“You can’t see the forest for the trees” is a well-known idiom, dating back to at least 1546.
“from him who sees no wood for trees
And yet is busie as the bees
From him that’s settled on his lees
And speaketh not without his fees”.
It describes the tendency to focus so intently on details that the bigger picture is lost.
This mindset has also shaped canine nutrition. The emphasis on essential nutrients has led to a reductionist approach, overlooking the vast array of other compounds that contribute to overall health. While nutrient guidelines have successfully prevented deficiencies, they have also unintentionally narrowed our understanding of what constitutes optimal nutrition.
Beyond Essential Nutrients
The current list of essential nutrients is largely based on necessity—what a dog needs to avoid deficiency diseases. But what about the many other bioactive compounds in food? Some may be essential in ways we have yet to understand simply because no one has systematically deprived dogs of CoQ10, Carnitine, Creatine etc. to study the consequences.
A major reason for these gaps in knowledge is historical: early nutrition guidelines were developed when technology couldn’t accurately measure many compounds or their biological functions. Some were assumed to be present in adequate amounts based on ingredient selection, leading to low research priority.
It was happenstance that the essentiality of Choline was discovered, as the researchers were actually looking into insulin.
Additionally, many compounds that might not be essential in youth become critical as dogs age, when their natural biosynthesis declines.
Vitamin D: A Recent Example
Only recently was a study conducted to assess whether dogs can meet their vitamin D needs with vitamin D2 (found in plants) instead of vitamin D3 (from animal sources). The assumption was that pet food would always contain enough D3 from meat ingredients, so no one questioned it.
Now there is still more research to be done regarding the long-term use of Vitamin D2 instead of vitamin D3 (The study was only 12 weeks), given that they do produce different metabolites, but the study was an important first step toward determining the adequacy of meeting a dogs vitamin D requirement using the vitamin D2 isomer instead of vitamin D3.
The study was a vital step in determining how different vitamin D forms affect canine health, though more research is needed on long-term effects.
Lutein, Zeaxanthin, and Vision Health
A study in primates found that a diet devoid of lutein led to retinal damage and increased vulnerability to blue light. Supplementation with lutein and zeaxanthin corrected these issues.
While dogs are unlikely to develop severe lutein deficiencies due to its presence in many foods, this highlights how bioactive compounds, even if not deemed essential, still play a crucial role in health.
PQQ: A Critical Compound?
In mice fed a diet devoid of pyrroloquinoline quinone (PQQ), the mice grow poorly, fail to reproduce, become osteolathyritic (not to be confused with osteoarthritic), have thin skin, and have defects in amino acid, lipid and energy metabolism.
The identification of the above issues with PQQ deprivation suggests that PQQ does play a fundamental role in health. While no one has conducted a study on dogs to confirm PQQ's essentiality, there’s little reason to withhold it just to prove a point.
Shifting the Focus from Deficiency to Optimization
The goal of nutrition should not be merely to prevent disease but to optimize health. Other fields of animal nutrition, such as swine and poultry science, have made greater strides in recognizing the importance of non-essential compounds.
A Classic Example: Vitamin C
In school, we learn that vitamin C prevents scurvy. But avoiding scurvy is not the same as achieving optimal health. Vitamin C plays key roles beyond being an antioxidant—it aids in collagen formation, fatty acid metabolism, and neurotransmitter production.
Beyond Essential Nutrition: When we Know Better We Do Better
While infant formula is still not a perfect replacement for breast milk, there have been great strides on improving the composition of infant formulas to better mimic human breast milk. Over the past 15 years, scientific research has led to substantial improvements in formula composition, incorporating key bioactive compounds found in breast milk. These include Milk Fat Globule Membrane, Lactoferrin, Milk Oligosaccharides, Colostrum, various peptides, and nucleotides—all of which play vital roles in health and development. As our understanding of nutrition deepens, we continue to refine dietary formulations, ensuring they provide more comprehensive support for optimal growth and well-being.
Amino Acids: More Than Just Protein Building Blocks
Pet food guidelines focus on ten essential and two conditionally essential amino acids. However, many others serve important physiological functions. Some are assumed non-essential because the body can synthesize them, but providing them preformed in the diet could reduce metabolic strain and enhance health.
While there could be some improvements as to the amino acid requirements, particularly for adult dogs (Nitrogen Balance is not very accurate), we should by no means completely ignore the other amino acids simply because they can be synthesized by the body. Which is one aspect where Chicken and Swine Nutrition are ahead of canine and feline nutrition.
