Late introduction of fish and eggs is associated with increased risk of allergy development – results from the FARMFLORA birth cohort

ABSTRACT

The prevalence of allergy is markedly low in children growing up on farms. An increasing number of studies indicate that the timing of food introduction may affect allergy development. We aimed to investigate if protection against allergy in farm environments may be mediated through differences in food-introduction practices between farm and non-farm families, using an explorative approach. Twenty-eight farm and 37 non-farm children were included in the FARMFLORA birth cohort. Practices of breastfeeding and introduction of formulas and complementary foods were collected by questionnaires at 6, 12, and 18 months of age. Allergy was diagnosed by pediatricians at 3 years of age. The only difference in food-introduction practices observed between farm and non-farm children was an earlier introduction of nuts in farmers (median month: 11 [IQR: 8–6] in farmers, 15 [12–19] in non-farmers). One farm child (4%) and 10 non-farm children (27%) were allergic at 3 years of age. Lower risk of allergy development was associated with early exclusive breastfeeding (continuous variable; OR = 0.59, 95% CI: 0.39–0.89), but also having received eggs (OR = 0.08, 95% CI: 0.13–0.54) and fish (logistic regression not applicable, P = 0.01 in likelihood ratio testing [χ²]) at 10 months of age or earlier compared to later. Our results were not affected by reverse causation, as judged by a questionnaire sent to the families in retrospect. Timing of introduction of complementary foods is unlikely to contribute to the lower risk of allergy among farm children. Although early exclusive breastfeeding was associated with a lower rate of allergy development, postponed introduction of complementary foods might increase the risk of developing allergy. Owing to the limited sample size, our results are only indicative, but support prior findings.

KEYWORDS:

• farmers
• allergy
• breastfeeding
• complementary foods
• introduction of solids
• fish
• eggs

Acknowledgments

We thank the study nurses Helen Andersson and Anders Nordberg for their skillful work in coordinating sampling and questionnaires. Also, we gratefully acknowledge pediatricians Margareta Ceder, Gunhild Lindhagen, Stefan Stentoft and Carl-Johan Törnhage who diagnosed the children, and all the families for their participation in this study. The FARMFLORA birth cohort was supported by the Swedish Research Council for Environmental, Agricultural Sciences and Spatial Planning (Formas) under Grant number 222-2004-1958; the Ekhaga Foundation; Food and Health Concept Centre, Gothenburg, West Gothia Region (VGR); Torsten and Ragnar Söderberg Foundation; and the Swedish federal government under the LUA/ALF agreement and the Swedish Research Council (VR, No. 521-2013-3154).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Swedish Research Council for Environmental, Agricultural Sciences and Spatial Planning (Formas) under Grant number 222-2004-1958; the Ekhaga Foundation; the Food and Health Concept Centre, West Gothia Region (VGR); the Torsten and Ragnar Söderberg Foundation; the Swedish federal government under the LUA/ALF agreement; and the Swedish Research Council (VR) under Grant number 521-2013-3154.