Why Your Dog Needs Fiber
I get a little excited when I talk about fiber's role in the canine diet - it's a bit of an unsung hero - but it makes a huge contribution to our dogs' health. Most people know how important fiber is for their own health; the Canadian Cancer Society recognizes that diets high in fiber decrease the risk of certain cancers, it's an important component in the management and prevention of diabetes, heart disease, and it supports digestive health. Fiber is just as important for dogs!
Dietary fiber is the edible part of plant matter that is not broken down by enzymes in the intestines. In the wild, carnivores get fiber from the fur and feathers of wild prey, and some from the small amount of plant matter they consume. For pet parents, unless you are going to feed your dog whole prey (meaning the entire animal, feathers and fur included), you need to make sure your dog gets fiber by offering a selection of vegetables and fruit. Since both the type and amount of fiber to feed can vary greatly from dog to dog it's an area of the diet that often needs adjustments.
Research has come a long way in understanding the connection between nutrition, gut health, immune health and freedom from disease. We now know that a diverse and robust community of microbes in the gut have a profound effect on all aspects of health. And one of the ways we can support the gut microbiome is to feed vegetables and fruit in order to provide our dogs with dietary fiber.
Nutrition Class: Fiber 101
As I just mentioned, fiber is the non-digestible part of plants. There are two types of fiber, insoluble and soluble, and some sources of fiber are a combination of both types. Soluble fiber partially dissolves in water and becomes gel-like in the digestive system. Insoluble fiber does not dissolve in water, and is what our moms might call 'roughage'. Insoluble fiber tends to "increase fecal mass and decrease intestinal transit time" - which is text-book way of saying that insoluble fiber helps to regulate the size of the stool and the speed at which it passes.
While enzymes in the dog's digestive system do not digest fiber, bacteria in the large intestine do. When bacteria 'digest' fiber, it is called 'fermentation', and the rate at which fiber ferments is categorized as low, moderate, or high. Soluble fiber is much more fermentable than insoluble fiber - too much highly fermentable fiber, such as brussels sprouts or certain fruits tends to result in gas or diarrhea. The by-products of fermentable fiber are called short chain fatty acids.
Depending on the Type, Fiber ...
Adds bulk to the stool and regulates the rate of digestion
Creates a feeling of stomach fullness
Regulates blood sugar; prevents blood sugar spikes
Food source for the beneficial bacteria in the gut which is important for maintaining healthy populations of good bacteria
Soluble fiber is fermented (or digested) by bacteria in the large intestine and this produces short chain fatty acids, SCFA. These SCFAs are fuel for the cells that line the gastrointestinal tract which helps maintain gut health. SCFAs also aid in the digestion and absorption of nutrients
SCFAs help maintain the mucous membrane in the gut, which is important for gut health: healthy gut equals healthy dog
Butyrate is an important SCFA. Research shows that butyrate supports the immune system, reduces inflammation and has disease prevention and anti-cancer functions
That's a pretty impressive list!
As wonderful as fiber is, it's one component of the diet where more is not necessarily better. Too much of one type of fiber can create havoc in the dog's digestive system and produce a range of unpleasant and smelly symptoms. As well, too much fiber in the diet can dilute nutrients and have a negative impact on a dog's nutritional and health status.
Finally, a Few Fiber Recommendations ...
Feed plants, but not too much
Include a combination of insoluble and soluble types of fiber
Be aware of which types of fiber have a high fermentability rate and how that might affect your dog's digestion
Monitor your dog's stools for signs that you are on the right track or in need of an adjustment
Recognize that the optimal amounts and types of fiber to feed vary greatly between dogs
Benefits [of fiber] are maximized by feeding optimal amounts of moderately fermentable fiber sources that provide optimal levels of SCFAs and at the same time have a nonfermentable component to provide bulk - (Case, Daristotle, Hayek, Raasch. Canine and Feline Nutrition: A Resource for Companion Animal Professionals)
Further Reading ...
This review focuses on the effects of butyrate on gastrointestinal health, cancer, and the immune system.
This article is for information and education purposes. Every dog is unique and may have specific dietary requirements. Please consult your veterinarian if you have a health concern about your dog.