Heidi Kirn and her 11-year-old son, Charlie, spend much of their day thinking about how to protect him from his life-threatening peanut allergy.

He sits at a separate lunch table at school. He carries his epi pen everywhere. He reads labels and they avoid Thai restaurants, where peanuts are a common ingredient. He is constantly aware of what he’s touching and who around him might be eating peanut butter.

“In our case, my son was allergic almost from the time he was born,” said Kirn, of Kennebunk. “He had all kinds of allergies and outgrew all of them except for peanuts.”

So when scientists on Monday published a study in the New England Journal of Medicine showing that exposing infants to peanuts sharply reduces their risk of developing peanut allergies, Kirn took notice even though it’s too late to help Charlie.

“Anything is hopeful because it’s such a frightening allergy,” she said.

The new study punches a big hole in the conventional wisdom that young children at risk of developing allergies should avoid peanuts altogether. In 2000, the American Academy of Pediatrics issued guidelines recommending avoidance until age 3. In 2008, those guidelines were revised to say no evidence existed that avoidance worked beyond ages 4 to 6 months. But they stopped short of recommending early exposure to peanuts.

If she could turn back time, Kirn would try giving her infant some peanut protein, even though she remains a little skeptical. “If it was in a controlled situation and there were doctors that were able to expose him in small amounts, I would be all for it,” she said.

Other Maine parents also are reacting to the study with caution – and even some guilt.

“It’s frustrating because for so many years the focus has been on avoidance,” said Michelle Brooks of Portland, whose 10-year-old daughter has peanut allergies and is receiving oral immunotherapy at the New England Food Allergy Treatment Center in West Hartford, Connecticut. “I don’t know that this would have necessarily helped my child, but it might have.”

As soon as the study came out Monday, parents on Jenny Sprague’s website began buzzing about what it meant. Sprague, who lives in Gray and has two sons with peanut allergies, runs an online support group called “Multiple Food Allergy Help.”

Sprague said so many conflicting arguments exist about why children suffer more from allergies today than in the past that parents often feel responsible – that something they did or did not do may have harmed their child. This latest news pushed those buttons.

“We all feel that guilt,” she said. “So when the study came out, it does make some people go, ‘Are you telling me that if I had fed my kid this as an infant? … Well, the doctor said not to.’ ”

HOPE TEMPERED BY CAUTION

While the study offers hope for slowing the national epidemic of peanut allergies, Sprague and her online cohorts urged parents to be cautious.

“Part of the problem with the study is that it’s not going to cure anybody who already has a peanut allergy,” she said. “And the other thing is, the study was done with very controlled groups. My concern is that people are going to start trying to do this at home, and not under the supervision of physicians and allergists.”

Children in the study were high-risk infants, meaning they already had eczema, an allergy to eggs or both.

Local physicians agree that high-risk children should be exposed to peanuts only under medical supervision, but they also are excited about a possible new tool for preventing allergies.

“It’s great good news for families,” said Dr. Marguerite Pennoyer, a Scarborough allergist. “What we’re hoping is it’s going to help prevent some of this rising epidemic.”

Nearly 8 percent of American children are at risk for developing peanut allergies, she said. “The discouraging part,” she said, “is the kids who are already allergic, obviously this (study) won’t apply to them.”

Dr. Carah Santos of Allergy and Asthma Associates of Maine echoed others in saying parents should keep in mind that the study targets a specific population of high-risk children. Studies are underway to see if the results apply to the general population as well, she said.

“The take-home message of this study is if you’re a parent of a child with severe eczema or a strong family history (of allergies), definitely have your child seen by our allergy clinic so we can further do testing and discuss whether or not your child might benefit from introducing peanut butter early on and regularly consuming it,” Santos said.

BANS STILL ON

Many schools and local day care centers ban peanuts from their premises to safeguard children with peanut allergies. Directors of two local day care centers who do so said they have no plans to change their policies in the wake of the new study.

As for parental guilt? Santos said there’s no need for that, and she reminded parents of older children not to give up hope.

“On the one hand, while some kids may have developed food allergies that perhaps could have been prevented, it’s important for (parents) to know that there’s still research on the horizon that could potentially treat those who have already been diagnosed.”