Analysis by Dr. Karen Shaw Becker
- Despite growing concerns about the connection between grain-free formulas containing pulse crops and dilated cardiomyopathy (DCM) in dogs, the processed pet food industry continues to talk up the use of fava beans in grain-free pet food
- In addition to the DCM connection, there are many other reasons pulse crops such as fava beans don’t belong in dog and cat food, e.g., they contain substances pets’ bodies can’t digest, that also interfere with mineral absorption
Despite the much-publicized suspected link between grain-free diets high in legumes and diet-related dilated cardiomyopathy in dogs, the processed pet food industry remains very committed to searching out biologically inappropriate pulse crops for potential use in dog and cat food.
A recent favorite is fava beans (also called faba and broad beans), which “may be the next new grain-free ingredient in the pet food aisle,” according to a recent article in a pet food industry publication.1 Last year the same publication promoted a 2017 study that suggests fava beans are an “effective ingredient for use in a commercial dog diet.”2
“It appears fava beans were well tolerated at all levels tested and only influenced digestibility at higher levels,” reported study co-author Greg Aldrich, PhD. “The dehulled fava beans in our study processed well in extrusion. They would be a solid contributor as an ingredient choice in modern pet foods.”3
This study is typical of pet food industry scientific research designed to see how much of a biologically inappropriate ingredient pets can ingest before it interferes with their digestion in an immediately measurable way. The dogs in the study didn’t develop noticeable digestive issues until they were subjected to higher levels of fava beans.
This is a considered a win by the industry, because they now have yet another inexpensive, plentiful, plant-based (i.e., biologically inappropriate) ingredient they can use to inflate the protein percentage in their formulas, and also potentially use to replace meat protein in vegetarian or vegan pet foods.
Why Pulse Crops Don’t Belong in Pet Food
Pulse crops, also called pulses or legumes, are plants with a pod. “Pulse” is the term used to identify the edible seeds of legumes, and is derived from the Latin word puls, meaning thick soup. The Food and Agriculture Organization of the United Nations (FAO)4 recognizes 11 primary pulses:5
|Dry beans (kidney, lima, azuki, mung, black gram, scarlet runner, ricebean, moth, and tepary)||Lentil|
|Dry broad beans (fava, horse, broad, field)||Bambara groundnut|
|Dry peas (garden, protein)||Vetch|
|Dry cowpea||Minor pulses (lablab, jack, winged, velvet, and yam beans)|
Because they are high in fiber, folate, iron (when eaten with a source of vitamin C), and complex carbohydrates, and are also low in fat, pulse crops are considered nutritious for humans by some nutritionists, and not by others. Some experts advise keeping legume intake minimal for the same reason I recommend avoiding feeding these foods to pets — the presence of phytates and lectins that are naturally found in legumes.
Phytates are substances that carnivores can’t break down because they lack phytase, the enzyme necessary to process phytic acid. Phytates bind minerals (including zinc, iron, calcium and magnesium), leeching them out of your pet’s body. Lectins are sticky proteins that when consumed in large quantities may contribute to gastrointestinal (GI) disturbances and leaky gut.
Pet food producers and their ingredient suppliers are aware that many pet parents tend to believe foods that are healthy for humans are also healthy for dogs and cats. In fact, they use pet owners’ lack of knowledge about pet food ingredients to create and market biologically inappropriate diets. For example, one of the marketing approaches used to promote pet foods containing bean meal is weight loss.
The nutrient profile in beans may benefit some humans and other omnivores and herbivores, but carnivores thrive on animal — not plant — protein, and they don’t benefit physiologically from starch or high levels of dietary fiber. Cats are true carnivores and dogs are facultative carnivores, not omnivores or herbivores, but that pesky little fact certainly hasn’t diminished the pet food industry’s love affair with ingredients nature didn’t design dogs and cats to eat.
Most Pet Food Research is Conducted for the Benefit of Pet Food Companies, Not Dogs and Cats
Also good news for pet food producers is that fava beans “processed well in extrusion.” Extrusion, as we know, is a manufacturing method that has been used by the pet food industry for decades. About 95% of dry pet diets are produced using the extrusion process.
Batches of raw ingredients are mixed, sheared and heated under high pressure, forced through a spiral shaped screw and then through the die of the extruder machine. Extrudate is the result — a ribbon-like product that is then knife-cut and dried.
The high temperature used in extrusion (nearly 400°F) and the short time frame to process (under 5 minutes) creates continuous chemical and physical alterations to the ingredient mixture. This not only changes the molecular activity of the food, but also potentially contributes to a heavier carcinogenic load and profound levels of advanced glycation end products (AGEs). So, to review, the pet food industry’s takeaways from the study are:
- Fava beans hold up well in the extrusion process
- Fava beans in moderate amounts can be tolerated by dogs
- Fava beans can be used to boost the protein percentages (misleadingly, in my opinion) in pet food formulas
Honestly, the simple fact that an ingredient such as fava beans must be tested in pets to see how much they can tolerate before they become ill is all the proof anyone should need that they didn’t evolve to eat that ingredient. Therefore, the intent and result of this study is 100% for the benefit of big pet food, and 0% for the benefit of the dogs and cats who will at some point be fed processed diets containing fava beans.
Legumes and Grain-Free Pet Food
As I mentioned earlier, there’s also cause for concern now that a link has been established between grain-free dog food containing legumes and a growing number of cases of the heart disease dilated cardiomyopathy (DCM) in dogs. Of the DCM cases the FDA reviewed for its report published in June, 91% of the diets were grain-free and 93% contained peas and/or lentils.
It’s important to note that while legumes are being singled out as a potential problematic ingredient, no definitive test results have been released. However, grain-free kibble is often much higher in both whole carbohydrates and purified starches (e.g., pea starch, potato starch and tapioca starch) than grain-based dry dog food.
The higher the starch level in any pet food, the less protein is included (hence my suggestion to avoid both grains and other sources of unnecessary starch in all pet food). You can find my most recent update on the grain-free kibble/DCM issue, including feeding recommendations, here.