A new study shows the lack of exposure to germs may increases your child’s chances of developing an allergic disease, such as a peanut allergy.

While peanut butter is used on many kids’ finger foods, a rising number of children have become severely allergic to it, with greater rates of peanut allergy found in families with higher incomes, according to a new study presented at the American College of Allergy, Asthma and Immunology’s (ACAAI) Annual Scientific Meeting.

This study supports allergists’ “hygiene hypothesis” that a lack of early childhood exposure to germs increases one’s chance of developing an allergic disease, and that over-sanitation might suppress the natural development of the immune system.

According to the ACAAI, peanut allergies affect more than 400,000 school-aged children in the United States. One previous study concluded that the incidence of peanut allergy among children more than tripled from 1997 to 2008. It is also one of the food allergies most commonly associated with sudden and life-threatening reactions, such as anaphylaxis, which is a severe, whole-body allergic reaction to a particular chemical.

In this study, researchers found that rates of peanut allergies were generally higher in males and racial minorities across all age groups. They also found that peanut-specific antibody levels peaked in 10 to 19-year-old children, but tapered off after middle age. Household income was associated with peanut sensitization in children ages one to nine.

“This may indicate that development of peanut sensitization at a young age is related to affluence, but those developed later in life are not,” said allergist Sandy Yip, lead study author and an ACAAI member.

While researchers once believed that a peanut allergy was lifelong, studies have shown that about 20 percent of individuals with a peanut allergy actually outgrow it over time. However, this is a small percentage, and precautions should still be taken.

“It’s important that children remain under the care of a board-certified allergist to receive treatment,” ACAAI president Stanley Fineman said.

This study examined 8,306 patients, 776 of which had an elevated level of peanut antibodies. Antibodies are proteins created by the immune system in response to what it sees as harmful invaders—in this case, peanuts.

How to prevent a peanut allergy from developing in the first place is unclear, and past research has provided a wide range of suggestions, from avoiding peanuts all together to questioning whether avoidance might itself be part of the problem.

However, there are many things parents can do to prevent a peanut-allergic child from having a potentially life-threatening reaction.

The Mayo Clinic and peanutallergy.com recommend these four tips for parents:

  • Read food labels carefully, and avoid foods that may have come in contact with peanuts. Manufacturers are required to clearly state whether foods contain any peanuts, and whether they were produced in factories that also process peanuts.
  • Use peanut butter substitutes, such as sunflower seed butter, that allow for safe enjoyment of popular snacks.
  • If your child has already had a severe reaction to peanuts, have him or her wear a medical alert bracelet or necklace.
  • Talk with your child’s doctor about emergency medications, such as EpiPens.

In a study published in 2008 in the Journal of Allergy and Clinical Immunology, researchers sought to determine the prevalence of peanut allergies among Israeli and UK Jewish children, and to evaluate the relationship between peanut allergies and infant and maternal peanut consumption. They concluded that despite the fact that Israeli infants consume higher quantities of peanuts in their first year of life than UK infants, Jewish children in the UK have a prevalence of peanut allergies 10 times greater than that of Jewish children in Israel. These findings raise the question of whether early introduction of peanuts during infancy, rather than avoidance, will prevent the development of a peanut allergy.

A previous study, published in 2000 in the Journal of Allergy and Clinical Immunology, searched for evidence that genetic factors influence peanut allergies by comparing the concordance rate for this allergy among twins. Researchers concluded that genetics may in fact play a significant role in peanut allergy development.

In a case-control study published in the British Medical Journal in 1998, researchers explored why some children grow out of their peanut allergy while others do not. They found that of the 15 children with a resolved peanut allergy and 15 with a persistent allergy, both groups had a similar median age of first reaction to peanuts, as well as similar symptoms. However, allergy to other foods was less common in children with a resolved peanut allergy.