Evidenced Based Medicine
Ever hear the saying “you are what you eat?” It is a very simple statement with a lot of truth behind it. It applies, not only to your pet’s physical well being, but to its mental health as well. The pet food industry is an extremely competitive market. It is estimated that Americans spend 17.4 BILLION dollars a year on pet food. With this amount of money being spent, it’s no wonder why companies are trying desperately to convince you that their product is the best. Some of the claims out there are true, some are outright false, and some are purposely meant to deceive you. I will do my best to clear things up.
First, lets start with a little background. Definitions and statistics can be a bit boring, so please bear with me. I’d like to talk about the quality of information (see page 2 of the link) that we come across (that we are bombarded with would actually be more accurate). Lets start at the bottom, Category 4. Category 4 information is the weakest category. It includes research from other species, pathophysiological rationales such as basing decisions on basic scientific information without experiments to prove its validity, and research performed in a non-live animal model like test tubes and cultures in a laboratory setting. Also included in this category are the opinions of others, such as friends, relatives, people who have “had dogs that lived to be 30 years old and ate table food all their lives,” and the 18 year old kid that works at your local pet store. Just because you hear something from someone you like, love, or trust, does not make that information accurate.
The next category would be Category 3. This category includes case reports (detailed report of the symptoms, signs, diagnosis, treatment, and follow-up of an individual patient), case series (medical research that tracks patients with a known exposure that are given similar treatments and the outcomes are examined), and models of disease (comparing a disease in humans to the same or similar disease in animals). This is where a significant amount of veterinary evidence comes from.
Category 2 information includes epidemiological studies like cohort (an analysis of risk factors), cross-sectional and case control studies. These are studies of groups of people and they analyze how they respond to various changes.
Category 1 is the best, and the strongest form of evidence we can gather, the double blind study. A double blind study is an experiment that tests a hypothesis. The person who collects the information has no idea which subject received which treatment, and neither do the test subjects.
So, what does all this boring stuff mean? Let me give you an example, say a food company tells you that their food is the best because it is as close to a wolves diet that can be replicated. Their platform is that dogs are descended from wolves, and we believe them. By the way, dogs were domesticated of 15,000-50,000 years ago, and medical knowledge doubles at a rate of every 8 years, A LOT has changed over those 15,000-50,000 years :-). This is category 4 evidence. This is opinion based and it is based on another species.
Okay, say you read an article in Dog Fancy that says food X is what you need to feed because it made a certain number of dogs have a shiny coat. This is Category 3 based evidence, a case history. Remember, this is where most of our information in veterinary medicine comes from.
Now, say you come across an article that says an experiment was done on 500 dogs and they were all fed the same diet over the past 4 years. Over that time span, a certain percentage of them developed disease X while eating this food. This is Category 2 evidence and there is a much stronger link of cause to effect than in Categories 3 and 4.
Category 1, the double blind study, is the gold standard, but is expensive to perform and therefore is not always accomplished. An example would be if you were to take 100 dogs with dental disease and feed half of them diet X and the other half diet Y over a period of one year. Obviously the dogs will not know which food they are eating, but neither do the people who are judging tartar reduction or build up. There is no bias or opinion in this, just fact. Is there more or less tartar than when we started and which food was better? Hopefully this would carry more weight than a cleverly put together TV commercial with lots of fancy words like “holistic” or “all natural.”
Carnivore – An animal subsisting primarily on animal tissue.
Herbivore – An animal subsisting primarily on plant tissue
Omnivore – An animal subsisting on both animal and plant tissue.
Dogs are omnivores, but cats are true carnivores. Cats do not need ANY carbohydrates in their diets. Most dry foods out there are between 30-50% carbohydrates. No cat should ever be fed dry food ( the exception to this rule is prescription Hills M/D and Purina DM ).
Organic – Grown with only animal or vegetable fertilizers, such as manure, bone meal, compost, etc. According to the United States Department of Agriculture (USDA) and Agriculture and Agri-Food Canada (AAFC) rules, the term “organic” may only be applied to pet food labels that meet regulations.
Natural – 1) of or arising from nature; in accordance with what is found or expected in nature. 2) Produced or existing in nature; not artificial or manufactured. According to the Association of American Feed Control Officials (AAFCO), the term “natural” requires a pet food to consist of only natural ingredients without chemicals.
Holistic – There is no legal definition of this term under laws devoted to pet foods. Any manufacturer can make claims of “holistic” in literature and brochures regardless of ingredients chosen.
MYTH – Natural means organic. The terms are not interchangeable. Other truthful claims, such as free-range, hormone-free, and natural, can still appear on food labels. However, do not confuse these terms with “organic.” Only food labeled “organic products” has been certified as organic in accordance with USDA and AAFCO regulations.
Under the new regulations, four categories were created for the term “organic”:
- 100 Percent Organic – May carry the new USDA Organic Seal.
- Organic – At least 95% of the content is organic by weight (excluding salt and water) and may carry the new USDA Organic Seal.
- Made with Organic – At least 70% of the content is organic and the front product panel may display the phrase “Made with Organic” followed by up to three specific ingredients. This product cannot carry the USDA Organic Seal.
