Reference
Kiefte-de Jong JC, de Vries JH, Franco OH, et al. Fish consumption in infancy and asthma-like symptoms at preschool age. Pediatrics. 2013;130:1060-1068.
Design
A population based prospective birth cohort, an arm of the Generation R Study.
Participants
7,210 children born between April 2002 and January 2006 in Rotterdam, Netherlands were studied. Confounding variables were considered and assessed such as infant’s gender, gestational age, birth weight, maternal smoking and alcohol intake, maternal folic acid intake, family history of asthma, eczema, hayfever, and dust allergy, in addition to breastfeeding data, daycare attendance, and infant vitamin D supplementation.
Primary Outcome Measures
Nutritional data was collected at age 14 months using a semi-quantitative food frequency questionnaire (FFQ) that had been previously validated.1 The survey divided fish into 2 groups based on their fat content: (1) fatty fish including herring, mackerel, eel, and salmon and (2) other fish such as tilapia, tuna, sole, trout, cod, swordfish, white fish, squid, flounder, pollock, haddock, and wolf fish. Parents were also queried on when fish was introduced into the diet and how often it was given per week. The children were then assessed at 36 and 48 months for asthma-like symptoms using an age-adapted version of the International Study of Asthma and Allergies in Childhood, a questionnaire that has been previously validated.2 The study aimed to determine an association between the timing of fish introduction in the first year of life and the development of asthma-like symptoms among preschoolers.
Key Findings
Infants who were introduced to fish between 6 and 12 months had a statistically significant lower incidence of wheezing at 48 months when compared to infants who were not introduced to fish in the first year of life (OR: 0.64%; 95% Cl: 0.43–0.94). Infants who were introduced to fish between 0 and 6 months had slightly higher risk of wheezing at 48 months (not statistically significant). The consumption of less than 1/2 serving per week of fatty fish was associated with a significantly higher incidence of wheezing at 48 months; however, once confounding variables were taken into consideration, the amount of fish consumed in the diet was not correlated to asthma-like symptoms. Timing of fish introduction and asthma-like symptoms were not different when family history of atopy, breastfeeding duration, and type of fish consumed were considered.
Practice Implications
The timing, quality, and type of food introduced during the first year of life is a common topic of discussion during routine well child exams. Contrary to earlier belief, delaying introduction of solid foods does not appear to be associated with a lower prevalence of allergic hypersensitivity reactions.3–5 Of note, a 2009 birth cohort following 994 Finnish children for the first 5 years of life demonstrated that delaying food introduction past 6 months of age was associated with an increased risk of allergic sensitization to food and inhalant allergens.6 The authors found that late introduction of eggs (>10.5 months), fish (>8.2 months), meat (>5.5 months), wheat (>6 months), and rye (>7 months) had a significant positive association with sensitization to food allergens, even after adjusting for potential confounders. In addition, late introduction of potatoes and fish had a significant association with sensitization to inhalant allergens.
This is the first study of its kind to investigate optimal timing of fish introduction in relation to asthma risk reduction, demonstrating that there may be a window of opportunity between 6 and 12 months when fish introduction and consumption can reduce the risk of developing childhood asthma. In comparison, no fish introduction in the first year and early introduction (before 6 months of age) were associated with an increased prevalence of asthma-like symptoms. These findings complement prior findings suggesting a “window of opportunity” in the first year of life in which exposure to environmental factors may influence the risk of asthma.7
Contrary to earlier belief, delaying introduction of solid foods does not appear to be associated with a lower prevalence of allergic hypersensitivity reactions.
Given that fish is high in anti-inflammatory and immune-modulating omega-3 fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA),8 one would expect that the amount of fish (and therefore, the amount of omega-3 fatty acids) consumed would have a dose-dependent protective effect. However, the study did not demonstrate an association between the amount or the type of fish consumed in the first year and the prevalence of asthma-like symptoms in young children. The authors speculate that the benefit of omega-3 fatty acids could have been offset by the contamination of fish with mercury, dioxins, and polychlorinated biphenyls (PBCs); however, numerous studies have shown that any number of early-life immune insults such as second-hand tobacco, diesel exhaust, microbial exposure, and antibiotics also play a role in the development of childhood allergy and immune dysfunction.9,10 More clinical studies investigating the optimal timing of food introduction would be beneficial, but I believe there is evidence demonstrating that introducing fish between 6 and 12 months may help reduce the risk of childhood asthma.
