Processed Food vs. Whole Food for Pet Cancer Patients — What’s Better? Part 1

Patrick Mahaney, VMD, CVA, CVJ
Published: February 19, 2016
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When a pet is diagnosed with cancer, a series of life-changing events occur. The pet is potentially faced with a treatment protocol involving surgery, chemotherapy, radiation, or some combination of the three on a short or long-term basis. The owner is faced with the uncertainty of not knowing how long the beloved pet will live, in addition to the financial and time-management aspects of managing the cancer.

The process of getting a pet’s cancer treated involves many factors that come into play. As I work alongside veterinary oncologists providing chemotherapy or radiation to treat canine and feline cancers, I’ve observed that often the conversation about how to nutritionally support the body to best handle the prescribed treatment may not be part of the initial treatment conversation.

Yet, the “you are what you eat” perspective especially applies to cancer patients. The treatments used to manage the disease, or the cancer itself, can affect a pet’s appetite and ability to digest food and absorb nutrients. This is why owners must be proactive in ensuring that the meals entering their pets’ mouths contain ingredients that are highly bioavailable (easily absorbed) so that the nutrients can be readily utilized to fight cancer’s effects, reduce inflammation, resolve infection, and manage other ailments.

My own dog, Cardiff, exclusively eats a whole-food based diet and treats (The Honest Kitchen, Lucky Dog Cuisine, and human foods), and has since he was a puppy. So, even though I took all measures to prevent him from consuming foods and treats that are known to have toxins or are known to be carcinogenic, his body had other ideas and he still developed cancer.

Yet, I generally see that my patients who eat whole-food diets throughout their lives have fewer health problems. Additionally, my patients undergoing chemotherapy, including Cardiff, typically tolerate chemotherapy better than those eating processed pet foods.

Here in part 1 of 2, I will be sharing my perspective on this topic.

What Are the Differences Between Processed and Whole Foods?

Commercially-available kibble and many canned pet diets undergo significant processing to achieve the final product and are thereby considered processed foods. Processed foods contain fractionated ingredients (a process that separates the components of whole foods into smaller parts), like meat and grain “meals and by-products,” which either don’t exist in nature or are radically changed from what nature created.

Conversely, whole foods appear identical or very similar to their natural form. Whole foods contain vitamins, minerals, carbohydrates, and proteins that all work best when consumed together. By breaking nutrients apart, the synergistic qualities of whole foods can be lost. Co-factors essential for digestion may be lacking and can lead to poor absorption of nutrients and digestive tract upset (inappetence, vomit, diarrhea, flatulence, etc.).

Synthetic vitamins may not be efficiently absorbed as compared to natural vitamins existing in whole foods due to improper binding with receptors inside the digestive tract (see visual examples in Good Food/Bad Food: A Little Book of Common Sense Nutrition). Additionally, the body may identify synthetic vitamins as foreign and eliminate them in a process that creates free radicals that are harmful to internal organs.

Natural, whole-food vitamins are generally better absorbed as a result of improved binding with digestive tract receptors, and are not eliminated in a manner that creates additional stress on the body like their synthetic counterparts.

Is Kibble Considered Whole Food?

No, kibble is not considered to be whole food. Even from a visual perspective, which is what drives many owners to feed particular types of food or treats to their pets, kibble doesn’t lend a natural appearance.

Kibble is produced through a moisture-depleting cooking process called extrusion, which requires the body’s gastric acid and pancreatic enzymes, or an external water source, to facilitate digestion. Extrusion also denatures proteins and deactivates enzymes that are essential to the digestive process.

After being high-heat cooked, kibble is sprayed with rendered fat to improve its taste and is also often artificially colored (caramel coloring, etc.).

Kibble is often associated with gastric dilatation volvulus (GDV or “bloat”) in dogs, and vomiting in cats.

Many types of kibble, and some canned foods and treats, have caramel color added to make them appear more like real meat. When it comes down to it, dogs and cats don’t care about the color of their food. The aroma and flavor, yes; the color is added to satisfy humans.

According to information I received while on a media tour at a major pet food brand that produces many types of kibble, studies showed that pet owners responded better to kibble that included caramel color to make it look meatier.

But caramel color has come under fire as a toxic food additive, as it contains 4-methylimidazole (4-MIE), a known animal carcinogen. Studies have found that long-term exposure to 4-methylimidazole (4-MIE) caused lung cancer in mice, so it’s been added to California’s list of Chemicals Known to the State to Cause Cancer or Reproductive Toxicity.

So, by choosing to feed a their pets a diet with ingredients that have been radically modified from nature’s version and added color to replicate real meat, owners may be unknowingly predisposing their beloved canine and feline companions to develop cancer. Considering most pets eat the same 4-MIE-containing foods for morning and evening meals on a daily basis, we’re continually showering their internal organs with a carcinogenic substance that could otherwise be avoided if whole food options were fed instead.

If you haven’t already done so, it’s time to move away from kibble to fresh, moist, whole foods.

Are Canned Foods Considered to Be Whole Foods?

Canned or moist food has water as the primary ingredient and often appears closer to a whole-food format. Some even have real pieces of meat, vegetables, fruit, and whole grains. Such options are better choices for pet owners seeking to feed a whole-food diet than canned foods that appear smooth and “pate-like” without discernible chunks of whole-food ingredients.

Yet, some canned foods appear to have chunks simulating meat but which are actually conglomerations of meat and/or meat and grain “meals and by-products” that appear different from real meat when examined in cross section (after cutting in into the piece). So, make sure to use a discerning eye when comparing canned food options to make sure your pet consistently eats canned diets that are whole-food based.

Unfortunately, many canned or moist foods are congealed or have a glistened appearance; this is due to stabilizing agents like guar gum, xanthan gum, or carrageenan.

Guar gum has its origins in ground guar beans and is a polysaccharide (complex carbohydrate). Let’s Take Back Your Health-Starting Now reports that guar gum actually has some health benefits, as rodent studies showed “reduced body weight and lower blood glucose, even with guar gum making up 15% of the diet.”

Yet, 15 percent of the diet is “over 100 times the FDA Acceptable Daily Intake” for humans and is something I don’t recommend you provide for your pets. Guar gum is linked to digestive tract upset, including soft stools and gas-related bloating.

Xanthan gum is also a polysaccharide—the product of fermentation by  Xanthomonas campestris bacterium. Fortunately, xanthan gum hasn’t been correlated with cancer. However, xanthan gum is reputed to be indigestible and, as with Guar gum, animals with digestive tract sensitivities can experience vomiting or diarrhea after eating xanthan gum-infused diets.

Carrageenan is derived from red algae and is another polysaccharide. The International Agency for Research on Cancer (IRAC) has reported “sufficient evidence for the carcinogenicity of degraded carrageenan in animals to regard it as posing a carcinogenic risk to humans.” Like Guar and Xanthan Gum it is also correlated with digestive tract upset.

If you were making home-prepared pet food, you would not add guar gum, xanthan gum, nor carageenan to make the food smooth and shiny. You’d just use basic, whole-food ingredients, perhaps slightly warm the food to release aroma, and then feed it to your pet.

Feeding fresh, moist, human-grade meals during times of illness and wellness is my recommendation.

Make sure to check back for Part 2 of this article where I delve further into whole food feeding for cancer patients.

Editor's note: petMD does not endorse any of the products listed here. The use of supplements and specialty diets for pet health is a personal decision that should be made by owners in collaboration with their veterinarians.