De gustibus non disputandum est. — Confucius

We’re talking about foods, not whether you prefer Beethoven or Lil’ Wayne.

Certainly there are broad correlations between the foods people enjoy and their ethnicity/social class. If you know whether I chose fried okra, chicken feet, gefilte fish, escargot, or grasshoppers for dinner, you can make a pretty good guess about my background. (Actually, I have eaten all of these things. The grasshoppers were over-salted, but otherwise fine.) The world’s plethora of tasty (and not-so-tasty) cuisines is due primarily to regional variations in what grows well where (not a lot of chili peppers growing up in Nunavut, Canada,) and cost (the rich can always afford fancier fare than the poor,) with a side dish of seemingly random cultural taboos like “don’t eat pork” or “don’t eat cows” or “don’t eat grasshoppers.”

But do people vary in their experience of taste? Does intelligence influence how you perceive your meal, driving smarter (or less-smart) people to seek out particular flavor profiles or combinations? Or could there be other psychological or neurological factors at play n people’s eating decisions?

This post was inspired by a meal my husband, an older relative and I shared recently at McDonald’s. It had been a while since we’d last patronized McDonald’s, but older relative likes their burgers, so we went and ordered some new-to-us variety of meat-on-a-bun. As my husband and I sat there, deconstructing the novel taste experience and comparing it to other burgers, the older relative gave us this look of “Jeez, the idiots are discussing the flavor of a burger! Just eat it already!”

As we dined later that evening at my nemesis, Olive Garden, I began wondering whether we actually experienced the food the same way. Perhaps there is something in people that makes them prefer bland, predictable food. Perhaps some people are better at discerning different flavors, and the people who cannot discern them end up with worse food because they can’t tell?

Unfortunately, it appears that not a lot of people have studied whether there is any sort of correlation between IQ and taste (or smell.) There’s a fair amount of research on taste (and smell,) like “do relatives of schizophrenics have impaired senses of smell?” (More on Schizophrenics and their decreased ability to smell) or “can we get fat kids to eat more vegetables?” Oh, and apparently the nature of auditory hallucinations in epileptics varies with IQ (IIRC.) But not much that directly addresses the question.

I did find two references that, somewhat in passing, noted that they found no relationship between taste and IQ, but these weren’t studies designed to test for that. For example, in A Food Study of Monotony, published in 1958 (you know I am really looking for sources when I have to go back to 1958,) researchers restricted the diets of military personnel employed at an army hospital to only 4 menus to see how quickly and badly they’d get bored of the food. They found no correlation between boredom and IQ, but people employed at an army hospital are probably pre-selected for being pretty bright (and having certain personality traits in common, including ability to stand army food.)

Interestingly, three traits did correlate with (or against) boredom:

Fatter people got bored fastest (the authors speculate that they care the most about their food,) while depressed and feminine men (all subjects in the study were men) got bored the least. Depressed people are already disinterested in food, so it is hard to get less-interested, but no explanation was given of what they meant by “femininity” or how this might affect food preferences. (Also, the hypochondriacs got bored quickly.)

Some foods inspire boredom (or even disgust) quickly, while others are virtually immune. Milk and bread, for example, can be eaten every day without complaint (though you might get bored if bread were your only food.) Potted meat, by contrast, gets old fast.

Likewise, Personality Traits and Eating Habits (warning PDF) notes that:

Although self-reported eating practices were not associated with educational level, intelligence, nor various indices of psychopathology, they were related to the demographic variables of gender and age: older participants reported eating more fiber in their diets than did younger ones, and women reported more avoidance of fats from meats than did men.

Self-reported eating habits may not be all that reliable, though.

Autistic children do seem to be worse at distinguishing flavors (and smells) than non-autistic children, eg Olfaction and Taste Processing in Autism:

Participants with autism were significantly less accurate than control participants in identifying sour tastes and marginally less accurate for bitter tastes, but they were not different in identifying sweet and salty stimuli. … Olfactory identification was significantly worse among participants with autism. … True differences exist in taste and olfactory identification in autism. Impairment in taste identification with normal detection thresholds suggests cortical, rather than brainstem dysfunction.

(Another study of the eating habits of autistic kids found that the pickier ones were rated by their parents as more severely impaired than the less picky ones, but then severe food aversions are a form of life impairment. By the way, do not tell the parents of an autistic kid, “oh, he’ll eat when he’s hungry.” They will probably respond politely, but mentally they are stabbing you.)

