Continuous rather than solely early consumption of farm milk protects from hay fever development

Published: November 7, 2022

Early life farm exposures; i.e. consumption of unprocessed cow’s milk (farm milk) and exposure to animal sheds; and gut microbiome composition have been shown to have a protective effect on asthma, hay fever, and atopic sensitization consequently proposing an important window of opportunity for these diseases. However, it is unknown whether hay fever with a peak incidence around late school age to adolescence is only determined very early in life or whether later exposure before the onset of disease matters most.

In the recent, issue of The Journal of Allergy and Clinical Immunology: In Practice, Pechlivanis et al. studied the temporal pattern of the protective farm exposures on hay fever development. The authors further investigated the role of the gut microbiome on hay fever. For the present study, the authors used the longitudinal data of the PASTURE study, which is a prospective birth cohort study, started in 2002 and conducted in children from rural areas of five European countries (Austria, Finland, France, Germany, and Switzerland). The study was designed to evaluate risk and preventive factors for atopic diseases.

Using repeated measure latent class analyses, farm milk consumption and exposure to animal sheds assessed at multiple time points from infancy to age 10.5 years were classified into temporal pattern of exposure as ‘continuous exposure’, ‘only early exposure’, ‘only late exposure’ and ‘no exposure’. The temporal pattern of exposure were then studied for the association with hay fever. Additionally, fecal samples at age 2 and 12 months were sequenced by 16S rRNA to investigate the role of the early life gut microbiome on hay fever.

The result of the study showed that continuous consumption of farm milk is necessary for optimal prevention of hay fever, thereby arguing against the notion of an early-determined trajectory governing later outcomes such as hay fever. In contrast, exposure to animal sheds only exerted a trend towards protection early in life. Both exposures, farm milk and animal sheds, in infancy increased gut microbiome richness at age 12 months, which partly explained the protective effect of these exposures on hay fever. These results emphasize the preventive potential of continuous rather than only early life consumption of unprocessed cow’s milk for hay fever protection.

The Journal of Allergy and Clinical Immunology: In Practice is an official journal of the AAAAI, focusing on practical information for the practicing clinician.

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