Cat Cravings

A mutated feline receptor for sweet tastes explains why cats don’t love sugar but do dig mushrooms.

By | January 1, 2012

ANDRZEJ KRAUZE

Several years ago, mycologist Ellen Jacobson was preparing a meal in her Colorado kitchen when her cat Cashew appeared, whining and brushing against her legs. She attempted to interpret her feline companion’s cries and guessed that he was begging for a taste of the porcini mushroom she was chopping. A sucker for a good meow, Jacobson obliged, tossing Cashew a few pieces, which he gobbled up, immediately meowing for more.

Jacobson soon discovered that Cashew’s gourmet tastes weren’t limited to boletes, but also included other expensive fungi, such as oyster mushrooms and morels. Her other cat, Lewis, also seemed to have a taste for mushrooms, as did many of the cats belonging to her friends and relatives. But what was it about these mushrooms that made cats crave them so? she wondered.

The answer, it turns out, is all in the taste buds, and specifically in the taste receptor proteins that lie within taste buds. Sensations of sweet and umami (the taste of the amino acid glutamate) are driven by three receptors in the mouth—T1R1, T1R2, and T1R3. Sweet tastes are triggered by the binding of food molecules to T1R2 and T1R3, while umami tastes result from activation via T1R1 and T1R3 receptors. Both sensations are pleasurable to most mammals, including humans, and drive the consumption of carbohydrates and amino acids—necessary components of healthy diets.

But cats are different, says behavioral biologist Gary Beauchamp of Monell Chemical Senses Center in Philadelphia. Thirty-five years ago, he recognized that the domestic cats he studied had no interest whatsoever in sweets. Curious to see if that was “an anomaly of domestication,” he and his colleagues headed over to the Philadelphia Zoo, where they conducted simple taste tests with a variety of wild felines, including lions, tigers, leopards, and jaguars. Beauchamp’s team replicated the same preference result they’d noticed in domestic cats: “there was no particular response to carbohydrate sugars or any other sweetener,” he recalls.

It wasn’t for another 30 years, however, that the molecular basis for those feline taste preferences came to light. In 2005, a few years after the T1R family of taste receptors had been identified, Beauchamp and his colleagues decided to take a closer look at the receptors in cats. What they found confirmed a suspicion Beauchamp had held ever since those studies on wild felines back in the 1970s: cats didn’t have a specific aversion to sweet flavors; they just couldn’t taste them at all. Sequencing the genes that coded for the T1R receptors, the researchers identified a 247-base-pair deletion in the feline T1R2 gene, which rendered the gene nonfunctional (PLoS Genet, 1(e3):0027-35, 2005). “I was delighted,” notes Beauchamp, who is now exploring the molecular makeup of such receptors in other carnivore species. “It was nice to see that there was a very dramatic explanation for our inability to find any response to sweeteners.”

And the results make sense given cats’ meat-rich diets, says University of Colorado School of Medicine otolaryngologist Sue Kinnamon, who studies taste transduction and the cellular basis of taste (see “Matters of Taste,” The Scientist, November/December 2011). “Because they are hunters, and they don’t actually see many sweet things in their diet, there’s just no selective pressure to maintain the sweet gene,” she says. “It’s just become a pseudogene.”

These taste preferences also explain Cashew’s love of mushrooms, adds cellular and developmental biologist Tom Finger, also of the University of Colorado School of Medicine, and coauthor with Kinnamon of “Matters of Taste.” Mushrooms, he explains, have relatively high glutamate levels, which activate the cat’s intact umami receptors. “[Cats] are not designed to like mushrooms; they’re designed to like protein [and amino acid] sources.”

But just because Cashew likes mushrooms doesn’t mean they’re good for him, warns Deb Zoran, a veterinary internist at Texas A&M University. Unlike omnivores, such as dogs or people, which can synthesize the fatty acids and amino acids their bodies need from other foods, such as plants, cats cannot, she explains. “Their bodies didn’t create those enzymes in order to convert those protein sources into the amino acids they need. They have to have them in their diet.”

“They are wonderful beasts, but they are very different [from other mammals],” Zoran adds. “A cat diet needs to be very high in meat-based protein.”

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Comments

Avatar of: Michael Roth

Michael Roth

Posts: 1

January 5, 2012

My cat gets all the protein he needs from a vegan diet.

Avatar of:

Posts: 0

January 5, 2012

My cat gets all the protein he needs from a vegan diet.

Avatar of:

Posts: 0

January 5, 2012

My cat gets all the protein he needs from a vegan diet.

