Scientists Just Discovered Why Wet Cat Food May Be Better for Your Cat’s Health

Kirsten McCarthy / Cats.com

We humans often hear about the role our gut microbiome plays in our health, and we see many products on the market designed to grow and nourish healthy microbes that strengthen our immune system, help manage weight, improve digestion, and more. Our cats have a microbiome, too – and, according to a recent study, the microbiomes of cats who eat a dry food diet is significantly different than that of cats who eat a canned wet food diet.

It’s not just that the microbiomes are different. The study – published in March in npj Veterinary Sciences, a peer-reviewed journal – suggests that the microbiome of cats who eat a diet of wet food is healthier than the microbiome of cats whose diet is based on dry kibble, says Dr. Celeste Allaband, the study’s co-author with the University of California San Diego.

Dr. Allaband, though, states that more research needs to be done – which she hopes to do – and that it’s hard to draw broad conclusions from this one study alone, which studied 156 cats. She said that many studies with conflicting results have been done about cat diets over the years, and that some results can be misleading.

In one 2004 study about the effect of high carbohydrates published in the Journal of Feline Medicine and Surgery, for instance, researchers only fed 10 cats, all males, for just three weeks, and the effects of high carbohydrates can take years, Dr. Allaband says.

Aside from the carbohydrates question, though, wet food contains much higher moisture that is good for cats, since many don’t drink enough water. The benefits of wet food are unquestionable, she says.

“If you have the ability, try and feed at least one meal (a day) with wet food until we get more data and hopefully can dig into this more,” says Dr. Allaband. She feeds her two long-haired cats – Cindy Clawford and Patches – wet food for dinner, and dry food in the morning.

“In general, what I’m seeing is that wet food is generally better than dry food,” Dr. Allaband says.

Ultimately, she says, the more wet food you feed, the better.

“Wet food appeared better for the microbiome,” Dr. Allaband says. “It generally looked better and had less microbes associated with metabolic disease and other conditions.”

In the study, which re-examined Kittybiome data from previous research and focused specifically on diet, the feces of cats who ate a dry diet showed enriched gut bacteria called Prevotella, Bifidobacterium, and Megamonas, which are linked to carbohydrate metabolism. This makes sense, because dry food diets have a much higher carbohydrate content than canned wet food; on average, dry foods have about 45 percent carbohydrates, compared to about 10 percent for wet food, the study says. The carbohydrates provide structural support during the shaping process.

However, high levels of these carbohydrate-associated microbes – which also appear in other species, including humans – is not necessarily a good thing, says Dr. Allaband, who is both a small animal veterinarian and has a Ph.D. in biomedical sciences with an emphasis on microbiome. Though cats are an understudied species and more research needs to be done about their microbiome, in the most studied species – humans and mice – microbes that digest carbohydrates are associated with obesity because they convert carbs to sugar, she says.

“One of the key ways that your diet interacts with your metabolism is that the microbes … dictate how your diet makes it to your bloodstream and all parts of your body,” Dr. Allaband says. “We know in the microbiome, it’s second only to antibiotics; your diet has the most impact on your microbiome.”

The microbiome plays a crucial role in the immune system for cats, humans and other species, according to the study. The good bacteria crowd out the bad bacteria that can cause illness.

“In pretty much every species we’ve looked at so far, the microbiome helps train the immune system, in that it helps establish it and can make it better or worse,” Dr. Allaband says. “When your immune system gets used to your gut … it recognizes intruders. It helps them recognize infections and protects against microbes, and tries to keep those pathogens out.”

What about probiotic supplements for cats, which have become popular? Dr. Allaband is skeptical about many probiotics on the mass market because she hasn’t seen good evidence that they are effective, and they often don’t contain cat-specific microbes. One brand she recommends is AnimalBiome, a California-based company that makes probiotic capsules specifically for a feline’s microbiome and participated in the research for this study.

“I’m still very skeptical of many,” Dr. Allaband says. “Both in people and in pets, probiotics have a long way to go.”

As for feeding wet food, it is definitely less convenient than dry food, especially when some cat parents may not be home as much. But, Dr. Allaband says, we should try to provide at least a mixed diet with some wet food.

“Many cat owners have very different lifestyles,” she says. “If they have the ability to feed a canned diet, even if it’s just for one meal, I would say please do try.”

We have published many articles on Cats.com about a cat’s microbiome and ways to boost it. We provide a complete guide to probiotics and a guide to prebiotics, which are plant-based foods like pumpkin that act as food for beneficial bacteria in the gut. We also review many foods that contain probiotics.