Wealthier families are more likely to have cleaner homes –– and that could be increasing their children's likelihood of developing peanut allergies, according to new research.
A study presented at a US conference about allergens found more affluent homes are more likely to be "over-sanitised", which could suppress immune system development.
Allergies occur when the body mistakenly believes something is harmful to the body, which causes an immune system reaction.
Most people who are allergic to peanuts experience a rash and swelling of the face when exposed to peanuts, but it can even be life-threatening and lead to anaphylaxis in extreme cases.
"Overall household income is only associated with peanut sensitisation in children aged one to nine years" study author Sandy Yip said in a media release.
"This may indicate that development of peanut sensitisation at a young age is related to affluence, but those developed later in life are not."
The study looked at 8306 people, 776 of whom had an elevated antibody level to peanuts. They found that peanut allergy tended to be higher in men and that antibody levels were usually highest between the ages of 10 and 19, then lowered after middle age.
Peanut allergy was also found to be higher in racial minority groups.
But allergist Professor Katie Allen, from the Murdoch Children's Research Institute, says the link between wealth and allergies is weak.
"They're making a link that more affluent families are more hygienic, and I just don't agree with that –– it's a big stretch to say that the wealthier you are, the cleaner you are," Professor Allen said.
"They have shown a difference in ethnicity and unfortunately ethnic minorities are more likely to be less wealthy. So in fact what they may be describing is a genetic tendency in different racial groups."
Professor Allen said parents needn't fret about creating a home that's too clean.
"It's not at a personal hygiene level, it's at a general population hygiene level," she said.
"At a general population level, the environment that we live in is becoming more sanitised generally. Our food and water supply are cleaner, which are good things and we certainly don't want to reverse those. But perhaps we are not stimulating our intestines with a variety of bugs in the same way we were."
Now Professor Allen said the challenge is to find a way to reverse the trend.
"It's only happened in the last 20 years, so that's why we're so keen to work out which bugs can stimulate the intestine without making you sick at the same time," she said.