Protein, carbohydrates, and fat, the three macronutrients in a dog’s diet, all provide energy to the body. However, there is no requirement for carbohydrates for dogs. Yet, most commercial dog food is relatively high in carbohydrates compared to the ancestral diet of fresh food, leading many dog lovers to switch to raw or homemade diet plans.

Human evolution was shaped by diets primarily composed of 65-75% fat, 20% protein, and 5-10% carbohydrates. The introduction of refined carbohydrates, a relatively recent occurrence over the last two centuries, has impacted both human and canine nutrition.

It's crucial to recognize that fiber, while technically a carbohydrate, does not convert into sugar during digestion. Instead, it undergoes fermentation by the gut microbiome, offering digestive benefits and falling outside the conventional "carbohydrates" category. Fiber's role in promoting a healthy gut microbiome is well-established.

Consuming a diet rich in refined carbohydrates has been linked to various health issues, including cancer, obesity, diabetes, and heart disease. Furthermore, their addictive qualities are due to the release of endorphins, acting as painkillers and providing pleasurable sensations within the body.

Nonetheless, carbohydrates are not inherently detrimental to human or canine health when consumed in moderation. They can serve as a rapid energy source, offering an extra boost when needed. The key lies in their occasional use, rather than constituting a primary dietary component.

While humans have the flexibility to consume both plant and animal-based foods, leading to diverse dietary trends such as paleo, keto, and Mediterranean diets, dogs are facultative carnivores, inclined toward a meat-based diet. Dogs do not have specific dietary requirements for carbohydrates and derive energy more efficiently from fats and proteins.

The prevalence of carbohydrate-rich kibble in commercial dog food is influenced by economic factors and the necessity for ingredient cohesion. This process, known as encapsulation or agglomeration, enables kibble to be molded into small, bite-sized forms. Carbohydrates are favored for this purpose due to their cost-effectiveness and binding properties, making them a common choice in dog food manufacturing.

The glycemic index (GI) of a carbohydrate serves as a measure of its rate of digestion and subsequent entry into the bloodstream. Foods with a higher GI tend to elevate blood sugar and insulin levels more rapidly.

However, it's important to recognize that the GI provides only a partial picture. It does not consider the carbohydrate's quality or the quantity consumed in a single serving, both of which can have health implications if not carefully managed. Rather, it solely indicates how quickly a food impacts blood sugar levels.

A low GI signifies that a high-quality carbohydrate is digested slowly over time, avoiding blood sugar spikes. Nevertheless, a food may possess a low GI but still be detrimental to overall health if it contains excessive sugar and refined starches, as seen in products like white bread or pasta. Consequently, consumption of such foods can result in an initial insulin surge followed by a subsequent crash within a few hours, even if they appear to have fewer grams of digestible carbohydrates compared to nutritionally deficient options like sugary breakfast cereals.

In most plant-based diets, carbohydrates can be obtained and provide a quick source of energy. Carbohydrates are derived from plants that contain a variety of sugars (varying glycemic index) and fibers (useful for digestive health). Although your dog's body needs fiber and phytochemicals for optimal health, they don't need sugar or starch within their diet. 

Simple and complex carbohydrates share several similarities, but they also exhibit distinct characteristics. Notably, simple carbohydrates are swiftly absorbed by a dog's body, while complex carbohydrates undergo a slower absorption process.

Both categories of carbohydrates serve as sources of energy for dogs, primarily in the form of glucose, which is vital for cellular functioning.

However, when a dog consumes simple carbohydrates, these are rapidly converted into glucose, leading to pronounced spikes in blood sugar levels, a phenomenon referred to as "spiking" or "sugar spiking." In response to this rapid surge in blood glucose, the dog's body releases insulin to restore equilibrium. Consequently, the ingestion of simple carbohydrates prompts a more significant release of insulin compared to the consumption of complex carbohydrates.

Complex carbohydrates present a contrast as they necessitate an extended period for enzymatic breakdown within the digestive system. Even after the breakdown process, the absorption into the bloodstream is a slower and more gradual process compared to the rapid uptake associated with simple carbohydrates.

Monosaccharides, or simple carbohydrates, are divided into three categories:

Glucose: Glucose is produced by plants through the process of photosynthesis. All fruits and vegetables contain glucose stored in the plant's cell walls. A large portion of the plant's glucose is used to produce other carbohydrates, such as starch and fiber.

Fructose: Fructose is the sweetest carbohydrate. Plants produce fructose to entice insects and other species that help with pollination and reproduction. Animals consume the fruit, excrete the seeds in their waste, and those seeds eventually sprout into new plants.

Galactose: Galactose is found in dairy products. However, it is frequently combined with glucose to form a disaccharide. Food rarely contains galactose in its monosaccharide form.

Disaccharides Contain Two Sugar Molecules

Disaccharides are the second type of simple carbohydrate. Only two sugar molecules are linked together in their chemical structure. Disaccharides are divided into three categories:

Maltose: Two glucose molecules that have been joined together make up maltose. It does not naturally occur in foods, with the exception of cereals that have been sprouted. As grains sprout, their starches degrade and produce maltose.

