seasonal allergens.
  • Use high-particulate air (HEPA) filters inside to reduce most airborne contaminants, especially in bedroom locations.
  • In humid areas, use a dehumidifier to limit mold development.
  • Buy allergy-proof bedding, including mattress and pillow case covers, to reduce allergy symptoms, and regularly wash sheets, blankets and pillow cases in hot water.
  • Stuffed animals and real animals alike can contribute to allergic rhinitis, so wash them frequently.
  • Consider removing carpeting in bedrooms or use area rugs which can be cleaned regularly. Vacuum all carpets and floor surfaces weekly with a HEPA-filter equipped appliance.
  • Limit lawn mowing and other gardening activities at peak allergy times; avoid use of chemical pesticides and outdoor products.
  • Use environmentally- and health-safe household cleaners.
  • Eat healthy, whole organic foods with plenty of anti-inflammatory antioxidants.
  • Avoid use of herbal products and foods that can cross react with seasonal allergens; for some people this may include Echinacea species16 and certain fruits and vegetables (this is known as the “oral allergy syndrome”17).
  • To prevent allergic disease in babies, consider perinatal avoidance of known food allergens, especially if there’s a family history of atopic disease; breastfeeding is known to be protective as well.18,19
  • Look into using specific natural health product supplements, like probiotics and essential fatty acids, which may lower your risk of developing allergies.20,21
  • Think about taking up a stress-coping technique, like yoga or meditation.22

accessed 2/13/07.
Asher MI, et al: Worldwide time trends in the prevalence of symptoms of asthma, allergic rhinoconjunctivitis, and eczema in childhood: ISAAC Phases One and Three repeat multicountry cross-sectional surveys. Lancet 368:733-43, 2006.
Eder W, Ege MJ, von Mutius E: The asthma epidemic. N Engl J Med 355: 2226-2235, 2006., accessed 2/13/07.
Agrawal A, et al: Thimerosal induces TH2 responses via influencing cytokine secretion by human dendritic cells. J Leukoc Biol 2006 Nov 1; [Epub ahead of print]
Bornehag CG, et al: The association between asthma and allergic symptoms in children and phthalates in house dust: a nested case-control study. Environ Health Perspect 112: 1393-1397, 2004.
Chalubinski M, Kowalski ML: Endocrine disrupters--potential modulators of the immune system and allergic response. Allergy 61: 1326-1335, 2006
Sherriff A, et al: Frequent use of chemical household products is associated with persistent wheezing in pre-school age children. Thorax 60: 45-49, 2005.
Van Den Hazel P, et al: Today’s epidemic in children: possible relations to environmental pollution and suggested preventive measures. Acta Paediatr Suppl 95: 18-25, 2006.
Wright RJ, Cohen RT, Cohen S: The impact of stress on the development and expression of atopy. Curr Opin Allergy Clin Immunol 5: 23-29, 2005.
Kidd P: Th1/Th2 balance: the hypothesis, its limitations, and implications for health and disease. Altern Med Rev 8: 223-246, 2003.
Calder PC, et al: Early nutrition and immunity - progress and perspectives. Br J Nutr 96: 774-790, 2006.
Chung EK, et al: Antenatal risk factors, cytokines and the development of atopic disease in early childhood. Arch Dis Child Fetal Neonatal Ed 92: F68-73, 2007.
Noverr MC, Huffnagle GB: The ‘microflora hypothesis’ of allergic diseases. Clin Exp Allergy 35: 1511-1520, 2005.
Stern DA, et al: Exposure to a farming environment has allergen-specific protective effects on T(H)2-dependent isotype switching in response to common inhalants. J Allergy Clin Immunol 119: 351-358, 2007.
Charrois TL, et al: Echinacea. Pediatr Rev 27: 385-387, 2006.
Purohit-Sheth TS, Carr WW: Oral allergy syndrome (pollen-food allergy syndrome). Allergy Asthma Proc 26: 229-230, 2005.
Kramer MS, Kakuma R: Maternal antigen avoidance during pregnancy or lactation, or both, for preventing or treating atopic disease in the child. Cochrane Database Syst Rev 2006 July 19;3:CD000133.
Friedman NJ, Zieger RS: The role of breast-feeding in the development of allergies and asthma. J Allergy Clin Immunol 115: 1238-1248, 2005.
Kalliomaki MA, Isolauri E: Probiotics and down-regulation of the allergic response. Immunol Allergy Clin North Am 24: 739-752, 2004.
Denburg JA, et al: Fish oil supplementation in pregnancy modifies neonatal progenitors at birth in infants at risk of atopy. Pediatr Res 57: 276-281, 2005.
Wright RJ: Alternative modalities for asthma that reduce stress and modify mood states: evidence for underlying psychobiologic mechanisms. Ann Allergy Asthma Immunol 93 (Suppl 1): S18-S23, 2004.


close (X)