Eating fast food three or more times a week significantly increases the severity of allergic asthma, eczema and rhinitis among children and adolescents, according to a new study published in the journal Thorax. The findings also suggest eating three or more weekly portions of fruit reduces symptom severity between 11% and 14% among teens and children, respectively.
The researchers suggest there are plausible explanations for the findings: fast food contains high levels of saturated and trans fatty acids, which are known to affect immunity, while fruit is rich in antioxidants and other beneficial compounds. They emphasized their results do not prove cause and effect, but they do warrant further investigation.
“If the associations between fast foods and the symptom prevalence of asthma, rhinoconjunctivitis and eczema is causal, then the findings have major public health significance owing to the rising consumption of fast foods globally," they said.
For the study, researchers at the University of Auckland examined data from more than 319,000 13- to 14-year olds from 107 centers in 51 countries, and more than 181,000 6- to 7-year olds from 64 centers in 31 countries who participated in the International Study of Asthma and Allergies in Childhood (ISAAC), which is a collaborative research project involving more than 100 countries and nearly 2 million children.
Teens and the children’s parents were asked about their weekly diet and whether they had symptoms of asthma, rhinoconjunctivitis and eczema. Questions focused particularly on the severity of symptoms over the preceding 12 months—including frequency and interference with daily life and/or sleep patterns—and certain types of food already linked to protective or damaging effects on health. These included meat, fish, fruits and vegetables, pulses, cereals, bread and pasta, rice, butter, margarine, nuts, potatoes, milk, eggs and fast food/burgers. Consumption was categorized as never; occasionally; once or twice a week; and three or more times a week.Analysis showed fast food was the only food type to show the same associations across both age groups, prompting the authors to suggest “such consistency adds some weight to the possible causality of the relationship." It was associated with current and severe symptoms of all three conditions among the teens— across all centers in the participating countries, irrespective of gender or levels of affluence.
The pattern among children was less clear-cut, but a fast food diet was still associated with symptoms across all centers—except for current eczema—and poorer countries—except for current and severe asthma. The researchers said the difference might have to do with the fact that children have fewer options about their food choices.
Results found three or more weekly servings were linked to a 39% increased risk of severe asthma among teens and a 27% increased risk among children, as well as to the severity of rhinitis and eczema, overall.
Conversely, fruit seemed to be protective in both age groups across all centers for all three conditions among children—both current and severe—and for current and severe wheeze and rhinitis among the teens. Eating three or more weekly portions was linked to a reduction in symptom severity of between 11% and 14% among teens and children, respectively.
