Formulating with fiber: A multi-functional ingredient

This article was published in the January/February 2025 issue of Pet Food Processing. Read it and other articles from this issue in our January/February digital edition.

Fiber is a nutrient of concern among Americans, as many do not consume enough on a daily basis. When it comes to our furry friends, fiber has long been viewed as a cheap filler in foods and treats. That opinion is changing. Dietary fiber is now recognized as assisting cats and dogs with their digestive health and bowel movements, among contributing other health and wellness benefits. Prebiotic fibers, in particular, have become an attractive feature in some pet foods, as they are associated with improving gastrointestinal health.

Dietary fiber is essential for human and pet health. It is one of many carbohydrates naturally present in plants. It can be consumed via the plant, or an isolated, concentrated form or a synthetic form can be added to food. Whatever the format, all dietary fibers influence digestion, providing benefits that range from supporting regular bowel movements to decreasing inflammation to fueling the growth of the microflora in the gut, thereby boosting immune function.

Natural Balance’s Health Protection recipes include prebiotic fiber and probiotic-coated kibble, as well as ingredients such as brown rice and pumpkin to deliver additional fiber.

Source: Natural Balance Pet Foods

“Today, fiber’s benefits are widely known by consumers, and people with pets are no exception,” said Jon Copeland, research manager, Nextin Research by MarketPlace, St. Louis, Mo. “We conducted a survey of US pet parents in 2024 and found that about half said they have a general understanding of dietary fiber.”

On top of that, one in four consumers said they have a deep understanding of fiber, and three in four have a positive view of fiber in their pet’s nutrition. Only 3% had a negative view of fiber for their pet.

It’s no wonder that more and more pet products are touting fiber content. Natural Balance Pet Foods, Brownwood, Texas, for example, recently rolled out Health Protection. Developed with veterinarian and pet nutrition experts, the kibble supports six key health benefits: digestive health, skin and coat, heart support, bones and teeth, immune system, and hips and joints. The recipes include prebiotic fiber and probiotic-coated kibble, alongside gentle ingredients like brown rice and pumpkin that deliver additional fiber to promote optimal digestion.

Not all fibers are created equal

It took a pandemic to get people interested in how digestive health influences overall wellness. Many are still learning about the role dietary fiber has in gut health.

Science shows that abundant, flourishing good gut bacteria (probiotics) promote a healthy immune system by staving off foodborne pathogens and viruses. Prebiotics are the fuel for probiotics to proliferate in order to positively impact the body. Prebiotics are frequently equated with dietary fibers, but only a subset of dietary fibers actually qualify as prebiotics.

“For decades, the role of the large intestine and gut microbes was completely misunderstood,” said Trevor Faber, director of companion animal nutrition and technical service, Trouw Nutrition USA, Highland, Ill. “We now know the significance the gut plays in health and wellbeing of the animal, including immune and cognitive function. We must properly feed the microbes to promote the growth and diversity of beneficial microbes.

“Prebiotic fiber in pet food becomes more attractive as consumer awareness of its benefits grows,” said Jon Copeland, MarketPlace.

“That ‘cheap filler’ was actually serving as a good food source for the microbes, but pet owners didn’t realize the value and nutritionists likely didn’t fully appreciate the true functionality,” Faber said. “In today’s diets, we are just more conscious of dietary fiber type, variety and supplement with prebiotics in an effort to enhance overall gut health. The ‘filler’ ingredients are just viewed with a different perspective now.”

Copeland added, “Prebiotic fiber in pet food becomes more attractive as consumer awareness of its benefits grows. Some pet parents are prebiotics-curious. Our survey of US pet parents showed that about 17% said they have spent more than an hour researching prebiotics in the prior year.”

Exploring fiber options

While many whole plant foods are inherent sources of soluble and insoluble fiber, most pets are not interested in cut-up apples or a side of green beans. To ensure an adequate amount, formulators rely on fiber ingredients.

“Veterinarians have long recommended [fiber-rich] foods like pumpkin and sweet potatoes to address diarrhea and other gastrointestinal issues,” said Thom King, chief innovations officer, Icon Foods, Portland, Ore. “This isn’t new information, but the growing awareness among consumers about the connection between fiber and overall wellness — both for themselves and their pets — has brought fiber ingredients into the spotlight. This shift shows that fiber isn’t just a filler. It’s a valuable and strategic ingredient for enhancing health, flavor and texture in pet treats and foods.”

There are many varied fiber ingredients available to pet food formulators. The simplest way to categorize them is as soluble and insoluble. Both can provide function in both the food — by binding water, contributing to texture, influencing crunch, etc. — and the animal.

“Insoluble fiber supports the movement of material through the gastrointestinal system, while soluble fiber absorbs water, which contributes to increased fecal moisture,” said Gary Davenport, pet technical sales manager, ADM, Chicago. “Fiber may also be viscous, forming a gel that slows digestion. Fermentability in the gastrointestinal tract is another notable property. As our understanding of the gut microbiome continues to expand, scientists and nutritionists are increasingly interested in the functional benefits of fiber.

“ADM’s core plant-based fiber ingredients include beet pulp, chicory root, oat, pea, rice, soy hulls, tomato pomace and wheat,” he added. “We also partnered with Gnubiotics to offer unique glycopeptide compounds that are fermentable fibers with properties known to support digestive health and the growth of beneficial gut bacteria.”

