Dogs Fed Kibble Have Elevated Levels of Metabolic Stress and Systemic Inflammation

Story at-a-glance -

  • My guest today is Robin Moore, a student at the University of Helsinki who is involved in the DogRisk research project to learn more about how nutritional, environmental and genetic factors influence disease in dogs
  • Robin is involved in a Dogrisk metabolomics study to better understand the relationship between canine health and diet
  • His study results to date suggest dogs fed a dry diet undergo significant metabolic stress
  • The dogs on a dry diet also showed elevated levels of homocysteine, a marker for inflammation

By Dr. Becker

My third guest this week is Robin Moore, a student at the University of Helsinki and member of DogRisk, a Finnish research project to learn more about how nutritional, environmental and genetic factors influence disease in dogs. Robin joined the DogRisk team about a year ago.

“I started working with Anna [Professor Anna Björkman, leader of the DogRisk team] because she came to the realization that a novel approach to studying canine diet and physiology is on a molecular level,” explains Robin. “Things get really complicated on a molecular level because there's a lot of space for a lot of things to happen.

What has emerged in the field of molecular study of dogs are different omics based studies. Now, ‘omics’ just simply means a holistic view. For example, Johanna [Dr. Johanna Anturaniemi of DogRisk] will be talking to you about nutrigenomics and a holistic picture of genes in response to nutrition.

Now, you can look at many different layers, such as proteomics, lipidomics, and microbiomics as Hanna [Dr. Hanna Sinkko of DogRisk] will be talking about, plus something I think is incredibly important to add to the discussion, metabolomics, which is the study of metabolites in the body.”

Metabolomics Can Increase Our Understanding of the Relationship Between Canine Health and Diet

Robin continues:

“We need to look at it on a molecular level. We can look at genetic changes in response to diet by analyzing gene sequences in different tissue samples and in the same way, we can also look at proteins or lipids or metabolites. However, you can't get all of the answers from just one method.

So you're going to want to combine a lot of different approaches in order to get the best picture possible. However, all of these different approaches are new in themselves. So studying just them individually also deals with a lot of new information.

I’m currently studying the response dogs have on a metabolic level to food and different diets. It's important to note this field is actually called metabonomics. Metabolomics is an interchangeable term nowadays.

So I'm focused on metabolites because metabolites have such a crucial role in our physiology and a strong link to what we eat. Hippocrates said, ‘Food is thy medicine.’ What we eat is what makes us. So, I figured metabolites is a really great way of studying exactly how nutrition affects dogs.

We are looking at the energy and the nutrients that are going into the dog, the food that is broken down and then utilized, and how efficiently it's utilized and to what extent. I think a lot of diseases occur due to discrepancies or disruptions in different metabolic pathways.”

Fascinating Research and Thought-Provoking Results

I asked Robin to discuss the fascinating research he’s doing as well as some of the truly mind-blowing results of his studies.

“If we're focusing on metabolomics it's worthy to note that there's two types of metabolomic analysis that you can perform,” explains Robin. “You can either perform a targeted or untargeted metabolomic analysis. What we've done so far is something called targeted metabolomics.

We targeted a subset of metabolites that we know exist in dogs. We then processed the results from our targeted metabolites that we wanted to analyze with different tissue samples. We focused on urine samples and different types of blood samples.”

metabolites

“The first result that I think is really fascinating and that you saw when you visited here, was that we can do pure metabolomic analysis. Even targeted metabolomic analysis, in which we simply got a snapshot of what the metabolome looks like for a dog after having been on a diet that's unknown to us. Our baseline dogs actually had random metabolite values. There weren't any significant discrepancies in their values in our baseline.”

metabolome

“Now what's interesting is that we then compared that with the metabolomic profile of targeted metabolites after a dietary intervention with both raw and dry food, and we noticed that the metabolomic profile actually changed quite significantly between these two groups.”

Dietary Intervention Study Showed Profound Differences Between Dry and Raw Fed Dogs

The DogRisk team fed some of the dogs in the study a low-fat, high-carb processed and extruded dry food, while other dogs were fed a high-fat, low-carb nonheat-processed raw food for three or four months. Then Robin did his metabolomics analysis and there were some profound differences.

