Whether you consider yourself a picky eater or an adventurous one, just about everyone has those foods they loathe or just won't touch. Polarizing foods, such as cilantro, mushrooms, or olives, can render a dish inedible for some. Others feel a bit queasy at the thought of eating offal, the internal organs of an animal, such as brain, testicles and heart. And to the average American, bugs are creatures never to be eaten except perhaps by accident.

But from where do our food aversions originate, and why do we feel disgusted by certain edible items and not others? Are there ways to overcome food aversions, or are they somewhat innate?

Let's start with perhaps the most polarizing food of all: insects. While tempura-fried crickets or mealworm tacos may not sound appetizing, entomophagy[time.com] or insect consumption is practiced regularly by at least 2 billion people worldwide with more than 1,900 edible species. Despite all the benefits — insects can be highly nutritious, environmentally friendly, tasty, and safe for consumption — seeing bugs as food remains hard for most Western societies to swallow.

“Almost everything that's disgusting is of animal origin, but cultures vary as to what they find disgusting,” said Paul Rozin, professor emeritus in psychology at the University of Pennsylvania, who is often called the father of disgust for his extensive research on the subject. “We eat cheese — rotted milk — but other cultures find that disgusting. South Asian cultures eat fish sauce which is made of rotted fish, but they love it.”

If so many other societies are happily feasting on insects as a source of protein, our aversion must be psychological in origin. The disgust reaction is based not on taste, said Rozin, but on knowledge of the nature or origin of the food in question. Our brains can't shake the feeling of pure disgust when thinking about taking a creature normally avoided at all costs, putting its dead carcass in our mouths, and crunching down on it.

“If you take a glass of clearly good juice and pour it right out of the closed container, people drink it of course. If you drop a dead, sterile cockroach in it and take it out immediately, people won't drink it,” he said, referring to a study he actually performed using undergraduates and a 4-inch cockroach carcass. “These disgusting things have the power to make something inedible even if they briefly touch it.”

In psychological terms, the juice has taken on some property of the cockroach in the subject's mind despite the bug being sterilized and safe — the juice has been effectively “roached.”

However, dipping a piece of broccoli into the glass of juice wouldn't have nearly the same effect as the cockroach, even on someone who despised the vegetable. So the reasoning behind these more ordinary types of food aversions must have a different origin — one that still remains largely a mystery.

“Every person has a bunch of foods they like, and a bunch of foods they don't like, and we can't explain why,” said Rozin. “Almost everyone likes chocolate because it's got everything in it — fat, sweet, aroma. Pizza is another one.”

Humans have an innate taste for sweet and fat and a built-in dislike of bitter and spicy substances, but the rest is learned. Hence, our upbringing plays a large role in what we find disgusting. Food aversion can also be acquired through a single unfortunate incident, like getting sick after eating, that gets forever burned into your brain. For instance, pickiness in children is thought to be associated with a negative experience such as vomiting, choking, an allergic reaction, or force-feeding.

Oversensitivity to certain flavors is another cause of food aversions. Genetic studies have shown that how strongly we sense bitter and sweet flavors is influenced by a single gene that codes for a taste receptor on our tongues. Research has also identified a genetic component to the perception of cilantro that may explain why its haters claim it tastes soapy rather than refreshing.

To learn more about how to overcome food aversions, Rozin has studied the odd case of the chili pepper. It is one of the most common spices used throughout the world, yet contains an irritant substance called capsaicin that causes a burning sensation in the mouth when ingested. This family of chemicals serves to normally deter mammals who happen to sample a pepper from ever eating them again.

Infants and young children (usually) don't like spicy food, and even older people who try it for the first time don't always enjoy it. Often, spice lovers will cite a past negative experience where they ventured too far beyond their tolerance, resulting in painful consequences. So why do people so commonly acquire a taste for hot foods?

Repeated exposure, as well as what Rozin calls “benign masochism.” As far as we know, humans are the only species to enjoy initially negative experiences under safe or controlled conditions. Similar to roller coasters, haunted houses, or tearjerker movies, eating chili peppers allows us to brave a negative situation without really putting ourselves in harm's way.

With spicy eating challenges now being offered by restaurants across the nation, perhaps eating bugs will become the next food dare? Regardless, Rozin thinks that disgust can be overcome either by positive exposures or by not thinking about the origin of the food. For instance, with entomophagy, enthusiasts can go the route of making insects taste delicious or completely hiding their bugginess by grinding them up — like with cricket flour that is being marketed as the next big thing in protein powder.

“The problem is getting over the first step. It's like getting into the ocean — it's cold at first, but it only lasts a few seconds,” Rozin said. “People do all sorts of things that are disgusting. They go to the bathroom, that’s disgusting. So the trick [to having people eat something disgusting] is to get them over the initial hump.”

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