Higher dietary fiber intake in childhood reduces risk for allergic rhinitis in adulthood

Key takeaways:

• There was an inverse overall association between fiber intake at age 8 years and allergic rhinitis symptoms at age 24 years.
• Higher fiber intake in childhood also was associated with reduced likelihood of sensitization to specific allergens including birch and soy.
• When participants with allergy symptoms related to food were excluded from analysis, associations were attenuated and were no longer significant.

Children who ate more fiber had reduced odds for allergic rhinitis and sensitization to specific airborne and food allergens through early adulthood, according to a study published in Clinical and Translational Allergy.

However, these protective associations may be driven by avoidance of foods that can trigger allergic symptoms among patients with allergic rhinitis, Emmanouela Sdona, MD, PhD, researcher with the Institute of Environmental Medicine, Karolinska Institutet, Stockholm, and colleagues wrote.

The researchers examined data from 2,285 participants of the BAMSE prospective birth cohort who were recruited at an average age of 2 months between 1994 and 1996 in Stockholm. Participants answered questionnaires about their lifestyles, exposures and symptoms of allergic diseases at age 8, 16 and 24 years and they had clinical exams including blood sampling at age 4, 8, 16 and 24 years.

Median energy-adjusted total fiber intake at age 8 years was 18.3 g per day for girls and 17.6 g per day for boys (P < .001), or 18 g per day overall. At age 16 years, totals included 18.2 g per day for girls and 16.3 g per day for boys (P < .001), or 17.1 g per day for both groups combined.

Asthma prevalence was 10.8% at age 8 years, 14.8% at age 16 years and 14.6% at age 24 years. Prevalence of allergic rhinitis increased from 14.2% at age 8 years to 25.5% at age 16 years to 30.9% at age 24 years.

Similarly, prevalence of sensitization to airborne allergens increased from 26.2% at age 8 years to 44.6% at age 16 years and to 44.9% at age 24 years. Prevalence of sensitization to food allergens decreased from 20.3% at age 8 years to 13.7% at age 16 years and 10.4% at age 24 years.

According to the researchers, there was an association between higher fiber intake at age 8 years and reduced odds for prevalent allergic rhinitis symptoms up to age 24 years (OR per 5 g per day = 0.86; 95% CI, 0.77-0.96), although no association was observed with asthma.

The researchers also found an inverse association between total fiber intake at age 8 years and sensitization to airborne (OR = 0.74; 95% CI, 0.62-0.89) and food allergens (OR = 0.69; 95% CI, 0.54-0.88) among participants with allergic rhinitis through age 24 years.

Higher childhood fiber intake also reduced the likelihood of IgE sensitization to specific airborne and food allergens as well, including birch (OR = 0.77; 95% CI, 0.67-0.88) and soy (OR = 0.68; 95% CI, 0.53-0.87), up to age 24 years.

The reduced likelihood for allergic rhinitis persisted when researchers analyzed fiber from fruit (OR = 0.79; 95% CI, 0.67-0.94) and other sources such as potatoes, chips or popcorn, legumes and nuts (OR = 0.71; 95% CI, 0.5-0.99), but not cereal or vegetable fiber.

But when participants with allergic symptoms related to food were excluded in sensitivity analyses, the researchers found that these associations were attenuated and became nonsignificant at age 24 years.

This shift in significance indicates that disease-related modification of consumption may have contributed to results as children avoid or less frequently eat foods that induce immediate symptoms, resulting in an apparent protective association.

The researchers further suggested that the lack of significant associations between fiber intake and asthma could be due to antioxidants or better diet quality in general, based on adjustment by dietary total antioxidant capacity.

Concluding that there is an association between higher fiber intake in mid-childhood and reduced odds for allergic rhinitis and sensitization to specific allergens in adulthood, the researchers still cautioned that further studies on and increased awareness of fiber intake are needed.