Genetics: The Universe Within — Ch 8: What we found: Food preferences — Can knowing more about your genes help you eat, move, and live better?

It’s been more than a decade since the first genetic studies of human eating behavior were published, and those studies have been joined by many more. In fact, the latest research has been so impactful that it’s hard to keep up with all the new data. We know there are genes that affect our hunger and satiety hormones, and recent studies have begun looking at the impact of those genes on feeding behavior. Some of the concepts discussed in the video include how the “fiber gap” can be filled with foods that are low in fat, sugar, and calories, and how to make your diet much more enjoyable by pairing foods that are high in fat with foods that are high in flavor.

As a behavioral geneticist, my goal is to understand the vast influence of our genes on our lives. We know that our lifestyle–and the genes that influence us–shape us in unique ways. For example, the genetics of food preferences are complex, and some foods seem to be more appealing to some than others. For example, eating a lot of chocolates at a young age may lead a person to crave more sweets in adulthood. And regardless of how many sweets you eat, there’s a good chance that you will become overweight.

Today we are going to talk about food preferences and how they can be used to help you eat, move, and live better. We’ve looked at how the connections between our genes and our health can affect our food choices.

Chapter 8

What we discovered was that people had different food preferences.

This chapter will teach you the following:

We’ll look at the following topics in this chapter:

• some of the genetic and environmental variables that may influence our food preferences and decisions, such as whether we like:
  • sweet flavors;
  • greasy flavors;
  • sour flavors; or
  • coriander (coriander) is a herb that comes from the coriander family.
• What genetic testing can teach us about food preferences (and what it can’t).

There are two key things to remember:

• While science is fascinating, and we have some intriguing genetic discoveries and topics for future research, we still know a lot.
• Just because a genetic test can tell you what flavors you like doesn’t imply it can tell you what diet or supplement is best for you.

Keep in mind our normal warning as you read this chapter:

There are numerous complicated, overlapping variables in most preferences, health concerns, and hereditary characteristics.

There is virtually never a single gene that causes a certain outcome.

Any genetic information we provide is just a starting point for further investigation.

Why isn’t there a single “best” diet or workout routine?

At PN, we’ve always been fascinated with the concept of a “best diet” – specifically, refuting it.

We’ve spent years studying human diversity and why a singular, one-size-fits-all “ideal diet” doesn’t make sense.

More information about this may be found here.

Nutrition and dietary choices may be influenced by non-genetic variables.

When creating a “optimal” nutrition plan for each of our customers, there are numerous non-genetic variables to consider.

For example, we could inquire:

• What is the general public’s understanding of nutrition?
• What can individuals do? (Can they, for example, cook?)
• What can individuals do on a regular basis? What behaviors are they able to adhere to in a realistic and consistent manner?
• Is there anything else going on in their lives? Are they occupied? Working? Students? Parents?
• What is the environment like around them? Is there fresh food available to them?
• How active and fit are they?
• What sports or activities do they participate in if they are active?
• What are their ages? Babies? Seniors? Teens?
• What are their favorite things to do?
• What is their social and cultural surroundings like?
• What are their culinary customs and values?
• What is the current state of their gastrointestinal tract?
• What about their oral hygiene?
• What is their current state of health? Are they hurt or sick?
• What are their emotional connections to food?
• Etc.

Nutrition and dietary choices may be influenced by genetic factors as well.

Consider the following scenario:

Taste preferences may be influenced by genetic factors.

This may be due to the following reasons:

• of the physical architecture of taste (such as the number of taste buds we have and how tightly they are packed);
• of how we process those flavors on a molecular level (for example, whether we can chemically smell certain chemicals); and
• We are inclined to perceive some flavors to be “good” or “compelling.”

Food tolerance may be influenced by genetic factors.

Does eating make you feel happy… or bad?

Do your intestines complain when you drink milk or consume ice cream?

What about some high-fructose fruit or a couple pieces of bread?

Our genetic composition, along with other variables such as the health of our gastrointestinal system, may influence which meals we digest well and which foods we don’t.

In Chapter 9, we’ll examine into food tolerance.

Our ability to digest nutrients may be influenced by genetic variables.

