March 29, 2018

Allergies and Allergic Rhinitis

Allergies, seasonal allergies, “hay fever”, or in medical jargon, “allergic rhinitis” (AR) are all names for essentially the same thing.  AR is extremely common affecting up to 25% of the Canadian population; and curiously, the incidence has been increasing over several decades.

Risk factors that may explain the increasing incidence of Allergic Rhinitis

Environmental
– improved hygiene but reduced exposure to allergens early in life
– worsening air quality (ex. pollution from vehicular exhaust)
– toxicants such as phthalates, bisphenol A, pesticides, and endocrine-disrupting agents

Diet and Lifestyle
– increased time spent indoors (decreased exposure to outdoor allergens)
– decreased activity levels (decreased respiratory fitness)
– increased processed/refined food intake
– decreased fruit, vegetable, fiber, antioxidant and essential fatty acid intake

Medical
– early childhood antibiotic use
– decreased childhood bacterial/viral infection
– poor vitamin D status
– decreased breastfeeding

Allergic Rhinitis results from an abnormal immune reaction in the airways (primarily in the nasal passages) resulting in symptoms such as runny nose, congestion, sneezing, and itchy, watery eyes.  These reactions occur in response to a variety of allergens, once the immune system has become sensitized.  Examples of common allergens causing AR include pollen, grasses, weeds, pet dander, insect faces, and mold spores.  AR can also worsen asthma symptoms (shortness of breath and wheezing) and increase the risk of other respiratory complications such as bronchitis, ear and sinus infections.  In terms of quality of life reduction, AR can contribute to disturbed sleep patterns, fatigue, poor concentration, impaired performance, and low self-esteem. It carries a high economic burden once productivity, missed work days, and medical expenditures are factored in.

The most effective treatment for allergic rhinitis is to avoid the causative allergen, however this may be difficult or impractical in many cases.  Identification of allergens can sometimes be done with testing, such as skin scratch testing or blood testing.  Indoor air quality can be improved by minimizing dust, minimizing carpets/curtains, and using HEPA air purifiers in some cases. Humidity and water damage are other important factors as excess moisture can contribute to mold, mildew and dust mite growth.

Antihistamine medications are often used for symptomatic relief, along with nasal decongestants and corticosteroids.  Although effective, some of these medications cause undesirable side effects which may explain why approximately 50% of allergy sufferers seek some form of natural therapy.  Natural therapies are generally less effective for improving AR symptoms immediately, however there are several evidence-based therapies that can reduce the frequency and severity of AR.

Nasal/sinus irrigation with saline solution is a simple and reasonably effective way to reduce symptoms and medication use related to AR. There are a variety of options available at most pharmacies.  Care should be taken to properly mix solutions and clean irrigation devices between use as per manufacturers directions.

Nutrition is a major factor in preventing allergic disease – even before we are born!  Maternal diet and nutrition has a profound impact on the allergic tendencies of her offspring.  High maternal intake of processed foods and vegetable oil increases risk of allergies in children.  In contrast, the Mediterranean diet (a diet rich in vegetables, fruits, leafy greens, legumes, nuts, seeds fish, and essential fatty acids) shows the opposite effect.  Breastfeeding children is associated with tolerance to allergens, and decreased allergic tendencies.  Interestingly, allergic disease typically shows up early in life.

Poor dietary habits in both children and adults can promote inflammation and immune system dysfunction which may also play a role in allergic tendencies.  However, high dietary intake of fruits, vegetables, fibre, essential fatty acids, and various antioxidants have all been linked to decreased risk of allergies.  Food reactions can also contribute to AR, however this happens very infrequently in isolation.  Food reactions are more often observed with other allergic symptoms such as asthma, eczema, hives, and gastrointestinal symptoms.  Dysbiosis (defined as a lack of beneficial intestinal microbes such as Bifidobacterium and Lactobacillus species) also increases the risk of allergic disease; and various probiotic therapies have shown promise for reducing AR symptoms.

Vitamin D is crucial for maintaining a healthy immune system.  Poor vitamin D status increases the risk of allergic disease like AR; and the majority of Canadians (especially those who do not supplement with daily vitamin D) have sub-optimal vitamin D levels.  Supplementing with vitamin C, and the bioflavonoid quercetin can also help reduce histamine levels and improve symptoms. Butterbur (Petasites hybridus) root extract has also demonstrated similar effectiveness to antihistamine medication at reducing AR symptoms in several clinical trials.

Immunotherapy is a way of desensitizing the immune system by using very low doses of allergen formulas over a long period of time.  There are several different therapies available, but most are given by injection in a doctor’s office, or sublingually (under the tongue) at home. Sublingual immunotherapy (SLIT) is growing in popularity due to its safety, effectiveness and the convenience of treatment.  These therapies generally take several months to achieve their full effect but can produce great results.

