For instance, parents were told to hold off on introducing eggs until kids turned 2. Doctors recommended against adding fish and nuts until age 3. But, increasingly, the evidence is pointing in a new direction.
In fact, in the new guidelines, the committee of allergists cites seven studies that suggest that delaying beyond 4 to 6 months of age the introduction of solid foods, especially highly allergenic foods, may actually increase the risk of food allergies or eczema.
Instead, they suggest introducing some foods that can cause allergies between 4 and 6 months of age, at a rate not faster than one new food every three to five days.
The details of the guidelines are included in this paper, first published in January. Allergist David Fleischer, of National Jewish Health, will present the guidelines in October at a meeting of pediatricians in Orlando, Fla.
If you listen to my story on Here & Now, you'll hear Dr. Fleischer explain why there's still a lot to learn.
Many of the studies evaluating the timing of introducing foods are suggestive, but not conclusive. And many studies are still ongoing.
For instance, allergists don't yet know whether holding off on introducing peanut butter until the toddler years will result in fewer peanut allergies among kids.
There are currently studies underway here in the U.S. and in the United Kingdom that will help answer this question.
Experts say babies with severe eczema or early allergic reactions to food should develop a personalized plan to introduce foods with an allergist.
The shift in thinking about the timing of introducing allergenic foods has been gradual. Back in 2008, the American Academy of Pediatrics changed its policy.
A committee within the AAP concluded that there was no evidence that delaying the introduction of allergenic foods such as fish, eggs and peanuts beyond 4 to 6 months of age protects against the development of allergies.
So, on this topic, stay tuned: There are plenty of questions yet to unravel.