Avatar of:

Posts: 0

January 6, 2012

Interesting but a bit reductionist. Nutrition is infinitely more complex than scientists lead people to believe by classifiying it as protein, carbohydrates, lipids and vitamins.

And as for selective pressure, this is a GIANT assumption in regard to taste receptors. There exist in nature a plethora of fruit that are eaten by felines if they are hungry enough. Domestic cats also will routinely eat grass and pumpkin seeds. Since these habits don't fall into the view that felines are obligate carnivores, scientists charge off into the "they eat it because it has medicinal value, helps digestion or their taste buds get "help" in sensing protein".

Note to scientists: Nutritional ignorance and arrogance is what has lead to GMO making monsters like Monsanto. It's time for some humility. A cubic inch piece of prime top soil with 50 million organisms is not simply certain proportions of Potassium, Nitrogen and phosphates! The scientifically derived chemical fertilizer is killing our planet's soil.

Nutrition involves eating things that have millions of organisms in them too. And those organisms play an important and little understood role in health that science has not explained. But I guess today's corporate science isn't interested in complexity. Corporations and corporate owned governments don't like to give grant money to discover that 20th century eating and farming habits are poisoning the planet and providing humans with poor nutrition.

Avatar of:

Posts: 0

January 6, 2012

Well, I know opposite examples!
my cat loves sweet stuff: does not drink milk, but loves chocolate milk, eggnog, likes cakes, etc… I don’t give him these since I know his natural diet would not contain simple carbohydrates, but once in a while he gets it as a treat.
My dad’s cat even stole chocolate from his hand!

Avatar of:

Posts: 0

January 6, 2012

my cat loves sweets, especially chocholate pudding

Avatar of:

Posts: 0

January 6, 2012

Interesting but a bit reductionist. Nutrition is infinitely more complex than scientists lead people to believe by classifiying it as protein, carbohydrates, lipids and vitamins.

And as for selective pressure, this is a GIANT assumption in regard to taste receptors. There exist in nature a plethora of fruit that are eaten by felines if they are hungry enough. Domestic cats also will routinely eat grass and pumpkin seeds. Since these habits don't fall into the view that felines are obligate carnivores, scientists charge off into the "they eat it because it has medicinal value, helps digestion or their taste buds get "help" in sensing protein".

Note to scientists: Nutritional ignorance and arrogance is what has lead to GMO making monsters like Monsanto. It's time for some humility. A cubic inch piece of prime top soil with 50 million organisms is not simply certain proportions of Potassium, Nitrogen and phosphates! The scientifically derived chemical fertilizer is killing our planet's soil.

Nutrition involves eating things that have millions of organisms in them too. And those organisms play an important and little understood role in health that science has not explained. But I guess today's corporate science isn't interested in complexity. Corporations and corporate owned governments don't like to give grant money to discover that 20th century eating and farming habits are poisoning the planet and providing humans with poor nutrition.

Avatar of:

Posts: 0

January 6, 2012

Well, I know opposite examples!
my cat loves sweet stuff: does not drink milk, but loves chocolate milk, eggnog, likes cakes, etc… I don’t give him these since I know his natural diet would not contain simple carbohydrates, but once in a while he gets it as a treat.
My dad’s cat even stole chocolate from his hand!

Avatar of:

Posts: 0

January 6, 2012

my cat loves sweets, especially chocholate pudding

Avatar of: susan

susan

Posts: 1457

January 6, 2012

Well, I know opposite examples!
my cat loves sweet stuff: does not drink milk, but loves chocolate milk, eggnog, likes cakes, etc… I don’t give him these since I know his natural diet would not contain simple carbohydrates, but once in a while he gets it as a treat.
My dad’s cat even stole chocolate from his hand!

Avatar of: Seda Kilic

Seda Kilic

Posts: 1457

January 6, 2012

my cat loves sweets, especially chocholate pudding

Avatar of: agelbert

agelbert

Posts: 50

January 6, 2012

Interesting but a bit reductionist. Nutrition is infinitely more complex than scientists lead people to believe by classifiying it as protein, carbohydrates, lipids and vitamins.

And as for selective pressure, this is a GIANT assumption in regard to taste receptors. There exist in nature a plethora of fruit that are eaten by felines if they are hungry enough. Domestic cats also will routinely eat grass and pumpkin seeds. Since these habits don't fall into the view that felines are obligate carnivores, scientists charge off into the "they eat it because it has medicinal value, helps digestion or their taste buds get "help" in sensing protein".

