July 14, 2024, 1:38 pm | Read time: 5 minutes
Cat owners, who want to get their pets to eat, often resort to a reliable option: canned tuna. Many cats cannot resist this tasty treat. Researchers have now discovered for the first time why this is, and why cats may have no choice when it comes to their love of tuna.
For many cats, canned tuna is a special delicacy. Whether dealing with finicky eaters or a cat that refuses medication, owners often entice their pets with the help of tuna. In nature, however, the fast swimming fish of prey and the nimble-footed cat, which has its origins in deserts, do not cross paths. Moreover, a cat would not be able to kill a tuna that is several meters long and weighs more than one hundred kilograms (220 pounds) on its own. So, what makes tuna so irresistible to cats? An international team of researchers from the UK, the USA, and Germany investigated this question. Study results published in the scientific journal “Chemical Sense” in August 2023 show that the cats’ genes play a special role here.
Overview
Characteristics of the feline taste sense
As “true” carnivores, cats feed mainly on meat and are dependent on nutrients that only occur naturally in this food source. Their sense of taste is correspondingly unique. Mammals have five basic tastes, including sweet, sour, salty, and bitter, as well as umami. Umami is hearty and full-bodied. It is a taste that is found in various types of meat, but also in mushrooms and cheese.
Cats seem to prefer the umami taste above all others, while their ability to perceive bitter tastes is reduced. This is unsurprising for obligate carnivores. Neither is their lack of interest in sweet foods. Cats are not able to taste sugar or sweeteners. The reason for this is that the gene that would allow them to taste sweetness is not functional.
Author Scott McGrane explains this characteristic by saying that meat, the cat’s main food, contains no sugar. Over the course of evolution, this trait has probably been lost. “If you don’t use it [the gene], you lose it,” McGrane explains to the online journal “Science“.
Cats take a taste test
In humans and a number of other animals, two genes (Tas1r1 and Tas1r3) encode the proteins that make up the umami receptors in the taste buds, the authors describe in their study. Until now, however, only the Tas1r3 gene was known to be found in cats. McGrane and his team are now providing new insights into the taste preferences of cats.
The first clue came from a biopsy of the tongue of a six-year-old cat that was euthanized for health reasons independent of the study. Using the biopsy, the scientists proved for the first time that a cat possessed both genes required for recognizing umami, along with the corresponding receptors.
To rule out the possibility that this was an isolated case, the researchers subjected 25 other cats of different age groups to a taste test. They offered them two bowls with different contents. These contained either pure water or water that had been mixed with various combinations of amino acids and nucleotides. The cats showed a preference for water with an umami-like taste.
Tuna is particularly tasty for cats
The results of the study prove that the taste buds of cats contain the receptors for the perception of umami. However, that’s not all. The researchers also came to the conclusion that cats’ receptors are specifically tuned to the molecules found in high concentrations in tuna. This is shown by the selection of the preferred tuna dishes in the taste tests.
McGrane described the contained combinations of molecules to “Science” as “preferred combinations” and a kind of “sweet spot of umami”. The latter refers to the optimal expression of a flavor, in this instance, the umami flavor. The combination of molecules enhances the taste cats prefer. According to the study, the umami receptors in cats are also crucial for their ability to recognize important flavors in meat.
Although the flavor intensity of tuna is particularly appealing to cats, the fish should not be fed without restriction. This is due to the fact that tuna, especially in large quantities and when canned, can be detrimental to a cat’s health. This is due to its high salt and mercury content.
Findings on tuna flavor could help cats
These novel study findings could hold particular importance for cat owners troubled by their finicky felines, as well as for the pet food industry. McGrane notes in “Science” that new, more appetizing foods could be developed than what was previously available. He believes that administering an umami-flavored substance by the spoonful could simplify the administration of medication to cats in the future. However, the findings so far only represent new possibilities and solutions that have yet to be developed.
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How cats acquired a taste for tuna remains a mystery
Referring back to the original habitats of tuna and cats in order to find out how cats first acquired a taste for tuna still doesn’t give us an answer. Although fish and tuna could hardly have been on the menu for desert cats in the Middle East around 10,000 years ago, cats were already depicted as fish-eaters in the art of Ancient Egypt around 1500 BC. Especially in port cities, carnivores could have had access to fish (waste).
How their preference for tuna developed can only be speculated on. Fiona Marshall, a zooarchaeologist at Washington University in St. Louis, speculated in “Science” that cats with a preference for fish, especially tuna, may have had an evolutionary advantage over other cats. The enticing effect of the umami flavor aligns perfectly with their evolutionary development as carnivores.