“The metabolite concentrations between these two groups after the dietary intervention were quite significantly different,” explains Robin.

“What you can do with metabolomic analysis, which is so new and novel compared to other types of epidemiological studies, is that instead of maybe looking for just one marker in the blood, you can determine an entire set of markers simultaneously. So, instead of just looking at the rise in concentrations of one thing, we're also able to detect patterns of changes.”

I asked Robin to discuss the patterns his analysis revealed.

“This is where things get interesting because you can introduce the field of bioinformatics. There's actually a ton of information about molecular biology available in different databases. So you can take the results that we got from our dogs and say okay, well these metabolites all significantly changed between the raw and dry group.

Let's compare these metabolites with known metabolic pathways that are found in the dogs’ blood serum and see how relevant they might be. So, we did that and we actually found there are some metabolic pathways that are significantly disrupted by changing the diet from raw to dry, or from dry to raw.

By analyzing the end results in the dogs and the different dietary groups and measuring the different changes of metabolites, you can actually take that data and compare it to databases online about metabolic pathways. And through that you can then get a pretty good picture of which metabolic pathways are disrupted based on diet.

We found that the metabolism of a metabolite called methionine as well as vitamin B metabolism were both significantly altered. And I think that it's fascinating that we were able to get this kind of result with targeted metabolic analysis, because we weren't particularly looking for disruptions in this metabolic pathway.”

Dogs Fed Dry Diets Undergo Increased Biological Stress

I asked Robin what other markers he discovered in his analysis.

“I think it's fascinating that it's exactly these metabolic pathways that have been upregulated because these have to do with all kinds of DNA methylation and anti-oxidation processes throughout the body,” he replied. “So as a preliminary guess it seems like these metabolic pathways are significantly upregulated in dogs being fed dry food and what this means is that it sort of seems like there's more stress in dogs that eat dry food.

Metabolites that are central for DNA methylation are significantly upregulated, which signifies that certain quite central and well regulated pathways are working at an elevated rate. The reason for this is a mystery and this is something we need further metabolomics analysis for in the future.”

This is an area of DogRisk research that could be greatly expanded with additional funding.

“Targeted metabolomics is a great place to start this research,” says Robin, “but it's the tip of the iceberg in terms of what's possible with this technology. Johanna will be mentioning how she will be performing RNA transcription and through that will find new candidate genes.

We can do exactly the same thing with metabolomics and it can get really interesting because you're not only detecting certain metabolite concentrations, you're also detecting full patterns of metabolite concentrations that may be correlated with disease or the predisposition for disease.”

To summarize Robin’s study results for pet parents out there: he looked at sets of metabolites that demonstrate that feeding dry food is harder on a dog's body — “harder” meaning the dry diet caused the dogs’ bodies to work more aggressively in an attempt to process the food.  We don't yet know precisely why that is, but dry food seemed to be more metabolically stressful on the body than the analysis of raw food showed.

Dry Diets May Disrupt the Function of Organ Systems

“It's important to point out that we have a dataset of targeted metabolites so we can't say for sure that all metabolites are simply in significantly higher concentrations,” says Robin. “However, these metabolites are involved with anti-oxidation and cell maintenance, especially lymphatic cells, and hepatic cells of the liver, are significantly upregulated, which means there's more activity.

Now why that is could be for a couple of reasons. Simply, these metabolites could be present in the food that the dog eats, more so in dry diets and thus accumulate in the blood. However, I think that is unlikely since there are so many steps between entering the dog's mouth and being present in the bloodstream.

The other alternative is that the organs that are used to maintain and regulate the metabolite concentrations for some reason aren't working as well as they should be. For example, the liver and the kidneys might be somehow down regulated, or might be stressed for some reason and not working efficiently.”

Dry Fed Dogs Showed Significantly Elevated Levels of Homocysteine, a Marker for Systemic Inflammation

The metabolite homocysteine is a general inflammatory marker. Some veterinarians and many medical doctors use homocysteine as a marker for chronic disease. I asked Robin to talk about what he’s found relative to dry fed and raw fed dogs and homocysteine levels.