We saw in Chapter 6 how different forms (aka polymorphisms) of the vitamin D cell receptor, as well as genes coding for proteins involved in vitamin D metabolism and transport, can affect our risk of chronic diseases and whether we need to supplement extra vitamin D (if we don’t get enough from sunlight).

Vitamin D isn’t the only vitamin whose digestion, absorption, or use is influenced by genetics.

In Chapter 10, we’ll go further into nutritional use.

We’ll start with dietary choices in this chapter.

Why do we like certain flavors?

Our taste preferences are heavily influenced by the cultural and social environment in which we grew up.

If you grew up in North America as an Anglo, you undoubtedly have distinct taste preferences and eating habits. For example, toast or cereal with orange juice might constitute your breakfast. You probably like items that are sweet, and you don’t care for harsh or spicy flavors.

In the meanwhile, you could be having fish and miso soup for breakfast in Japan. You might be eating smoked herring and dark rye bread smorgs (open-faced sandwiches) with strong coffee in Sweden. You may miss your grandmother’s traditional akamu, or fermented sour corn porridge, if you live in Nigeria.

Tastes may be changed. They are subject to change.

Travel may help us discover (and enjoy) new flavors and sensations, whether we journey to new locations or just explore the world of food around us.

Our preferences are influenced to some extent by genetics, according to genetic research.

If you’ve always preferred sweets, or if you despise cilantro (coriander), or if you find it difficult to eat veggies… There may be a cause for this.

What is the process of tasting?

Taste receptors are a kind of sensory receptor that detects

Taste receptors are proteins that attach to certain chemicals, much like the other receptors we’ve studied about.

Perceiving and understanding taste, like other sensory information (such as sights, scents, and sounds), requires a collaboration between one or more specialized receptors and our brains.

To transmit a signal to our brains, a chemical must connect with a taste receptor. The flavor is next evaluated by our brains to determine if it is excellent, terrible, or something to totally disregard.

• Sweetness is detected by TAS1R receptors.
• Bitterness is detected via TAS2R receptors.
• Heat is detected by TRPV1 receptors (e.g., from chili peppers).
• Cold is detected by CMR1 receptors (e.g., from mint).
• Ion channels, such as the epithelial sodium channel (ENaC) or the acid-sensing ion channels (ASICs), sense other tastes (salty and sour), and can determine how much of a chemical (such as salt) is in a solution.
• Our nose’s olfactory receptors add information from what we smell, influencing our brain’s sense of taste.

Figure 8.1: Taste receptors in action

We may differ in:

• The physical architecture of our taste buds, as well as the number of taste receptor proteins we have.
• How sensitive they are (or how much of a certain chemical signal is required for them to “get the message”).
• Our brains’ interpretation of the data received from our receptors.
• We have “taste” receptors throughout our gastrointestinal system, including in our nasal epithelia, tracheas, stomachs, bile ducts, and small intestines, in addition to those in our mouths. Skin, thyroid, bladder, testes, and bone all have these kinds of receptors.

Taste receptors are used for more than simply taste.

For example, they may be engaged in:

• immunity;
• our reaction to pharmaceutical medications;
• TAS2R receptors, for example, may interact with hormone-secreting cells in our GI tract, such as those that make cholecystokinin (CCK), one of our satiety hormones; appetite control
• or glucose homeostasis
• if we prefer to smoke or drink alcohol

Many of these characteristics are formed by our genes, which implies that genes may influence the meals we intuitively prefer or avoid to some extent.

Here are several examples:

• TAS2R16 gene variants may influence how humans experience the bitterness of some plant chemicals as well as our alcohol preferences.
• A TAS2R19 mutation may influence how much we like grapefruit or quinine (a bitter extract used in some soft drinks like Brio, or the tonic water in your cocktail)
• TAS2R31 polymorphisms seem to be linked to how we perceive artificial sweeteners like saccharin and acesulfame-K, whereas TAS2R4 and TAS2R14 variants may influence whether we detect a nasty aftertaste from steviol glycosides, which are some of the active components in stevia.
• Many artificial sweeteners, such as aspartame, neotame, cyclamate, and neohesperidin dihydrochalcone, may be tasted by humans. Other animals, such as mice, are unable to detect sweet-tasting proteins such as brazzein, monellin, and thaumatin.
• Gustin is a protein that aids in the formation of taste buds. We’ll look at how variations in the CA6 gene, which codes for gustin, may influence “super-tasting.”

