Food allergies on the increase - why?

[DrDeth]

@md2000

As a few others have mentioned - we’re too clean. We immunize. Basically, one theory says that the immune system gets 9used to get) a workout in children, to get us ready to fight diseases as adults. So many infections are known as childhood diseases, everyone used to get them as a child, usually have a mild fever and recover. With constant hand washing, anti-bacterial soap, hovering parents keeping kids away from wild spaces, dragging them to the doctor for antibiotics at the first sniffle, more apartment buildings and so fewer pets - kids’ immune systems have less opportunity to learn what’s really harmful and adjust to that. So instead, the immune system becomes hypersensitive and attacks any instance of “alien” substances in the body.

Immunizations have nothing do do with it.

[snowthx]

I tend to agree with the Hygiene hypothesis as well. However, I do have a question: When my ancestors came to the US from eastern Europe over 100 years ago, I presume they had not encountered such things as bananas and peanut butter, ever, in their lives back in the old country. Why, then, would they, and other immigrants, not have had such reactions upon their first taste? Maybe it was not documented if they did? And likewise for more recent immigrant groups, from places where exposure to peanuts/butter would not be expected. is there any evidence that immigrant groups are impacted disproportionally compared to native populations where peanut butter is generally available?

[DSeid]

@snowthx

I tend to agree with the Hygiene hypothesis as well. However, I do have a question: When my ancestors came to the US from eastern Europe over 100 years ago, I presume they had not encountered such things as bananas and peanut butter, ever, in their lives back in the old country. Why, then, would they, and other immigrants, not have had such reactions upon their first taste? Maybe it was not documented if they did? And likewise for more recent immigrant groups, from places where exposure to peanuts/butter would not be expected. is there any evidence that immigrant groups are impacted disproportionally compared to native populations where peanut butter is generally available?

Absolute lack of exposure prevents allergies. A strong exposure early on prevents allergies (by triggering a suppressor response). It is the (unrecognized unintended but unavoidable) small intermittent exposure that occurs when late introduction is attempted in a world that contains the substance hidden in small amounts in other products and on surfaces that primes for later allergic reactions most strongly.

You really want to limit your kids’ allergy risk (including asthma) raise them on a on single-family dairy farm, and use horses for fieldwork and transportation, like the Amish do. Really a fascinating study.

… we designed a study that compares two distinctive U.S. farming populations — the Amish of Indiana and the Hutterites of South Dakota — that recapitulate the differences in the prevalences of asthma and allergy observed in farmers and nonfarmers in Europe. These two particular groups of farmers originated in Europe — the Amish in Switzerland and the Hutterites in South Tyrol — during the Protestant Reformation and then emigrated to the United States in the 1700s and 1800s, respectively. Both groups have since remained reproductively isolated.8,9 Their lifestyles are similar with respect to most of the factors known to influence the risk of asthma, including large sibship size, high rates of childhood vaccination, diets rich in fat, salt, and raw milk, low rates of childhood obesity, long durations of breast-feeding, minimal exposure to tobacco smoke and air pollution, and taboos against indoor pets. However, whereas the Amish practice traditional farming, live on single-family dairy farms, and use horses for fieldwork and transportation, the Hutterites live on large, highly industrialized, communal farms. Strikingly, the prevalence of asthma in Amish versus Hutterite schoolchildren is 5.2% versus 21.3% and the prevalence of allergic sensitization is 7.2% versus 33.3%, as previously reported.10,11 …

… Our studies in Amish and Hutterite schoolchildren revealed marked differences in the prevalence of asthma despite similar genetic ancestries and lifestyles. As compared with the Hutterites, the Amish, who practice traditional farming and are exposed to an environment rich in microbes, showed exceedingly low rates of asthma and distinct immune profiles that suggest profound effects on innate immunity. Data generated in an experimental model of asthma support this notion by showing that the protective effect of the Amish environment requires the activation of innate immune signaling.
…

Note that both populations have “high rates of childhood vaccination” …

Anecdotally, as a pediatrician, I see fairly high rates of allergies in the few vaccine refusers we have. My guess is a selection bias but still.

[Broomstick]

You have to be exposed to something before you develop an allergy to it. For people with food allergies, it’s not unusual for them to be OK the first time they have something and then have allergic reactions after eating the substance a subsequent time.

There are probably multiple reasons people develop allergies these days. Some of them might be trade-offs (possibly better sanitation and hygiene mean fewer deadly epidemics but more allergies). Some of them might be due to timing in introducing new foods. Probably other factors at work, too.

Not all food allergies are OMIGOD GOING TO DIE!!! serious. As noted by someone up thread, you might just be a bit itchy. These days, though, docs are still going to recommend avoiding the food in question because it could become far more serious. Maybe it will, maybe it won’t. Docs are going to err on the side of caution and mark down one more person allergic to food(s). A few generations ago such a person might never have been diagnosed as allergic, they just didn’t like a particular food because it made them feel funny or whatever.