Is There a Connection Between Carbs and Yeast Infections in Pets?

Ken Tudor, DVM
Vet Reviewed
By Ken Tudor, DVM on Sep. 15, 2015
Is There a Connection Between Carbs and Yeast Infections in Pets?

Have you heard that carbohydrates in your pet’s food are causing yeast skin infections? If you haven’t I am amazed.

It is the latest popular reason for purchasing grain-free pet foods. I have listened to countless pet food store employees and pet food company representatives scare pet owners that the smallest amount of grain in their pet’s food would spawn a horrific yeast skin infection. There are even those advocating a “yeast starvation” diet to rid your pet’s body of nasty carbohydrates.

Never mind that the starvation diet is completely nutritionally un-balanced. Unfortunately, all of this comes from taking isolated scientific facts and spinning them into illogical biological and physiological fantasy.

Yeast and Carbohydrates

How many of you have had an alcoholic drink, made bread or rolls, or grew mold on damp bread in elementary school? All of these have yeast in common. Yeast loves carbohydrates and makes these wonderful products (alcohol and bread), as well as the yeast mold that destroyed the bread.

In laboratory petri dishes, fungi like yeast grow crazily on carbohydrates. This relationship has unfortunately led to the illogical conclusion that if yeast likes carbohydrates, then carbohydrates in the diet must promote yeast infections of the skin. In other words, more carbs in the diet equals more yeast infections. Except bodies don’t work that way.

Carbohydrate Metabolism

All carbohydrates are sugars in various forms. When we or our pets eat carbohydrates and absorb those sugars they are all changed to glucose. The sudden increase in blood glucose triggers the pancreas to release insulin. Insulin is necessary to usher this post meal glucose rush into all body cells for energy, or to be converted to amino acids or stored as glycogen or fat.

The insulin response makes sure that circulating blood glucose levels stay between 70-150mg/dl. The body always adjusts insulin levels or glucagon levels (glucagon hormone increases blood glucose when it is low) to maintain this harmonious steady state. Too little blood glucose can cause neurological problems and seizures, while too much can cause acidosis. Blood sugar levels stay within this physiological range.

In other words, no matter how much carbohydrate is eaten, the skin will only see the same glucose level as the other cells of the body, 70-150mg/dl. Skin yeast are not getting excess sugar and growing explosively, no matter what diet they are eating.

But what about diabetic pets that don’t produce enough insulin?

 Diabetes and Yeast

Yeast is a natural part of the ecology of skin. We share that trait with our pets. When normal, our and our pets' immune systems keep the population of yeast on our skin, in our ears, and on our nail beds in check so there is a peaceful harmony without disease. It is only when the populations of yeast and/or bacteria get out of control that skin disease occurs.

The acidosis caused by diabetes suppresses the immune system, so diabetics are subject to all forms of infection, including fungal. But these infections are systemic or internal, and often in the urinary tract.

There is no evidence to suggest that diabetic pets are more susceptible to skin or ear yeast infections than normal pets because of their elevated blood sugar levels. They are prone to infections because of the immune-suppression due to their diabetes. In fact most diabetics are on diets low in carbohydrates or carbohydrates with a low glycemic index. Carbohydrates with low glycemic indices are more complex, harder to digest, and release glucose into the blood stream at a slower rate.  

Grain-Free is not Carbohydrate-Free

The even more sad reality of the crusade against grain in pet food is the notion that somehow grain-free diets are carbohydrate-free diets. They are not. Potatoes, sweet potatoes, beets, tapioca, beans, peas, vegetables, and fruits all contain sugar that is turned into glucose once it is absorbed. Glucose is glucose whether it comes from grain or other carbohydrate sources. If grains cause yeast infections then so would the wholesome grain substitutes listed above.

As you know, I am not a commercial pet food advocate, but the skin-yeast promotion argument against commercial and homemade pet foods that contain grain is in a word, ridiculous.

Your pet does not have a skin yeast infection due to carbohydrates in its diet. Your pet more likely has allergies or other immune disorder problems that allow abnormal fungal overgrowth. The key is finding the combination of food or medical intervention that promotes health and well-being, whether the food contains grains or not.

Dr. Ken Tudor

Image: Thinkstock

Ken Tudor, DVM
Vet Reviewed


Ken Tudor, DVM


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