Are GMOs the cause of rising allergy rates?

What causes hay-fever and asthma?

One pet-dog is good for reducing allergies; two dogs are even better.

With the rise in allergies such as hay-fever suffered by children over recent years, it's natural for parents to ask Why us?

Some even go as far to speculate that GM foods are causing a rise in allergies. But rises in allergies and hay-fever occurred in countries that do not have GM foods, and happened in countries, such the UK, well before any GM foods reached that market place.

It's fascinating to realise this problem may be caused by homes that are just too clean and mothers who try too hard to protect their children from normal dirt and grime.

Grubby Eastern Germany before the fall of communism used to be blessed by much lower allergy rates than those that afflicted its sparkling clean, richer sister nation, Western Germany.

Communist homes were not too clean it seems, and red children got well exposed to dirt, giving their immune systems just the right kind of training to avoid a badly programmed system that in older children gives rise to allergies.

Dirty pets help too.

Dirty animals help too. Children who had pet dogs to lovingly lick them suffer on the average less from allergies than children who grow up in dog-less families. Families with two dog pets are even better off on the hay-fever and allergy front. Farm animals too, are good for healthy dirt to properly prime the immune system.

So, as with bee colony collapse disorder, it's probably wrong to blame GMOs for allergies just on the basis of rumours.


See also earlier post: post hoc ergo procter hoc

Prevalence of respiratory symptoms, bronchial hyperresponsiveness and atopy among adults: west and east Germany.

Nowak D, Heinrich J, Jörres R, Wassmer G, Berger J, Beck E, Boczor S, Claussen M, Wichmann HE, Magnussen H. Eur Respir J. 1996 Dec;9(12):2541-52. Zentrum für Pneumologie und Thoraxchirurgie, Grosshansdorf, Germany.

The prevalence of respiratory symptoms, atopic sensitization and bronchial hyperresponsiveness was compared in a random sample of adults, 20-44 yrs of age, in two cities in West and East Germany, Hamburg and Erfurt, respectively. There were much higher levels of outdoor air pollution due to sulphur dioxide and suspended particulates in Erfurt, and major differences in living conditions during the last 40 yrs. Within the European Respiratory Health Survey, a short questionnaire was answered by 3,156 (80% response rate) subjects in Hamburg and 3,272 (74%) in Erfurt. A subset of responders to the short questionnaire completed a long questionnaire, spirometry, methacholine or bronchodilator test, skin test, and total and specific immunoglobulin E (IgE) measurements, with a total number of 1,159 participants in Hamburg and 731 in Erfurt.

Six out of 8 questions on respiratory symptoms and diagnoses were answered in the affirmative more frequently in Hamburg than in Erfurt. In Hamburg, mean forced expiratory volume in one second (FEV1)% of predicted was 105 vs 107% in Erfurt (p less than 0.0001), and bronchial hyperresponsiveness was more frequently observed in Hamburg than in Erfurt (25 vs 19%; p less than 0.05). Atopic sensitization was more prevalent in Hamburg than in Erfurt regarding the results of skin tests against grass pollen (24 vs 19%; p less than 0.05), birch pollen (19 vs 8%; p less than 0.0005), cat (10 vs 2%; p less than 0.0005), and Dermatophagoides pteronyssinus (14 vs 10%; p less than 0.05). This was reflected by the prevalences of positive specific IgE values, which were higher in Hamburg than in Erfurt for grass (26 vs 20%; p less than 0.05), birch (20 vs 10%; p less than 0.0005) and cat (12 vs 8%; p less than 0.05). In Hamburg, compared to Erfurt, there was: a lower mean number of siblings (p less than 0.005); a higher degree of childhood and current exposure to environmental tobacco smoke (p less than 0.005); and a higher frequency of fitted carpets and reported mould or mildew inside the house (p less than 0.005). Therefore, these data may support the hypothesis that childhood factors and exposure to indoor allergens and irritants may have been more relevant for the development of asthma and atopy than the potential long-term exposure to high concentrations of sulphur dioxide and particulate matter.

Increasing prevalence of hay fever and atopy among children in Leipzig, East Germany.
von Mutius E, Weiland SK, Fritzsch C, Duhme H, Keil U.
Lancet. 1998 Mar 21;351(9106):862-6.

Lancet. 1998 Mar 21;351(9106):862-6.
Comment in: Lancet. 1998 Jul 25;352(9124):318. Lancet. 1998 Jun 13;351(9118):1813-4. Lancet. 1998 Jun 13;351(9118):1813; author reply 1814. Increasing prevalence of hay fever and atopy among children in Leipzig, East Germany. von Mutius E, Weiland SK, Fritzsch C, Duhme H, Keil U. University Children's Hospital, Munich, Germany.

BACKGROUND: Several surveys in children and adults have shown significantly lower prevalences of asthma and allergic diseases in eastern Europe than in western countries. In the former East Germany tremendous changes towards western lifestyle have occurred since unification. The aim of this survey was to investigate time trends in the prevalence of asthma and allergic diseases among children living in the eastern part of Germany.

