Cats Cannot Taste Sweets (2007)

[BearOso]

> "This may be why cats are getting diabetes," Brand offers. "Cat food today has around 20 percent carbohydrates. The cats are not used to that, they can't handle it."

It's worse than that, usually 35-50% carbohydrates. The good (expensive) dry stuff is usually 10-20%. Wet food is often lower, depending on the type, as low as 7% as-fed with pates.

The weight-control labelled food is terrible both for weight and diabetes risk. It trades protein for carbohydrates under the assumption that cats don't absorb the carbohydrates as easily because the cat's liver has to process them. But this means the liver processes them to body fat, and the lack of protein leaves the cat less satiated, so it eats more food.

[andrewla]

I found this out when asking myself the question "are animals fooled by artificial sweeteners". The rabbit hole that that led into is not only do we not know the answer to that question, many animals don't even taste "sweetness" (or if they taste it they don't like it or don't prefer it). Not even all primates, if I recall correctly.

And we've seen drift -- apparently we used to be able to bait cockroaches with sweet bait (through the middle of the century), but they have adapted to it and it no longer works as bait.

Taste and smell are very strange and defy attempts at reductionism; our brains are basically very evolved olfactory organs. Dealing with smells was so hard that brains evolved to deal with the problem, and then it was just evolution asking the question "what else can we do with this giant block of computational power -- what about ... memory? vision? hearing?"

[mattkevan]

Some of the stuff I've seen our cat eating, it's both obvious and a blessing that he doesn't have much of a sense of taste.

Goes nuts for the plastic wrappers you get around Pepsi cans and won't stop licking them. Little weirdo.

[MisterTea]

I have a cat who loves to lick crinkly plastic wrappers and bags. I use shopping bags for my bedroom trash can and I'll wake up to him just sitting there licking the folded over edge for upwards of 10 minutes.

Two theories I've heard are that beef tallow is sometimes used in the manufacture of such bags so they might be smelling that. Or it could be as simple as they enjoy the sensation and/or sound of licking the bag. Though, they certainly are weirdos.

[ajross]

Cats' taste (in the strict sense) sense isn't great but isn't awful by mammal standards. What's notable, as pointed out in the article, is that the specific receptor for sugars is broken. Their ancestor lost it due to a mutation, and because the species was a strict carnivore it wasn't selected against.

But the "taste" you're talking about is the one we tend to use in general language, and it's a complicated mix of touch/texture/temperature sense in the mouth and tongue, taste bud chemical reception, and more than anything else smell, which "fills in the chemical blanks" that the coarse taste senses miss.

Cats miss one but have the others in spades. When they lick and eat random junk, it's for a very good sensory reason. Still weirdos, obviously, but ones with a good excuse.

[gwern]

One thing I've noticed with cats in general is they seem to have a thing for human earwax. I'm not the only one to have noticed this: https://www.gwern.net/Questions#cats-earwax

[pitzips]

I hear ya! Mine is obsessed with eating cobwebs.

[Smithalicious]

I had a cat that went nuts for spaghetti. He'd jump up on the counter and slurp the noodles. Same cat also loved cucumbers.

My mom's cat prefers to drink water from a glass like a human. Either that, or from the toilet (to which he can open the door).

[keitmo]

One of our cats loves to lick the adhesive side of packing tape.

[JoelMcCracken]

Knowing this, when my cats desire something sweet that I was eating, I have always assumed they wanted something else they tasted in the food -- if ice cream, then the cream, etc.

[foobiekr]

I realize that raisins are not safe for cats and did not feed them to my cat deliberately.

That said, I had a cat that was absolutely obsessed with eating raisins to the point where we simply couldn’t have them around. To this day I cannot understand what was going on if sweetness was not a factor.

Same cat ate the tops off an entire box of glazed donuts once as well while we were out.

[shagie]

Many of the things that we eat that have “sweet” as part of the flavor profile also have fats as part of ingredients - those are things that cats do taste and recognize.

When one looks at cat treats, the fat component is higher than non-treat cat food.

[cmiller1]

Fun fact: the sodium lauryl sulfate in toothpaste dulls the sweetness receptors on your tongue. The taste of orange juice after brushing your teeth is what it would ALWAYS taste like to cats.

[lightedman]

This leaves me with more questions as I have a cat that absolutely will not leave you alone if you're holding ANY fruit. She will cry and whine and do all she can to get to that fruit. Apple, plum, orange, grapefruit, pineapple, melons, it doesn't matter. She goes especially nuts for dragonfruit.

[xyzzy_plugh]

Cats are weird. My cats will gag if you hold fruit near their nose. Same goes with most people-food. They are interested in meat though.

When I was younger, we had a cat would get into literally any food available. Fruit, cheese, Doritos, salad.

Though, people are weird, too.

[weaksauce]

My cat went bananas for the smell of strawberries. No interest in eating them but adored the smell.

[powersurge360]

Citrus in particular is famous for cats disliking. Interesting that your cat enjoys those.

[DaiPlusPlus]

I would not describe grapefruit or melons as “sweet” at all.

[pcwalton]

Evolutionarily, this makes sense. All felids are obligate carnivores that rely on meat for nutrients—for example, they need taurine for vision, which they can't synthesize and is only found in meat. So there's an evolutionary advantage for cats to not want to eat anything else.

