A randomized, placebo-controlled study, published in the American Journal of Clinical Nutrition (2012 Sep; 96(3): 534-43), looked at dietary intake in 137 adults with asthma. At the end of the two weeks, the group receiving the high-antioxidant diet had measurably better breathing capacity (as measured by forced expiratory volume and percentage predicted forced vital capacity). Those eating the diet low in antioxidants had an increase in C-reactive protein (a substance that increases with inflammation and is used as an indicator of inflammation).
Just as vegetables are beneficial to asthmatics, junk food makes symptoms worse. Research appearing in the European Respiratory Journal (2009; 33:33-41) looked at the dietary habits of 54,672 French women and the association with asthma attacks. Of the subjects, 1,063 currently had asthma with 206 having asthma attacks at least once per week. There was a strong correlation between the frequency of asthma attacks the adherence to a “Western” diet including pizza, cured meats, sweets and other processed foods.