Taste perception and dietary choices are influenced by a number of genes.

And since there are numerous genetic differences both within and between individuals, we can’t predict what a person’s preferences or taste sensations will be.

Do you like sweet things?

The majority of us have an inherent preference towards sweetness.

This is logical in evolutionary terms. Sweetness typically indicated that something was tasty and high in energy (like honey or fruit). Sucrose (sugar) solutions are preferred by even newborn infants over water.

So, what are some genetic factors that influence sweet taste preference?

TAS1R2 and TAS1R3 are two types of TAS1 receptors.

TAS1R2 and TAS1R3 are two genes that code for taste receptor proteins that respond to sweetness.

Researchers looked at two kinds of sweetness preferences in a European population in one study:

• the sweetness of something (intensity); and
• how well it was received.

They discovered that although genetic variance did not fully explain people’s preferences for intensity, it did somewhat explain (between 30 and 50 percent) their preferences for sweetness.

FGF21

FGF21 stands for fibroblast growth factor 21, a protein involved in a variety of metabolic activities, including glucose absorption and starvation adaptation.

In comparison to people with AG (adenine-guanine) or GG (adenine-guanine) variations in the rs838133 SNP of FGF21, about 120,000 people of European descent with the AA (adenine-adenine) variation in the rs838133 SNP of FGF21 were a little more likely to prefer sweet tastes to savory or salty tastes, according to 23andMe data (guanine-guanine).

Surprisingly, virtually none of the people polled at PN had the FGF21 variant’s AA genotype. We were about half AG and half GG.

People who have had GG are, indeed, “meh” about sugar. They’re bored after one mouthful.

However, John, an AG, claims to be a “desert monster.”

Interesting tidbit!

Krista’s note: This is correct. I’ve seen John’s fervent need for cookies firsthand.

The FGF21 gene and its protein product have an impact on more than simply whether we go for the candy dish. They also have additional functions in metabolism and may be linked to metabolic health. In Chapter 10, we’ll delve further into FGF21.

The short version is that sweet taste preference is most likely only one component of a much broader system of genetic and epigenetic metabolic control.

GLUT2 and SLC2A2

Glucose transit in the body may influence health, as we learned in the metabolism chapter. It seems to have an impact on taste preferences, according to research.

We need to transfer glucose someplace once we consume anything sweet or starchy and break it down to glucose (such as storing nutrients in cells). GLUTs, a class of glucose transporter proteins, are responsible for this.

The GLUT2 transporter, which is present in the pancreas, liver, small intestine, kidney, and brain, is encoded by the SLCA2 gene. It’s likely involved in local glucose transport as well as detecting general glucose levels throughout our bodies because of these sites.

The SLC2A2 rs5400 SNP may be linked to sweet taste preferences.

Individuals with a CT (cytosine-thymine) or TT (thymine-thymine) at rs5400 ate more sweet foods, according to two investigations of prediabetics and young, healthy people in their 20s. These SLCA2 rs5400 variations, as well as another SNP, rs5393, are linked to a greater risk of Type 2 diabetes.

What did our sample reveal?

You may recall our FTO gene from Chapter 7’s discussion of body weight.

The FTO SNP rs1421085, like the FGF21 SNP rs838133, is linked to a sweet taste preference.

Here’s what we discovered in our research:

rs1421085 is an FTO variable.		rs838133 FGF21
CC – sweet preference is more likely.	16%	AA indicates a greater likelihood of a sweet inclination.	3%
CT – average probabilities	53%	AG – standard odds	50%
TT – less likely to enjoy sweets	31%	GG – standard odds	47%

 

What are your thoughts on sugar?
I am a sucker for sweets. Once I start eating sweets, it’s difficult for me to quit.	30%
Sweets are fine, but I’m not a sugar addict.	39%
Sugar isn’t something I’m particularly fond of.	30%

To begin, you’ll observe that most individuals have a hereditary predisposition to favor sweet meals.

