This may be a shocker to some, but the truth is, there is not a direct cause-and-effect link between canine dilated cardiomyopathy (DCM) and grain-free petfoods. In fact, there has never been a single research study to demonstratethe relationship; rather, the fact is: The association between DCM and grain-free foods has been weak at best.
DCM and grain-free pet food facts
It appears that some veterinarians, especially in academia, and even some ofmy colleagues in the pet food industry conveniently ignore that even the Foodand Drug Administration (FDA) has acknowledged that DCM is a scientificallycomplex, multi-faceted issue. This is sad, considering that practicingveterinarians often do not have time to research the topic themselves andactually look to these experts for legitimate and truthful information.
Additionally, FDA acknowledged that out of the more than 2,000 casesinvestigated, only 1,100 could be confirmed as DCM (note: NOT nutritional DCM,as there are many types). Meaning, veterinarians were inaccurate in theirdiagnosis for 45% of the cases submitted to FDA versus other potential cardiacissues, such as heart murmurs. Lastly, FDA even noted that pulse ingredientshave been used in pet food for a long time, and again, there is no evidence toindicate that they are inherently dangerous to dogs.
Also, many veterinarians conveniently ignore that DCM is the second mostcommon heart disease affecting dogs, with prevalence greater than 50% in somebreeds. In 2006, Sanderson estimated that the prevalence of DCM ranged from0.5% to 1.1% in the overall population of dogs. Said differently, that meansthere would be 450,000 to 990,000 DCM cases in the current 90 million dogsliving in the U.S. Assuming Sanderson’s estimate was indeed accurate, far morecases should have been reported to FDA based on the expected prevalence in thepopulation of dogs in the U.S. today. Yet, most veterinarians I talk to havenever seen a single case. Go figure!
I guess it’s just a US problem!
At what point do the leaders of this saga realize that many of the“problematic” foods are shipped worldwide? Unless other countries have a DCMvaccine, or the dogs there are immune to DCM, why doesn’t the problem existoutside of the U.S.?
For example, the recent Salmonella recall by Midwestern Pet Foods shed lighton where their products are sold from the Monmouth, Illinois, manufacturingfacility. This one plant resulted in contaminated products across eightMidwestern Pet Food brands, which were also shipped to 19 other countries.
Specifically, one of Midwestern’s most popular brands, Earthborn Holistic, issold in the U.S. and 34 other countries. Ironically, Earthborn was tied forthe fourth spot for dog food brands most frequently fed in reported DCM casesby FDA. Since this brand is clearly also shipped worldwide, where are the DCMgrain-free cases in the rest of the world? I make this point because othercountries have been laughing at the U.S. about this debacle and how long ithas lasted.
Strike 3: Still no evidence to make a connection
Recently, a Tufts study funded by Nestlé Purina PetCare, “Investigation ofdiets associated with dilated cardiomyopathy in dogs using foodomicsanalysis,” is being touted in the popular press as identifying a “link”between certain dry pet foods and DCM. Although it makes good headlines, thiscouldn’t be farther from the truth. I studied and developed foods for Hill’sPet Nutrition with traditional nutrient and chemistry screen analysis,genomics, proteomics and metabolomics over a decade ago before it was “sexy,”and I didn’t make up silly terms like “foodomics”, so a study like this isfrustrating and sad to see. If anything, it just adds to the confusion andcontributes nothing to the science of nutrition.
Although the terminology is being used today, in the Tufts study it is beingmisused. Simply performing metabolomics on a food is not “foodomics.” Tounderstand why this important, you should know that metabolomics is thescientific study of the set of metabolites (chemical compounds) present withinan organism, cell or tissue. It is not equivalent to food analysis or foodforensic chemistry. “Foodomics” requires the combination of food chemistry,biological sciences and data analysis. Considering this, note that the Tuftsstudy only looked at food chemistry via one analysis (metabolomics) andtherefore does not fulfill the remainder of the definition of foodomics.
No validation of data in the Tufts DCM study
When looking at metabolomic data, people often forget that “fold changes” donot always equate to biological relevance. For some metabolites, a differenceof 1X could be a big deal, while for others, a 5X may not be relevant. So,what do I mean? If the authors wanted to validate some of their conclusionsfor B vitamins, there are known Association of Official Analytical Chemists(AOAC)-approved B-vitamin analyses that could and should have been conductedto make this an actual “foodomics” study. If the authors had analyzed the Bvitamins via traditional methods, they could have validated their theories ofthe fold changes observed via metabolomics.