Fats: More Than Just Omega-3s
EPA and DHA, often touted for their benefits, are not considered essential for adult dogs according to AAFCO. Yet human nutrition authorities like the NIH and FDA actively encourage increased intake due to their widespread health benefits beyond survival.
Beyond omega-3s, fats include other important categories such as phospholipids, glycolipids, and sphingolipids, which support cell membranes, nutrient absorption, and cell signaling.
Carbohydrates: More Than Just Energy
The claim that “dogs don’t need carbs” is widespread on social media, but carbohydrates are not the villain they’re often made out to be. In fact, they have been part of canine diets for thousands of years.
While carbohydrates are classified as non-essential, that doesn’t mean they lack value. They provide a readily available energy source and play crucial roles in cell signaling and metabolic processes.
Glucose is the brain’s preferred fuel and the only energy source for red blood cells, which lack mitochondria. While dogs can produce glucose through gluconeogenesis using amino acids, glycerol, and lactate, relying too heavily on this process may not be ideal. Conserving amino acids for their primary functions rather than using them as an energy source can be more efficient in the long run. Additionally, protein metabolism generates ammonia, which the body must filter out—a process that places extra strain on the kidneys.
The optimal balance of protein, fat, and carbohydrates in a dog’s diet remains an open question, likely varying by breed, activity level, and life stage. The same holds true for cats. Rather than dismissing carbohydrates outright, a more nuanced approach recognizes their potential benefits within a well-balanced diet.
Energy Metabolism in Working Dogs
When it comes to energy needs, the ideal macronutrient composition varies significantly based on a dog's activity level, duration, and intensity. A study on racing greyhounds found that dogs consuming a diet with 43% of their calories from carbohydrates and 24% from protein performed better than those receiving 30% of calories from carbohydrates and 37% from protein. In contrast, sled dogs, which engage in prolonged endurance activities, benefit from a diet higher in fat—up to 60% of their total energy intake—to sustain performance.
|
Type |
Intensity |
Duration |
|
Sled Dogs |
Moderate |
Long |
|
Racing Greyhounds |
High |
Short |
|
Working Farm Dogs |
Moderate |
Long |
|
Agility/FASTCAT |
High |
Short |
Fiber: A Critical but Overlooked Nutrient
Not all carbohydrates are fiber, and not all fibers act as prebiotics, but fiber plays a crucial role in overall health. Despite this, both the pet and human food industries often prioritize probiotics over addressing the root issue—insufficient fiber intake.
While probiotics can be beneficial, they do not permanently colonize the gut microbiome; they simply pass through. In contrast, fiber and prebiotics provide essential nourishment for beneficial gut bacteria, supporting long-term digestive health. Diets low in fiber can lead to the erosion of the colonic mucus barrier, the body's first line of defense in the gut. Yet, because probiotics are a popular trend, they are often emphasized over increasing fiber content in diets.
Although fiber will never be classified as an essential nutrient, it remains a vital dietary component—especially given that many dogs' gut microbiomes are still in a post-antibiotic state, requiring better support for long-term health.
A diverse gut microbiome is critical for overall well-being, yet most dogs' microbiomes are in a post-antibiotic state. While fiber may never be classified as essential, even though germ free mice often fail to reproduce, it remains vital for digestive and immune health.
Phytochemicals: Nature’s Bioactives
While beta-carotene is the most famous phytochemical, mostly due to its pro-vitamin A activity; A number of other phytochemicals can be beneficial.
There are other phytochemicals with significantly greater antioxidant capacity than beta carotene, and different phytochemicals have been found to positively influence a number of different pathways.
There are approximately 1100 carotenoids found in nature, and the current estimate is between 500,000 and 5,000,000 different phytochemicals in nature.
Some of these phytochemicals have been synthesized or modified in labs to be used as medicine i.e.. Aspirin (acetylsalicylic acid is Salicylic acid treated with acetic anhydride. Salicylic acid is found in many plants historically used for pain such as White Willow Bark, Meadowsweet, Thalecress among many others. Aspirin is far from the only example of medicines derived from compounds found in nature, whether that is from plants, algae, or bacteria, which means we should not be so quick to discount the benefits of different phytochemicals.
Now is Resveratrol the live-extending compound that some claim? Probably not. Are all phytochemicals going to have a substantial and immediate impact no, but that doesn’t mean they don’t positively influence health via different pathways.
Improving the Nutrient Guidelines
While there are changes AAFCO could realistically make right now to improve the nutrient guidelines i.e. Follow FEDIAF example by reducing the assumed energy consumption from 130 kcals per KG BW^.75 to 95 Kcals kb bw^.75.
At the end of the day, improving the guidelines has as much to do if not more to do with non-essential nutrients and compounds as it does with essential nutrients.