Debunking common pet food myths - Part 1: The ingredients list

On any given day as a veterinarian, I am confronted with recurring questions and often determined (but scientifically questionable) statements from well-meaning pet owners. The vast majority of these discussions center around pet nutrition. Pet nutrition is such a heated subject that I will admit to sometimes avoiding engaging in further nutritional discussions and education with clients because I may not have the time or because I am easily discouraged. It can be overwhelming trying (and often failing) to constantly compete with opinions and poorly-sourced information found on the World Wide Web. Pet owners love their furry companions and one way to express their love is through food. Naturally, most owners want to feed their pets the “best” and many have strong opinions about which brands and ingredients are “best”. My goal for this series of nutrition articles is to address the most common myths and misconceptions regarding pet nutrition.

Before launching into these myths, I feel the need to provide some basic information about nutrition. All animals require essential nutrients from their diet in order to sustain long and healthy lives. Macronutrients (proteins, carbohydrates and fats that provide calories) and micronutrients (vitamins and minerals) must be present in the correct amounts and proportions to create a complete and balanced diet. Proteins are made up of amino acid building blocks, and are provided by both plant and animal sources in pet foods. When additional protein is ingested beyond the nutritional needs of an animal, it is metabolized and excreted by the kidneys. Fats are made up of fatty acid building blocks, and are essential to health and energy storage within the body. Excess ingested fat remains stored within an animal’s body (contributing to obesity and other chronic diseases) and can cause gastrointestinal illnesses. Although carbohydrates are not essential sources of calories in cats and dogs, they are well tolerated and allow for lower fat, lower calorie, and higher fiber diets. Only small amounts of extra carbs can be stored in the liver during shorts periods of fasting.

The Association of American Feed Control Officials (AAFCO) provides guidelines for pet food composition, with the goal of minimizing the risk of malnutrition in pets. If pet food manufacturers choose to follow AAFCO recommendations, they can indicate so on the product label. Although AAFCO creates minimum standards for pet food labeling and feeding trials, many board-certified veterinary nutritionists recommend that pet food companies provide testing above and beyond these minimum AAFCO trials. AAFCO does not regulate pet food adequacy or safety. In fact, in Canada, the pet food industry remains unregulated. This means that in Canada, it is up to the pet food manufacturers, not the CFIA, to issue voluntary recalls.

December 7, 2018 Canada’s unregulated pet food industry

Armed with some basic pet nutrition knowledge, we are ready to dive into some common myths!

The ingredients list on my cat’s Hill’s TD diet

Pet Nutrition Myth #1: Using the ingredients list to choose a pet food

The majority of pet owners choose a pet food based on the ingredient list. According to board-certified veterinary nutritionists, here are some reasons why this is one of the worst ways to judge the quality of a pet food!

ingredients are listed in order by weight from heaviest to lightest. Ingredients high in water content (meat and vegetables) will be listed before other dry ingredients despite potentially contributing fewer nutrients to the diet. For example, a diet with chicken (over 70% water content) listed as the first ingredient may have less actual chicken than a diet made with chicken-meal (less than 10% water content) that is listed as the second or thirst ingredient.
some manufacturers add ingredients to the diet purely as a marketing strategy. Such ingredients have unfounded benefits and may be found in tiny amounts. A perfect example is a diet advertising a whole food such as blueberries, where the blueberries are listed after the vitamins and minerals (this would mean that there are less than a few grams of blueberries per pound of food).
some manufacturers describe individual ingredients as “human grade”. First of all, there is no evidence to suggest that human grade ingredients are always more nutritious or safe than those destined for pet food. Secondly, once an ingredient is going into a pet food, it is automatically no longer “human grade” (unless the pet food is manufactured in a human food processing plant - which doesn’t happen - and unless the ingredient never leaves the human food chain - by going into pet food, it will leave the human food chain). So, the unregulated term, “human grade”, as it relates to pet food ingredients, is another marketing strategy.
the ingredients list does not provide any information about the quality of the ingredients or the nutritional composition of the diet. I will explore this idea in subsequent nutrition articles, using specific ingredients as examples.

While the ingredients list doesn’t give us information to judge the quality of a pet food, it can provide some important insights:

some commercial diets don’t contain enough ingredients to be truly complete and balanced. For example, a diet listing various meats, animal organs, and carbohydrates (ie. no supplemental vitamins and minerals) is not sufficient. Be ware of diets that do not list vitamins and minerals in addition to other essential nutrients.
the term, “100% natural” on a food label should be a red flag. Most vitamins and minerals are synthetic, so if a diet is truly “100% natural”, it is most certainly not complete and balanced.

If scanning the ingredients list isn’t helpful in gauging the quality of a pet food, how should owners be choosing the best food for their beloved pets? The World Small Animal Veterinary Association (WSAVA) has created several recommendations for gathering useful information to select pet foods.

The first piece of information is provided on the pet food label:

All pet foods sold in Canada and the US must have a nutritional adequacy statement written on the label, which provides the following information:

Whether the diet is complete and balanced according to AFFCO guidelines
How the company determined that the food is complete and balanced (by formulation and/or by feeding trials)
The life stage that the diet is appropriate for

A reputable pet food company should also provide the following information to its customers, upon request:

employment of a full time qualified nutritionist (PhD in animal nutrition or board-certified veterinary nutritionist)
who formulates the diets and a list of their credentials
location of food production and manufacturing
whether the diets are tested with AAFCO feedings trials or by formulation to meet AAFCO nutrient profiles. If the formulation method is used, is the finished product analysed?
details of quality control measures used to ensure consistency and quality of ingredients and of the end product
a complete nutrient analysis of the diet (not just the guaranteed analysis, which only indicates minimums and maximums). Each nutrient should be accounted for in grams per 100 kilocalories or grams per 1000 kilocalories rather than on an “as fed” or “dry matter” basis, which doesn’t account for different energy densities of different foods
calorie content per gram, can, or cup of the diet
product research with results published in peer-reviewed scientific journals

If the above information cannot be obtained from the pet food company, owners should be cautious about purchasing the brand. Choosing the right pet food can be an overwhelming experience for owners. In addition to the infinite options of commercial diets found at pet stores, supermarkets and veterinary clinics, owners are exposed to a constant barrage of unfounded opinions, myths, dietary fads and marketing ploys. Stay tuned for future articles that will continue to probe and debunk pet nutrition myths so that owners can base their pet food choices on facts not fluff.

Sources:

Association of American Feed Control Officials website: https://www.aafco.org/Consumers

Cummings Veterinary Medical Center at Tufts: Clinical Nutrition Service and Petfoodology website: https://www.vetnutrition.tufts.edu/petfoodology/

World Small Animal Veterinary Association Nutrition Toolkit: https://www.wsava.org/nutrition-toolkit