Introduction

Based on the Global Burden of Disease Study, ~0.4 million people died from asthma in 2015 [1]. The risk of asthma increases by 50% in every 10 years of a person’s life [2]. In Qatar, the prevalence of asthma is 9% among adults [3]. The known risk factors of asthma are genetics, age, gender, and environmental factors [4]. Diet is considered as a modifiable risk factor for the progression of chronic diseases, such as respiratory disorders [5]. Recent evidence suggests that individual food and nutrients are associated with asthma [6,7,8,9,10]. Intakes of dietary antioxidants [5], fiber, fruit and vegetable [11], fish, and omega-3 fatty acids [12] have been shown to be inversely associated with asthma risk. This is more likely due to their anti-inflammatory effects. In contrast, high intake of fast foods [13] and sodium [11] is directly related to asthma.

During the past decade, there was an increased number of studies reported an association between food intake patterns and asthma [14,15,19, 29, 30]. Frequent consumption of foods high in sugars could increase susceptibility to allergic airways inflammation, promote oxidative stress [31], induce obesity, and increase respiratory dysfunction (such as asthma symptoms) [32]. In addition, fast foods tend to be high in saturated fats, trans fats, and sodium. High levels of fat could suppress the immune system and cause atrophy of airways, induce obesity and arise oxidative stress and complications including asthma [33]. It is known that Qatar has a high prevalence of overweight/obesity and diabetes [34]. These findings emphasize the importance of promoting healthy eating.

We found no relationship between Traditional and Prudent dietary patterns and asthma prevalence. A study in France found that consumption of Western diet was associated with an increased risk of frequent asthma attacks [29]. Although a review of ten observational studies conducted among adults in North America, Europe, and Asia did not support an association between Western diet and asthma incidence or prevalence. However, it suggested a possible link between Western pattern and asthma morbidity [19]. We were unable to assess the relationship between dietary pattern and asthma morbidity as these data are not available in QBB. Similar to the Western food pattern, the association between Prudent pattern or Traditional pattern and lung function is also inconsistent. Although some studies showed that fruits and vegetables [6, 10, 35] and fish (Prudent diet) [8, 36] had a protective effect on asthma, several studies failed to prove that relation. Prudent dietary pattern which consists mainly of “fruits, vegetables, and fish”, is inversely associated with asthma [20, 29]. In a randomized clinical trial, consumption of diet low in fruits and vegetables has been shown to increase the risk of asthma exacerbation among asthmatic individuals [37]. A cohort study in China showed that Traditional dietary pattern was a risk factor for asthma [38]. Another study found that Traditional pattern had a detrimental impact on lung function [39]. However, several studies were consistent with our study and reported that there were no significant associations between Traditional food pattern and asthma [20, 39].

A strength of this study is the large sample size. This increases the precision of estimates. In the QBB survey, various demographic, health, and nutritional markers were collected from the participants. This allowed us to adjust regression models with various confounding variables. Because the data used in this study were taken from a random sample of Qatari population, results of this study can be applied to the Qatar population at large. Another strength is that the FFQ used in this study has covered a wide range of foods (102 items) commonly consumed in Qatar [40].

Because this study is based on a cross-sectional design, the cause and effect relationship should not be assumed. Another limitation of the study is the use of FFQ without portion sizes. The qualitative FFQ (i.e., without portion size) has been used to construct meaningful dietary patterns [40]. Moreover, the data on portion size add very little to the food intake variance and most of the variance is explained by frequency of consumption [41]. As with many dietary intake studies, dietary intake assessment with FFQ is also prone to measurement error due to subjects’ inability to recall foods consumed accurately [42]. Due to the lack of homogeneity between men and women in various demographic characteristics of the sample, the results of this study may not be extrapolated to the population at large. Finally, asthma was self-reported by the subjects. So, it is possible that the prevalence of asthma may have been under- or over-reported. We were unable to verify that the asthma cases were diagnosed by a physician. However, it is not known how this misreporting might have affected the results of this study.

In conclusion, fast food/sweet pattern was directly associated with the prevalence of asthma in adult Qatar population. Traditional and Prudent dietary patterns were not associated with asthma. Promoting food habits leading to the reduced consumption of foods high in sugar and fast foods may be beneficial in improving the lung health of Qatar population. Long-term studies are needed on the effects of fast food and sweet intake in the etiology and pathogenesis of asthma.