cosmocreator
07-17-2004, 10:50 PM
http://yalenewhavenhealth.org/HealthTopics/asthma/Jul04ascMain.htm
Farm Life Seems to Protect Kids from Asthma
Early exposure to endotoxins may build immunity
(HealthDayNews) -- Farm living does more than build muscles. It also appears to protect children from asthma and allergies, Canadian researchers report.
A survey of 1,158 4-H Club members revealed that asthma cases were lowest among children who lived on farms. And when the researchers tallied the number of kids who had ever wheezed, the fewest cases came from among farm kids, even if the children no longer lived on a farm.
Allergies in general were less common among farm children, and the research team found the most allergic symptoms among urban or rural residents who did not keep livestock.
The reason may be the so-called "protective farm factor," according to Dr. Helen Dimich-Ward, an associate professor at the University of British Columbia in Vancouver.
Children who grow up on farms are less likely to develop asthma and allergies because they have increased exposure to endotoxins. Endotoxins are found on the bacterial cell wall in livestock feces, barn and house dust, and mattresses, according to the researchers.
Exposure to high levels of endotoxins early in life toughens up the immune system, protecting children from allergies or asthma. However, for someone with asthma or allergies, exposure to high levels of endotoxins can aggravate the condition.
"Endotoxin exposure is an appealing explanation," Dimich-Ward told HealthDay. But, she added, it is not certain that exposure to endotoxins is the complete explanation.
"Rather, lower risks for allergic symptoms were associated with living on a farm or rural area and having livestock currently and at an early age," she said.
Dimich-Ward's findings, first presented at an American Thoracic Society conference in Seattle last year, are similar to those of a study published in 2002 in the New England Journal of Medicine. In that study, researchers evaluated more than 800 Swiss, German and Austrian children and found that asthma and allergy were less common among the 319 who grew up on farms.
Another study, reported in the American Journal of Respiratory and Critical Care Medicine in 2000, also found fewer cases of asthma in farm children, even after taking smoking habits into account.
Other explanations for this phenomenon, according to Dimich-Ward, include children who live on farms having parents who are not allergic, which suggests that families with allergies leave farm life. Few parents of the farm children she surveyed had a history of allergies, she noted.
Dr. Alex Marotta, a fellow at the National Jewish Medical and Research Center in Denver and an expert on allergies and asthma, told HealthDay, "What's really needed is a longitudinal study going from birth."
It still needs to be proven that endotoxins are the reason farm children have fewer cases of asthma and allergy, he added.
For urban parents, there's not much they can do, Marotta said.
Whether having a cat or dog could help "needs to be studied more," he said. But, "once you have developed asthma and allergies, having a cat in the house is bad."
Farm Life Seems to Protect Kids from Asthma
Early exposure to endotoxins may build immunity
(HealthDayNews) -- Farm living does more than build muscles. It also appears to protect children from asthma and allergies, Canadian researchers report.
A survey of 1,158 4-H Club members revealed that asthma cases were lowest among children who lived on farms. And when the researchers tallied the number of kids who had ever wheezed, the fewest cases came from among farm kids, even if the children no longer lived on a farm.
Allergies in general were less common among farm children, and the research team found the most allergic symptoms among urban or rural residents who did not keep livestock.
The reason may be the so-called "protective farm factor," according to Dr. Helen Dimich-Ward, an associate professor at the University of British Columbia in Vancouver.
Children who grow up on farms are less likely to develop asthma and allergies because they have increased exposure to endotoxins. Endotoxins are found on the bacterial cell wall in livestock feces, barn and house dust, and mattresses, according to the researchers.
Exposure to high levels of endotoxins early in life toughens up the immune system, protecting children from allergies or asthma. However, for someone with asthma or allergies, exposure to high levels of endotoxins can aggravate the condition.
"Endotoxin exposure is an appealing explanation," Dimich-Ward told HealthDay. But, she added, it is not certain that exposure to endotoxins is the complete explanation.
"Rather, lower risks for allergic symptoms were associated with living on a farm or rural area and having livestock currently and at an early age," she said.
Dimich-Ward's findings, first presented at an American Thoracic Society conference in Seattle last year, are similar to those of a study published in 2002 in the New England Journal of Medicine. In that study, researchers evaluated more than 800 Swiss, German and Austrian children and found that asthma and allergy were less common among the 319 who grew up on farms.
Another study, reported in the American Journal of Respiratory and Critical Care Medicine in 2000, also found fewer cases of asthma in farm children, even after taking smoking habits into account.
Other explanations for this phenomenon, according to Dimich-Ward, include children who live on farms having parents who are not allergic, which suggests that families with allergies leave farm life. Few parents of the farm children she surveyed had a history of allergies, she noted.
Dr. Alex Marotta, a fellow at the National Jewish Medical and Research Center in Denver and an expert on allergies and asthma, told HealthDay, "What's really needed is a longitudinal study going from birth."
It still needs to be proven that endotoxins are the reason farm children have fewer cases of asthma and allergy, he added.
For urban parents, there's not much they can do, Marotta said.
Whether having a cat or dog could help "needs to be studied more," he said. But, "once you have developed asthma and allergies, having a cat in the house is bad."