Despite this, approximately a third of respondents indicated they like sweets and found it difficult to quit consuming sugar once they began.

The choices of many individuals did not reflect their SNPs.

Many individuals with the TT allele of the FTO SNP, for example, who should have disliked sugar, did. Sugar was disliked by several individuals with an AA form of the FGF21 SNP, who should have enjoyed it more.

You may wonder:

• What effect does being health- and fitness-conscious have on sweet taste preferences?
• Is it more probable that the PN sample has retrained their palates and is less inclined to desire sweets as a result of their healthy eating habits?
• Do we have additional genes that influence our taste preferences?

We can’t be certain right now.

However, the long-term effects of excellent diet, regular exercise, and a lean and healthy body composition (which usually indicates that glucose and insulin mechanics are working well) are crucial variables we can’t overlook.

What does this mean to you?

• It’s possible that your genetic composition influences your taste for sweet meals. Genetic testing may reveal more about your inherent proclivities.
  • FTO rs1421085 and FGF21 rs838133 are tested by 23andMe.
  • The rs5400 variant on the GLUT2 gene is tested by Nutrigenomix.
• Your taste for sweet meals is influenced by your surroundings. If you grew up eating Sugar Frosted Marshmallow Flakes for breakfast, these and other sweet processed foods are likely to have influenced your taste preferences.
• If you enjoy sweet foods, you probably don’t need a genetic test to find out. The majority of individuals already know whether or not they do.
• It doesn’t mean you’re a “sugar addict” or “doomed by your genes” if you like sweets. Simply said, in a world where sugar and sweets abound, you’ll have to be cautious to make smart choices, and you may have to fight a bit more to overcome your natural inclinations.
• Tastes may change over time. Though our genes influence our taste, they do not decide it. One of our senses, taste, is one of the most changeable. Regardless of our genetic composition, we may learn to enjoy or hate any meal. You may also find that as you get older, your taste for sweet foods changes.
• Basic dietary concepts apply regardless of your genetic composition. We’ll offer you some additional suggestions in Chapter 12 if you wish to enhance the quality and variety of your meals for health or other reasons.

Do you like being chubby?

In a restaurant, you order salad. It’s topped with avocado, bacon, and blue cheese, as well as an oily dressing. What’s your reaction?

Wow, that’s a lot of money!

Or

This blue cheese has far too much lettuce in it!

If you fall into the second category, you may have a hereditary predisposition towards fatty flavors and textures.

Fat can make meals wonderful, whether it’s butter, cheese, avocado, bacon, extra olive oil for dipping, or that peanut butter that’s like a black hole for your spoon.

However, not everyone like meals that are thick, creamy, and greasy. What’s to stop you?

CD36

CD36, a glycoprotein with many functions, is encoded by the CD36 gene.

Glycoproteins are proteins that have carbohydrates attached to them (in the metabolism chapter, we discussed lipoproteins, which are proteins that may bind to lipids). Follicle-stimulating hormone (FSH), luteinizing hormone (LH), and thyroid hormone are examples of glycoproteins.

Because glycoproteins may attach to a wide range of molecules, they can perform a wide range of functions. Cellular receptors are often involved.

CD36 is a transmembrane protein (a protein that bridges the interior and outside of a cell membrane) that connects to items like:

• proteins found in connective tissue;
• proteins from the immunological and vascular systems; and
• Lipoproteins, phospholipids, and long-chain fatty acids are all examples of lipids.

We’re particularly interested in the last function, since CD36 is found in our lips, small intestines, and hypothalamus, all of which regulate taste and energy balance.

Certain fatty acids form strong connections with CD36. People with CD36 gene variations (such as a GG or GA at the rs1761667 SNP, or a TT or CT at rs1527483) seem to be more sensitive to fattier tastes than others.

This may imply that less is more for some individuals; since fat has a stronger flavor, they may choose to consume less fat or find certain meals to be excessively rich.

People who have a lower fat tolerance (such as those with an AA at rs1761667) may like it more.

Indeed, studies show that individuals who are more sensitive to fatty tastes consume less overall and less fat in particular, as well as weigh less.

Many groups, including individuals of European, Latin American, Middle Eastern, and African heritage, seem to have a consistent link between CD36 polymorphisms and body weight.

