Part III – Should Your Pet Eat Soy?

Next to corn, soy is the second most grown crop in the United States with an astounding 76 million + acres planted in this country alone! Welcome to part three of our series in understanding what is in your pet’s food! In this part, we will be looking at Soy as an ingredient in pet food; why it is used and if it is healthy for your pets.


Why Do Some Pet Foods Contain Soy?

In the last part of this series we covered the use of corn in pet foods (if you have not read it yet, you can read it here). In short though, I mentioned there that corn is typically used in pet foods because it is a cheap source of carbohydrates and calories and because it can be easily mixed into just about any food product.


Like corn, soy is a very common ingredient in many of the more popular pet foods that you see on the shelves of your local stores. Why? Well like corn, soy as an ingredient is cheap. Unlike corn however, soy provides pet food manufactures even more bang for their buck as this ingredient is actually a good source of protein. Thus, by including soy in their food formulas, these pet food manufactures can boost the amount of protein that their foods offer, without having to include more expensive ingredients such as fresh meats.

Protein is More than Just a Number

On the surface, and for most pets, a food with an increased percentage of protein seems like a great deal (except of course for those pets the require less protein in their diets). I mean after all, as I mentioned in an earlier part of this series, your pet’s nutrient requirements are only slightly different from their Great, Great Grandparents.

Unfortunately, like anything that sounds too good to be true (i.e. low fat pizza), this is not the case with soy. Although soy does indeed provide a source of protein, it is not considered a complete protein by pet nutritionists. These little legumes (I always chuckle when I write that!) simply do not stack up to their meaty counter-parts in the nutrients that they provide.

Other Health Risks Associated with Soy in Pet Food

In the last several years, there have been a many studies conducted by universities and nutritionists to uncover what effects, if any, that soy has on your pet’s health and wellbeing. At the risk of sounding like a mood killer, the results of these studies have not left me with a warm and fuzzy feeling about feeding my pets food with this ingredient. Ill summarize some of the findings below, if you are interested in reading these studies (be prepared for a complex, but rather interesting read) I will post links to the studies I read in the comments section below.

Increased Levels of Phytoestrogens – Without getting to in the weeds here, phytoestrogens are a hormone that are similar to the estrogen which is found in female mammals and allows for fertility and reproduction. This hormone is created by eating plants that naturally contain it, such as soy. While there are definitely some positive benefits to this hormone, consuming it in large quantities can actually cause physical changes in your pet which are not beneficial. In small quantities, these hormones have little to ne effect, but keep in mind, if you are feeding your pet food that contains soy, your pet is consuming this each time they eat throughout the day, day after day.

Bloating and Allergies (I know not a fun topic) – Soy has also been shown to cause issues with a pet’s digestive system, including bloating, and upset stomachs. In addition to this, a lot of pets have or can develop sensitivities and allergies to soy or soy based ingredients, making for one unhappy pet!

Does My Pet’s Food Contain Soy?

At first this may seem like a really easy question to answer, however I have found that not all pet food manufactures directly list soy as an ingredient on the back of the bag (a red flag?). Some things to look for if you would like to know if your pet’s food contains soy are: soybean meal, soybean germ meal, soy flour, soy grits, soy hulls, soy protein concentrate, soy isoflavones, isolated soy protein and textured vegetable protein (TVP).

Final Thoughts & The Question of the Day

On the surface soy seems like a decent ingredient, however this pet owner has some serious concerns about including it in his pet’s diets. Though it is a decent source of protein, it is not as beneficial as meat based proteins. As such for me, the risks of feeding it definitely do not out-weigh any benefits there may be. Though foods that include only meat based proteins cost a little more, that cost is worth it for my furry pals for sure!

Like all things that concern your pet’s health and nutrition, I ask that if you have any concerns about what you are feeding your pet, please consult a pet food nutritionist and/or your local veterinary clinic if they have someone there that specializes in nutrition.

Question of the Day

Do you agree that your pet’s food should only include meat based protein sources? Why or Why Not?

I hope that you enjoyed this second part of our series! Keep reading the remaining parts to learn more about your pet’s food!