The Cause of Food Allergies and Intolerances


In 2000, the American Academy of Pediatrics said that children should delay consuming milk until age 1, eggs until age 2, and peanuts, shellfish, tree nuts and fish until age 3. After seeing no evidence that these delays helped prevent food allergies they rescinded these guidelines in 2008. In 2016, the EAT study did the opposite: they introduced allergenic foods earlier than usual. They were successful in lowering food allergy rates among test subjects.

Beginning in the 1960s, there has been an increase in the incidence of allergies in developed countries. This trend has led to the “hygiene hypothesis,” which says that today’s children are raised in sterile environments—more sterile than ever before. It suggests exposing young children to germs and certain infections to toughen up their immune system and thus not develop food allergies.

Technically, an allergy is an overcompensation by the body’s immune system when confronted with something that the body views as an invader. In the case of food allergies, the immune system recognizes a certain food as not being safe to consume. Eight foods account for 90% of all food allergies: milk, eggs, peanuts, tree nuts (e.g. walnut, cashew), fish, shellfish, soy, and wheat. Apparently, a person can be allergic or intolerant to any food. Food intolerance is a digestive issue rather than an immune response.

Finally, there’s food poisoning. This is when you feel sick, get diarrhea, etc. for ~2 days. It’s caused by eating food contaminated by bacteria, such as salmonella, E. coli, etc., or viruses, such as norovirus. The origin of bacteria and viruses is animal feces. All types of bacteria and viruses can be killed by cooking food.


Food allergy, food intolerance, food poisoning—I believe they’re all related. I hypothesize that a food allergy develops from trying a new food and getting food poisoning from it. In other words, if you introduce someone to a new food tainted with trace amounts of feces then they will become allergic to that food.

How did I come to this conclusion? I see a commonality among the list of common food allergies (milk, eggs, peanuts, tree nuts, fish, shellfish, soy, and wheat). These foods are often consumed raw, or undercooked. This means the bacteria and viruses, which originated from animal poop, have not been killed off. Let’s go through the list of 8.


In America, milk is always pasteurized before being sold. This means it is heated up just long enough to kill off the bacteria. It’s basically flash-cooked. I don’t think this is sufficient. I believe milk needs to be cooked more thoroughly via ultra-high-temperature processing (UHT) to not trigger a negative immune response. UHT milk can also be found in the US but is often mocked as not being as real as everyday milk since UHT milk doesn’t even need to be refrigerated.


I’m sure you’ve seen chicken, duck, or quail poop on eggshells before. Sometimes, trace amounts get on the chef’s fingers or fall into the pan. This should still be okay, though, so long as the egg + bacteria are cooked thoroughly. I presume hard/soft-boiled eggs are perfectly safe, because there’s virtually a 0% chance that the outer surface of the eggshell would taint the inside.


The problem here is the big factory hastily roasting the nuts. Peanuts grow in the ground, which is partially made of feces. The dirt sticks on the peanut shell and little amounts end up in the roasting phase. If the peanuts are not cooked thoroughly then they’ve become contaminated with bacteria. And I’m sure you’ve eaten a peanut that tasted off compared to the others—it’s undercooked. Many recent studies have found boiled peanuts to be less likely to cause an allergic reaction to develop than roasted peanuts. Just like with eggs, we crack the peanut shell and then cook the peanut—a problematic procedure that increases the odds of contamination.

Tree Nuts

Tree nuts grow above ground and away from poop, so it may not be obvious how these become tainted. I believe it has to do with the fact that they are processed in the same factory as peanuts. A likely scenario is that peanut shell dust—contaminated with bacteria—floats into the roasting vat.


Fish is often consumed raw in the form of sushi which means that if any bacteria or viruses were on the fish meat, they did not get cooked off.


Humans eat the entire body of the clam, oyster, mussel, etc. Unfortunately this includes the stomach and poop chute, which are laden with bacteria. We even eat oysters raw. Failing to thoroughly cook shellfish and its digestive system is a big problem, in my opinion.


A lot of conjecture here, but I suspect the hairy soybean pod catches a lot of airborne bacteria. Later in the factory process, this bacteria gets brushed off while popping the beans out of the pod—imagine squeezing a tube of toothpaste. Peaches also have high allergy rates relative to other fruits. I think both of these can be attributed to their hairy exterior catching harmful bacteria.


E. coli is often found in wheat flour and leads to product recalls. This would not be a problem if food was fully-cooked, but wheat often isn’t. It’s intentionally undercooked in the case of soft-baked cookies, and intentionally raw in cookie dough ice cream. It’s often unintentionally uncooked in pizza or some pastries, like Beef Wellington.

Uncooked pizza dough.


Similar to food allergies, I hypothesize that a food intolerance, which manifests as a stomachache, is caused by continually eating a food in its raw or undercooked form. So the initial exposure to the food was fine—there is no allergic reaction. Also, the food is not tainted with bacteria or viruses, it is merely raw or undercooked. The most common culprits of food intolerance are probably milk and wheat, a.k.a. lactose intolerance and gluten intolerance, respectively. For milk, I blame the USPHS/FDA’s low pasteurization requirements for everyday milk. As for wheat, I believe we are just bad at baking and often under-bake dough.

Lastly, the cause of food poisoning is already known. It is when food is tainted with bacteria or viruses. This risk can be minimized by thoroughly cooking all food. The first exposure to the food was fine, so there is no allergic reaction.

Let’s go back to the EAT study from the beginning. The focus of the study was on timing the introduction of new foods. One group of babies was only breastfed for 6 months. Another group received common allergenic foods before 6 months. Over a thousand babies were fed Weetabix at 4 months. The results showed a lower incidence of wheat allergy among test subjects. Their conclusion was that it was the early timing that did it. High fives all around—not so fast. Weetabix is processed and cooked wheat. I argue that the success was due to the initial exposure being bacteria-free.

I attribute the rise in food allergies over the last few decades to the modern trend of eating raw food. Today, people believe that eating food in its raw state is natural and therefore best for humans. I disagree and actually believe the opposite: it is human nature to cook the things we eat and therefore cooked food is best for humans. I believe harnessing fire and utilizing tools to cook and eat are part of being a civilized human. In conclusion, preventing food allergies is not a matter of when a new food is introduced; it’s a matter of how well it is cooked.

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