Study of Folate Status Among Egyptian Asthmatics

Abstract

Objective To compare serum folate levels between atopic asthmatics, non-atopic asthmatics, and healthy controls. Methods This case-control study included 60 asthmatics with at least one positive skin prick test (SPT) reaction (atopic asthma group), 60 asthmatics with negative SPT reactions (non-atopic asthma group), and 60 healthy controls with no history of asthma or other allergic diseases, and with negative SPT reactions. Serum folate and total IgE levels were measured in all subjects. In addition, lung functions were assessed by spirometry. Results Serum folate levels were significantly lower among the atopic asthma group [9.1 (4.9, 12.1) ng/ mL] as compared to the non-atopic asthma group [11.3 (7.5, 14.8) ng/mL] and the control group [12.0 (8.3, 15.1) ng/mL], p= 0.001. Among atopic asthmatics, serum folate levels were inversely correlated with total serum IgE levels (r=-0.483, p<0.001), and the number of positive SPT reactions (r=-0.442, p<0.001). Atopic asthmatics with a total serum IgE !200 IU/mL had significantly higher levels of serum folate than those with a total serum IgE >200 IU/mL. Regression analysis showed that higher folate levels independently predicted lower total serum IgE levels. Folate was not found to be an independent predictor of asthma. No association was observed between serum folate levels and values of forced expiratory volume in 1s. Conclusion Among asthmatics, serum folate levels are significantly lower among atopics, and correlate inversely with the degree of atopy.

Folate and Asthma

“…Seven cross-sectional studies have yielded conflicting findings for folate and asthma or atopy (15,16,(21)(22)(23)(24) (Table 1).…”

“…Although three case-control studies with small sample size (including preschool children [24], adolescents [16], and adults [22]) found no significant association between dietary intake (16) or serum level of folate (22,24) and asthma (16,22) or atopic dermatitis (24), a larger case-control study of 1,030 British adults found a significant inverse association between dietary folate intake and physician-diagnosed asthma (adjusted [a] odds ratio [OR] for each quintile increase in intake ¼ 0.89, 95% confidence interval [CI] ¼ 0.81-0.98) (25). In contrast to findings from case-control studies, a cross-sectional study of 1,601 Australian adults showed that dietary intake of folate was positively associated with having ever had physician-diagnosed asthma (OR for each mg ¼ 2.2, 95% CI ¼ 1.2-3.9) but not with current asthma, airway responsiveness, or atopy (23).…”

Relationships between folate and inflammatory features of asthma

“…Recent studies suggest that folate may influence the risk of developing atopy and lower respiratory tract disease in children 1 and adults, 2–4 but there have been no studies, to our knowledge, that examine the relationship between folate status and allergic inflammation and asthma control among individuals with established disease. Because population-based data have shown an inverse association between serum folate levels and atopy, 2 wheeze, 2,3 and asthma, 3 it is plausible that serum folate levels may also be inversely associated with these outcomes among individuals with established asthma.…”

Folate Deficiency, Atopy, and Severe Asthma Exacerbations in Puerto Rican Children

“…Similarly, serum folate was inversely associated with total IgE in a study of 120 adults with asthma (10). In contrast to findings from those cross-sectional studies (9, 10), a multivariate analysis of data from a 1-year prospective study of 144 children with persistent asthma (aged 5-17 yr) showed that serum folate was not significantly associated with symptoms or acute visits for asthma, lung function, fractional exhaled nitric oxide, number of positive skin tests to allergens, or asthmarelated hospitalizations; although folate level was significantly but nonlinearly associated with total IgE, such finding is of unclear relevance, given all other negative results.…”

“…This question is relevant, given results of a recent metaanalysis of 11 observational studies, which showed that high dietary intake of vegetables (a source of folate) is associated with 11% reduced risk of wheeze in children and adults (8). Moreover, folate deficiency or a low folate level has been associated with increased risks of wheeze, atopy, or an elevated total IgE in cross-sectional studies of children and adults (9,10).…”