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As a parent, it sometimes feels like you have a lot to worry about. And if your kid happens to have food allergies, that can make things even more complicated.

Like, not only do you have to keep them away from electrical outlets and busy streets, but you also have to keep them far away from foods like peanuts, shellfish, milk, and eggs. After all, symptoms like a tingling or itchy mouth, hives, and difficulty breathing can quickly balloon into a life-threatening emergency. Basically, childhood food allergies are no joke.

So it might make you cringe to learn that, not long ago, doctors were making recommendations about them we now believe were totally backwards—and could even have made things worse. But how did we misunderstand this so badly? This all started in the mid-1990s, when the number of kids with food allergies was on the rise.

So the medical community raised the alarm, searching for ways to prevent these allergies from happening. One approach came in 2000, from the American Academy of Pediatrics. They started recommending that people not give some of the most common allergenic foods to kids who had a high risk of allergies until they were a little older.

That meant no milk until after a kid was 1, no eggs until age 2, and no peanuts or seafood until age 3. These guidelines were mostly based on experts' hunches, but there were a few studies to back them up. For example, there was one from 1990 that followed a group of children in New Zealand until they turned 10.

It found that, if kids were given a full diet of diverse allergens before they turned 4 months old, they were more likely to have recurrent or chronic eczema, which often goes hand in hand with food allergies. Similarly, a 1994 study looked at 113 Finnish children whose parents had food allergies. And it found that at age 5, food allergies were significantly more common in kids that started solid foods at 3 months old than those who started solids later.

In 1999, there was even a formal report supported by leading European medical societies that suggested that introducing solid foods before 5 months could increase the risk of food allergies. Over time, more and more medical societies began to agree that yes, doctors should keep advising parents to put off feeding allergenic foods to their babies. But then, starting around 2006, studies started coming out suggesting the exact opposite.

There don't seem to have been any flaws in the older studies that scientists can put their collective finger on. Nevertheless, the data began to reflect a different perspective. For instance, a study published that year that followed more than 1600 children from birth to age 5.

It found an increased risk of having a wheat allergy in kids who started eating wheat later— after 6 months of age. The emerging data soon came to a tipping point and, in 2008, the American Academy of Pediatrics reversed their stance. Again, other leading health and medical institutions followed suit.

They issued guidelines for introducing the most common allergenic foods as soon as babies showed that they could handle solid food, which typically happens at 4 to 6 months old. And if you're wondering why the data pulled a one-eighty, so are the experts. Doctors don't quite understand why earlier studies suggested a benefit to delaying allergenic foods.

But more and more research shows that they were totally wrong. For example, the 2015 Learning Early About Peanut trial showed that introducing peanut protein early is actually a good thing. And the 2016 Enquiring About Tolerance study also found it was safe to introduce a handful of allergenic foods to infants under 6 months old.

So there's plenty of evidence to back up the reversal of previous guidelines. Unfortunately, though, there still isn't a whole lot of specific advice when it comes to actively preventing food allergies across the population. Studies so far have looked at variables like exactly how much of each allergen to introduce to babies and how often.

They've also studied whether those recommendations should differ based on geographical location, and whether the same advice applies to infants with and without risk factors that predispose them to developing food allergies. But there isn't enough evidence yet to translate those studies into real recommendations for parents. That's going to take more research—like more studies into how factors other than when you first eat a food affect whether you develop an allergy.

And more studies that aren't just about peanuts. One thing's clear, though: That old advice to delay infants' exposure to allergenic foods still has a hold on the parenting world, and not everyone is totally caught up on the latest guidelines. Thankfully, the most up-to-date recommendations do tell parents not to bother delaying common allergens like wheat and peanuts.

Instead, they say to start introducing plenty of different foods as soon as your baby is ready for them. But when it comes to your individual kids, don't take it from us, and definitely don't take it from random strangers on the internet parenting forums. If you're really concerned about food allergies in your kids, consult a pediatrician.

Thanks for watching this episode of SciShow. We couldn't make smart, free videos like this without the help of our supporters. To learn more, check us out at patreon.com/scishow. [OUTRO ♪].