Note to scientists: Nutritional ignorance and arrogance is what has lead to GMO making monsters like Monsanto. It's time for some humility. A cubic inch piece of prime top soil with 50 million organisms is not simply certain proportions of Potassium, Nitrogen and phosphates! The scientifically derived chemical fertilizer is killing our planet's soil.

Nutrition involves eating things that have millions of organisms in them too. And those organisms play an important and little understood role in health that science has not explained. But I guess today's corporate science isn't interested in complexity. Corporations and corporate owned governments don't like to give grant money to discover that 20th century eating and farming habits are poisoning the planet and providing humans with poor nutrition.

Avatar of: GilesBrooke

GilesBrooke

Posts: 3

January 9, 2012

Seda, you shouldn't give your cat chocolate pudding, or anything chocolate. Chocolate contains theobromine, which is toxic to cats.http://www.knowyourcat.info/info/cats... 
http://www.cat-world.com.au/ch... 

Avatar of: GilesBrooke

GilesBrooke

Posts: 3

January 9, 2012

Susan, you shouldn't give your cat chocolate milk, or anything chocolate. Chocolate contains theobromine, which is toxic to cats.
http://www.knowyourcat.info/in... 
http://www.cat-world.com.au/ch... 

Avatar of: GilesBrooke

GilesBrooke

Posts: 3

January 9, 2012

Feeding a cat a non-meat diet is basically animal abuse. Cats are obligate carnivores. Plant protein is not the same amino-acid composition as animal protein. Additionally, there are many other essential nutrients for cats that are simply not present in vegan diets. Taurine is just 1 example, 

Taurine is an amino acid essential for cats as unlike other mammals, cats cannot synthesize it. In the absence of taurine, a cat’s retina slowly degenerates and the cat suffers eye problems and can become irreversibly blind. This condition is called central retinal degeneration (CRD). Cow’s milk is a poor source of taurine and there is none in plant foods. The only rich source is meat. http://www.essentialvegetarian... Would you feed a pet rabbit on a meat-only diet?

Avatar of:

Posts: 0

January 9, 2012

Seda, you shouldn't give your cat chocolate pudding, or anything chocolate. Chocolate contains theobromine, which is toxic to cats.http://www.knowyourcat.info/info/cats... 
http://www.cat-world.com.au/ch... 

Avatar of:

Posts: 0

January 9, 2012

Susan, you shouldn't give your cat chocolate milk, or anything chocolate. Chocolate contains theobromine, which is toxic to cats.
http://www.knowyourcat.info/in... 
http://www.cat-world.com.au/ch... 

Avatar of:

Posts: 0

January 9, 2012

Feeding a cat a non-meat diet is basically animal abuse. Cats are obligate carnivores. Plant protein is not the same amino-acid composition as animal protein. Additionally, there are many other essential nutrients for cats that are simply not present in vegan diets. Taurine is just 1 example, 

Taurine is an amino acid essential for cats as unlike other mammals, cats cannot synthesize it. In the absence of taurine, a cat’s retina slowly degenerates and the cat suffers eye problems and can become irreversibly blind. This condition is called central retinal degeneration (CRD). Cow’s milk is a poor source of taurine and there is none in plant foods. The only rich source is meat. http://www.essentialvegetarian... Would you feed a pet rabbit on a meat-only diet?

Avatar of:

Posts: 0

January 9, 2012

Seda, you shouldn't give your cat chocolate pudding, or anything chocolate. Chocolate contains theobromine, which is toxic to cats.http://www.knowyourcat.info/info/cats... 
http://www.cat-world.com.au/ch... 

Avatar of:

Posts: 0

January 9, 2012

Susan, you shouldn't give your cat chocolate milk, or anything chocolate. Chocolate contains theobromine, which is toxic to cats.
http://www.knowyourcat.info/in... 
http://www.cat-world.com.au/ch... 

Avatar of:

Posts: 0

January 9, 2012

Feeding a cat a non-meat diet is basically animal abuse. Cats are obligate carnivores. Plant protein is not the same amino-acid composition as animal protein. Additionally, there are many other essential nutrients for cats that are simply not present in vegan diets. Taurine is just 1 example, 

Taurine is an amino acid essential for cats as unlike other mammals, cats cannot synthesize it. In the absence of taurine, a cat’s retina slowly degenerates and the cat suffers eye problems and can become irreversibly blind. This condition is called central retinal degeneration (CRD). Cow’s milk is a poor source of taurine and there is none in plant foods. The only rich source is meat. http://www.essentialvegetarian... Would you feed a pet rabbit on a meat-only diet?

Avatar of:

Posts: 0

January 12, 2012

Feeding a vegan diet to a cat is animal abuse. They are obligate carnivores and need nutrients such as taurine that are found only in meat, not plant-based foods.

