People who eat avocados in Finland are probably doing other things differently too, not just consuming weird tropical American fruit. Any of those different things could also change the study results. Maybe avocado eaters tend to be more outdoorsy people.
Exposing kids beginning in infancy to barns where animals are kept has been found to reduce the incidence of allergies, too.
Exactly. These population studies are notoriously unreliable both because of the obvious associational differences (e.g., those consuming or not consuming avocados in Finland), as well as the cherry-picking for whatever stands out in such a study by the mere chance of statistics.
One study I read of showed that country kids have fewer allergies than city kids, and dairy farm kids have the fewest of all. And virtually all the dairy farm kids I knew grew up drinking well water and drinking their own raw milk.
Also the youngest in a family has fewer allergies than the older kids.
Early exposure to dirt and germs to train the immune system seems to be the biggest factor. Our super cleaner, sanitize and sterilize everything life style doesn’t help the kids in the least.
Now, if they’d just figure out some way of boosting or retraining an adult’s immune system after the damage was done.