One of the subjects that holistic vets and other advocates of alternative practices get really passionate about is the evils of commercial and conventional diets. They promote a laundry list of myths about pet food, many of which I’ve addressed before:
- Raw is better than cooked-
2.Vets know nothing about nutrition-
This is particularly hypocritical given that the claims made about the evils of commercial food and the virtues of alternative diets are generally made by—yup vets!— and these folks have no more training or expertise than the rest of us. In fact, the most reliable source of expertise on pet food are board-certified veterinary nutritionists, veterinarians with extensive training in nutrition. However, their claims are casually dismissed with innuendos or accusations about financial bias by vets who themselves make their living selling the stuff they advocate for.
3. You can tell the quality of a food from reading the ingredients on the label-
Sorry, you can’t. Partly this is the fault of regulators, who don’t require truly important information to be put on pet food labels in a clear and understandable way. And partly the uselessness of labels as a measure of food quality comes from the meaningless vagueness of the concept of “quality” and all the myths and misconceptions about specific ingredients promoted by these vets.
A recent article from the ever-unreliable Dogs Naturally Magazine gave some alternative vets a platform for repeating some myths and misconceptions about what are often called “prescription diets,” though this is technically incorrect. These are better referred to as “therapeutic diets” because they are intended to be useful in treating or preventing specific medical problems, not simply provide good overall nutrition, but they do not actually require a prescription, merely oversight from a qualified veterinarian.
The evidence for these diets varies from strong (e.g. kidney diets for cats with kidney disease) to weak (e.g. some of the diets for cognitive dysfunction in older dogs), but while there are some good arguments against some of these foods, none of the ones made in this article are worth taking seriously.
The article begins by asking a bunch of holistic vets to rank a few foods based only on the ingredient lists, with one food being a prescription diet. Not surprisingly, the vets tended to rank this diet quite low, based on these sorts of arguments:
Dr Marty Goldstein, author of The Nature of Animal Healing [said] Food #3 ranked last, based on the use of corn for its first ingredient, followed by by-product meal.
Dr Jodie Gruenstern: “This food was the lowest quality in the list. It contains GMO corn, soy (lots of it!), which is a common allergen, synthetic vitamins/minerals, shavings (if you didn’t know, the ingredient cellulose is literally sawdust), natural flavors, which usually mean MSG.”
Dr Jean Dodds: “Poor quality food: the first ingredients are corn, which is often GMO, and chicken by-product meal rather than whole chicken. Flax and soy are phytoestrogens.”
Dr Judy Morgan: “This is a Pet Store Food. Corn is the first ingredient, no muscle meat used, only by-product meal, synthetic vitamin/mineral supplement, corn and soybean are GMO, waste fillers are abundant. Overpriced in my opinion, considering the poor quality, cheap ingredients used).”
Dr Dee Blanco: “This one starts with corn to increase inflammation, then adds lighter fluid to it with soybean products and poor quality protein. Then it tries to make up for the poor quality foundational ingredients by adding synthetic supplements of the poorest quality, such as calcium carbonate, folic acid, ‘generic Vit E supplement’, etc. Looks like they added l-tryptophan to calm the nervous system down after putting the body into overdrive inflammation. Natural flavors?? Could be an entire cadre of carcinogens, allergens and toxins. Argh!”
So we have a long list of villainous ingredients supposed to cause inflammation and other health problems. Any truth in this fear mongering?
Corn and Soy are Evil–
Obviously, this sort of simplistic characterization of foods as inherently good or evil is not scientific in tone, and in the case of the particular claims she makes about these ingredients they are not consistent with mainstream opinion or the evidence. Veterinary nutritionists agree that particular sources of protein and carbohydrate in canine diets are not intrinsically harmful or beneficial and that the health effects of diet are a complex set of interactions between many factors. Duck and bison are no more nor less likely to trigger food intolerance than chicken or beef, and tapioca or potatoes or green peas are no better nor no worse than corn and wheat and soy as carbohydrate and protein sources.
GMOs are Evil–
This is a hot-button issue these days, and while it is complex, the evidence to date does not support the sort of hysteria about GMOs these vets promote. This is, of course, a topic which deserves multiple posts on its own. Dr. Dodds and others regularly list GMO ingredients as unhealthy, promoting inflammation and food intolerance, and there is no evidence to support this. While there is always the potential that particular modifications of food crops and animals could lead to health risks, the anxiety about genetically modified organisms is generally ideological and based on misconceptions or poor understanding of the relevant science. It is part and parcel of the Appeal to Nature Fallacy, and the existing evidence does not support most of the hysterical fears about GMO. Dr. Dodd’s claims are not based on research from nutrigenomics but are simply part of her own beliefs and prejudices, and she provides no compelling scientific evidence to support her claims. Relevant discussion of this issue and the evidence can be found here: 1, 2, 3, 4, 5, 6, 7.
