Why Cats Are Such Picky Eaters: a Better Bitter for Felines

If you've ever owned a cat, you know that they can be pretty picky and about what they eat. This has often been associated with the "stuck up" nature of cats, but as most cat-lovers will tell you, the animals are not nearly as self-centered as their aloof natures would imply. So why so picky? A new study has determined that it may be all about how cats perceive bitter flavors.

Why bitter? For many mammals, bitter flavors hint at potentially harmful ingredients, such as toxic compounds often found in plants. Some plants have likewise taken advantage of this adaptation by boasting misleadingly bitter flavors even when perfectly harmless.

However, unlike apes, humans, or even bears, most wild felines are practically purists when it comes to their carnivorism, consuming little to no plant material in their everyday lives. If they only encounter plant toxins in trace amounts or in contaminated meats, it stands to reason that their perception and sensitivity for bitter tastes might vary greatly from humans.

This, experts have argued, could explain for why some foods and even medicines just don't appeal to many cats, despite the fact that - by human standards - they should be pretty tasty.

Now, according to a study recently published in the BioMed Central journal Neuroscience, researchers have identified the first hard evidence of just how different a cat's taste really is.

"Feline bitter taste has not been well studied," Co-author Joseph Rucker, from Integral Molecular, explained in a statement. "We applied our experience in studying membrane proteins, such as taste receptors, to enable this first glimpse into how domestic cats perceive bitterness in food at a molecular level."

"We were surprised to see that one of the cat taste receptors responded to a more limited range of bitter compounds compared to humans," he added.

Specifically, compared with the human receptor for bitterness (TAS2R38), the cat version was tenfold less sensitive to a key bitter compound known as PTC and did not respond at all to another bitter compound called PROP.

However, in the case of the compound denatonium (often used to deter children and pets from consuming chemicals such as antifreeze), cat receptors proved far sensitive compared to our human versions. They also found cats likely ignore saccharin, an artificial sweetener that tends to have a bitter aftertaste for people.

"We confront the challenge of 'finicky cats' every day. As such, it is exciting to find an unexpected receptor response to bitter compounds that has never been described in the literature to date for any other species," added co-author Nancy Rawson from AFB International, a pet food flavor company. "These insights and future discoveries will be invaluable in formulating appealing food for cats, as well as enhancing the acceptability of their medications."

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