On brainstem vs. cortical function–it appears that we do some of our basic flavor identification way down in the most instinctual part of the brain, as Facial Expressions in Response to Taste and Smell Stimulation explores. The authors found that pretty much everyone makes the same faces in response to sweet, sour, and bitter flavors–whites and blacks, old people and newborns, retarded people and blind people, even premature infants, blind infants, and infants born missing most of their brains. All of which is another point in favor of my theory that disgust is real. (And if that is not enough science of taste for you, I recommend Place and Taste Aversion Learning, in which animals with brain lesions lost their fear of new foods.)

Genetics obviously plays a role in taste. If you are one of the 14% or so of people who think cilantro tastes like soap (and I sympathize, because cilantro definitely tastes like soap,) then you’ve already discovered this in a very practical way. Genetics also obviously determine whether you continue producing the enzyme for milk digestion after infancy (lactase persistence). According to Why are you a picky eater? Blame genes, brains, and breastmilk:

In many cases, mom and dad have only themselves to blame for unwittingly passing on the genes that can govern finicky tastes. Studies show that genes play a major role in determining who becomes a picky eater, including recent research on a group of 4- to 7-year-old twins. Part of the pickiness can be attributed to specific genes that govern taste. Variants of the TAS2R38 gene, for example, have been found to encode for taste receptors that determine how strongly someone tastes bitter flavors. Researchers at Philadelphia’s Monell Chemical Senses Center, a scientific institute dedicated to the study of smell and taste, have found that this same gene also predicts the strength of sweet-tooth cravings among children. Kids who were more sensitive to bitterness preferred sugary foods and drinks. However, adults with the bitter receptor genes remained picky about bitter foods but did not prefer more sweets, the Monell study found. This suggests that sometimes age and experience can override genetics.

I suspect that there is actually a sound biological, evolutionary reason why kids crave sweets more than grownups, and this desire for sweets is somewhat “turned off” as we age.

From a review of Why some like it hot: Food, Genetics, and Cultural Diversity:

Ethnobotanist Gary Paul Nabhan suggests that diet had a key role in human evolution, specifically, that human genetic diversity is predominately a product of regional differences in ancestral diets. Chemical compounds found within animals and plants varied depending on climate. These compounds induced changes in gene expression, which can vary depending on the amount within the particular food and its availability. The Agricultural Age led to further diet-based genetic diversity. Cultivation of foods led to the development of novel plants and animals that were not available in the ancestral environment. … There are other fascinating examples of gene-diet interaction. Culturally specific recipes, semi-quantitative blending of locally available foods and herbs, and cooking directions needed in order to reduce toxins present in plants, emerged over time through a process of trial-and error and were transmitted through the ages. The effects on genes by foods can be extremely complex given the range of plant-derived compounds available within a given region. The advent of agriculture is suggested to have overridden natural selection by random changes in the environment. The results of human-driven selection can be highly unexpected. … In sedentary herding societies, drinking water was frequently contaminated by livestock waste. The author suggests in order to avoid contaminated water, beverages made with fermented grains or fruit were drunk instead. Thus, alcohol resistance was selected for in populations that herded animals, such as Europeans. By contrast, those groups which did not practice herding, such as East Asians and Native Americans, did not need to utilize alcohol as a water substitute and are highly sensitive to the effects of alcohol.

Speaking of genetics:

Indians and Africans are much more likely than Europeans and native South Americans to have an allele that lets them eat a vegetarian diet:

The vegetarian allele evolved in populations that have eaten a plant-based diet over hundreds of generations. The adaptation allows these people to efficiently process omega-3 and omega-6 fatty acids and convert them into compounds essential for early brain development and controlling inflammation. In populations that live on plant-based diets, this genetic variation provided an advantage and was positively selected in those groups. In Inuit populations of Greenland, the researchers uncovered that a previously identified adaptation is opposite to the one found in long-standing vegetarian populations: While the vegetarian allele has an insertion of 22 bases (a base is a building block of DNA) within the gene, this insertion was found to be deleted in the seafood allele.

Of course, this sort of thing inspires a wealth of pop-psych investigations like Dr. Hirsch’s What Flavor is your Personality? (from a review:

Dr. Hirsh, neurological director of the Smell and Taste Research and Treatment Foundation in Chicago, stands by his book that is based on over 24 years of scientific study and tests on more than 18,000 people’s food choices and personalities.)

that nonetheless may have some basis in fact, eg: Personality may predict if you like spicy foods:

Byrnes assessed the group using the Arnett Inventory of Sensation Seeking (AISS), a test for the personality trait of sensation-seeking, defined as desiring novel and intense stimulation and presumed to contribute to risk preferences. Those in the group who score above the mean AISS score are considered more open to risks and new experiences, while those scoring below the mean are considered less open to those things. The subjects were given 25 micrometers of capsaicin, the active component of chili peppers, and asked to rate how much they liked a spicy meal as the burn from the capsaicin increased in intensity. Those in the group who fell below the mean AISS rapidly disliked the meal as the burn increased. People who were above the mean AISS had a consistently high liking of the meal even as the burn increased. Those in the mean group liked the meal less as the burn increased, but not nearly as rapidly as those below the mean.

