Protective effects of farming on allergies and asthma: have we learnt anything since 1873?

Douwes, Jeroen; Brooks, Collin; Pearce, Neil

doi:10.1586/eci.09.19

Cited by 12 publications

(6 citation statements)

References 75 publications

(104 reference statements)

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“…Previous studies of associations between exposure to farm environments in early life and atopic sensitization and asthma in adulthood have yielded inconsistent results. There are studies indicating that rural/farming childhood may decrease the risks of atopy and asthma , although long‐term continual exposure may be required to maintain optimal protection . In our study, there was also evidence that continued consumption of unpasteurized milk in adulthood offered additional protective effects; this is consistent with other evidence indicating that farming in adult life may additionally offer protective effects .…”

Section: Discussionsupporting

confidence: 90%

Consumption of unpasteurized milk and its effects on atopy and asthma in children and adult inhabitants in rural Poland

Sozańska

Pearce

Dudek

et al. 2013

Allergy

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Section: Discussionsupporting

confidence: 90%

Consumption of unpasteurized milk and its effects on atopy and asthma in children and adult inhabitants in rural Poland

Sozańska

Pearce

Dudek

et al. 2013

Allergy

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“…Blackley first reported the protective effect of farming exposure on allergic conditions as early as 1873 [20]. However, it is only recently that multiple studies have focused on identifying which individual aspects of farming lifestyles may contribute to protection from allergic disease.…”

Section: Introductionmentioning

confidence: 99%

Exposure to ‘farming’ and objective markers of atopy: a systematic review and meta‐analysis

Campbell

Lodge

Lowe

et al. 2015

Clin Experimental Allergy

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There is growing interest in the 'farm effect' on the spectrum of allergy. Evidence concerning the farm effect on asthma, eczema, and allergic rhinitis has been systematically synthesized, but without a specific focus on objective markers of sensitization. This focus is important, as farm exposures may be related to allergy but not to non-allergic phenotypes of disease. We aimed to systematically review and meta-analyse literature that has investigated associations between farm exposure at any age and objective measures of atopy, that is serum IgE or skin prick tests results. Using predefined inclusion and exclusion criteria, we identified 29 articles for review. IgE levels were measured in either childhood or adulthood by eighteen studies, while skin prick testing was performed in sixteen studies. Newcastle-Ottawa Scale quality assessments indicated that the majority of these studies demonstrated a representative sample of selected participants. Due to significant heterogeneity in study measures and methodology between studies, only few were meta-analysed. This meta-analysis showed a significant protective effect of farm exposure before 1 year of life on allergic sensitization (OR = 0.60 [0.52-0.70]). Farm exposure during childhood was also associated with a reduced risk of sensitization to cat or timothy (OR = 0.60 [0.51-0.70]; OR=0.46 [0.41-0.51]). Studies investigating the effect of farm exposure in adult life could not be meta-analysed, and their results were inconsistent. Insufficient studies investigated food sensitization as an outcome to allow synthesis. The majority of studies included in this review investigated childhood farm exposure, finding evidence to support a protective childhood 'farm effect' against subsequent atopy. There is inconsistent evidence on the association between farm exposure in adulthood and allergic sensitization. Further studies are needed to tease out the exact exposures and timing associated with farming environments that protect against allergic disease.

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“…These findings, published for young farmers [76 ], school children in Alpine regions [77–80 ] and confirmed in studies from many other countries [7, 10, 11, 42, 81–94 ], revived nineteenth century knowledge that hay fever is rare in farmers [95 ]. A commonly accepted explanation holds that the developing immune system of farm children is primed towards a state of non‐atopic responsiveness or immune tolerance for allergens [42, 77, 81, 84, 96 ], by chronic inhalation of farm dust containing pro‐inflammatory “microbe—associated molecular patterns” (MAMPs) (see paragraph on mechanisms), and/or by frequent ingestion of unpasteurized milk that also may contain enhanced concentrations of such MAMPs and in addition other agents with immunoregulatory properties like prebiotics and various cytokines; according to these theories it would be the very early or even prenatal farm exposures that protect against type I allergies. These protective effects might be most pronounced for traditional small‐scale farming, as in children studied in the original reports from Alpine regions [77, 78, 80 ].…”

Section: Main Textmentioning

confidence: 99%

“…Table 3 summarizes studies on the prevalence of atopy and atopic disease in farmers and non‐farmers, with farm childhood also taken into account. In many studies, a farm childhood appeared to confer a long‐lasting protection into adulthood [7, 10, 11, 82, 83, 85–89, 91–93, 101–103 ], while some also reported evidence that current farm work may additionally protect against sensitization to common allergens and/or atopic illness [88, 89, 96, 102, 103 ]. One longitudinal study found a lower risk of new pollen sensitization in young adulthood, especially in those with high animal stable dust and endotoxin exposures [42 ].…”

Section: Main Textmentioning

confidence: 99%

“…HWS bias seemed unlikely, since the frequencies of NSBHR and wheezing are higher or similar among the highly exposed workers, and protection in adulthood appeared to be mainly restricted to atopic sensitization. It especially pertained to hay fever, pollen sensitization [11, 42, 96, 101 ] and atopic asthma, while non‐atopic wheezing and NSBHR are more prevalent at high farm dust exposures [8, 76, 89, 101, 104 ]. Thus, farm work‐associated exposures may, in addition to a farm childhood, protect against persistence of, or newly originating atopic sensitization to pollen and possibly other common allergens [10, 11, 101 ].…”

Section: Main Textmentioning

confidence: 99%

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Respiratory diseases and allergy in farmers working with livestock: a EAACI position paper

Sigsgaard

Basinas

Doekes

et al. 2020

Clin Transl Allergy

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Farmers constitute a large professional group worldwide. In developed countries farms tend to become larger, with a concentration of farm operations. Animal farming has been associated with negative respiratory effects such as work‐related asthma and rhinitis. However, being born and raised or working on a farm reduces the risk of atopic asthma and rhinitis later in life. A risk of chronic bronchitis and bronchial obstruction/COPD has been reported in confinement buildings and livestock farmers. This position paper reviews the literature linking exposure information to intensive animal farming and the risk of work‐related respiratory diseases and focuses on prevention. Animal farming is associated with exposure to organic dust containing allergens and microbial matter including alive microorganisms and viruses, endotoxins and other factors like irritant gases such as ammonia and disinfectants. These exposures have been identified as specific agents/risk factors of asthma, rhinitis, chronic bronchitis, COPD and reduced FEV1. Published studies on dust and endotoxin exposure in livestock farmers do not show a downward trend in exposure over the last 30 years, suggesting that the workforce in these industries is still overexposed and at risk of developing respiratory disease. In cases of occupational asthma and rhinitis, avoidance of further exposure to causal agents is recommended, but it may not be obtainable in agriculture, mainly due to socio‐economic considerations. Hence, there is an urgent need for focus on farming exposure in order to protect farmers and others at work in these and related industries from developing respiratory diseases and allergy.

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Protective effects of farming on allergies and asthma: have we learnt anything since 1873?

Cited by 12 publications

References 75 publications

Consumption of unpasteurized milk and its effects on atopy and asthma in children and adult inhabitants in rural Poland

Consumption of unpasteurized milk and its effects on atopy and asthma in children and adult inhabitants in rural Poland

Exposure to ‘farming’ and objective markers of atopy: a systematic review and meta‐analysis

Respiratory diseases and allergy in farmers working with livestock: a EAACI position paper

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