SOURCES: Malcolm Sears, M.B. Ch.B, professor, division of respirology, department of medicine, McMaster University, Hamilton, Ontario, Canada; Maxwell Tran, health sciences student, McMaster University; Jennifer Appleyard, M.D., chief, allergy and immunology, St. John Hospital and Medical Center, Detroit; May 18, 2016, presentation, American Thoracic Society meeting, San Francisco
WEDNESDAY, May 18, 2016 (HealthDay News) -- Doctors have long warned parents to delay introducing certain foods to babies to decrease the risk of a potential allergic reaction, but a new study suggests that strategy probably doesn't help.
The study of about 1,400 children found that when babies were given peanuts, eggs or cow's milk during their first year, they were less likely to become "sensitized" to those common allergy-causing foods.
Being sensitized to a food means a child tests positive on a skin test. "That doesn't necessarily mean a food allergy as such, but it indicates the child is on that pathway," said the study's senior author, Dr. Malcolm Sears.
The goal is to reduce the risk of sensitization, which also reduces the risk of allergy, said Sears, a professor in the division of respirology at McMaster University in Hamilton, Ontario, Canada.
The study's lead author, Maxwell Tran, said this study, along with other research, "supports the paradigm shift that parents should not hesitate to introduce allergenic foods, especially cow's milk, peanuts and eggs. This will reduce the likelihood of sensitization." Tran is a health sciences student at McMaster.
Sears reiterated: "Earlier is better. Don't be afraid to introduce these foods." But he added that even early introduction of a food doesn't guarantee a child won't eventually develop a food allergy.
Tran is scheduled to present the study's findings Wednesday at the American Thoracic Society meeting in San Francisco. Findings presented at meetings are generally viewed as preliminary until published in a peer-reviewed journal.
According to Tran, previous guidelines recommended waiting a year before introducing cow's milk and cow's milk products, such as cheese, yogurt or ice cream. Doctors recommended delaying eggs until age 2 years, and peanut-containing products until age 3.
Since other studies have hinted that earlier introduction of these foods might be beneficial instead of harmful, the researchers behind the new study looked at a sample of children already involved in a large Canadian child development trial. Sears noted that this was not a group of children that would be considered at high risk for allergies.
Just over 1,400 youngsters from that study had their skin tested for allergen sensitization at 1 year. Nutrition questionnaires were completed by parents when the kids were 3, 6, 12, 18 and 24 months old, the researchers said.
The researchers found that almost half the babies had consumed cow's milk by 6 months, and the other half had milk by 12 months. Just 4 percent didn't have milk until they were 1 year old, the study revealed.
Only 6 percent of the babies had eggs by 6 months, while 76 percent had them before 12 months. And about 19 percent first had eggs after their first birthday, the study showed.
Parents were much more likely to delay peanuts. Only 1 percent of the children had peanuts by 6 months, and 41 percent had peanuts introduced in their diet between 7 and 12 months. Fifty-eight percent of the children were over 1 year of age when they first had peanuts, the study found.
The researchers found that early introduction of any of the allergic foods was linked to a lower risk of sensitization for that food. Giving a child egg before age 1 also reduced the odds of sensitization to any of the three tested foods, the study found.
Dr. Jennifer Appleyard is chief of allergy and immunology at St. John Hospital and Medical Center in Detroit. She said, "The old train of thought was that the immune system is in flux for the first three years of life, and if exposed during that vulnerable period, food allergies might develop. But some of the old thoughts on how allergies develop and how best to treat them are changing."
She said that parents who followed that advice and waited to give their child these foods didn't cause any allergies. "So many different things influence allergies... Things we do may affect a health outcome in some way, but it doesn't completely control how allergies develop," she said.
There's still a lot of research looking into the development of allergies, Appleyard noted, adding for now, early introduction of foods seems okay.
If you come from an allergic family, particularly one with food allergies, Appleyard said it's best to talk with your doctor about the introduction of common allergy-causing foods.
Learn more about food allergy from the American College of Allergy, Asthma and Immunology.