Pumpkin and sweet potatoes are common vegetables included in pet food formulations to aid in digestion and help prevent diarrhea.

Source: ©LADDA-STOCK.ADOBE.COM

ADM also offers a resistant maltodextrin with prebiotic properties. It is a non-viscous, soluble and fermentable dietary fiber produced from corn starch.

Many dietary fibers are human-grade ingredients and sourced from suppliers to the human food and beverage industries. Amsterdam-based Green Boy, for example, opened a new plant-based pet food division in April 2024, expanding its international footprint to supply premium plant-based pet food ingredients — including numerous types of dietary fiber — to pet food producers globally. Its fiber ingredients come from chicory root, fava bean, Jerusalem artichoke, pea, potato and tapioca.

The chicory root and Jerusalem artichoke, as well as agave, are used to isolate inulin, a natural prebiotic soluble fiber. The concentrated ingredient is an additive to human and pet foods.

“This pure white powder can be added to any food format, treat or supplement at a low inclusion rate of 0.5% to 1.5% of the total diet,” Faber said. “It is easily solubilized and has minimal impact on the food or treat.”

Numerous research studies in a variety of species, including dogs and cats, have shown inulin to positively influence the gut environment. Other benefits include improved nutrient absorption and possibly decreasing urinary ammonia in cats.

“Fructooligosaccharides (FOS) are short-chain fructans that also resist digestion and promote the growth of beneficial gut bacteria for microbial diversity,” King said. “Soluble tapioca fiber, derived from the cassava root, is a resistant starch that acts as a prebiotic in the gut. During fermentation in the large intestine, it can produce [beneficial] short-chain fatty acids such as butyrate.

“Using a combination of fibers maximizes gut health benefits while maintaining gastrointestinal tolerance,” he added. “For a single fiber, usage levels are typically 4% to 5% of the total solution weight. But by stacking fibers — such as combining soluble tapioca fiber with inulin or FOS — you can increase inclusion up to 8% without triggering gastrointestinal issues as the different fibers have various rates of breaking down.”

Dietary fiber will have an impact on the production process. Stacking can help minimize any negative drawbacks.

“While the gelling properties of fiber can be beneficial, they can also be a challenge depending on the production process,” King said. “If fiber levels are too high, it can make the mixture difficult to work with, particularly if using depositors or extrusion equipment. Excessive gelling can cause the mixture to bind up, leading to inefficiencies or even production delays. It’s best to keep total fiber levels under 10% to avoid these technical challenges.”

As with any nutrient, there is an optimal range of intake for dietary fiber. It is also important to balance insoluble and soluble fibers.

“Too much soluble fiber can lead to loose stools and flatulence,” Faber said. “The loose stools over time can lead to dehydration and other health issues.”

“Too much fiber can result in inadequate caloric intake for dogs or cats with high energy needs, while too little fiber may negatively impact overall digestive health,” said Gary Davenport, ADM.

Davenport added, “Too much fiber can result in inadequate caloric intake for dogs or cats with high energy needs, while too little fiber may negatively impact overall digestive health.”

There are differences with how cats and dogs tolerate fiber, too.

“Dogs and humans tolerate dietary fiber in a similar manner due to the length and function of the large intestine,” said Faber. “The dog has actually served as an animal model for human nutrition in numerous studies. Cats, however, being carnivorous, have a smaller large intestine and don’t tolerate soluble fibers to the same degree that dogs and humans can. Cats tolerate dietary fiber well, but one needs to pay closer attention to the fiber type and amount.”

Quantifying fiber content

One of the greatest challenges with dietary fiber — added via whole food ingredients or isolated fibers — is testing methodology. In pet food, a measurement of crude fiber has traditionally been used.

Dogs and cats need fiber in their diet to assist with digestive health and bowel movements and for overall health and wellness.

“Crude fiber has historically been the nutritional guarantee required on all pet food labels; however, advances in nutritional science have shown that dietary fiber is a better indicator of the actual fiber content of a product,” said Austin Therrell, executive director, Association of American Feed Control Officials (AAFCO), Champaign, Ill. “For this reason, AAFCO incorporated a new dietary fiber guarantee (Total Dietary Fiber, or TDF) in place of crude fiber on pet food labels. As the Pet Food Label Modernization initiative moves forward, and states update their pet food regulations, consumers will begin seeing new fiber guarantees in place of the old ones.”

Crude fiber methodology only quantifies the amount of insoluble fiber. The TDF method, as the name suggests, measures total fiber content.

“The TDF method provides much more practical information, but yet has its challenges,” Faber said. “It doesn’t capture all oligosaccharides, such as fructans and galactooligosaccharides. In addition, method modifications are required based on the ingredient matrix and nutrient profile. If not modified, the TDF value can be skewed. This can lead to formulation challenges if one doesn’t understand the nuances and limitations of the methodology.”

The TDF labeling change is a positive step forward. This change is beneficial for both consumers and suppliers, as it provides transparency about the nutritional content.

“For pet owners, especially those managing pets with specific health conditions, this labeling makes it much easier to select the best foods for their pets,” King said.

Read more about product development, ingredients and formulation.

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