27/02/2024
🍚 🥯 🍕 Do Dogs NEED Carbs? 🍕🥯🍚
The short answer is, no.
The NRC guidelines state that there is no essential nutritional requirement for carbohydrates in the canine diet at any life stage.
However. The long answer is, not really….but…
➡️ Let’s discuss 😉
If we look at the biochemistry of a dog, they lack salivary amylase as an essential initial stage of carbohydrate digestion. I would like to argue whether salivary amylase would be overly beneficial as dogs don’t chew to grind their food, so regardless the pancreatic enzymes would be more heavily relied upon anyway. Dogs do have pancreatic enzymes, and since domestication they have more genes coding for this adaptation than their wild counterparts, the wolf. But. The fact that dogs don’t participate in much mechanical oral digestion of food which is really required for efficient raw plant matter digestion does also suggest that carbohydrate possibly aren’t a major essential nutrient within their diet.
Carbohydrates in general, specifically those with a high glycemic index, “simple carbs”, induce a spike in glucose levels in the blood. Insulin is released to bring levels back into balance, but in turn insulin has other impacts on the body, including promoting fat and energy storage rather than fat burning. This means that, even if you are calorie restricting your overweight or obese dog, they will struggle to move those extra kilos on a high carb diet.
Elevated glucose causes inflammation. Immune cells and inflammatory molecules in the blood, such as white blood cells and cytokines, work to instigate glucose breakdowns. Systemic, chronic inflammation in a holistic sense is the root cause of all disease, leading to tissue and organ degradation. Inflammatory conditions include but are not limited to skin issues, joint issues and gut issues.
Of the grains commonly used in commercial processed pet food (rice, corn, wheat, barley, sorghum), rice has the highest glycemic response. Glucose spikes = weight gain and inflammation. Due to the fibre and starch combination, brown rice will have a lessened blood glucose response than white rice. However. Brown rice contains more arsenic than white rice along with anti-nutrients phytic acid and lectins found in the bran. (Note: if you are choosing to feed rice of any sort, opt for white batsami or long grain rice (lower GI than sushi rice or medium grain rice) and soak overnight or wash with vinegar and water. This will reduce the arsenic by up to 80%).
A 2017 gut microbiome study on adult labradors and beagles, measured the impact of high carbohydrate / low protein diets compared to high protein / low carbohydrate diets. The impact of a high carbohydrate diet on the gut microbiome showed an increase in mainly Bacteroides uniformis and Clostridium butyricum species. Where as, a high protein diet instead favoured the colonisation and population of Clostridium hiranonis, Clostridium perfringens, and Ruminococcus gnavus and enriched microbial gene networks associated with weight maintenance. The high carbohydrate diet demonstrated a decreased diversity in microbiota, with the species present being generalised for carbohydrate fermentation rather than a variety of specialised microbes. Other than the impact on weight, which this study was measuring, a decrease in microbial diversity could also impact nutrient digestion and the gut’s ability to defend itself against pathogenic or opportunistic bacteria.
➡️ What role could carbohydrates possibly play in the diet of a facultative carnivore?
Carbohydrates ideally shouldn’t form the majority of the diet unless there is a specific disease, illness or need requiring this.
However there are nutritional benefits of foods that contain carbohydrates. Carbohydrates are not just sourced from grains, legumes and white potatoes. Brightly coloured and leafy green vegetables also have carbohydrate content, in varying degrees, in the form of cellulose and starch. Blueberries, bananas and apples contain carbohydrates in the form of cellulose, starch, disaccharides such as sucrose and monosaccharides like fructose. If we are eliminating these from our dogs’s diet, what health and nutritional benefits are we also eliminating?
Feeding brightly coloured vegetables and berries with a low carbohydrate content provide an array of both essential nutrients as well as antioxidants.
🥬 Leafy greens - Potassium, Magnesium, Calcium, Iron, Manganese, Vitamin A, Vitamin B6, Vitamin C, Vitamin K, flavonoid Kaempferol, antioxidant Lutein.
🥦 Broccoli - Vitamin A, Vitamin B6, Vitamin C, phytonutrient Sulforaphane.
🌶️ Bell peppers - Vitamin C, Antioxidant Beta-cryptoxanthin, flavonoid Anthocyanin.
🫐 Blueberries - Potassium, Manganese, Vitamin C, Vitamin K, flavonoid Anthocyanin.
🍇 Blackberries - Copper, Manganese, Vitamin C, Vitamin K, polyphenols Quercetin, Anthocyanin, and Cyanidin.
We should also be considering the place of more high carbohydrate, starchy vegetables in our dog’s diet. Pumpkin, sweet potato, carrot, beets and other root vegetables. Cooked and cooled white rice and white potatoes. Even garlic is almost 20% carbohydrate. These “high carb” ingredients have prebiotic benefits which when fed in appropriate quantities help boost the microbial diversity of the gut. The inclusion of prebiotic vegetables promotes the population of specific beneficial bacteria within the intestine.
🦠 Prevotella is a member of the Bacteroidetes phylum, which is found in greater numbers in the microbiota of animals who consume plants. This microbe breaks down complex carbohydrates within the gut, including tough plant fibers like xylan (found in grass) but also simple sugars like glucose. Promoting the population of Prevotella within the gut will not just assist with the digestion of plant material, but lack of this bacteria has a correlation with gastro intestinal disease in dogs.
🦠 Bifidobacterium, Lactobacillus, and Faecalibacterium are also fed using plant prebiotics. Their benefit is due to their role in carbohydrate fermentation, which produces butyrate. This short chain fatty acid improves the gut barrier, supports gut healing and reduces inflammation through providing an energy source for the colonocytes.
You can read more about high and low carb probiotics here 👇
https://www.facebook.com/share/fN4f8pdcV42mMwc4/?mibextid=WaXdOe
The NRC guidelines state that there is no essential nutritional requirement for carbohydrates in the canine diet at any life stage. Instead, the requirements for energy, protein, fat and nutrients change based on life stage. We can consider carbohydrates as an energy source, and there may be specific disease, condition or need in which a higher than “species appropriate” quantity of carbohydrates are provided.
During a transition period from a highly processed diet to a whole foods diet, higher quantities of appropriate carbohydrates may be beneficial. Diets that are low phosphorus for dogs with kidney disease or low purine also require a different balance of carbohydrates to protein compared to that of the average dog. Some dogs with GI issues benefit from more carbohydrates in their diet. A dog on a low fat, high protein diet should be provided with an alternate source of energy like beneficial carbohydrates to reduce the quantity of nitrogenous substances produced, like ammonia and urea, from protein metabolism.
Please note that the above relates to whole food carbohydrates. Highly processed carbohydrates in commercial dog food that has undergone extrusion may be marketed as being “highly digestible” and having “prebiotic potential”. However the formation of advanced glycation end products (AGEs) which occurs during the processing of these low quality carbs in dog food far out weights any marketed “benefits”. There is little to no nutritional properties of these carbohydrates and their only real purpose is to hold the little pellet of kibble together and contribute to the overall caloric content of the food.
Dogs do not have an essential requirement for carbohydrates. But I would like to argue that carbohydrates from appropriate sources have beneficial biological and nutritional impacts, and certainly have their place in the diet of today’s canines.
