The journal Thorax recently published a research study which examined 400,000 children in 51 different countries. They found a link between fast food consumption and an increase in asthma and allergies. In fact, 39 percent of teens and 27 percent of younger children were more likely to have severe asthma if they ate the most fast food. Additionally, children who ate 2-3 servings of fruit were 11-14% less likely to develop asthma or allergies. The findings were the same regardless of economic status, country of origin, or sex of the children.
This link may be related food and/or environment. It may be due to issues with the immune system, saturated and trans fat, sodium, sugar or preservatives.