Just a reminder that biology, and especially metabolism, is a complicated system: Variations in CD36 have also been linked to:

• hypertension and cardiovascular illnesses are risks;
• Alzheimer’s disease risk;
• cancer risks; and
• During exercise, fatty acids are oxidized.

In Chapter 11, we’ll go into exercise in more depth.

What does this mean to you?

• Your fatty food preferences may be influenced by your genetic composition. Genetic testing may reveal more about your inherent proclivities.
  • The rs1761667 SNP of CD36 is tested by Nutrigenomix.
• Your taste for fatty meals is also influenced by your surroundings. What we eat as children and what we select on a regular basis will influence our taste preferences, just as it does with sweet foods.
• If you enjoy fatty meals, you probably don’t need a genetic test to find out. The majority of individuals already know whether or not they do.
• It doesn’t mean you’re a “fat junkie” or “doomed by your genes” if you like fatty foods. Simply said, if you live in an area where fatty meals are plentiful and often paired with sweets or carbohydrates (which makes them double tasty), you’ll have to be cautious to make smart choices and may have to work a bit more to overcome your natural inclinations.
• Tastes may change over time. Though our genes influence our taste, they do not decide it. One of our senses, taste, is one of the most changeable. Regardless of our genetic composition, we may learn to enjoy or hate any meal. You may also find that as you get older, your taste for fatty meals changes.
• Basic dietary concepts apply regardless of your genetic composition. We’ll offer you some additional suggestions in Chapter 12 if you wish to enhance the quality and variety of your meals for health or other reasons.

Do you find bitterness to be unpleasant?

While many of us grow to like bitter flavors as adults (think coffee or tea, lime, radicchio (called red chicory), hoppy brews, and dark chocolate), others will have a lifelong dislike for bitterness.

We tended to avoid bitterness in our evolutionary history, which may indicate that some meals are unhealthy. As a result, it’s not surprising that some of us are more sensitive to bitter tastes than others.

Extra sensitivity to bitter tastes is, in fact, a highly heritable characteristic formed mostly by your genes and influenced less by your environment or learning. Many vegetables have a bitter taste that sensitive individuals may perceive and dislike due to their chemical makeup.

Consider the following foods:

• cabbage;
• sprouts from Brussels;
• kale;
• greens from dandelion;
• rapini;
• peppers, green;
• rutabaga and turnips; and
• broccoli.

Many of these foods include bitter-tasting chemicals (such as sulfur compounds and/or terpenes, which are linked to turpentine).

In humans, there are about 25 genes that code for TAS2R bitter taste receptor proteins. Bitterness was traditionally associated with poison, thus having several methods for sensing it was advantageous.

Here’s an illustration of how this might influence your choices.

TAS2R38

TAS2R38 is a gene that influences how well you taste bitter substances including 6-n-propylthiouracil (PROP), phenylthiocarbamide (PTC), goitrin (present in cruciferous vegetables), and other molecules.

TAS2R38 has been linked to a variety of alcohol preferences.

On this gene, 23andMe looks for the SNP rs713598. In TAS2R38, the G form of the SNP is prevalent. This implies that even if we just have one copy of PROP, we’ll be able to taste bitter PROP-like chemicals.

You may be able to taste another kind of bitter chemical in addition to the PROPs if you obtain one C and one G. This provides you a heterozygote advantage, which is a twofold evolutionary benefit.

What we discovered in our research

There were few shocks, at least for this SNP. People’s choices matched their anticipated genetic connections fairly well.

Picky eaters and those who claim they “don’t like veggies”

The homozygous bitter tasters, or GGs, disliked vegetables and were more likely to identify themselves as “picky eaters” who ate just a restricted variety of meals.

The CGs who disliked vegetables were also more likely to characterize themselves as “picky,” implying that their heterozygous SNP combination made them bitter.

The “I’ll eat anything” bunch, on the other hand, was more likely to be CCs or CGs, who had the heterozygous variation that prevented them from overtasting bitterness.

However, there will always be a few outliers that skew the results.

With the GG form of the SNP, we had a few of anticipated bitter tasters who enjoyed veggies just fine. They also said that they would eat anything.

