Human-grade pet foods are becoming increasingly popular. I have written about this category of foods on several occasions and have reviewed recent studies of how these food tend to perform when fed to dogs.

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What do we currently know?

To date, we know a few things about human-grade dog foods:

• Higher Digestibility Values: These products are more digestible than pet-grade kibble and pet-grade fresh cooked foods (“New Scoop“). In some studies, these differences were dramatic, especially for protein digestibility values (“Human-Grade“).
• Lower Fecal Volume: Feeding a human-grade dog food leads to lower total fecal output compared with feeding pet-grade products (i.e. less poops).
• Gut Microbiome Changes: Dogs fed human-grade foods show significant qualitative (type) and quantitative (number) shifts in their gut microbiota. However, conclusions regarding the meaning of these shifts are not completely clear.

Are there health benefits?

We have evidence that the nutritional value of human-grade foods is superior to that of highly processed (i.e. kibble), pet-grade foods. Although more studies (of additional products) are certainly needed, current data suggest that human-grade foods are of high quality.

We tend to assume that feeding our dogs a high quality food will directly lead to health benefits. However, is there any evidence that feeding dogs human-grade foods contributes to their health? Dr. Kelly Swanson’s team of researchers at the University of Illinois recently published a paper that asked this question (1).

The Study

The researchers examined the effects of feeding a mildly-cooked, human-grade food on dogs’ skin/coat health, gut microbiome make-up, and systemic measures of inflammation and oxidative stress.

A group of twenty adult dogs was randomly allotted to one of two diets (10 dogs in each group). One group was fed a commercial dry, extruded, pet-grade dog food (Blue Buffalo, Life Protection Formula, Chicken and Brown Rice). The second group was fed a mildly-cooked, human-grade product (Just Food for Dogs, Chicken and White Rice). Dogs were fed their assigned food for 12 weeks.

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Results

After 12 weeks of feeding, a few differences were found:

• Gut Microbiome Changes: Dogs fed the human-grade food showed dramatic gut microbiome changes that were not observed in dogs fed the pet-grade kibble. These changes included both increases and decreases in more than 30 different bacterial species and influenced over 160 metabolic pathways.
• Probiotic Bacteria: Two bacterial species that increased in dogs fed the human-grade food were Bifidobacterium and Lactobacillus. These species are considered to be beneficial gut bacteria and are commonly included in probiotics for dogs.
• Reduced Skin Water Loss: Dogs fed the human-grade food had reduced water loss from skin (i.e. maintained skin hydration better). However, other measures of skin health were similar between the two groups and were not significantly influenced by diet.
• No Change in Inflammation/Oxidative Stress: Gene expression measures of inflammation and oxidative stress were not significantly influenced by the food that was fed.

A Few Observations……

These results agree with those of other studies showing that feeding dogs less highly processed foods leads to shifts in the gut microbiome and supports a more diverse population of microbial species that includes several that are considered beneficial.

Conversely, obvious skin and coat health benefits to feeding a human-grade food were not found. This does not mean that a human-grade food is detrimental to skin health – only that a clear set of benefits was not evident. In my opinion, these results should not be a concern. Despite the ubiquitous use of label claims for this type of benefit, an argument can be made (as I do elsewhere and frequently) that feeding a high quality, digestible, nutritious food that is designed to nourish our dogs should, by definition, support a healthy skin and coat. It should not be considered extra…… or a pet food benefit…..or a label claim. Rather, such effects should be expected when we feed our dogs well. So, in my mind, the human-grade food did just fine.

An interesting caveat…… when I searched for skin and coat health claims on human-grade dog food labels, they were NOT to be found. It appears that producers of these foods have not yet jumped onto the extravagant and excessive health claims gravy train. Let’s hope that they continue to resist….. My search did however find plenty of these claims on highly-processed pet-grade dog food labels.

Go figure.

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Take Away for Dog Folks

So, as dog owners and pet professionals, what can we do with this new information?

Well, practically speaking, it is important to note that there are multiple processing and nutrient differences between mildly-cooked, human-grade foods and the more traditional, dry, extruded, pet-grade products. These differences can be sorted into three large (but still complex) categories:

• Degree of Processing: Highly processed foods (sometimes called “ultra-processed”) are those that typically include feed-grade, rendered animal protein meals (the first high-heat processing step). They are further processed via extrusion (dry foods) or retorting (canned/pouched foods). Although heat treatment does increase the digestibility of some nutrients (and enhances flavors and acceptability), high heat processing also causes nutrient loss and damage, and can result in the production of potentially harmful compounds such as Advanced Glycation End Products (AGEs). Foods that are less intensely heat processed include mildly-cooked (fresh-cooked) foods, dehydrated and freeze-dried products, and raw foods.
• Ingredient Source/Quality: The vast majority of commercial pet foods are produced using pet-grade (also called feed-grade) ingredients. There are real and significant differences between these two ingredient classes that include original source, handling, transport and storage. I cover these differences in detail in “Human-Grade “.
• Macronutrient Distribution: The proportions of protein, fat, digestible carbohydrate (starch) and fiber vary considerably when we compare foods across the processing and ingredient spectrums. For example, in the current study, the human-grade food was higher in protein and lower in starch when compared with the kibble. Its fiber sources were also considerably different – coming primarily from fruits and vegetables rather than from different grain sources. These variations can all contribute to the observed differences in product quality when fed to dogs.

Although we know for certain that all three of these food attributes are important, carefully separating out their influences can be difficult. (Though many kudos and thanks to the researchers who are trying and are reporting their results!). At this point in time, be aware of all three when you are evaluating and selecting foods. To get started, ask these questions:

• How was the food processed? (Ultra, Moderate/Mild, Low)
• What are the primary sources of ingredients? (Pet-grade, human-grade, rendered meals)
• What is the relative macronutrient make-up of the food? (Protein, fat, digestible carbohydrate, fiber)

Until Next Time – And the Next Study!

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Cited Study: Geary El, Oba PM, Applegate CC, Clark LV, Fields CJ and Swanson KS. Effects of a mildly cooked human-grade dog diet on gene expression, skin and coat health measures, and fecal microbiota of healthy adult dogs. Journal of Animal Science 2022; 100:1-15. doi.org/10.1093/as/skac265.

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