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The Science Behind Picky Eating

Why are some people so selective towards food?

People averse to many types of foods are dubbed picky eaters. Picky eaters are often resistant to eating anything that contains even the smallest amount of a food they dislike. You might picture them as five-year-olds on carb-only diets of bread, spaghetti, and Tyson Chicken Nuggets. However, sometimes, these kids don’t grow out of their particularity towards food and turn into picky adults. So why would anyone, of any age, be selective towards food–specifically of the healthy kind? 

Picky eating is clinically described as the consumption of an inadequate variety of food and is generally a very normal part of childhood and even adolescence.

Vegetables are the arch nemeses of picky eaters. Genetics, senses, and evolution play a large part in this common aversion.

GENETICS (1)

Danielle R. Reed of the Monell Chemical Senses Center states, “Just like we all differ in our ability to see and to hear, people differ in their ability to taste.”

Taste buds are clusters of nerve endings on our tongue that provide the sense of taste in five flavors: sweet, salty, bitter, sour, and umami. When taste receptors on the buds bind to food, they send a signal through a chemical pathway right to the brain, where we compartmentalize what everything tastes like. Taste receptors are actually proteins that contain the blueprint of our selves: DNA.

The four nucleotides—guanine (G), adenine (A), thymine (T), and cytosine (C)— make up our DNA. Our DNA is packed into 23 pairs of chromosomes, which are threadlike structures of nucleic acids and protein that carry our genetic information in the form of genes. Genes are specific sequences of nucleotides. Each pair of chromosomes is made up of one chromosome from your mother and the other from your father. Figure 1 shows how our genetic information is stored in the nucleus of our cells.

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Figure 1 – Image from the Mayo Clinic

What determines whether or not you taste bitter harshly is the pattern of nucleotides on the TAS2R38 gene that codes for the bitter taste receptor, given to you by your parents. Being a taster, partial-taster, or non-taster is completely hereditary and is determined by which gene sequence is created. The sequences and their respective tastes are shown in  Figure 2 below.

Result Gene Sequence
Non-Taster GTA GTA
Partial Taster (Medium Bitter) CCG GTA
Taster CCG CCG

Figure 2

If you have the bitter-tasting gene sequence, you are much more likely to be a picky eater than non-tasters. If you do not have the time or cannot afford to undergo full genomic analysis, an easier way to know which sequence, and taste type, you have is through the PTC test. Phenylthiocarbamide (PTC) is a liquid used as a genetic marker for the TAS2R38 gene. To tasters, the liquid tastes very bitter, and to non-tasters, there is absolutely no taste. Vials of 100 PTC strips are sold on Amazon for $5.00. If you are interested in buying, click on the link in Figure 3 and try them with your friends and family! 

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Figure 3 – Vial of PTC Strips

SENSES

Flavor is evaluated by more than just your taste buds; the way the food smells, looks, and feels affects the way we taste. In an episode of Nova ScienceNow entitled “The Science of Picky Eaters” (2), everyone’s favorite astrophysicist, Neil deGrasse Tyson, participated in an experiment: he ate food while blindfolded and with a blocked nose. With two of his senses impaired, he could not determine what exactly he was eating—it was tasteless to him. The senses are very much interdependent, so when they were recovered, he regained his taste for Jell-O.

EVOLUTION

In regards to evolution, our caveman ancestors had to use all of their senses to figure out what was safe to eat for survival. People way back then, and today, regardless of whether a picky eater or not, are enticed by sweets because the sugar in them gives an energy boost. The bitterness in vegetables, such as broccoli, is very often rejected by the sensitive taste buds of picky eaters.

So are parents supposed to just let their kids eat junk food because their genes say so?

Well, no. According to the Child Mind Institute, “Some kids have a heightened sense of smell that makes them taste flavors more intensely than most people” (3). Over time, our sense of smell changes and, more often than not, becomes much more accepting of different smells. This affects our sense of taste because, once again, our senses are interdependent.

What about the adults that continue to be picky eaters?

A much more severe form of picky eating identified in adults is called Avoidant/Restrictive Food Intake Disorder (ARFID), which was classified as an eating disorder in the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition, published in 2013. While this article was dedicated to analyzing picky eating, the next article will discuss its more dangerous counterpart, ARFID.


References

(1) Kim, U K, and D Drayna. “Genetics of Individual Differences in Bitter Taste Perception: Lessons from the PTC Gene.” National Center for Biotechnology Information, U.S. National Library of Medicine, Apr. 2005, http://www.ncbi.nlm.nih.gov/pubmed/15733260.

(2) “The Science of Picky Eaters – Nova Science Now.” PBS, YouTube, 25 Sept. 2011, http://www.youtube.com/watch?v=mffC4hKBd2A.

(3) Ehmke, Rachel. “More Than Picky Eating.” Child Mind Institute, Child Mind Institute, 10 Apr. 2018, childmind.org/article/more-than-picky-eating/. 

(4) Featured Image of Little Girl and Vegetables. Getty Images. 

1 comment on “The Science Behind Picky Eating

  1. Pingback: Avoidant Restrictive Food Intake Disorder – The Student Scientist

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