By Steven Reinberg
THURSDAY, May 2 (HealthDay News) -- 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 percent 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 percent in 1997 to 5.1 percent in 2011. With skin allergies, the overall rate increased from 7.4 percent in 1997 to 12.5 percent in 2011. The prevalence of respiratory allergies remained constant, at 17 percent, between 1997 and 2011, although it remained the most common type of allergy affecting children, according to the NCHS report published May 2.
Pediatric 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 pediatric 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.
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 percent versus 12 percent, respectively), but less likely to have respiratory allergies (15.6 percent versus 19.1 percent, 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 percent of those aged 4 and younger had them, while 13.1 percent of those aged 5 to 9, and 10.9 percent of those aged 10 to 17 had them.
The opposite was true for respiratory allergies: 10.8 percent of those aged 4 and younger had them, while 17.4 percent of those aged 5 to 9 and 20.8 percent of those aged 10 to 17 had them.
Last, but not least, there was the income gap.
Among families making less than 100 percent of poverty level, 4.4 percent of those children had food allergies and 14.9 percent had respiratory allergies. Among families making more than 200 percent of poverty level, 5.4 percent of those children had food allergies and 18.3 percent 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."