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Fiber. Not Just for Dog Owners.


The R&D team at Nom Nom has done a deep dive into fiber. Part one of the three-part series took a look at what fiber is and what role it plays in diets in general. This second article focuses on fiber and its place in the canine diet, while part three explores the role of fiber in the feline diet. 

Should dogs eat fiber?

Dogs, like humans, are omnivores (specifically, facultative carnivores — feeding on both animal and non-animal foods). So they can harness the energy and nutrients from both animal- and plant-based ingredients. And they often respond favorably to (you guessed it) fiber.1

Gut check on fiber

Fiber has gained a lot of recognition for being one of the key ingredients for microbiome health in dogs. The bacteria in the canine gut produces short-chain fatty acids (SCFAs) during the digestion of certain types of fibers. And SCFAs are what fuel the intestine.2

Prebiotics — known to positively influence gastrointestinal microbiota populations — are actually just fermentable fibers, like beet pulp.3 And when we say just, we mean anything but. Prebiotics can increase beneficial bacteria, prevent growth of harmful bacteria and promote SCFA production.2, 4, 5 Which is why beet fiber is so often found in dog kibble.

Plus, fiber can improve regularity and stool quality.6 – 8 Helping to prevent both extremes of overly soft stool (diarrhea) and overly hard stool (constipation). And, consistent eliminations can limit exposure to toxins and carcinogens and may lower the risk of canine colon cancer.2 

Finally, for dogs with inflammatory bowel disease (IBD), emerging evidence is also showing symptom relief with prebiotic interventions.9

Immune Health

Prebiotic fibers are known for their ability to beneficially alter the canine microbiome, and may also strengthen the canine immune system by heightening its ability to fight infection and disease.21 

Dogs fed fermentable fibers, notably fructooligosaccharides (FOS) and mannan-oligosaccharides (MOS), showed improved cell-mediated immune function (immune response that doesn’t involve antibodies), enhanced ability to fight infection, positive microbial population changes, and overall improved immune status.22 – 24 While more research is required to truly understand the significance fermentable fibers have on immune parameters, current evidence is promising.

Cardiovascular Health

In the U.S., about 10% of dogs suffer from some sort of heart health issue.25 Many of these conditions are acquired — which means that they can be prevented. Dietary intervention, like the addition of fiber, can go a long way toward cardiovascular health.

Unlike humans, dogs can consume diets higher in fat without the same cardiovascular risk, and don’t suffer from the same build up of cholesterol.26 However, higher cholesterol levels in dogs can occur and be indicative of other health conditions and endocrine disorders. 

Inclusion of soluble fibers in the canine diet can help reduce cholesterol levels,27 likely by reducing cholesterol absorption by binding and eliminating it in our dog’s poop.28, 29 Another study showed that the addition of 10% moderately fermentable fibers significantly lowered blood cholesterol in healthy Beagle dogs.5 

Just another reason to love fiber.

Renal Health

Historically, protein-restriction is the dietary recommendation for dogs facing renal disease. This is because kidneys are the organ responsible for processing nitrogen, and nitrogen is found in a high amount in protein-rich diets. But many clinicians, concerned with the burden on the kidneys, are turning to fermentable fibers. 

By increasing populations of intestinal bacteria that consume nitrogen, fermentable fiber can increase nitrogen elimination via the feces, relieving the kidney from a nitrogen burden.30 

Healthy dogs on a low-protein diet fed soluble fibers demonstrated an amino-acid-sparing effect (or protein sparing effect, since proteins are made up of amino acids) and increased fecal elimination of nitrogen.31 This highlights the ability of fiber and gut bacteria to influence the absorption and excretion of nutrients, potentially allowing for continued protein consumption while maintaining kidney function.

Diabetes and fiber

Including fiber in your dog’s diet can be a great way to help control their blood sugar levels. Which is good, because dogs can suffer from diabetes mellitus — just like humans. In dogs, type 1 diabetes is the most common, affecting their body’s ability to control blood sugar levels due to insulin deficiency.10 

If your dog is obese on top of having diabetes they will be more prone to have insulin resistance in addition to not making enough.10 Fermentable prebiotic fibers, like short-chain FOS, can help overweight and obese dogs improve glucose control and decrease insulin resistance.5,11 

Meanwhile, in healthy dogs, inclusion of short-chain FOS and other fermentable fibers has also demonstrated improved blood sugar levels and insulin control.5,12 Insoluble fibers have their role in diabetes management too, as they have also demonstrated their ability to reduce blood sugar levels after meals in dogs with diabetes.13 

Fiber’s role in weight loss

Dogs are not exempt from the struggles of weight management, with approximately 30 – 40% classified as obese — and that number is on the rise.14 However, inclusion of fiber in the canine diet may be a useful weight management tool to help promote satiety (feeling full), dilute calories, and encourage fat loss.2,15 

Multiple studies in dogs confirm the ability of high fiber diets for weight loss, weight management, reduced caloric consumption, obesity prevention, and body fat loss.18 – 20 Even with similar calorie intakes, dogs lose more body fat on high-fiber diets than low-fiber — and even more on a high-fiber, high-protein regimen.16, 17  

In particular, insoluble fibers tend to be more advantageous for weight loss, and the focus of most studies. One of the main controversies remains, however: whether fiber is needed in diets that are otherwise high in protein, low in fat, and reduced in calories.

In all things, moderation

Fiber = good. There is no doubt. But — as with all things — you can overdo it. 

High amounts of insoluble fiber can lead to gastrointestinal disturbances, rapid weight loss, dull coat, and decreased nutrient and calorie absorption.2 Likewise, too much soluble fiber can leave your dog’s stomach cramped and upset.15 And excessive consumption of fermentable fiber is known to specifically interfere with protein absorption in dogs.32, 33 

Beyond the impact on nutrient digestion and the GI tract, overconsumption of fiber can also lead to liver complications.34

The inclusion of intermediate amounts (≤ 30 g/Mcal - or ≤ 30 grams per every 1000 kilocalories) of total dietary fiber can provide your dog a host of benefits.

As always though, the decision to add additional fiber to your dog’s diet is one that should be made with your veterinarian. 

The Nom Nom R&D team is on the lookout for dogs that experience regular diarrhea to participate in their new GI microbiome study. Sound like someone in your house? See if your dog qualifies for this paid research study here.


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