[starpilot]

Doesn't stop my cat from eating my plants.

[kjs3]

Spoken like someone who has never had a cat. Cat's do not only eat meat, anyone who's had one knows this, and it's apparently important for their health (see https://www.petmd.com/cat/wellness/evr_ct_eating_grass for example). Evolution is slightly more complicated than you understand.

[JumpCrisscross]

> there's an evolutionary advantage for cats to not want to eat anything else

Do we have evidence cats’ ancestors had such a receptor?

If not, it might be simpler to assume there wasn’t evolutionary pressure to not taste sweetness as much as there was a lack of any pressure to taste it.

[lisper]

> All felids are obligate carnivores

I think you meant "felines".

[UPDATE] Nope, the OP meant felids (though my old eyes parsed it as "fields" (never heard of a "felid" before) which is why I thought it was spell checking or voice recognition gone wrong).

[minikites]

So then why doesn't this appear in any other mammal obligate carnivores?

[tygg3n12]

Makes me wonder if this is just a result of genetic drift and/or bottlenecking. They clearly have no need for it, and are very specialized killers, but it being so widely present in mammals tells us that it's not really a costly gene to have.

I found the part about being able to register ATP interesting, as controlling for ATP is one of the most common techniques used to control the quality of hygiene in food production buildings and equipment. I don't know how this applies to nature where you would expect this to be found everywhere, but maybe it's valuable in deserts, snowy areas and similar? Or maybe higher than usual levels can be used to identify areas where rodents and other sources of food could be found?

[zdragnar]

For some reason, I had always assumed there were a number of mammals that didn't care much for sweets, even though in retrospect I know that ferrets, also carnivores, will obsess over sweet drinks.

[dghughes]

In case it isn't known artificial sweetener specifically xylitol is toxic to cats (and dogs). So things like toothpaste which has artificial sweetener for humans is bad for cat. I'm sure there are some people with cats who brush their cats' teeth.

[eigenschwarz]

Perhaps because mustelids have an extraordinarily high metabolism for their size? https://nyti.ms/1Ur6S6C

[pcwalton]

There are a few related species to ferrets, like sables and pine martens, that are omnivores and will eat berries and whatnot.

[starpilot]

If you're really interested in cat nutrition, comment history of alleged veterinary student https://www.reddit.com/user/Pguin15/ is gold. He posted a link for example that shows cats and dogs readily digest carbs, and that this is well known: https://en.wikivet.net/Digestibility_of_Carbohydrates

> Ground, cooked and extruded starches are almost 100% digestible in both dogs and cats, while digestibility of raw (uncooked) starches varies from 0-65% depending on the type of starch.

[phonebucket]

Related paper (from 2007): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2063449/

[peterhj]

Cool to see this on HN. I briefly worked there on a closely related project during high school after this paper was published. It was my first real experience doing wet lab work-- learned a bunch, met cool people, was fun. (Also did a lot of pipetting and PCR.)

[okonomiyaki3000]

For some reason, our cat used to be absolutely crazy for anko. The first time he ever encountered it, he stole a dorayaki out of someone's hands and hid with it in the closet growling (it was wrapped in plastic so he couldn't actually eat it). After that, I used to give him a tiny taste any time I had some but I noticed he would always throw up soon after. Now that he's a bit older he seems to have no interest in it at all.

Could it be that they can taste sweets at a young age but gradually lose that ability?

[HHalvi]

I used to think my kitten was after the sweetness when i noticed that she only likes/prefers milk based sweets. But then she does have same affinity for chocolates and strawberries too.

[immutate]

Reminder: Chocolate can be lethal for cats...

[bsenftner]

About cats only eating meat: I have 3 cats, and all of them love any blades of grass, eating a full 'salad' every day.

[devb]

Do you grow cat grass for them? Ours loves it. https://www.hillspet.com/cat-care/nutrition-feeding/cat-gras...

[immutate]

As obligate carnivores they don't only eat meat; they have to eat meat.

[RugnirViking]

As I understand it cats eat grass in order to deal with hairballs in their stomach caused when they clean themselves.

[goatinaboat]

There is a reason cats prefer meaty wet food to dry kibble, and disdain sugar entirely

This person has never met a cat. One of ours is obsessed with sweet foods like yoghurt, honey, pastries. Which we don’t generally let her have because of her teeth.

[ppcdeveloper]

Strange. My buddies cat loves sweets. Especially pecan pie. I'm not sure if she's just trying to bond with him by eating the same food at the same time or she has a sweet tooth.

[itsbenweeks]

A friend of mine was born without the ability to taste sweet things. That doesn't stop their body from reacting to it, though. Most of their favorite foods are incredibly sugary.

[dbtx]

{ plastic bags, various wires, a few DC adapter/chargers, the $10 soldering iron's AC cord, a used paper napkin that smelled like the sub sandwich it came with, crumpled up sheets of paper that are thrown and chased and batted around for some time, peanut butter, American cheese, tortilla chips (with or without Valentina and refried pinto beans and melted cheese), the spaghetti sauce or chili residue on the bowl, fluffy white rice, beef jerky (any flavor incl. peppered), roasted salted peanuts, dried fruits from trail mix, fresh voles }

[benibela]

What would happen if the cats eat miracle berries?