Dietary flavonoids and respiratory diseases: a population-based multi-case-control study in Italian adults.

OBJECTIVE

To analyse the associations between chronic respiratory diseases and intakes of total flavonoids and their major subclasses (flavanones, anthocyanins, flavan-3-ols, flavonols, flavones, polymers and proanthocyanidins).

DESIGN

Multi-case-control study.

SETTING

The analysis was conducted in the frame of the Genes Environment Interaction in Respiratory Diseases (GEIRD) study. The European Prospective Investigation into Cancer and Nutrition FFQ was used to ascertain dietary intake. Multinomial regression models adjusting for age, sex, centre, BMI, smoking habit, alcohol intake, education, total energy intake, vitamin C intake and total fruit intake were used to examine the associations between dietary exposures and the relative risk ratio (RRR) of being a case.

PARTICIPANTS

Individuals (n 990) hierarchically defined as follows: cases with asthma (current, n 159; past, n 78), chronic bronchitis (n 47), rhinitis (allergic rhinitis, n 167; non-allergic rhinitis, n 142) and controls (n 97).

RESULTS

An increase of 1 sd in flavanones was associated with a reduced risk of non-allergic rhinitis (adjusted RRR = 0·68, 95 % CI 0·47, 0·97); a similar result was found comparing the highest v. lowest quartile of flavanones intake (adjusted RRR = 0·24, 95 % CI 0·10, 0·59).

CONCLUSIONS

Flavonoids contained in fruits and vegetables, especially flavanones, might reduce the risk of non-allergic rhinitis. No associations were found between other flavonoids and the considered outcomes.