Antioxidant nutrients like carotenoids, tocopherols and vitamin C have been suggested to protect against allergic rhinitis and allergic sensitisation but scientific evidence is scarce. The aims of the study were to measure the plasma concentration of six carotenoids, α- and γ-tocopherol and vitamin C as biomarkers of the intake, absorption and subsequent metabolism of these nutrients, and to assess their association with allergic rhinitis and sensitisation.
Data from a cross-sectional study on representative dietary and lifestyle habits of the population of Bavaria, Germany, were analysed. The plasma levels of six carotenoids (α-carotene, β-carotene, lycopene, lutein/zeaxanthin, canthaxanthin and cryptoxanthin) as well as of α-tocopherol, γ-tocopherol and vitamin C were measured in 547 adults aged between 19 and 81 years. Participants with specific serum immunoglobulin E ≥700 U l−1 were categorised as sensitised. The association of plasma antioxidant levels, allergic rhinitis and allergic sensitisation was assessed by means of unconditional logistic regression models.
We observed a negative association between plasma total carotenoids and the prevalence of allergic rhinitis, with odds ratio (95% confidence interval) of 1.13 (0.54–2.39) for the second, 0.72 (0.33–1.58) for the third and 0.44 (0.19–1.03) for the fourth quartile of total carotenoids concentration (P for trend = 0.0332); results for lycopene failed to reach statistical significance (P = 0.0608). Other single carotenoids, tocopherols and vitamin C were unrelated to allergic rhinitis. Allergic sensitisation was negatively associated with plasma γ-tocopherol, with odds ratio (95% confidence interval) of 0.92 (0.51–1.65) for the second, 1.00 (0.56–1.80) for the third and 0.45 (0.23–0.88) for the fourth quartile of plasma γ-tocopherol concentration (P for trend = 0.0410). No other antioxidant was significantly related to allergic sensitisation.
High plasma carotenoid concentrations reflecting a diet high in various fruits and vegetables might have a protective effect on allergic rhinitis in adulthood.
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