Dietary Fiber and Reduced Cough with Phlegm

Abstract

Smoking is the major risk factor for chronic respiratory symptoms, but dietary factors may also play a role. Most studies of diet and lung disease have been cross-sectional and conducted in populations with a Western-style diet. We analyzed the relation between dietary intake at baseline and new onset of cough with phlegm in a population-based cohort of 63,257 middle-aged Chinese men and women initiated in Singapore between 1993 and 1998. Beginning in 1999, we ascertained respiratory symptoms by telephone interview and have identified 571 incident cases of cough with phlegm among the 49,140 cohort members with completed follow-up. Nonstarch polysaccharides, a major component of dietary fiber, total fruit, and soy isoflavones had the strongest associations. Odds ratios comparing highest and lowest quartiles after adjustment for age, sex, dialect group, total energy intake, and smoking were 0.61 (95% confidence interval [CI]: 0.47, 0.78; p for trend < 0.001) for nonstarch polysaccharides, 0.67 (95% CI: 0.52, 0.87; p for trend = 0.006) for fruit, and 0.67 (95% CI: 0.53, 0.86; p for trend = 0.001) for soy isoflavones. These data suggest that a diet high in fiber from fruit and, possibly, soyfoods may reduce the incidence of chronic respiratory symptoms. Associated nutrients, such as flavonoids, may contribute to this association.

Can dietary interventions improve asthma control?

“…As noted by the authors, relatively little attention has been paid to soy intake in relation to respiratory or allergic diseases. [8][9][10][11] In a cross-sectional study of young adults in Australia, the consumption of soy beverage was associated with an increased prevalence of current asthma, doctor-diagnosed asthma and bronchial hyperresponsiveness. 8 In another cross-sectional study among Japanese pregnant women, dietary intakes of total soy product, soy protein, daidzein, and genistein in the fourth quartile (as compared to the first quartile), were independently associated with a reduced prevalence of allergic rhinitis, although no significant dose-response relations were observed.…”

“…9 In a longitudinal study among middle-aged Chinese men and women, total soyfood and soy isoflavone (daidzein, genistein, and glycitein) intakes had modest inverse associations with incident cough plus phlegm. 10 Among asthmatic adults enrolled in a vaccination trial, the authors noted a cross-sectional association between high consumption of genistein and better lung function. 11 Overall, three studies out of four were cross-sectional, and the only longitudinal study was on cough plus phlegm (not asthma).…”

A review of the Hispanic paradox: time to spill the beans?

“…Although previous epidemiological studies have implicated the antioxidant effects of flavonoids (especially from apples, tea and pears) in reducing lung function decline [62,63], increased dietary fibre has been linked to reduced respiratory symptoms [64], better lung function [59,60] and reduced respiratory mortality [65,66]. Surprisingly, in the study on mortality [65], the protective effect conferred by a high fibre diet was greater for respiratory deaths than for cardiovascular disease and cancer, further implicating an anti-inflammatory mechanism [66].…”

“…Here we present data to suggest that the increased consumption of high-fibre foods such as legumes, primarily in the form of beans, may provide an alternate explanation for the Hispanic paradox [43,48,[52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67]. Data on bean consumption shows that Hispanic subjects, who represent 11% of the USA population, are the largest consumers of beans (accounting for 33% of all consumption) [52].…”

Suppressed anti-oxidant capacity due to a cellulose-free diet declines further by cigarette smoke in mice

“…There is no consensus of prophylaxis for progression of COPD except for cigarette smoke cessation (Scanlon et al, 2000). Recently, some epidemiological studies demonstrated that dietary fiber mitigated cough and sputum in smokers and second hand smokers (Butler et al, 2004;David et al, 2005;Butler et al, 2006). Moreover, it has been demonstrated that intake of dietary fiber was associated with a better lung function and reduced prevalence of COPD (Kan et al, 2008).…”