By-Products are Evil–
Here’s what one nutritionist I’ve talked to has say about by-products:
A by-product only means that it was not the intended main product of the industry. It gives no indication on nutrient profile, digestibility and bioavailability, etc. Many people who dislike by-products will happily buy wheat bran (a by-product of the baking industry). Moreover, by-products vary according to country and culture. Liver, an excellent source of nutrition, is considered a by-product in the US because skeletal meat is the primary product of slaughtering an animal and many people do not eat organs any more. By-products can be excellent ingredients in pet food and it would be wasteful (and terribly self-centered) to not use it to nourish humans or animals.
The concept is meaningless, and used to demonize foods that people think of as “icky” without any reference to their real nutritional value.
Let’s look at some of the other claims. he idea that corn is a major cause of inflammatory diseases is an unproven hypothesis. The claim that phytoestrogens in soy used in pet foods have negative effects on health is an unproven theory. Both of these are presented as facts when they are just personal beliefs.
“Natural flavors” usually means hydrolyzed animal tissues, not MSG, so this is just false. And “synthetic” vitamins are identical to those extracted from plants, so the idea that they are somehow less useful or more harmful is just the Naturalistic Fallacy in action.
The bit about “sawdust is particularly silly. Cellulose is a natural part of the wall of plant cells. Sure, it is present in wood, but it is also present in all the fruits and vegetables that these vets would laud as healthy for our pets. The usual source of cellulose as a dietary fiber in pet foods is the bran from cereals such as wheat, not “sawdust.” Such hyperbole is clear evidence of a preference for ideology over facts.
The article also uses a bit of drama to suggest that therapeutic diets are poor-quality or identical to over-the-counter diets and the designation only serves to justify charging more.
Now, a 30lb bag of the regular food is $47.99 at Petsmart. The prescription diet dog food can also be purchased at Petsmart for $84.95 for a 27.5lb bag. It’s twice as expensive!
Now, you might be thinking this is because the prescription diet was formulated and tested with a specific condition in mind. This is completely false.
While an over-the-counter food with a health claim (such as controls weight) is subject to FDA regulations and enforcement, the FDA practices “enforcement discretion” when it comes to veterinary diets. Put another way, this means the FDA has not reviewed or verified the health claims on any veterinary diet. Did you catch that? There are very few ingredients in veterinary diets that aren’t also in other regular diets.
In the example above, I’d say the pet store brand is a better quality food, wouldn’t you? The prescription diet contains by-product meal (which comes straight from the rendering plant), lots of soybean and corn products (a cheap replacement for animal protein) while the regular food contains more expensive, higher quality ingredients.
Again, here’s the response of a nutritionist who actually knows something about veterinary diets to this claim:
This is a misrepresentation. Veterinary diet claims do have to be substantiated as well. The FDA did have some leniency regarding veterinary diets regarding the extent of their health claims because they are usually used under the guidance of a veterinarian to improve the life of the pets. However, the FDA is concerned about many so called therapeutic diets now marketed directly to the consumer, so they might start enforcing legislation if they are not used properly, i.e. under veterinary involvement
Regarding price, good companies invest in research, that goes into designing the food, sometimes funding basic research that would further our knowledge on particular diseases (without an immediate product to market and sell) plus trials in healthy and diseased pets, etc. So, I understand why a veterinary diet from a responsible company costs more money, not because the ingredients are more expensive, but due to the knowledge invested behind it.
These holistic vets are so ideologically biased against commercial diets that they even claim that ingredients they routinely recommend as beneficial for many health conditions magically become harmful when included in such foods:
And fish oil is a terrible addition to pet foods. It’s much too fragile to be added to processed foods and as soon as the bag is opened, it will oxidate and cause inflammation in your dog. Ironic isn’t it, when the food is supposed to be treating inflammation in the first place?
Actually, it’s not ironic, it’s just a bit of ignorance and prejudice masquerading as an informed opinion. Fish oils can be added to foods in a manner that has all the same health benefits of giving them separately, if this is done properly by a company with real nutrition experts who know what they are doing.
I usually write brief summary of my conclusions for these posts, but in this case I could not write anything that makes the point better than the following, again from a nutritionist knowledgeable about these issues:
All these arguments are just guilt trips and not based on reliable science and assume the quality of a final product depends solely on certain random criteria form the individual ingredients rather than in deep knowledge of the current state of nutritional science, excellent quality control during formulation, reception of ingredients, extrusion, and storage conditions.
What we have here is unsubstantiated belief presented as fact. And this kind of fear mongering has real dangers. There is, for example, very good evidence that feeding commercial diets for cats with kidney disease can reduce suffering and prolong life. Yet I have seen clients feeding unbalanced and completely inappropriate homemade concoctions instead because they have been frightened and misled by this kind of propaganda and are unwilling to feed diets with proven benefits.
As I’ve said many times, no one knows the perfect diet for any given patient, and I am open to the possibility that there are benefits to feeding alternatives to the usual canned and dry commercial diets. But these benefits must be proven, not simply invented out of whole cloth or wrung out of twisted misrepresentations of nutrition science.