Grade school kids may be more likely to develop asthma if they consumed lots of drinks sweetened with sugar and high fructose corn syrup or if their mothers drank these beverages often during pregnancy, a recent study suggests.
To assess the connection between childhood asthma, sodas and other sugar-sweetened beverages, researchers examined data about eating habits from about 1,000 mother-child pairs as well as information on kids' health, including whether they had an asthma diagnosis by ages 7 to 9.
After accounting for maternal obesity and other factors that can also influence kids' odds of developing asthma, researchers found that women who consumed the most soda and sugary beverages during pregnancy were 70 per cent more likely to have a child diagnosed with asthma by mid-childhood than mothers who never or rarely had sodas during pregnancy.
Women who had the most total fructose during pregnancy were 58 per cent more likely to have kids with asthma than women who had little to no fructose.
"Previous studies have linked intake of sugary beverages with obesity, and obesity with asthma," said study co-author Sheryl Rifas-Shiman, a researcher at Harvard Medical School and Harvard Pilgrim Health Care Institute in Boston.
"In addition to influencing asthma through increasing the risk of obesity, we found that sugary beverages and high fructose may influence the risk of asthma not entirely through obesity," Rifas-Shiman said by email. "This finding suggests that there are additional mechanisms by which sugary beverages and fructose influence asthma risk beyond their effects on obesity."
What kids ate and drank also mattered. Even after accounting for prenatal exposure to sodas, kids who had the most total fructose in their diets earlier in childhood were 79 per cent more likely to develop asthma than children who rarely or never had fructose.
Once researchers also factored in whether children were overweight or obese, kids with the highest fructose consumption were still 77 per cent more likely to have asthma.
Mothers who consumed more sugary beverages tended to be heavier and have less income and education than women who generally avoided sodas and sweet drinks. But the connection between sodas, sugary drinks and childhood asthma persisted even after accounting for these factors.
"We don't know for certain the exact pathways by which sugary beverages and fructose lead to asthma," Rifas-Shiman said. "We believe at least in part they act by increasing inflammation, which may influence the child's lung development."
The study wasn't a controlled experiment designed to prove whether or how sodas or sugary drinks might cause asthma.
Another limitation is that researchers relied on women to accurately recall and report on soda consumption for themselves and their young children, which may not always be accurate, researchers note in the Annals of the American Thoracic Society.
Even so, the findings add to the evidence that women should avoid sodas and sugary foods and drinks during pregnancy and also limit these things for their young kids, said Dr. Leda Chatzi, a researcher at the Keck School of Medicine at the University of Southern California in Los Angeles who wasn't involved in the study.
"Pregnant women should stay away from sugar sweetened drinks and foods with added sugars," Chatzi said by email.
"Healthy eating during pregnancy is critical to their baby's growth and development of chronic diseases such as asthma later in life," Chatzi added. "A healthy dietary pattern during pregnancy contains a variety of food groups, including fruits and vegetables, breads and grains, protein sources and dairy products."