~ Dr. Tim

References:

1.   Agency for Healthcare Research and Quality. “Evidence Report/Technology Assessment Number 54: Management of Allergic and Nonallergic Rhinitis” <http://www.ahrq.gov>

2.  Anderson SE, Franko J, Kashon ML, et al. Exposure to triclosan augments the allergic response to ovalbumin in a mouse model of asthma. Toxicol Sci 2013; 132:96.

3.  Aryan Z, Rezaei N, Camargo CA Jr. Vitamin D status, aeroallergen sensitization, and allergic rhinitis: A systematic review and meta-analysis. Int Rev Immunol. 2017 Jan 2;36(1):41-53.

4.  Beck I, Jochner S, Gilles S, et al. High environmental ozone levels lead to enhanced allergenicity of birch pollen. PLoS One 2013; 8:e80147.

5.  Bégin P, Nadeau KC. Epigenetic regulation of asthma and allergic disease. Allergy Asthma Clin Immunol 2014; 10:27.

6.  Cingi C1, Demirbas D, Songu M. Allergic rhinitis caused by food allergies.  Eur Arch Otorhinolaryngol. 2010 Sep;267(9):1327-35.

7.  Eder W, Ege MJ, von Mutius E. The asthma epidemic. N Engl J Med 2006.

8.  Gascon M, Casas M, Morales E, et al. Prenatal exposure to bisphenol A and phthalates and childhood respiratory tract infections and allergy. J Allergy Clin Immunol 2015; 135:370.

9.  Guo R, Pittler MH, Ernst E. Herbal medicines for the treatment of allergic rhinitis: a systematic review. Ann Allergy Asthma Immunol. 2007;99(6):483.

10.  Helms S, Miller A. Natural treatment of chronic rhinosinusitis. Altern Med Rev. 2006 Sep;11(3):196-207.

11.  Hunter JO. Food allergy-or enterometabolic disorder? Lancet. 1991;338(8765):495-496.

12.  Julia V, Macia L, Dombrowicz D. The impact of diet on asthma and allergic diseases. Nat Rev Immunol. 2015 May;15(5):308-22. doi: 10.1038/nri3830.

13.  Keith PK, Desrosiers M, Laister T, Schellenberg RR, Waserman S. The burden of allergic rhinitis (AR) in Canada: perspectives of physicians and patients. Allergy Asthma Clin Immunol. 2012;8(1):7.

14.  Kirjavainen PV, Gibson GR. Healthy gut microflora and allergy: factors influencing development of the microflora. Ann Med. 1999;31(4):288-292.

15.  Liu X, Ng CL, Wang Y. The efficacy of sublingual immunotherapy for allergic diseases in Asia. Allergol Int. 2018 Mar 15. pii: S1323-8930(18)30012-1.

16.  Malizia V, Fasola S, Ferrante G, et al. Efficacy of Buffered Hypertonic Saline Nasal Irrigation for Nasal Symptoms in Children with Seasonal Allergic Rhinitis: A Randomized Controlled Trial. Int Arch Allergy Immunol. 2017;174(2):97-103.

17.  Okada H, Kuhn C, Feillet H, Bach JF. The ‘hygiene hypothesis’ for autoimmune and allergic diseases: an update. Clin Exp Immunol 2010; 160:1.

18.  Passalacqua G1, Bagnasco D2, Ferrando M2, et al. Current insights in allergen immunotherapy. Ann Allergy Asthma Immunol. 2018 Feb;120(2):152-154.

19.  Patel S, Murray CS, Woodcock A, et al. Dietary antioxidant intake, allergic sensitization and allergic diseases in young children. Allergy 2009; 64:1766.

20.  Pearce N, Aït-Khaled N, Beasley R, et al. Worldwide trends in the prevalence of asthma symptoms: phase III of the International Study of Asthma and Allergies in Childhood (ISAAC). Thorax 2007.

21.  Peat JK, Li J. Reversing the trend: reducing the prevalence of asthma. J Allergy Clin Immunol 1999; 103:1.

22.  Platts-Mills TA. Asthma severity and prevalence: an ongoing interaction between exposure, hygiene, and lifestyle. PLoS Med 2005; 2:e34.

23.  Platts-Mills TA. The allergy epidemics: 1870-2010. J Allergy Clin Immunol 2015; 136:3.

24.  Seo JH, Kwon SO, Lee SY, et al. Association of antioxidants with allergic rhinitis in children from seoul. Allergy Asthma Immunol Res. 2013 Mar;5(2):81-7.

25.  Zuckerman GB, Bielory L. Complementary and alternative medicine herbal therapies for atopic disorders. Am J Med 2002;113:47S-51S.

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