And then there are the roughly 25% of us who are “supertasters“:

A supertaster is a person who experiences the sense of taste with far greater intensity than average. Women are more likely to be supertasters, as are those from Asia, South America and Africa.[1] The cause of this heightened response is unknown, although it is thought to be related to the presence of the TAS2R38 gene, the ability to taste PROP and PTC, and at least in part, due to an increased number of fungiform papillae.[2]

Perhaps the global distribution of supertasters is related to the distribution of vegetarian-friendly alleles. It’s not surprising that women are more likely to be supertasters, as they have a better sense of smell than men. What may be surprising is that supertasters tend not to be foodies who delight in flavoring their foods with all sorts of new spices, but instead tend toward more restricted, bland diets. Because their sense of taste is essentially on overdrive, flavors that taste “mild” to most people taste “overwhelming” on their tongues. As a result, they tend to prefer a much more subdued palette–which is, of course, perfectly tasty to them.

A French study, Changes in Food Preferences and Food Neophobia during a Weight Reduction Session, measured kids’ ability to taste flavors, then the rate at which they became accustomed to new foods. The more sensitive the kids were to flavors, the less likely they were to adopt a new food; the less adept they were at tasting flavors, the more likely they were to start eating vegetables.

Speaking of pickiness again:

“During research back in the 1980s, we discovered that people are more reluctant to try new foods of animal origin than those of plant origin,” Pelchat says. “That’s ironic in two ways. As far as taste is concerned, the range of flavors in animal meat isn’t that large compared to plants, so there isn’t as much of a difference. And, of course, people are much more likely to be poisoned by eating plants than by animals, as long as the meat is properly cooked.” …

It’s also possible that reward mechanisms in our brain can drive changes in taste. Pelchat’s team once had test subjects sample tiny bits of unfamiliar food with no substantial nutritional value, and accompanied them with pills that contained either nothing or a potent cocktail of caloric sugar and fat. Subjects had no idea what was in the pills they swallowed. They learned to like the unfamiliar flavors more quickly when they were paired with a big caloric impact—suggesting that body and brain combined can alter tastes more easily when unappetizing foods deliver big benefits.

So trying to get people to adopt new foods while losing weight may not be the best idea.

(For all that people complain about kids’ pickiness, parents are much pickier. Kids will happily eat playdoh and crayons, but one stray chicken heart in your parents’ soup and suddenly it’s “no more eating at your house.”)

Of course, you can’t talk about food without encountering meddlers who are convinced that people should eat whatever they’re convinced is the perfect diet, like these probably well-meaning folks trying to get Latinos to eat fewer snacks:

Latinos are the largest racial and ethnic minority group in the United States and bear a disproportionate burden of obesity related chronic disease. Despite national efforts to improve dietary habits and prevent obesity among Latinos, obesity rates remain high. … there is a need for more targeted health promotion and nutrition education efforts on the risks associated with soda and energy-dense food consumption to help improve dietary habits and obesity levels in low-income Latino communities.

Never mind that Latinos are one of the healthiest groups in the country, with longer life expectancies than whites! We’d better make sure they know that their food ways are not approved of!

(Just in case it is not clear already: different people are adapted to and will be healthy on different diets. There is no magical, one-size-fits-all diet.)

And finally, to bring this full circle, it’s hard to miss the folks claiming that Kids Who Eat Fast Food Have Lower IQs:

4,000 Scottish children aged 3-5 years old were examined to compare the intelligence dampening effects of fast food consumption versus “from scratch” fare prepared with only fresh ingredients. Higher fast food consumption by the children was linked with lower intelligence and this was even after adjustments for wealth and social status were taken into account.

It’d be better if they controlled for parental IQ.

The conclusions of this study confirm previous research which shows long lasting effects on IQ from a child’s diet. An Australian study from the University of Adelaide published in August 2012 showed that toddlers who consume junk food grow less smart as they get older. In that study, 7000 children were examined at the age of 6 months, 15 months, 2 years to examine their diet. When the children were examined again at age 8, children who were consuming the most unhealthy food had IQs up to 2 points lower than children eating a wholesome diet.