Can Dogs Digest Carbohydrates?
In the world of nutrition, carbohydrates play a crucial role as one of the three main macronutrients alongside proteins and fats. But with the rise of grain-free and raw diets, there has been much controversy as to whether dogs should be eating carbs. In this article I will dive into the realm of carbohydrates, exploring what they are, the types that exist, and whether dogs can and/or should incorporate them into their diet.
What are Carbohydrates?
Carbohydrates are organic compounds made up of carbon, hydrogen, and oxygen atoms, and serve as a source of energy for the body. Energy, or calories, only come from protein, fat and carbohydrates, however carbohydrates are the brain's preferred energy currency. There are two main types of carbohydrates – simple and complex, which includes fiber. Let’s explore how these are different and which are best for dogs, if any.
Simple Carbohydrates
Simple carbohydrates include monosaccharides such as glucose and fructose, and disaccharides such as sucrose and lactose. Due to their simple structure, these carbohydrates are quickly broken down by the body into individual sugar molecules. As a result, they are rapidly absorbed into the bloodstream, leading to a rapid increase in blood sugar levels. Consuming foods high in simple carbohydrates can cause a rapid spike in blood sugar levels, followed by a quick decline. This rapid fluctuation may contribute to feelings of energy crashes and hunger. Simple carbohydrates are often found in processed and sugary foods, and excess simple carbohydrates are more likely to be converted into fat and stored in the body. These carbohydrates are rarely included in pet food.
Complex Carbohydrates
Complex carbohydrates are larger molecules made up of multiple sugar units. Oligosaccharides contain a small number of sugar units, and polysaccharides, such as starch and glycogen, consist of long chains of sugar molecules. The complex structure of these carbohydrates requires more time for digestion as enzymes must break down the long chains into individual sugar units, leading to a slower release of glucose into the bloodstream. Foods rich in complex carbohydrates lead to a more gradual and sustained increase in blood sugar levels. This provides a steady supply of energy over a more extended period. Whole grains, vegetables, and legumes, which are sources of complex carbohydrates, typically contain additional nutrients, such as vitamins, minerals, and fiber. These types of carbohydrates are stored as glycogen in the muscles and liver, providing a reserve of energy for the body. These are the types of carbohydrates more typically found in pet food.
Fiber
Fiber is a type of complex carbohydrate that is not easily digested by the body. Unlike other carbohydrates, fiber consists of long chains of sugar molecules that are bonded in a way that the body's digestive enzymes cannot break down. As a result, fiber passes through the digestive system relatively intact.
Once in the colon, fiber is broken down by microbial enzymes, providing a food source for the bacteria in the large intestine. Upon fermentation of the fiber, these bacteria produce short-chain fatty acids (SCFAs) that nourish intestinal cells, help maintain the normal intestinal electrolyte fluid balance and intestinal motility, ameliorate intestinal inflammation, and prevent the overgrowth of pathogenic bacteria. Maintaining a healthy gut flora and gut lining is important as they act as barriers from invasion by gut pathogens. In fact, imbalances in the gut microflora have been linked to diseases such as allergies and inflammatory bowel disease. Furthermore, fiber aids in managing diseases such as obesity, diabetes, diarrhea, and constipation.
Can Dogs Digest Carbohydrates?
Yes, dogs can digest carbohydrates. Dogs diverged from wolves over 15,000 years ago (that’s a long time ago!), and evolved alongside humans, eating their scraps which included grains, fruits, and vegetables. As humans shifted from hunter-gatherers to ones dominated by agriculture, starch became a larger part of their diet, and in turn, they had to become better at digesting starch. Amylase is the enzyme responsible for starch digestion. At the outset of the agricultural revolution, which took place sometime between 11,500 and 6,000 years ago in western Eurasia, the genes responsible for producing amylase in saliva for humans were copied many times over in response to this selective pressure.
A similar process occurred in the ancestors of dogs, although the time frame remains vague. Since they lived alongside humans, they too began consuming more starch, and duplication of a gene called AMY2B gene, which is responsible for pancreatic amylase production, occurred. Modern day dogs have developed many more copies of these genes making them functionally omnivorous and able to eat and properly digest more starchy foods.
Gray wolves only possess 2–8 copies of this gene, with 60% of wolves having only two copies. As we know they are primarily carnivorous and likely more similar to early domesticated dogs. Dogs on the other hand can have anywhere from 4–34 copies, suggesting that dogs have adapted to a starch-rich diet.
So yes, dogs can digest carbohydrates, and starch is a necessary component of kibble as it is necessary for extrusion.
Should Dogs Eat Carbohydrates?
While omnivores have an energy requirement, they do not have a carbohydrate requirement per se because they can also use protein and fat for energy. This is the basis for the argument many proponents of raw feeding and keto diets try to make. And this would be a valid argument if it weren’t for several very important points.
First, carbohydrates are the easiest forms of energy for the body to break down. If there are not enough carbohydrates to produce the necessary glucose, amino acids will be shunted away from muscle growth, for example, to be used for glucose synthesis.
Second, and along the same vein, the alternative to not feeding carbohydrates is increasing the protein or fat content of a food to meet the body’s energy requirement. Protein is not only expensive, but we are facing a climate crisis so adding more protein to a diet, when carbohydrates can play the same role, is irresponsible.
As for fats, a group of researchers published a study in 2022 that compared the inflammatory response of dogs fed a high-starch vs. a high-fat diet and found that starch digestion conferred benefits that the high-fat diet did not such as anti-oxidative effects (Lyu et al., 2022).
Third, fiber is important for both digestive health and proper immune function. As mentioned, fiber serves as food for the beneficial gut bacteria. The result, a healthy digestive system.
And fourth, fruits and vegetables, which are carbohydrate sources, are packed with nutrients such as vitamins and minerals.
So, why are carbohydrates villainized? Well, it’s because of simple carbohydrates. Simple carbohydrates include processed sugars such as table sugar, and refined grains which are those that have had their fibrous and nutritious parts removed, such as white flour. Rest assured, however, these are not generally included in commercially prepared dog foods.
A Special Note on Wheat
Although I have illustrated why carbohydrates are an important component of dog food, it is important to mention that a common starch used in dog food is wheat, which is the fourth most common dog food allergen, following beef, dairy and chicken. Wild Earth’s formulas are devoid of wheat as well as all top food allergens for dogs, making it a great choice for food allergic dogs.
Do Plant-based Kibble Diets Contain More Carbohydrates than Meat-Based Kibble Diets?
Not necessarily. Let’s compare Wild Earth’s Performance diet to some of the leading dog foods on the market:
Wild Earth Performance Formula contains 43% carbohydrates on a dry matter basis.
Blue Buffalo Life Protection Chicken and Brown Rice Recipe contains 44% carbohydrates on a dry matter basis.
Complex Carbohydrates are Best
All in all, when it comes to providing optimal nutrition for our canine companions, the role of carbohydrates cannot be overstated. As we've explored in this blog, complex carbohydrates stand out as the preferred source for sustained energy and overall well-being in dogs. From whole grains to vegetables, these nutrient-rich options offer a gradual release of energy, supporting a stable blood sugar level and promoting long-lasting vitality. While it's crucial to consider individual dietary needs and consult with veterinarians, embracing the benefits of complex carbohydrates can undoubtedly contribute to the health and happiness of our four-legged friends. By prioritizing a well-balanced diet that includes these valuable nutrients, we can ensure that our dogs thrive and lead fulfilling lives.
