By Allergen Bureau

Environmental greenness exposure may raise food allergy risk

Exposure to environmental greenness in childhood appears to have an impact on the risk of developing allergic disease. Melbourne-based researchers have explored for the first time a possible link between exposure to environmental greenness and food allergy risk.

Environmental greenness encompasses trees, shrubs, and grasses growing in outdoor areas. Environmental green spaces are critical for not only encouraging active lifestyles, but for providing people with an opportunity to interact with diverse microbes, vegetation, soil, and pollen – all of which have previously been implicated to some extent in the development of allergies.

To explore the impact of exposure to environmental greenness on food allergy risk, more than 5,000 one-year-old infants (recruited to the large-scale HealthNuts study) underwent skin prick testing to peanut, egg, and sesame. Those showing signs of an immune response underwent food challenges to determine food allergy status.

Environmental greenness around each infant’s home was estimated using the normalized difference vegetation index (NDVI). An NDVI was measured for five zones around each infant’s home address: at the home, 100 m, 500 m, 800 m, and 1600 m radial distances.

Increased exposure to environmental greenness in the first year of life was found to be associated with an increased risk of food allergy. The authors propose this may be due to higher pollen levels coming from nearby trees, shrubs, and grasses, which may trigger immune responses.

However, given the mixed evidence for an association between exposure to environmental greenness in childhood and the risk of developing allergic disease more generally, the relationship with food allergy development appears complex. It may also be influenced by confounding variables outside those measured in this study, suggesting further research is needed.

Reference: Peters et al. 2022. Paediatric Allergy and Immunology. DOI: 10.1111/pai.13749

See also the 2022 Open Access Review article by Peters et al “An Overview of Environmental Risk Factors for Food Allergy”