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Fiber. Does It Have a Place in the Feline Diet?

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If you’ve ever wondered about fiber and your pet, look no further than the three-part series from the Nom Nom R&D team. Part one took a look at what fiber is and what role it plays in diets in general. Part two looked at the role of fiber in the canine diet. This third article focuses on fiber and its place in the feline diet.

Fiber in the Feline Diet

Most domestic cats today already consume fiber in their diet, as dry kibble, canned wet food, and fresh food, are all commonly produced with variable levels of dietary fiber and other plant derived nutrients.1, 2 

However, cats are carnivores, and their basic nutritional requirements can be met solely through animal ingredients.1, 3 Because they’re historically strict meat-eaters, their requirement for protein is high. Their digestive tracts are also shorter and aren’t built for less-digestible plant material.1 

But we have to remember — in the wild, a cat also consumes bones, cartilage and tendons as well as whatever their prey ate, usually grains and other plant material.3 Today, plant-based dietary fiber can serve a similar function for our feline friends, providing a source of intestinal bulk to aid in digestion, like bones once did. 

So while cats don’t require dietary fiber for survival, emerging evidence indicates that it does have some positive effects in the diet of our modern day feline companions. 

Digestion & Gut Health

Moderately fermentable fibers, like beet pulp, can play a helpful role in feline digestion and gut health. Their system is set up to produce short-chain fatty acids (SCFAs) from these fibers, helping to power their intestinal cells.1 They can also help improve the digestibility of certain nutrients5 and enhance stool quality and bulk.6 

Certain fermentable fibers, termed prebiotics, have advanced abilities to improve bacterial populations and microbiome health — increasing SCFA production and limiting odor-forming compounds in stool.7, 9, 10

These results have been seen from as little as 1 – 4% dietary inclusion of prebiotic fibers: fructan, fructooligosaccharide (FOS), galactooligosaccharide (GOS), and pectin.7 – 9 

Though there is evidence that dietary fiber may play a role in feline digestive health, less may be more. Cats consuming a low-fiber diet (only 1 gram per every 1000 kilocalories) were more regular with their bowel movements than those on a high-fiber diet (31 g/1000 kcal).4

Diabetes

In the US, it is estimated that 1 in 400 domestic cats will have feline diabetes, in particular, type-2 diabetes, with the prevalence increasing.2, 4 Similarly to humans, feline diabetes results in insulin resistance as a result of excess fat, and diet type and habits are both considered risk factors.2 

Research is showing that dietary fiber can positively impact feline diabetes, however, there are conflicting conclusions in regard to fiber quantity and type. 

Several studies in cats with diabetes have shown that low-carbohydrate, low-fiber diets can significantly reduce insulin dependence, with some cases even reaching diabetic remission.1,4 While in another study, cats provided a high-fiber diet also showed improved insulin sensitivity, it was still not to the same degree as cats on the low-fiber diet.4 And still, another study showed that cats provided a diet with 12% insoluble fiber had more success in controlling blood glucose levels than those on a low insoluble fiber diet.11 

More research is needed to really understand the impact of dietary fiber on diabetes in our carnivore companions. Nevertheless, these studies indicate that fiber can play a role in the management of feline diabetes.

Weight Loss

When weight loss is imperative to the health of your cat, poorly fermentable fiber can be used to dilute calories, increase stool volume, and promote weight loss.1,2 In obese diabetic cats, low-fat high-fiber diets have been used to help achieve weight loss goals.2 

However, high fiber diets for weight loss in cats should not be maintained for too long as they lower nutrient digestibility and can cause dehydration.1 Higher fiber diets may also be less palatable, and achieving a low-calorie food can also be done with high protein, high moisture, and low fat levels.

Emerging Benefits

Kidneys are where a lot of nitrogen processing happens. A new hypothesis suggests that fiber in the feline diet could help in the management of chronic renal failure.12 Researchers anticipate that fermentable fiber added to the feline diet can serve to increase nitrogen elimination via the feces, relieving the kidneys of this duty. 

Traditionally, protein intake is restricted with renal disease, which can be detrimental for cats as they have an extremely high requirement for protein. The addition of dietary fermentable fibers can limit the absorption of nitrogen from a protein-rich diet and reduce nitrogen levels in the blood, which can make some owners feel that their cat’s kidneys are improved.12 

However no studies exist that confirm that either protein restriction or lowered blood nitrogen levels due to increased soluble fiber increase longevity in cats with kidney disease. 

Risks

While evidence shows that cats, despite being carnivores, can tolerate inclusion of plant-based fibers in their diet, there are still associated risks. 

