Veterinary Practice News magazine interviewed four board-certified veterinary nutritionists on pet food allergies and the role grains play. They agreed on the following:
- Corn, wheat and soy are usually innocent when accused of causing food allergies.
- Clients, not veterinarians, often diagnose food allergies.
- There's a big difference between a true food allergy, which is rare, and a food intolerance.
Moreover, vilification of food grains as pet food ingredients may be myths started by small pet food companies as a way to compete with larger, established companies, according to four diplomates of the American College of Veterinary Nutrition.
“I honestly don’t know where that got started. It’s not based on any data, and there are excellent diets that contain one or more of those items,” said Cailin Heinze, MS, VMD, and a diplomate of the American College of Veterinary Nutrition (ACVN).
“It may have been started by companies that wanted to distinguish themselves, to sell diets in a crowded marketplace,” added Heinze, assistant professor at Cummings School of Veterinary Medicine at Tufts University. “To say that these ingredients are ‘common causes of food allergies,’ as I’ve seen reported, is not very accurate.”
“You just have to follow the money trail,” said Rebecca L. Remillard, DVM, Dipl. ACVN, of the North Carolina State University Nutrition Service. “If a company puts ‘no soy’ on the front of the bag, it invokes in people’s basic brain stem the question, ‘What’s wrong with soy?’
“Then, they go home and look at their dog food bag, and soy is one of the ingredients,” Remillard continued. “So they change foods without any real knowledge or thought put into why they are changing. Marketing is powerful.”
“Companies or salespeople often warn against corn, wheat or soy because of pet food marketing and propaganda, and then they develop a mythology about why all these might be harmful,” said Jennifer Larsen, DVM, Ph.D., Dipl. ACVN.
“There is no science to back up many claims. Americans love conspiracy theories, but they aren’t equally skeptical of all sources,” added Larsen, of the nutrition support service at the Pritchard Veterinary Medical Teaching Hospital at the University of California, Davis.
“Corn is not an inherently good or bad food for dogs and cats, and there have been very few corn allergies in dogs and cats in this country,” said Lisa Weeth, DVM, Dipl. ACVN, a clinical nutritionist for Red Bank Veterinary Hospital in Tinton Falls, N.J. “But corn is used frequently as an ingredient in lower-cost pet foods, so in my opinion the boutique pet food companies are looking for ways to distinguish themselves from the bigger, more established competition.”
Food allergy is an abnormal immune response only to a protein, not to a fat or carbohydrate, Remillard said.
Larsen added that an animal is more likely to have an allergy to something it is repeatedly exposed to. Corn is 8 percent protein and 80 percent starch, and rice has less than 10 percent protein, Remillard said.
“But if an animal is allergic to protein, it’s like a bee sting; any amount will trigger a reaction. The problem for vets is, you can have a food intolerance case in front of you, and the vomiting and diarrhea look the same,” she said.
“True incidents of food allergy are about 10 percent of the animal population,” she continued. “Most ‘people’ cases of food allergic reaction are thought to be actually food intolerance.”
Weeth agreed, saying that a food allergy is an antigen-antibody reaction to a protein component in a diet.
“It could be the protein in beef and corn, just as well as the protein in venison and quinoa,” she said. “It depends on what the animal has been exposed to in the past, and what their immune system reacts to. A food intolerance doesn’t have an antigenic component, and can occur in dogs and cats with poor digestibility of an ingredient or combination of ingredients, or how the food is prepared.”
The Association of American Feed Control Officials is an advisory body that publishes guidelines for each state to adopt in full or in part their own feed control laws, Larsen said. The association doesn’t endorse or approve foods. Each year, AAFCO publishes a model bill and regulations, uniform interpretation and guidelines, and feed terms and ingredient definitions. Feed control laws are written by state legislatures and enforced by individual state feed control officials. If a number of animals get sick, then the federal Food and Drug Administration gets involved.
Depending on the extent to which a manufacturer adheres to AAFCO nutrition guidelines, there are specifically worded statements which may be printed on a pet food label:
- "Pet food" is formulated to meet the nutritional levels established by the AAFCO (dog or cat) Food Nutrient Profiles for (maintenance; or growth; or gestation/lactation; or all life stages).
- Animal feeding tests using AAFCO procedures substantiate that "Pet Food" provides complete and balanced nutrition for (life stage).
- This food is intended for intermittent and supplemental feeding only.
"Pet food" provides complete and balanced nutrition for (life stage) and is comparable in nutritional adequacy to a product (state which one) which has been substantiated using AAFCO feeding tests.
According to Heinze, the “intermittent and supplemental feeding” statement means the food item doesn’t meet profiles, hasn’t passed feeding trials, and should be considered a treat rather than a complete diet.
“There are numerous products on the market that look like complete and balanced diets, but then say this on the back in very small font,” she said.
To comply with the regulation, AAFCO requires that “a signed affidavit attesting that the product meets the requirements of (the bulleted statement printed on the package) shall be submitted upon request,” Heinze said.
“I think a lot of the public has no idea what an AAFCO statement is,” she said. “Some believe that AAFCO ‘approves’ foods, and that’s not the case at all.”
Some smaller and boutique pet food companies claim that AAFCO trials are “not enough,” yet instead of doing additional research on their own, do nothing and sell the product as “formulated to meet” AAFCO standards, Heinze continued.
“Some of the bigger companies are certainly doing a lot more trials than AAFCO requires,” she said.
AAFCO guidelines set forth ingredient definitions to be used, she said.
“I commonly see companies write illegal ingredient definitions on their websites and marketing materials to bash other competing companies,” Heinze said. They avoid putting illegal stuff on the label, because labeling laws tend to be enforced, whereas advertisements and marketing come under much less scrutiny.”