Sucrose: One fructose molecule and one glucose molecule are combined to form sucrose. Like with fructose, plants produce sucrose to attract insects and other animals to eat the fruit and help in the seeding of new plants.

Lactose: One glucose molecule and one galactose molecule are joined to create lactose, sometimes known as "milk sugar." This kind of carbohydrate is only found in dairy products, which are the only animal-based foods that contain this type of carbohydrate.

Polysaccharides are a term used to describe complex carbohydrates that comprise several sugar units. The following are complex carbohydrates:

Since plants manufacture starch to store glucose, it functions as the storage form of carbohydrates in plants.  To provide energy for development and reproduction, starch is more prevalent in plants' roots and tubers.

In order for the body to be able to use starchy foods as an energy source, the starch molecules must be effectively broken down during the boiling process. Unless adequately cooked, starchy meals will not break down enzymatically and will instead ferment in the colon (similar to fiber fermentation).

Cooked carbohydrates are digested using enzymes after consumption to produce glucose for energy.

All animals store extra carbs as glycogen, which can be used as an energy source when necessary, in their liver and skeletal muscles. Although extra carbohydrates are kept in skeletal muscle, raw muscle meat does not contain them since they are broken down right away when the animal is killed.

Soluble fiber: Soluble fiber disintegrates in water and transforms into a gel-like substance. When stools are loose, soluble fiber is known to help regulate blood sugar levels.

Insoluble Fiber: Insoluble fiber gives feces volume and does not dissolve in water. By consuming more insoluble fiber, it is possible to reduce the frequency of bowel movements, irregular stool consistency, and constipation.

Processed foods, like kibble for dogs, use things like sugar, fat, and salt to make them last longer on the shelf. They also add stuff like flavor enhancers, thickeners, artificial colors, and other things to keep them fresh for a while. Sometimes, they even spritz used restaurant grease on kibble to make it taste better.

While dogs can survive on kibble, it's like eating fast food all the time. It's not the healthiest choice. According to a global food standard called NOVA, kibble falls into the same category as human junk food, ultra-processed. So, when dogs eat kibble regularly, it's like having junk food for every meal.

Remember, dogs don't really need carbs (except for fiber), but many dog food brands add them anyway. Even people who prefer to feed their dogs raw food often end up including carbs from vegetables to meet some basic nutritional guidelines.

Digestion and Absorption of Carbohydrates

In most species, the digestion of carbohydrates begins in the dog’s mouth with the digestion enzyme amylase. However, dogs lack saliva amylase, so carbohydrate digestion does not occur until the small intestines. The starches and simple sugars are primarily digested and absorbed in the small intestine.  

Most of the starches and simple sugars are digested by the amylase that is secreted by the pancreas. Additional enzymes within the small intestinal mucosal brush border aid in the final stages of carbohydrate digestion and absorption. 

If the body cannot fully digest all carbohydrates, they collect in the lumen of the small intestine, resulting in reduced water and mineral absorption due to an increase in the osmotic pressure. Excessive fermentation can also occur, leading to bacterial overgrowth, diarrhea, flatulence, and abdominal distention. A simple way to diagnose carbohydrate intolerance is a breath hydrogen analysis, as the increased gas production will cause an increase in the breath hydrogen level.	

There is no carbohydrate requirement for our dogs, but commercial kibble continues to incorporate up to 60% carbs in the diet.

Fiber is commonly excluded from the ‘bad carbs’ discussion and can be beneficial when handling diarrhea and constipation issues. 

Fiber can help maintain a healthy gut microbiome.

Habib, Rodney; Becker, Karen Shaw.  (2021). The Forever Dog. HarperCollins. Kindle Edition. 

Brady, C. (2020). Feeding dogs dry or raw? The science behind the debate. Farrow Road Publishing.

Small Animal Clinical Nutrition, 5th Edition 

Treatment of chronic idiopathic large-bowel diarrhea in dogs with a highly digestible diet and soluble fiber: a retrospective review of 37 cases 

Evaluation of the effect of dietary vegetable consumption on reducing risk of transitional cell carcinoma of the urinary bladder in Scottish Terriers 

FDA Investigation into Potential Link between Certain Diets and Canine Dilated Cardiomyopathy 

National Research Council of the National Academy of Sciences, "Nutrient Requirements of Dogs and Cats", 2006 Edition, National Academies Press, Washington, DC.

Death by Carbs: Added Sugars and Refined Carbohydrates Cause Diabetes and Cardiovascular Disease in Asian Indians - PMC 

Carbotoxicity—Noxious Effects of Carbohydrates - PMC 

Protein, <a href="https://feedreal.com/glossary/carbohydrates">carbohydrates</a>, and fat, the three macronutrients in a dog’s diet, all provide <a href="https://feedreal.com/glossary/adenosine-triphosphate">energy</a> to the body. However, there is no requirement for carbohydrates for dogs. Yet, most commercial dog food is relatively high in carbohydrates compared to the ancestral diet of fresh food, leading many dog lovers to switch to raw or homemade diet plans.

The Truth About Carbohydrates

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