METHODS: In 1995-96, 2334 (87.5%) schoolchildren in Leipzig participated in a cross-sectional study that used the same methods as a previous survey done shortly after the fall of communism in 1991-92. A self-administered questionnaire was distributed to the parents. Children underwent cold-air challenge and allergy skinprick tests to six common aeroallergens.
FINDINGS: The prevalence of hay fever (2.3% [34/1454] vs 5.1% [115/2252], p less than 0.0001) and atopic sensitisation (19.3% [252/1303] vs 26.7% [434/1624], p less than 0.0001) increased significantly between 1991-92 and 1995-96. However, there was no significant change in the prevalence of asthma, asthma-related symptoms, or bronchial hyper-responsiveness.

INTERPRETATION: These findings suggest important differences in the development of atopic disorders.
The children were born about 3 years before unification and were therefore exposed to western living conditions only after the third birthday. Thus, factors operating very early in life may be particularly important for the acquisition of childhood asthma, whereas the development of atopic sensitisation and hay fever may also be affected by environmental factors occurring beyond infancy.

Allergy. 2003 Nov;58(11):1136-43.
Allergy markers in adults in relation to the timing of pet exposure: the EGEA study.

Oryszczyn MP, Annesi-Maesano I, Charpin D, Kauffmann F.

Epidemiology and Biostatistics, INSERM U472-IFR69, Villejuif, France.

BACKGROUND: Studies suggest that early childhood exposure to pets may protect from the development of atopy, but limited information is available on adults. The association of allergy markers in adulthood with current and childhood exposure to pets was studied considering retrospectively the window of exposure.
METHODS: Immunoglobulin E (IgE), skin prick tests (SPT), eosinophils were related to exposure to pets in 187 adult asthmatic cases and 243 controls from the Epidemiological Study on the Genetics and Environment of Asthma, bronchial hyperresponsiveness and atopy (EGEA) study. Analyses were redone after exclusion of subjects who removed pets or experienced symptoms to animals to take into account selection in that retrospective study.
RESULTS: In asthmatic cases, current exposure to pets was unrelated to SPT positivity (+), whereas childhood exposure was significantly related to less SPT+ to any allergen, and to cat in particular, with an association restricted to those exposed before 2 years of age [OR = 0.30 (CI 0.12-0.76)]. Considering the relative timing of exposure in relation to asthma onset showed that the protective effect of exposure to pets occurs for pet exposure starting before asthma onset [OR for SPT+ = 0.19 (CI 0.08-0.48)].

CONCLUSION: Results support the hypothesis that exposure to pets in early life, and in particular before asthma onset, may protect against allergen sensitization in adulthood.

Curr Opin Allergy Clin Immunol. 2003 Dec;3(6):517-22.
Does exposure to dogs and cats in the first year of life influence the
development of allergic sensitization?

Ownby DR, Johnson CC.

Department of Pediatrics, Medical College of Georgia, Augusta, Georgia 30912,
USA. downby@mail.mcg.edu

PURPOSE OF REVIEW: The goal of the review is to place studies published after 1 June 2002, concerning the relationship between early life exposure to cats and dogs and the later development of allergy, within the context of the effects of other environmental exposures on allergic disease.
RECENT FINDINGS: Most of the recent studies have shown that exposure to cats and dogs early in infancy reduces the prevalence of allergic sensitization or allergic disease later in childhood.
While this general trend is relatively consistent, there are differences in specific findings between studies, such as the effect of parental allergies. Other studies suggest that the association between cat and dog exposure and a lower risk of allergy is due to either differences in other environmental exposures or to genetic differences between exposed and non-exposed children. It is impossible to directly compare the results from all of these studies since there are often important differences in racial/ethnic backgrounds of the
children, climate, housing conditions, and the family and social customs of those enrolled in different studies. SUMMARY: The risk of a child developing any form of allergy appears to depend upon many factors including a child's genetic constitution, early environmental exposure to allergens and to other agents which interact with the immune system, and to allergen exposure later in life. It appears that exposure to something that is increased in homes with cats or dogs reduces the risk of allergic sensitization.



JAMA. 2002 Aug 28;288(8):963-72.
Comment in: JAMA. 2002 Aug 28;288(8):1012-4. JAMA. 2003 Feb 19;289(7):841; author reply 841-2. JAMA. 2003 Feb 19;289(7):841; author reply 841-2. JAMA. 2003 Feb 19;289(7):841; author reply 841-2. JAMA. 2003 Feb 19;289(7):842; author reply 842-3.

Exposure to dogs and cats in the first year of life and risk of allergic sensitization at 6 to 7 years of age.

Ownby DR, Johnson CC, Peterson EL.

