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Strange but True: Cats Cannot Taste Sweets

mummummum
September 3rd, 2007, 11:18 AM
I thought this might be of interest ...

Strange but True: Cats Cannot Taste Sweets

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

Sugar and spice and everything nice hold no interest for a cat. Our
feline friends are only interested in one thing: meat (except for saving
up the energy to catch it by napping, or a round of restorative petting)
This is not just because inside every domestic tabby lurks a killer
just waiting to catch a bird or torture a mouse, it is also because cats
lack the ability to taste sweetness, unlike every other mammal examined
to date.
The tongues of most mammals hold taste receptors—proteins on the
cellular surface that bind to an incoming substance, activating the cell's
internal workings that lead to a signal being sent to the brain. Humans
enjoy five kinds of taste buds (possibly six): sour, bitter, salty,
umami (or meatiness) and sweet (as well as possibly fat). The sweet
receptor is actually made up of two coupled proteins generated by two separate
genes: known as Tas1r2 and Tas1r3.
When working properly, the two genes form the coupled protein and when
something sweet enters the mouth the news is rushed to the brain,
primarily because sweetness is a sign of rich carbohydrates—an important
food source for plant-eaters and the nondiscriminating, like humans. But
cats are from the noble lineage Carnivora and, unlike some of its lesser
members, such as omnivorous bears or, even more appalling, herbivorous
pandas, they exclusively eat meat.
Whether as a result of this dietary choice or the cause of it, all
cats—lions, tigers and British longhairs, oh my—lack 247 base pairs of the
amino acids that make up the DNA of the Tas1r2 gene. As a result, it
does not code for the proper protein, it does not merit the name gene
(only pseudogene), and it does not permit cats to taste sweets. "They
don't taste sweet the way we do," says Joe Brand, biochemist and associate
director at the Monell Chemical Senses Center in Philadelphia. "They're
lucky. Cats really have bad teeth as it is."
Brand and his colleague Xia Li first discovered the pseudogene after
decades of anecdotal evidencesuch as cats showing no preference between
sweetened and regular water, unlike other animals—testifying to their
indifference to the sweet stuff. Of course, there are also plenty of
anecdotal accounts pointing in the other direction: cats that eat ice
cream, relish cotton candy, chase marshmallows. "Maybe some cats can use
their [Tas1r3 receptor] to taste high concentrations of sugar," Brand
says. "It's a very rare thing but we don't know yet."
Scientists do know, however, that cats can taste things we cannot, such
as adenosine triphosphate (ATP), the compound that supplies the energy
in every living cell. "There isn't a lot hanging around in meat, but
it's a signal for meat," Brand says. And plenty of other animals have a
different array of receptors, Li says, from chickens that also lack the
sweet gene to catfish that can detect amino acids in water at
nanomolar concentrations. "Their receptor is more sensitive than the background
concentration," Brand notes. "The catfish that detects the rotting
food first is the one that survives."
So far, cats are alone among mammals in lacking the sweet gene; even
close relatives among the meat-eaters like hyenas and mongooses have it.
And cats may lack other components of the ability to enjoy (and digest)
sugars, such as glucokinase in their livers—a key enzyme that controls
the metabolism of carbohydrates and prevents glucose from flooding the
animal. Despite this, most major pet food manufacturers use corn or
other grains in their meals. "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." What these fearsome
predators of suburbia cannot taste may be hurting them. But it also
means that most cat lovers don't have to worry about Simon snatching their
unattended dessert.

http://www.sciam.com/print_version.cfm?articleID=32EA05AC-E7F2-99DF-3B28FBBB0352D1C3

SnowDancer
September 3rd, 2007, 04:29 PM
And yet, strangely, our deaf cat Blanche (more like a dog than a cat and now on the Bridge) LOVED fruit cake of all things - particularly the cherries in said cake. My husband had brought some of his mother's cake back from Ottawa and put it into the cupboard. We heard rustling and found her with hit - she was smart - very easy to open the cupboard - and she did like to share - first with our Beagle and then with our Dachshund - would pitch pieces right into their mouths. So we moved the cake - well nothing was beyond her. At least someone ate that cake!

growler~GateKeeper
September 3rd, 2007, 11:25 PM
:laughing: :laughing: :laughing:

They never met Duffy!

She LOVES:
ice cream
icing ~ either off cakes or out of cookies
cookies
donuts
cake
pie crust
Mc'Ds fries (do they sugar them?? tastes like it)
butter
pizza crusts
candy ~ usually doesn't want to eat it but loves to taste
chocolate
toffee/caramel
etc, etc :laughing:

Jim Hall
September 4th, 2007, 12:12 AM
lol you sure duffy is a cat? sounds like my dog

growler~GateKeeper
September 4th, 2007, 12:29 AM
:laughing: yup she's a Cat she grew up with Sibes & just thinks she's part Dog :cool: :laughing:

rainbow
September 4th, 2007, 02:09 AM
Growler, I've heard that McDs soaks their fries in a sugar solution before deep frying. Also heard they add flour to their shakes to thicken them. :shrug:

chico2
September 4th, 2007, 06:43 AM
Maybe my cats do not like,choclate,whippcream,icecream,popsicles,poundc ake for their sweetness,but they sure like it.
Of course they don't get more than one lick:cat:

ancientgirl
September 4th, 2007, 10:32 AM
I've read that before, but boy, the Dynamic Duo sure seemed to enjoy that piece of blueberry muffin I dropped this morning. Oksana also loves to lick a bit of my yogurt now and then too.