Hacker News Reader

Comment by luxurytent | Hacker News Reader

What makes sesame such a significant allergen?

Define significant. Sesame allergies are pretty rare, but, where present, are extremely dangerous. Generally these mandated warnings are based on some combination of prevalence and severity; sesame allergy is rare but use of sesame is common and the allergy is lethal, so it gets a warning.

The one that confuses me is lupin. It’s one of the 14 mandated allergen/intolerance warnings in Europe, but is not at all commonly used.

It's commonly used as an alternate plant in soy fields, for crop cycling purposes. I forget which nutrient it prevents oversaturation of, but there is one.

Lupine fixes nitrogen from air, making it effective as fertilizer.

Depends on the allergen and individual... What makes me feel sore or achy for a day or two might kill someone else.

Probably some combination of lack of exposure in early age, sterility hypothesis in the west and something in the way the food industry makes highly processed foods.

We discovered our kid's sesame allergy when I fed some hummus on a pita at age 18 months resulting in a serious reaction that almost had me calling 911. It wasn't lack of early exposure.

It's entirely possible that the allergy will go away though. The immune system can shift and change over time in ways that cause it to not overreact to the allergen anymore.

More likely the underlying causes are genetic.

Identical twins have 70% chance to share same allergic diseases vs 40% for non identical twins, and both of which is vastly more common than their prevalence in the general population. Though this also demonstrates environmental factors play a significant role.

That said, the human immune system includes significant randomness so environment may be even less important than generally assumed.

But why would it have apparently increased so much in the relatively recent past if the cause was genetics?

Changing rates of testing combined with false positives are presumably part of it. Apparently 10% of people think they are allergic to Penicillin but only 1% test positive and under 0.1% have a significant reaction.

That said, environment is a factor. People in the developing world test positive for fewer though by no means zero allergies compared to their relatives in the developed world.

There's also changes to breeds and varieties in common use. For example, modern wheat has like 20x the histamine response vs older varieties. These kinds of things will also affect different people differently.

_Has_ sesame allergy increased? Like, it’s _rare_; it’s just extremely nasty (it kills people).

It could be sampling bias or increased availability, but it does seem as if allergies in general are increasing: https://www.npr.org/sections/thesalt/2019/08/02/747545877/se...

I mean, that’s comparing one figure, which came from who-knows-where, to one new study; it’s not hugely convincing. Especially as at least the new figure is via self-reporting.

One thing I think people forget with this stuff, 50 years ago many people just weren’t exposed. I live in Ireland; when my grandparents were kids everyone in the country could’ve been allergic to sesame and no-one would have noticed; it just wasn’t part of the food culture.

Now, it is. In general, particularly in rural areas, most peoples’ diets were extremely restrictive until pretty recently; in industrialised countries people are exposed to a lot more variety than a couple of generations back.

Definitely the right questions to be asking, and I have no idea of the answers.

How do you compare non identical twins to the general population? Aren’t twins, even non identical likely to share the same diet, the same environmental factors and maybe even the same viruses etc - all could be contributing factors?

Non identical twins are still siblings so they share a lot of DNA while also growing up in similar environments.

The huge difference between identical and non identical twins is suggestive of a very strong genetic component.

And frankly some mix of self diagnosis/anxiety from parents. In my circle, there's a few obsessive mom-types that are so fearful of allergies/vaccines/etc but their kids have never actually been diagnosed by a doctor.

Reply on news.ycombinator.com