Carbohydrates 2.0

 GOLD PAW MODULE 2

Calculating Carbohydrates

Unlike protein and fat levels that are calculated based on protein content in ingredients, carbohydrate level is typically not provided for each individual ingredient in pet food. As a result, the percentage of carbohydrate in the food is calculated by using the content of the main nutritional constituents in the food and subtracting from 100%.

%Carbohydrates = 100% - (% Protein + % Fat + % Fibre + % Moisture + % Ash)

For example, if the guaranteed analysis on a pet food reads as follows:
Protein (min):                  32%
Fat (min):                        17%
Moisture (max):               10%
Fibre (max):                     6%
Ash (max):                       6%

Using the above equation, the % carbohydrates is calculated as: 

%Carbohydrate           = 100% - (32 + 17 + 10 + 6 + 6)
                                   = 100% - 71%
                                   = 29%

It can be concluded that pet food in this example would have ~29% carbohydrate content.  This would be an approximate value, given that the guaranteed analysis is often listed as maximums and minimums and oftentimes the level of ash in the product may not be listed.  As a general rule of thumb, most kibble would contain an ash content of 6-8% and most canned food would contain 2-3%.  For accurate information you may need to contact the manufacturer directly.

Given we already know that cats do not require carbohydrates, and dogs do not require a large quantity, calculating the carbohydrate content can help you decide what food might most beneficial for your dog or cat.

DIABETIC PETS

We have learned in previous modules that carbohydrates are broken down into the basic unit of energy, glucose. With this in mind, it should be understandable that the carbohydrate content of a diet should be of upmost consideration in diabetic dogs and cats: as it is the nutrient with the greatest effect on blood sugar (glucose) levels. In these animals, a lessened glycemic response is preferable as lower fluctuations in blood sugar helps to mediate the effects of diabetes and many corresponding complications.

GLYCEMIC INDEX

The glycemic index (GI) is a ranking system that associates a number to foods based on the speed at which they affect blood sugar levels. As a general rule of thumb, complex carbohydrates, such as starches, have a lower glycemic index rating than the more simplistic versions, such as sugars. This is because they require more time for digestion and absorption, releasing sugar into the blood stream more slowly.

Typically, foods with GI values below 55 are considered to be low GI, 56-69 is mid-range, and greater than 70 is considered high.  Examples of carbohydrates and their GI classification in dogs are as follows:

*adapted from Carciofi et al. 2008 Effects of six carbohydrate sources on dog diet digestibility and post-prandial glucose and insulin response
** Glycemic index data adapted from www.nutritiondata.com

Additionally, the ability of a dog to digest these particular carbohydrate sources must play into the dialogue. If the food is not digestible, it is passed as fibre and may not be as beneficial as a carbohydrate source that is used by the pet. Let’s take the above table and add in the digestibility percentages:

The tables turn when Many grains, in unprocessed whole grain form are just as, if not more digestible with a lower GI than many grain-free options, such as the potato, lentils and peas listed above. Grains are processed into their various constituents, such as gluten meals, starches, etc. Processed grains can affect blood sugar differently than whole grains. Considering the GI of ingredients in a food can be beneficial for pets, especially those that are overweight or diabetic.

QUANTITY

We have already learned about the role of carbohydrates in the diets of pets, how to calculate carbohydrate content in animal feeds, the special considerations of diabetic pets and how carbohydrates affect blood sugar by measure of glycemic index. All of these should be taken into consideration when selecting a food for your pet. For optimal health, it might be better that a food that lists meat as it’s first and possibly second ingredients rather than a carbohydrate source, such as corn or wheat. Although dogs are better equipped to digest carbohydrates, the same considerations should be made for dogs.