It’s worth asking once more:

What impact does a health-conscious populace have on eating habits?

The more bitter-averse individuals in the PN sample have learnt to enjoy numerous veggies, or have learned to cook them in ways that taste better (for instance, by adding a dash of maple syrup to a kale salad dressing, or roasting Brussels sprouts to amplify their sweetness). They prefer prepared veggies over raw ones.

As a result, they’re still eating veggies, but in ways that suit them and their tastes.

What does this mean to you?

If you have a bitter taste aversion:

• It’s possible that genetic testing may reveal why you dislike bitter foods.
  • rs713598, an SNP on the TAS2R38 gene, is tested by 23andMe.
• Your surroundings has an impact on your taste for bitter meals. As with sugary and fatty meals, our taste preferences are shaped by the things we eat as children.
• Tastes may change over time. Though our genes influence our taste, they do not decide it. One of our senses, taste, is one of the most changeable. Regardless of our genetic composition, we may learn to enjoy or hate any meal. You may also find that as you get older, your taste for bitter flavors changes.
• Experiment with a broad range of nutritious foods. You may find a few that you like.
• Try foods that are in season or at various stages of development. Baby kale, for example, may be acceptable, but adult kale is harsh.
• Experiment using a variety of cooking techniques. Small adjustments in the way you prepare, cook, and/or season meals may make a significant impact.

Cilantro flavor

Cilantro, also known as Coriandrum sativum, is a herb that resembles parsley and is used in a variety of cuisines. And it irritates a lot of people.

Interesting tidbit!

Cilantro is the name given to the fresh leaves, whereas coriander is the name given to the dried seeds.

Our olfactory (scent) receptors, like our taste receptors, aid in the perception of certain chemical substances. Aldehydes, a kind of molecule, are found in many volatile compounds in perfumes.

A SNP known as rs72921001 is located in a cluster of olfactory receptor genes (genes involved in recognizing the volatile chemicals that cause smells), including OR6A2, which likes to bind to many of the aldehyde compounds that give cilantro its distinct aroma.

Two additional markers, rs2741762 and rs3930459, both found near the olfactory receptor gene OR10A2, may aid in determining whether or not someone like cilantro.

What we discovered in our research

We didn’t have enough individuals in our sample who actively disliked cilantro to make any predictions about who would hate it.

However, the OR10A2 rs2741762 SNP was ambiguous in terms of actively enjoying it (thus not hating it). Every single person who should have disliked cilantro said it was delicious.

The rs3930459 SNP performed somewhat better: based on their CC allele variation, just one person should theoretically have disliked cilantro out of all the individuals who actively enjoyed it. TTs, who have a reduced likelihood of finding cilantro unpleasant, made for little under half of the cilantro fans. CTs and the aforementioned CC made up the remainder.

What does this mean to you?

• Genetic testing may reveal if you have the genetic variation that makes you dislike cilantro. Even if you’re one of those people who despises cilantro, you may like it.
  • On OR10A2, 23andMe tests for rs2741762 and rs3930459.
• You probably don’t need a DNA test to figure out whether you hate cilantro. Ignore the folks who ridicule you at Mexican, Thai, or Indian restaurants for plucking off the garnish. You make your own decisions.
• If you like cilantro, don’t keep telling your cilantro-hating pals that they’re taste troglodytes. Some individuals describe it as tasting like soap or dirt.

What’s next?

Dietary intolerances, which may also influence our food choices, will be discussed in the following chapter.

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In previous chapters we discussed the hormones that control appetite and inhibit eating. In this chapter we explore the impact of genetics on eating behavior.. Read more about nova’s ghost in your genes worksheet answer key and let us know what you think.

Frequently Asked Questions

Do genetics play a role in food preferences?

Yes, genetics can play a role in food preferences.

How does genetics affect eating habits?

Genetics plays a large role in how your body reacts to food. For example, some people are more sensitive to certain foods than others.

Can your genes really tell you what to eat?

Yes, your genes can tell you what to eat.

Related Tags

This article broadly covered the following related topics:

• how does the food we eat affect gene expression
• genes and nutrition
• dna and food choices
• do your genes influence what you eat
• how does diet and nutrition affect gene expression