They could have done the same with taurine, carnitine and other nutrients,which showed no differences in the foods via metabolomics. Again, they did notnor did they with other known nutrients that are easily measurable.Unfortunate, since this is supposed to be a “nutrition” paper written by“nutritionists.” It’s also unfortunate that this particular professor islikely damaging the reputation of her students before they even start theircareer due to her actions. Funnier still is the fact that the company thatfunded the study owns NP Analytical Laboratories, which specializes in vitaminand taurine analysis. So, it wasn’t due to a lack of funding.
In my opinion, the authors’ not connecting metabolomics and “foodomics”clearly demonstrates a lack of understanding and improper usage of metabolomictechnology and use of the “foodomics” nomenclature. There is no excuse for notsending out for analyses of B vitamins, taurine, carnitine and other knownnutrients. Especially when traditional nutrient analysis is inexpensive, andyou already have the foods to be sent out for such analysis. Better yet, havethe company that is funding you analyze the foods for you in their lab!
Lastly, metabolomics does not look for all compounds. That is why “foodomics”is a combination of various analyses in both foods and body versus just onesingle analysis. For example, would this method have identified melamine inthe 2007 pet food recalls? No, because melamine is not a metabolite. Whichgoes back to my prior misuse of metabolomics statement. Would it haveidentified L-Ascorbyl-2-Polyphosphate (a heat-stable form of vitamin C knownas Stay-C), which is the most used heat-stable source of Vitamin C in dryfoods? No, because it shows up in the plasma as vitamin C. What aboutaflatoxins in their natural form? Also no.
Would many of the other compounds measured in the Tufts study be digested andabsorbed as they are measured in the food? Also no, since metabolites presentin food may go through chemical changes within the body during normalmetabolism. I could go on, but you get the point: another huge miss for a“nutrition” paper written by “nutritionists.”
Limitations of the Tufts DCM study
When a paper has a “limitations of study” section longer than the abstract,that speaks volumes. It brings into question all of their data collection,analysis, results, conclusions and more. Some limitations of the studyincluded:
- The selection of diets was based on ones associated with DCM and NOT diets directly linked to DCM . Thus, there is still no true connection, as the authors allude to in their abstract and their interviews with the popular press.
- When you choose pea-based foods versus not-pea-based foods, of course you will see a difference in the two groups. The study was literally designed to do this from the beginning. Duh! If the researchers would have used foods containing peas that were not associated with DCM in the FDA investigation, that could have been a third group that served as a control, along with the grain-inclusive pet foods. This is the classic garbage-in and garbage-out situation, where poor study design leads to improper conclusions and you know the outcome before you analyze the foods. It’s unfortunate that in many cases surrounding this DCM debacle, peer review has not served the purpose it was supposed to. Nor has common sense.
- Even the authors acknowledge, “Although informative, the individual selections and even the diet categories may not be the optimal categorization, and additional research will continue to add to the knowledge base to refine the design of future studies and clinical recommendations.” I don’t believe one of the authors was quoted saying that in the press, though I could be wrong.
- They further acknowledge, “Some of the diet samples were obtained directly from owners of dogs with DCM; most of these diets had been opened and stored for variable periods of time, first by the owner and then by the investigators, so this could introduce variability and could bias the 3P/FDA (3P = pulses, potatoes or sweet potatoes) diets in having lower levels of certain nutrients that could degrade as a result of variable storage conditions.” Do you think? Did I mention garbage in and garbage out? Simply put, this means that the metabolite profile of these foods could vary drastically once the outer packaging is open and oxidation/degradation has set in.
Vendetta against peas?
This study does not show anything nor eliminate anything. Especially whenthere is a lack of control foods, processing temps, known inclusion rates,improper use of technology, lack of validation of technology, lack of controlin how products are sampled … I would keep going but my head hurts with allthe flaws in the study.
Just imagine if certain “researchers” took their valuable time and money andchose to spend it more wisely on real research as they were taught to do ingraduate school and as interns. The money would be better spent diagnosing thedisease earlier, looking at genetics, titrating out ingredients forrelationships and other things that make it real research. Clearly, certaingroups have a lack of knowledge in formulation, and one would say nutrition aswell, since they focus solely on ingredients and not on the underlyingnutrition of the food. Me personally, I do not eat peas. I also do not have avendetta against them, either.
Finally, at what point does the industry simply stop paying attention to thisnonsense? First it was BEG (boutique, exotic, grain free), second it wastraditional versus non-traditional diets and now 3P/FDA foods. As a fan ofbaseball, I think that makes 3 strikes!
Source: Ryan Yamka, PhD, is founder and an independent consultant with LunaScience and Nutrition, and founder of the Guardian Pet Food Co. He is boardcertified in companion animal nutrition by the American College of AnimalSciences and a fellow with the American College of Nutrition. Yamka calls onhis extensive background in pet nutrition, and multiple years developing,formulating and launching dog and cat foods as a senior executive with leadingpet food companies, to address common myths and misconceptions about petfood.
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