Is Soy Bad for Dogs?
We are now up to the letter “S” in our dog food ingredient series. Today we are writing about the somewhat controversial Soy, an alternative protein source in some dog foods.
What is Soy?
Soy and its derivatives come from the soybean, a legume that is native to East Asia.
Common names for Soy
Common names for soy include soybean, soya bean, large bean and yellow bean. In dog food we see soy listed in many forms including soy protein, soy flour, soybean meal, soy fiber, soybean mill run and soybean oil.
Why is Soy in Dog Food?
Soy is added to dog food because it is an inexpensive source of protein. Soy is also a good source of the many vitamins and mineral (see below).
Is Soy Commonly Used in Dog Food?
Soy is a fairly common ingredient in dog food. We found soy in about 17% of all dog foods. It is used often in both dry and wet recipes.
Common Benefits or Risks of Soy
Soy is high in protein and omega 3 fatty acids, as well as B vitamins, vitamin K, and the minerals iron, manganese, and zinc.
There is some research that supports other health benefits of soy:
Diabetes: research suggests that taking soy products reduces blood sugar levels in people with diabetes.
Cardiovascular health: researchers at the College of Medicine at the University of Kentucky analyzed previously published studies involving soy protein and risk of coronary heart disease (CHD) and found an overall decreased risk of CHD when approximately 30 grams of soy protein was consumed on a daily basis.
Cancer: although there is conflicting evidence, some studies that suggest that diets containing ample soy can lower the risk of some cancers including lung and thyroid cancers.
Brain function: some research suggests soy can improve memory.
Despite the aforementioned benefits, there is also a growing number of health concerns regarding the long term use of soy, some of which are in direct contradiction to benefits reported elsewhere. In an article published in the Huffington Post, Dr. Mercola lists several possible risks including malnutrition, digestive distress, immune system breakdown, thyroid dysfunction, cognitive decline, reproductive disorders and infertility and even cancer and heart disease. One of the primary reasons that soy is so controversial regarding its benefits and risks has to do with how it is farmed and processed.
GMO and Pesticides: according to the New York Times, more than 90% of the soybean crop in the U.S. is genetically modified. Further, a majority of the soybean crops are heavily sprayed with chemical pesticides, some of which are linked to cancer.
Anti-nutrients and Fermentation: soybeans contain “anti-nutrients” such as saponins, soyatoxin, and phytoestrogens. Traditional fermentation destroys these anti-nutrients, enabling the body to enjoy soy’s nutritional benefits. Commonly used fermented soy products include Miso and Soy Sauce. Some of the adverse health effects due the anti-nutrients in soy include reduced assimilation of many minerals, reduced protein digestion, pancreatic disorders, and thyroid problems to name a few.
A 2004 study was conducted at the University of Pennsylvania to determine the amount of phytoestrogens in 24 random commercial dog foods. Results revealed all the foods containing soy ingredients had concentrations of phytoestrogens (an antinutrient) in large enough quantities to have a biological effect on the pet in the long term. Said another way, the levels of soy in the randomly selected foods were high enough to be a concern if ingested over time.
Soy has been linked to gas and deadly bloat in dogs. It is high in purines and is therefore not an appropriate protein source for urate-forming dogs.
Slimdoggy Ingredient Comfort Level
Most normally healthy dogs should obtain their protein from the flesh of animals, not from plants or legumes like soy. Furthermore, unfermented and nonorganic soy, the form that is used in dog food, appears to have significant health risks with long term use. Thus, we give soy the SlimDoggy frown.
Miscellaneous Facts about Soy
Soy plants can grow as high as 6 feet.
Once a crop found only in the Far East, soybeans are now a major crop in the United States, Brazil, Argentina, and India.
Sources and further reading
Editor’s note: to view all of the dog food ingredients we have covered, search on the tag “ingredients” or click here:
We're joining the Tasty Tuesday Blog Hop sponsored by Sugar, the Golden Retriever and Kolchak from Kol's Notes: