A few years ago, peas and pulses and other legume seeds were featured as alternative carbohydrates in pet foods. These have become quite popular in the world of grain-free options. However, there is a conspicuous gap in the use of the legume seeds from the Phaseolus family, the so-called common beans (Phaseolus vulgaris L.). These include white beans, navy beans, pinto beans, kidney beans, black beans and a host of others. Why are they absent from pet foods? It could be consumer bias, perhaps a cost consideration or simply a lack of understanding about whether beans are a good option in modern pet foods.
Nutritional and anti-nutritional components of beans
These beans contain around 21–24 percent protein, 0.8–1.5 percent fat, 3.3–4.2 percent ash, 15–25 percent TDF (total dietary fiber) and the balance as starch. They are a good source of potassium and folate, but contain only small amounts of essential fatty acids — some of which include linolenic acid (omega-3). As for their protein content, they are usually sufficient in most amino acids except for methionine, which is first limiting. There is also interest in these beans for their levels of phytoestrogens (daidzein and genistein) and some poly-phenolic compounds.
On the other side, the big story for these beans usually pertains to the anti-nutritional compounds like phytic acid, tannins, phytohemagglutinins, trypsin inhibitors, amylase inhibitors and the oligosaccharides. The phytic acid and tannins may be reduced slightly by processing. At low levels, the proanthocyanidin “tannins” may actually provide health benefits, but at higher naturally occurring levels may influence the bitter astringent taste and beany aroma often associated with them. The more health-negative compounds like the phytohemagglutinins and the trypsin and amylase inhibitors are denatured by the cooking process (extrusion, baking, canning) and thus rendered inactive. So, beans in a cooked product should have minimal impact on health as it pertains to these compounds.
That leaves the oligosaccharides such as stachyose and raffinose that could be an issue. These soluble sugars can exceed 3 percent of the bean and have significant impact in the gut. They are indigestible by mammalian intestinal enzymes and escape to the colon, where they are readily fermented. This can lead to flatulence and soft stools. Their content can be reduced subtly by extrusion processing and more substantially by washing (leaching). In a complete diet, limiting their inclusion is also an option. Peas, lentils and chickpeas are also high in these oligosaccharides but that has not stopped their use in the grain-free products entering the market.
Beans research and dogs
Luckily there is some research available on beans, at least as a commercial washed bean powder, to provide some supporting information. For example, Forster et al. (2012a) reported that a diet containing 25 percent cooked navy bean powder fed to client-owned dogs for 28 days did not impact fecal scores, total fecal output, apparent total tract digestibility or major blood parameters. Further, no increase in flatulence was reported. Cooked bean powder was also reported to benefit microbial populations (Kerr et al., 2013).
In a second paper by Forster et al. (2012b), they evaluated a diet of 25 percent black or navy bean powder fed to client-owned overweight or obese dogs in a weight loss intervention study that targeted a >5 percent weight loss over four weeks. They found that dogs fed the bean-powder-containing diets had altered blood parameters with cholesterol, triglycerides, high-density lipoproteins and low-density lipoproteins lowered relative to the control. Blood urea nitrogen and creatinine, and alkaline phosphatase were also lower for dogs fed either or both beans.
This would suggest that bean consumption has a positive effect on lipid metabolism. With caloric intake restricted to create short-term and long-term (duration) weight loss in high body condition score dogs of various breeds, the bean diets were equally successful at achieving target weight loss without negative impact on health or blood parameters (Forster et al., 2015).
More data needed on common beans in pet food
There is a great deal of processing data reported for the common beans in human foods and snacks, but not for pet foods. In human food extrusion research, the inclusion of beans has been reported to be slightly less functional than the cereal grains, with the cultivar influencing the product’s physical properties. Regardless, reasonable quality products can be produced. Whether beans will perform in a similar fashion in complex pet foods is not clearly identified. In “undeveloped dough” baked products (e.g., dog treats), bean powders can be effective but only as a partial replacement for cereal grains. In canned foods, bean powders might be a suitable ingredient, but no data were readily available to support beans in a pate-like product. Most published research on the topic pertains to canned whole beans in a sauce. Not exactly a pet food application.
In the end, beans could easily find utility in pet foods if consumers were interested. There is sufficient information to suggest that they are nutritionally utilized and acceptable to pets, and with judicious use do not induce excessive flatulence or stool issues. Whether consumers are willing to accept them as a novel ingredient and/or if price becomes favorable remains to be seen. Given this “open door” perhaps we will see the common bean in the next generation of pet foods.
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Beans in pet food: the Dog and Cat Food Ingredient Database
Navy, White and Pinto beans are found in 1.5 percent of dry dog food recipes and 0.88 percent of dry cat food recipes in the Dog and Cat Food Ingredient Database. You can run a sample search for these, and other ingredients used in nearly 7,000 dog and cat food recipes, at www.pet-ingredients.com/search. Free registration is required to run a search.