Seeing soy in a dog food ingredient list may not sound like something a dog would like to eat. Indeed, ingredients like soybean meal, soy protein concentrate, soy protein isolate, and soybean oil may make you raise an eyebrow. But before you start searching pet-food shelves for soy-free dog food, let’s talk about what purpose soy serves in dog food. It’s a big one.
Soy Complements Animal Protein
To say that dogs have a protein requirement is misleading. Truthfully, dogs have amino acid requirements, which are the building blocks of proteins. Of the 20 amino acids, 10 are essential in dogs, meaning dogs cannot produce or synthesize high enough quantities of them to meet their biological requirement. They must instead obtain these amino acids from their diet.
Each protein source, whether plant or animal, has a different amino acid profile, with some levels of amino acids being higher than others. Proteins also vary in bioavailability, with some protein sources being utilized more efficiently than others. The term “limiting amino acids” refers to essential amino acids that are naturally in short supply but utilized in the highest quantities. In dogs, those amino acids include methionine and lysine.
That is where soy products come in. Soy is very high in lysine and complements animal protein sources very well. While raw soybeans do contain anti-nutritional factors that can negatively impact digestion, the soy products commonly used in commercial pet foods have had many of those components removed.
Soy That’s Good for Dogs
Obviously, soy that is used in dog foods should be included in a form that is easy to digest and benefits the dog’s health. These types of soy include:
- Soy protein concentrate. This is soybean meal that has gone through additional processing to further isolate the protein and contains much lower levels of oligosaccharides, decreasing its impact on digestibility and stool quality. This process results in a nutrient-dense, highly digestible ingredient.
- Soy protein isolate. This type of soybean protein contains none of the carbohydrates or fiber found in soybean meal. This ingredient is the most concentrated source of soy protein and is highly digestible by dogs.
- Soybean oil. As the name implies, soybean oil is the extracted fat from the whole soybean. Soybean oil provides energy and is a good source of the essential omega-6 fatty acid, linoleic acid.
The form of soy that most dog foods limit or avoid is soybean meal, which is the defatted flakes of soybeans. Soybean meal is used as a protein source as well as a source of energy. Of the soy ingredients used, this ingredient has the highest number of oligosaccharides, a type of carbohydrate that is not digested by dogs. The presence of oligosaccharides can negatively impact stool quality and increase flatulence. Because of this, soybean meal in dog food is limited.
From a nutritional standpoint, soy can provide a good source of digestible amino acids for pets. While some dogs may have sensitivities or allergies to soy products and should opt for soy-free dog food and treats, for many others, it is a viable ingredient.