Taurine is an amino acid essential for cats as unlike other mammals, cats cannot synthesize it. In the absence of taurine, a cat’s retina slowly degenerates and the cat suffers eye problems and can become irreversibly blind. This condition is called central retinal degeneration (CRD). Cow’s milk is a poor source of taurine and there is none in plant foods. The only rich source is meat. http://www.essentialvegetarian... 

Avatar of:

Posts: 0

January 12, 2012

You should not feed chocolate or chocolate-containing products to a cat. Chocolate contains a compound called theobromine which is toxic to cats.
http://www.knowyourcat.info/in...
http://www.cat-world.com.au/ch... 

Avatar of:

Posts: 0

January 12, 2012

You should not feed chocolate or chocolate-containing products to a cat. Chocolate contains a compound called theobromine which is toxic to cats.http://www.knowyourcat.info/info/cats...
http://www.cat-world.com.au/ch... 

Avatar of:

Posts: 0

January 12, 2012

Feeding a vegan diet to a cat is animal abuse. They are obligate carnivores and need nutrients such as taurine that are found only in meat, not plant-based foods.

Taurine is an amino acid essential for cats as unlike other mammals, cats cannot synthesize it. In the absence of taurine, a cat’s retina slowly degenerates and the cat suffers eye problems and can become irreversibly blind. This condition is called central retinal degeneration (CRD). Cow’s milk is a poor source of taurine and there is none in plant foods. The only rich source is meat. http://www.essentialvegetarian... 

Avatar of:

Posts: 0

January 12, 2012

You should not feed chocolate or chocolate-containing products to a cat. Chocolate contains a compound called theobromine which is toxic to cats.
http://www.knowyourcat.info/in...
http://www.cat-world.com.au/ch... 

Avatar of: Guest

Anonymous

January 12, 2012

You should not feed chocolate or chocolate-containing products to a cat. Chocolate contains a compound called theobromine which is toxic to cats.http://www.knowyourcat.info/info/cats...
http://www.cat-world.com.au/ch... 

Avatar of:

Posts: 0

January 12, 2012

You should not feed chocolate or chocolate-containing products to a cat. Chocolate contains a compound called theobromine which is toxic to cats.http://www.knowyourcat.info/info/cats...
http://www.cat-world.com.au/ch... 

Avatar of: Guest

Anonymous

January 12, 2012

Feeding a vegan diet to a cat is animal abuse. They are obligate carnivores and need nutrients such as taurine that are found only in meat, not plant-based foods.

Taurine is an amino acid essential for cats as unlike other mammals, cats cannot synthesize it. In the absence of taurine, a cat’s retina slowly degenerates and the cat suffers eye problems and can become irreversibly blind. This condition is called central retinal degeneration (CRD). Cow’s milk is a poor source of taurine and there is none in plant foods. The only rich source is meat. http://www.essentialvegetarian... 

Avatar of: Guest

Anonymous

January 12, 2012

You should not feed chocolate or chocolate-containing products to a cat. Chocolate contains a compound called theobromine which is toxic to cats.
http://www.knowyourcat.info/in...
http://www.cat-world.com.au/ch... 

Avatar of: jkrochko

jkrochko

Posts: 1

January 30, 2012

The issue is why do some cats LIKE sweets and also LIKE chocolate? - I had a cat that would steal the Hallowe'en candy and birthday cakes and Valentine hearts ....

Avatar of:

Posts: 0

January 30, 2012

The issue is why do some cats LIKE sweets and also LIKE chocolate? - I had a cat that would steal the Hallowe'en candy and birthday cakes and Valentine hearts ....

Avatar of:

Posts: 0

January 30, 2012

The issue is why do some cats LIKE sweets and also LIKE chocolate? - I had a cat that would steal the Hallowe'en candy and birthday cakes and Valentine hearts ....

Avatar of:

Posts: 0

February 12, 2012

Well, I tested mushroom preference of my cat. She didn't like any of the three types I fed to her (I didn't try porcini). On the other hand she loves doughnuts and cakes.

Avatar of:

Posts: 0

February 12, 2012

Well, I tested mushroom preference of my cat. She didn't like any of the three types I fed to her (I didn't try porcini). On the other hand she loves doughnuts and cakes.

Avatar of: Roman Jerala

Roman Jerala

Posts: 2

February 12, 2012

Well, I tested mushroom preference of my cat. She didn't like any of the three types I fed to her (I didn't try porcini). On the other hand she loves doughnuts and cakes.

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