“What we noticed was that homocysteine significantly increased in dry fed dogs,” says Robin. “Methionine increased significantly. Now, I mention methionine because homocysteine and methionine are pretty much almost the same molecule.

The only difference is that there's a methyl group attached to methionine which it then donates to homocysteine and vice versa depending on the needs of the body. This is really interesting because homocysteine has been traditionally a biomarker like you mentioned for all types of diseases, especially hepatic diseases and cardiovascular diseases.

There's also been information that homocysteine levels and obesity are strongly correlated. And so it definitely merits further research. And I think it's also really interesting that the breakdown of homocysteine actually occurs mainly via the methionine pathway, which is the most significant metabolic pathway in terms of disruption between these two diets.”

These Study Results Are Just the Tip of the Iceberg Until More Funding Is Secured

Despite the astounding results they’ve seen so far, Robin and the rest of the DogRisk team have barely scratched the surface of the life-saving research they are conducting. “Tip of the iceberg,” agrees Robin.

“There are so many ways we can go with this. What we can say for sure now and what we can publish, is that something happened due to a dietary intervention and it's a significant difference and it happened with these metabolites and these metabolites are all linked to a metabolic pathway that is very important in terms of cell regulation and maintaining a healthy organism.

So while that's fascinating, what we don't know is why it takes place. And since we've only studied targeted metabolomics, we really don't know what we're not seeing. We need to perform untargeted metabolomics to fill in the blanks. We've only looked at about 100 metabolites so far. There are thousands present in any living cell, so what we need to do is fill in the blanks.”

My goal is to help the DogRisk team achieve funding through this year. I asked Robin what other research projects he has in mind.

“We have two prospects that are on the table at the moment and both I think are great,” he responded. “One is very affordable in the sense that we could re-perform a targeted metabolomic analysis on the dog samples that we used, the blood samples or the urine samples.

We would focus on all the metabolites associated with the pathways that I'm studying and that would give us a lot more detail into exactly why we're seeing these results. We would also be able to better bind the data we get with the nutrigenomics research Johanna is conducting.

Another, far more expensive approach, which I mentioned earlier, is to perform an untargeted metabolomics analysis. Instead of actively searching for metabolite concentrations that we want to observe in dogs, we can just get a snapshot of all the metabolite concentrations that are present in tissue samples or the blood samples.

We are also going to perform pathway enrichment analysis in which we find the different metabolic pathways that are significantly altered due to diet. We can look at all the different metabolic pathways that are known to exist in dogs.”

Future Canine Studies May Provide Models for Human Health

I asked Robin for examples of future research that can be tackled based on the data he and the team have collected so far.

“Another question is: ‘What can we learn from this data about both canine nutrition and human nutrition,’” he replied. “Something that hasn't been talked about much is how currently, a lot of human health is studied on a molecular level with rat and mouse models and if you think about a rat and mouse, yes they are mammals, but their life does not really resemble a human life very well.

They're used, even though they don't work very well as models, simply because they're so cheap to study. A dog is genetically closer to a human than a rat or a mouse. Also, if you use a pet dog they actually share the same living environment as humans, and so we might be able to use them as a better model organism for human disease as well.”

Based on DogRisk Study Results, If Robin Had a Dog, He’d Feed a Raw Diet

I asked Robin to describe the changes he saw in the raw fed dogs in his study.

“So, I've been talking about two metabolic pathways,” he replied. “It's worthwhile to note that from the dataset we've used so far, actually a lot more than two, about nine metabolic pathways have been significantly altered. But I’ll leave the rest for you to read about when it is published.”

When I was in Helsinki meeting with the DogRisk team, I learned that Robin didn’t have a dog of his own. I also learned that he had never conducted any research on dog food until this project. So I asked him, based on his research, what he would feed a dog should he get one.

“To be honest,” says Robin, “I would feed raw food. My involvement with DogRisk has shown me many different sides to this matter, and I would refer not just my research, but the studies of others on the team as well.

The work Robin is doing with DogRisk is quite complex but very exciting, and is critically important for the advancement of objective research into how we nourish our dogs and the impact food has on their bodies. I greatly appreciate Robin taking the time to speak with me today.

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