60k kids have avoided peanut allergies due to 2015 advice, study finds

I wonder why the old advice was being given if it was so wrong? If nobody understood what to do, shouldn't there have been no advice instead of something harmful?

If people are developing allergies to food, isn’t a logical first step to not expose babies to the allergens? It seems logical. It turns out to be exactly backwards.

Lots of things kill infants that harm children, so keeping them away from things that harm some children probably seemed correct. The mechanism for allergy development wasn’t well known and it seems reasonably to avoid it in case it was genetic or something and would cause a hard to treat allergic reaction in the infant.

You seem to be suggesting that doctors should not suggest any health precautions until controlled experiments have found them effective. That is the position taken by the highly-cited paper "Parachute use to prevent death and major trauma related to gravitational challenge: systematic review of randomised controlled trials", which you must read immediately, because in a peculiar way it is a paper about you: https://pmc.ncbi.nlm.nih.gov/articles/PMC300808/

People did understand what to do, it just turns out their understanding was wrong. We might still be wrong though, one study isn't definitive proof of anything. We have to make decisions with the knowledge we have at the time, and it's normal for those decisions to look dumb in hindsight.

It would seem logical, until you learn what allergies are. They are the body's immune system overreacting to something that would normally be harmless, and acting as if it's an invading pathogen. Once you learn that, then realizing "hey, expose the body to this thing early on, and the body's immune system will treat it as normal" is a logical step.

If this theory (that early exposure teaches the immune system not to overreact) is right, then another logical consequence would be that kids who play outside in their early years would have fewer pollen allergies than kids who mostly play indoors and are exposed to far less pollen than the outdoors-playing kids. I don't know where to look for studies to prove or disprove that thesis; anyone have any pointers?

Hindsight is 20/20. The fact is that thousands of children were dying and public health officials were set to task to identify interventions that help.

They know that skin and mucosa sensitization can occur in response to allergens.

A reasonable hypothesis is that there’s some boot-up process with the immune system that needs to occur before anything happens. The kids are dying today. “Avoid the thing that can cause sensitization” is a conservative position.

It is unusual that it should have been opposite and that oral exposure induces tolerance. It’s the fog of war.

The standard conservative intervention has helped in the past: I’m pretty sure seatbelts didn’t have strong mortality data before they were implemented. If it had turned out that more people were killed by seatbelts that trapped them in vehicles it would make for a similar story. I think they also got rid of all blood from donors who were men who have sex with men during the initial stages of the HIV pandemic (no evidence at the time).

Edit for response to comment below since rate-limited:

Wait, I thought it was on the order of ~150/year people dying from food anaphylaxis though I didn’t research that strongly. It was off my head. If you’re right, the conservative advice seems definitely far too much of an intervention and I agree entirely.

There is a joke that the book "Immune System 101" is 1000 pages long. Meaning the immune system is one of the most complicated systems in biology, simple logic arguments like yours above rarely apply, everything needs to be tested to be sure.

Well, I mean, did you know that skin exposure can sensitize and oral exposure builds tolerance? I certainly didn’t. That’s a subtlety of the exposure game that I did not know.

E.g. from age 27 weeks my daughter has played in a little herb garden full of mud and grass I built for her. She grabs and eats leaves from the herb plants (the basil is entirely denuded so that’s a complete loss). At first I just wanted her to play in the garden out of the same naïve exposure to tolerance model. I never would have considered that skin exposure is different from oral exposure. As it so happened she ate the plant leaves and it doesn’t matter either way since this part of immunity (to microbes here) doesn’t work in the same way as peanuts anyway.

Bad advice that has a very long return on investment is quite sticky.

For instance the "cry it out method" did massive amounts of psychological damage to more than one generation, but it seemed to work in the short term as the babies eventually learned to "self-soothe".

Even now I still see parents and grandparents suggesting it in parenting groups; and taking extreme umbrage at the idea that it might have damaged them/their children.

"The fact is that thousands of children were dying"

What? That's insane, 4-5 kids were dying a year. The whole thing was mass hysteria, that then started to create the problem when there had been none.

You don't need a controlled experiment if you have a good enough understanding of the mechanism, such as with parachutes. But since they apparently had no idea how peanut allergies worked nor had any adequate studies, they should have just shrugged their shoulders when asked for advice.

Even with parachutes, you could do a study (not a RCT) by looking at historical cases of people falling with and without parachutes. The effect would be so strong that you wouldn't need those clever statistical tricks to tease it out.

The 2000 guidance was based on expert opinion because there were no studies. Leap was published in 2015 and it gave the first level 1 data on peanuts.

Anaphylactic shock is scary and peanut fear was a big deal in the late 1990s but actual risk of harm was very low. The guidance was more about the psychosocial burden placed on parents when there was no guidance. Anxious parents have been studied, that mechanism is reasonably well understood and that harm can be quantified.

You do not know what you don't know.

And the variations on "a little spanking", "spare the rod", "dad would take us out behind the woodshed"...

Careful studies have shown that violence used with children percolates back out of them, in rather rapid fashion. Something like a great majority of them go on to use violence to interact with others in the next two weeks.

So, yes, as it turns out: a little spanking did hurt... specifically, it hurt innocent bystander kids.

Cry it out is bad advice? A relative of mine is a psychologist phd and she does it with her baby for sleep training saying self-soothing is fine.

It's too big of a topic for a HN comment but do a google or LLM search and see. One widely-accepted aspect is that a child can not "self soothe" until 5-7 years. It's not developmentally possible, and using that language is a bit of a PR move to gloss over what is actually happening.

https://www.google.com/search?q=infant+co-regulation+vs+self...

https://en.wikipedia.org/wiki/Emotional_self-regulation

https://en.wikipedia.org/wiki/Co-regulation_(communication)

https://en.wikipedia.org/wiki/Attachment_theory

Man, you are going to be so upset when you learn about Phil Sokolof and Ancel Keys.

There were numerous studies that associated early exposure to peanuts with increased risk of peanut allergies, because that is much cheaper and easier and easier to justify ethically than random assignment trials. And for skin exposure via peanut oil, they were absolutely correct.

For example: https://www.nejm.org/doi/full/10.1056/NEJMoa013536 https://d1wqtxts1xzle7.cloudfront.net/74207249/j.1399-3038.1...

It is also the case that after sensitization, avoiding the food can lead to eventual desensitization (although it is riskier in the meantime), which was interpolated to support avoidance: https://onlinelibrary.wiley.com/doi/abs/10.1002/j.1536-4801....

Something to do with diet and health? What do you mean.

You should ask what she's basing that idea on. Maybe there's some research she knows about but the general world of public health doesn't? Seems more likely that she just doesn't know.

Similarly, my own position is that the person suggesting I ignore my baby's crying is the one who needs to do the explaining.