In the wild, the natural meat-based diet of the cat would only contain about 0.55% dietary fiber.3 This is consistent with the amount in many fresh diets. Appropriately, the feline digestive tract was not designed to process high amounts of fibers.1,2 Even fibers that can be fermented by cats are limited by the shorter colon length.2

As a result, higher levels of fibers are generally not ideal for cats. Inclusion of 15% insoluble fiber in feline diets has led to decreased nutrient and protein digestibilities, overgrowth of harmful intestinal bacteria, increased water loss (through stool), and constipation.1 

Likewise, high amounts of fermentable fibers have also negatively impacted nutrient digestibilities and led to loose stool.6 And high fiber diets also decrease the secretion of enzymes required for protein digestion and increase a cat's requirement for taurine, an essential feline amino acid.1, 3, 13 Taurine deficiency in cats can cause severe side effects including blindness and heart failure.14 

While inclusion of 4% poorly fermentable, moderately fermentable, and highly fermentable fiber have all been shown to be well tolerated in cats, additional research is needed to assess the long-term health impacts.8 

Small amounts of fiber, like those found in the evolutionary prey items of cats, likely help to maintain the cat’s unique microbiome and may confer some health benefits, but high fiber diets are best reserved for medical conditions where such a diet is necessary. 

That being said, the choice to add fiber to your cat's diet should be one made with a veterinarian, and often is guided by your cat’s underlying medical conditions.  

References: 

  1. Zoran, D. L. The carnivore connection to nutrition in cats. J. Am. Vet. Med. Assoc. 221, 1559–1567 (2002).
  2. Verbrugghe, A. & Hesta, M. Cats and Carbohydrates: The Carnivore Fantasy? Vet. Sci. China 4, (2017).
  3. Elisa Katz, D. V. M. Answers: Do Cats Need Dietary Fiber? Feline Nutrition Foundation https://feline-nutrition.org/answers/answers-do-cats-need-dietary-fiber.
  4. Bennett, N. et al. Comparison of a low carbohydrate-low fiber diet and a moderate carbohydrate-high fiber diet in the management of feline diabetes mellitus. J. Feline Med. Surg. 8, 73–84 (2006).
  5. de Godoy, M. R. C., Kerr, K. R. & Fahey, G. C., Jr. Alternative dietary fiber sources in companion animal nutrition. Nutrients 5, 3099–3117 (2013).
  6. Sunvold, G. D. et al. Dietary fiber for cats: in vitro fermentation of selected fiber sources by cat fecal inoculum and in vivo utilization of diets containing selected fiber sources and their blends. J. Anim. Sci. 73, 2329–2339 (1995).
  7. Kanakupt, K., Vester Boler, B. M., Dunsford, B. R. & Fahey, G. C., Jr. Effects of short-chain fructooligosaccharides and galactooligosaccharides, individually and in combination, on nutrient digestibility, fecal fermentative metabolite concentrations, and large bowel microbial ecology of healthy adult cats. J. Anim. Sci. 89, 1376–1384 (2011).
  8. Barry, K. A. et al. Dietary cellulose, fructooligosaccharides, and pectin modify fecal protein catabolites and microbial populations in adult cats. J. Anim. Sci. 88, 2978–2987 (2010).
  9. Barry, K. A., Hernot, D. C., Van Loo, J., Fahey, G. C., Jr & de Godoy, M. R. C. Fructan supplementation of senior cats affects stool metabolite concentrations and fecal microbiota concentrations, but not nitrogen partitioning in excreta. J. Anim. Sci. 92, 4964–4971 (2014).
  10. Barry, K. A. et al. Adaptation of healthy adult cats to select dietary fibers in vivo affects gas and short-chain fatty acid production from fiber fermentation in vitro. J. Anim. Sci. 89, 3163–3169 (2011).
  11. Nelson, R. W. et al. Effect of dietary insoluble fiber on control of glycemia in cats with naturally acquired diabetes mellitus. J. Am. Vet. Med. Assoc. 216, 1082–1088 (2000).
  12. Elliott, D. A. Nutritional management of chronic renal disease in dogs and cats. Vet. Clin. North Am. Small Anim. Pract. 36, 1377–84, viii (2006).
  13. Center, S. A. Nutritional support for dogs and cats with hepatobiliary disease. J. Nutr. 128, 2733S–2746S (1998).
  14. Taurine Deficiency in Cats. PetMD https://www.petmd.com/cat/conditions/cardiovascular/c_ct_taurine_deficiency?page=show (2010).

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