Section of Allergy and Immunology, Department of Pediatrics, BG-1019, Medical College of Georgia, Augusta, GA 30912-3790, USA. downby@mail.mcg.edu

CONTEXT: Childhood asthma is strongly associated with allergic sensitization.
Studies have suggested that animal exposure during infancy reduces subsequent allergic sensitization. OBJECTIVE: To evaluate the relationship between dog and cat exposure in the first year of life and allergic sensitization at 6 to 7 years of age.
DESIGN, SETTING, AND SUBJECTS: Prospective birth cohort study of healthy, full-term infants enrolled in a health maintenance organization in suburban Detroit, Mich, who were born between April 15, 1987, and August 31, 1989, and followed up yearly to a mean age of 6.7 years. Of 835 children initially in the study at birth, 474 (57%) completed follow-up evaluations at age 6 to 7 years.
MAIN OUTCOME MEASURES: Atopy, defined as any skin prick test positivity to 6 common aeroallergens (dust mites [Dermatophagoides farinae, D pteronyssinus], dog, cat, short ragweed [Ambrosia artemisiifolia], and blue grass [Poa pratensis]); seroatopy, defined as any positive allergen-specific IgE test result for the same 6 allergens or for Alternaria species.
RESULTS: The prevalence of any skin prick test positivity (atopy) at age 6 to 7 years was 33.6% with no dog or cat exposure in the first year of life, 34.3% with exposure to 1 dog or cat, and 15.4% with exposure to 2 or more dogs or cats (P =.005). The prevalence of any positive allergen-specific IgE test result (seroatopy) was 38.5% with no dog or cat exposure, 41.2% with exposure to 1 dog or cat, and 17.9% with exposure to 2 or more dogs or cats (P =.003). After adjustment for cord serum IgE concentration, sex, older siblings, parental smoking, parental asthma, bedroom dust mite allergen levels at 2 years, and current dog and cat ownership, exposure to 2 or more dogs or cats in the first year of life was associated with a significantly lower risk of atopy (adjusted odds ratio, 0.23; 95% confidence interval, 0.09-0.60) and seroatopy (adjusted odds ratio, 0.33; 95% confidence interval, 0.13-0.83).
CONCLUSION: Exposure to 2 or more dogs or cats in the first year of life may reduce subsequent risk of allergic sensitization to multiple allergens during childhood.

Eur Respir J. 1999 Oct;14(4):862-70.
Prevalence of respiratory and atopic disorders among children in the East and West of Germany five years after unification.
Weiland SK, von Mutius E, Hirsch T, Duhme H, Fritzsch C, Werner B, Hüsing A, Stender M, Renz H, Leupold W, Keil U.

Institute of Epidemiology and Social Medicine, University of Münster, Germany.

Living conditions in eastern Germany have changed rapidly since unification in 1990 and little is known about how these changes affect the prevalence of atopic diseases. This study describes methods and prevalences of a large epidemiological project investigating determinants of childhood asthma and allergies in eastern (Dresden and Leipzig) and western (Munich) Germany in 1995/1996. Community based random samples of 9-11 yr old children in Dresden (n=3,017) and Munich (n=2,612), and of 5-7 yr old children in Dresden (n=3,300), Leipzig (n=3,167) and Munich (n=2,165) were studied by parental questionnaires, bronchial challenges with hypertonic saline, skin examination, skin-prick tests, and measurements of specific and total serum immunoglobulin (Ig)E using Phase II modules of the International Study of Asthma and Allergies in Childhood (ISAAC). In 9-11 yr old children, the prevalence of physician diagnosed asthma (7.9% versus 10.3%; p less than 0.01) and bronchial hyperresponsiveness (15.7% versus 19.9%; p less than 0.05) was lower in Dresden than in Munich. No difference between Munich and Dresden was observed in the prevalence of diagnosed hay fever, skin test reactivity to greater than or = 1 allergen, and increased levels (greater than 0.35 kU x L(-1)) of specific IgE against inhalant and food allergens. Symptoms and visible signs of atopic eczema tended to be more prevalent in Dresden. Similar East-West differences between the three study areas were seen in the younger age group. These findings are in line with recently observed increases in the prevalence of hay fever and atopic sensitization, but not of asthma and bronchial hyperresponsiveness, among 9-11 yr old children in Leipzig.

Waser M, von Mutius E, Riedler J, Nowak D, Maisch S, Carr D, Eder W, Tebow G,
Schierl R, Schreuer M, Braun-Fahrlander C; The ALEX Study team. Exposure to pets, and the association with hay fever, asthma, and atopic sensitization in rural children.
Allergy. 2005 Feb;60(2):177-84.

Remes ST, Koskela HO, Iivanainen K, Pekkanen J.
Allergen-specific sensitization in asthma and allergic diseases in children: the study on farmers' and non-farmers' children.
Clin Exp Allergy. 2005 Feb;35(2):160-6.

Riedler J, Eder W, Oberfeld G, Schreuer M.
Austrian children living on a farm have less hay fever, asthma and allergic sensitization.
Clin Exp Allergy. 2000 Feb;30(2):194-200.

Oberle D, von Mutius E, von Kries R.
Childhood asthma and continuous exposure to cats since the first year of life with cats allowed in the child's bedroom.
Allergy. 2003 Oct;58(10):1033-6.

Holscher B, Frye C, Wichmann HE, Heinrich J.
Exposure to pets and allergies in children.
Pediatr Allergy Immunol. 2002 Oct;13(5):334-41.