# Diet and Asthma: A Narrative Review
## 4 Diet and Asthma
### Dietary Patterns
**is**not** **asthma** **prevalence. **isnot** **asthma** **prevalence. that an higher adherence to the Mediterranean diet during childhood is a protective factor for \"current wheeze\" and \"asthma ever\", but not for \"severe current wheeze\" [105]. Another systematic review reported that increased adherence to the Mediterranean diet was negatively associated with asthma symptoms in children [106]. More recently, a systematic review indicated a protective role of the Mediterranean diet on childhood asthma [107]. On the other side, school-aged children, who follow a strict Western diet high in total and saturated fat and processed foods, seem to be at a higher risk of asthma [33]. [PERSON] et al. [108] found in a cross-sectional study that better diet quality was associated with a lower odds of having asthma (OR = 0.83, 95% CI 0.72; 0.95) in children and adolescents [108]. Lower values in the Revised Brazilian Healthy Eating Index score, representing lower dietary quality, both at 18 and 22 years old, increased the odds of wheezing in the previous year, with an OR = 1.97, 95% CI 1.33; 2.91, and OR = 1.98, 95% CI 1.36; 2.87, respectively, in a longitudinal study. On the other side, remaining on a poor diet from ages 18 to 22 increased the odds of chest wheezing by more than three-fold (OR = 3.28; 95% CI 1.84; 5.84) compared to staying on a high-quality diet [109]. Findings from the PARIS birth cohort demonstrated that children in the higher tertile group of adherence to the Mediterranean diet, considered to have the higher diet quality, compared to children from the lowest tertile group, had a lower risk of having current asthma (aOR = 0.28, 95% CI 0.12; 0.64) [110]. Furthermore, adherence to the Mediterranean diet may modulate the production of several asthma inflammatory mediators: a higher adherence to this diet pattern was associated with lower IL-4 and IL-17 in asthmatic children [111]. Accordingly, a randomized controlled trial revealed that a Mediterranean diet supplemented by two meals of 150 g of cooked fatty fish weekly for six months, compared to the usual diet, reduced airway inflammation as assessed by eNO (\(\beta=-14.15\) ppb, 95% CI \(-27.39\); \(-0.91\)) in childhood asthma [112]. A study that observed associations between three different dietary scores with asthma symptoms and asthma control in French adults, found that higher dietary scores assessed by the Alternative Healthy Eating Index 2010 (AHEI-2010), the Mediterranean diet based on the literature (MEDI-LITE), and modified _Programming National Nutrition Sante_ Guideline Score were associated with a lower asthma symptom score [4]. However, when analyzing the association of a higher diet quality with asthma symptom score according to BMI, some of the statistically significant associations were lost when BMI is \(\geq\)25 and \(<\)30 kg/m\({}^{2}\), and most were lost when BMI is \(\geq\)30 kg/m\({}^{2}\)[4]. Individuals with obesity may present higher circulating concentrations of many inflammatory markers as a consequence of the disease [39], and GINA guidelines recommend weight loss as part of the strategy of asthma management in obese patients [2]. Knowing that obesity is a strong risk factor for asthma, having a higher diet quality may not be enough to counterbalance the negative effects that are associated with being overweight and obese. A systematic review found that, for obese asthmatic adults, the more effective dietary intervention seems to be energy restriction, regardless of the specific dietary components or dietary pattern [40]. A meta-analysis looked at the link between high adherence to the Mediterranean diet during childhood and the risk of asthma and wheezing in children, and although there is a trend towards high adherence to the Mediterranean diet in childhood to prevent current wheeze in later life, no inverse relationship was found for asthma (OR = 0.87, 95% CI 0.72; 1.04) or severe asthma (OR = 0.97, 95% CI 0.89; 1.06) [113].