The number of American children who suffer from food and skin allergies has increased dramatically in recent years, a new government report shows.
Interestingly, the prevalence of food and respiratory allergies rose with income: Children living in families that made more than 200% of the poverty level had the highest rates, the statistics showed.
"The prevalence of food and skin allergies both increased over the past 14 years," said report co-author LaJeana Howie, from the U.S. National Center for Health Statistics (NCHS), part of the U.S. Centers for Disease Control and Prevention. "This has been a consistent trend."
With food allergies, the overall rate went from 3.4% in 1997 to 5.1% in 2011. With skin allergies, the overall rate increased from 7.4% in 1997 to 12.5% in 2011. The prevalence of respiratory allergies remained constant, at 17%, between 1997 and 2011, although it remained the most common type of allergy affecting children, according to the NCHS report published May 2.
Paediatric allergists noted that they have been seeing the trend in their own practices.
Dr. Vivian Hernandez-Trujillo, director of allergy and immunology at Miami Children's Hospital, said: "We are certainly seeing increases in food and skin allergy in paediatric patients."
However, why these allergies are on the rise remains a mystery, another expert pointed out.
"We do not know why there has been an increase, but the theories include the 'hygiene hypothesis'; that reduced infection and reduced exposure to germs has left our immune systems 'looking for a fight' and attacking innocent proteins," explained Dr. Scott Sicherer, chief of the division of pediatric allergy and immunology at the Jaffe Food Allergy Institute at the Icahn School of Medicine at Mount Sinai in New York City.
In addition, there are theories about insufficient vitamin D, unhealthy fats in the diet, the obesity epidemic and processed food, none of which have been confirmed with hard science, he noted.
These increases are real, Sicherer added. "They speak to a need for more research toward prevention and cures," he said.
"We and others are undertaking studies to try to better understand the risk factors and opportunities for prevention, while aggressively doing research on multiple means to treat those with food allergies," Sicherer said.
Racial differences did emerge in the data.
Race, age and income group
The researchers found Hispanic children had the lowest prevalence of food, skin and respiratory allergies, compared with other groups.
And black children were more likely to have skin allergies than white children (17.4% versus 12%, respectively), but less likely to have respiratory allergies (15.6% versus 19.1%, respectively).
Age also was a factor in the prevalence of skin and respiratory allergies, the report noted.
With skin allergies, the rate dropped with age: 14.2% of those aged 4 and younger had them, while 13.1% of those aged 5 to 9, and 10.9% of those aged 10 to 17 had them.
The opposite was true for respiratory allergies: 10.8% of those aged 4 and younger had them, while 17.4% of those aged 5 to 9 and 20.8% of those aged 10 to 17 had them.
Last, but not least, there was the income gap.
Among families making less than 100% of poverty level, 4.4% of those children had food allergies and 14.9% had respiratory allergies. Among families making more than 200% of poverty level, 5.4% of those children had food allergies and 18.3% had respiratory allergies.
John Lehr, CEO of Food Allergy Research & Education, added that the report "confirms what we have already known, which is that millions of children are affected by food allergies, and this potentially deadly disease is a serious and growing public health concern. The CDC's report reinforces the need for education and awareness about food allergies across the country."
For more information on childhood allergies, visit the Nemours Foundation.