- Category 4 – Less than 70% of the content is organic and may list only those ingredients that are organic on the ingredient panel with no mention of organic on the main panel. This product cannot carry the USDA Organic Seal.
By-Products – Secondary products produced in addition to the principle product.
MYTH – Pet foods containing ingredients listed as by-products are inferior.
By-products are common ingredients in both human and pet food. A by-product is simply something produced in the making of something else. Common examples include:
- Vitamin E – A by-product of soybean processing.
- Vegetable Oils – Flaxseed oil, corn oil, and soy oil are all by-products extracted from the seeds that are processed for consumption purposes. Fish oil is also a by-product.
- Chicken Fat – A by-product of the chicken industry.
- Mixed Tocopherols – These are a by-product of the soybean industry and are used as natural preservatives of food.
- Pork, Beef, and Chicken Livers
- Beet Pulp
- Tomato Pomace
- Beef and Chicken Bouillon
Preservatives – Having the quality of preserving, e.g. a substance added to a food to keep it from spoiling.
- Natural preservatives include tocopherols (Vitamin E), spice extracts, and citric acid
- Antioxidant preservatives function to stabilize fats and fat-soluble vitamins against oxidation, which leads to rancidity and loss of nutritional value.
- BHA and BHT are examples of synthetic antioxidant preservatives. Many human foods, such as bread, cheese, margarine, potato chips, meat, and frozen and dried fruits contain BHA and BHT.
Pet Food Labels
Pet food labels can be very “misleading.” I put misleading in quotes because of the way companies market their ingredients. They are intentionally deceptive in their marketing. I will get to how the deception occurs, but for now, lets talk about the government’s role in the pet food label. The government regulates information on the label, therefore there are things that can and cannot be on the label. These regulations have absolutely NOTHING to do with advertisements and marketing campaigns.
The first thing you need to look for is the AAFCO statement. AAFCO is the Association of American Feed Control Officials and is a voluntary membership association of local, state, and federal agencies that regulate the sale and distribution of animal foods and drugs. They define the ingredients and the nutritional requirements for pet foods. While this may seem like a good thing, and for the most part it is, their nutritional guidelines have not changed since 1985 when the organization was first founded. Medical knowledge doubles at a rate of every 8 years. It’s time for an upgrade. Every container of pet food will have an AAFCO statement and the wording is strictly regulated. Foods are formulated to meet AAFCO standards for a specific life stage, or for multiple life stages, i.e. puppy, adult, or senior.
The best way to figure all this out, on the food company side, is to perform a feeding trial (Category 1 info). If the food is tested in this manner, it will say so on the AAFCO label, and by the way, there are only 2 companies of the hundreds of companies out there that do this, Hill’s and Purina. AFFCO food trails require that pets need to be fed a diet for 26 weeks (6.5 months). The company must show that the animals that are fed diet X are growing and doing well on the diet. There are foods out there that do not meet AAFCO standards.
The next part of the label that is of importance is the ingredient list. Ingredients are put on the label in order of weight with the ingredient weighing the most being first on the list. This is where the manipulation of the consumer (you) comes into play. For example, companies would have you believe that if chicken is listed first on the list that it is the “main ingredient.’ However, the ingredient list is weighed BEFORE processing. That means before the water weight is removed. All meat, chicken, beef, lamb, fish, whatever, is 75-80% water! If you remove the water weight, all of a sudden that ingredient slides way down on the list and, more than likely, the carb source will really be what’s first on the list. The only difference between chicken and chicken meal is that the water has been removed from the chicken before processing with chicken meal. So if chicken meal is the first ingredient you truly have a food that has a protein source as it’s first ingredient and it is likely of higher quality than a food with chicken as the first ingredient (the rest of the ingredient list is important).
The last thing to look at on the label is the guaranteed analysis. This will list the protein, fat, moisture, and fiber content of the food. Add these numbers and subtract from 100 to get the carb content. The carb content of most diets is almost the same at about 30%, no matter what the first ingredient on the list is.
The food label is a legal document; therefore all ingredients have a legal definition. Take the term ‘organic” for example. The legal definition of organic is foods that are produced using methods that do not involve modern synthetic inputs such as synthetic pesticides and chemical fertilizers, do not contain genetically modified organisms, and are not processed using radiation, industrial solvents, or chemical food additives. Any food company can put that word on the bag or can and be perfectly within their legal right to do so. However, unless the label, not the bag, has a USDA organic seal, the ingredient may not really be organic at all. It is very difficult to formulate an entire diet from organic ingredients because they are expensive and difficult to come by. So even if the meat in the diet is organic, it is likely that the rest of the ingredients are not.
For an ingredient to be considered organic, it must come from a USDA inspected source. This means that animals that come into a USDA slaughterhouse for human consumption are killed and their carcass is broken down. The human food goes one way, and the pet food ingredients go another. For an ingredient in a pet food diet to be considered “human grade” it cannot leave the USDA distribution chain until it reaches your home. That means a USDA inspected slaughterhouse, packing plant, transportation system, manufacturer, and distributor. This simply does not happen. So if you see this claim on a package of food, it is an outright lie.
There is a class of animal food protein source that falls below the USDA standards. For an animal to be inspected at a USDA facility, it must be able to walk. Cows, for example, that are too ill to walk are called Triple D cows, which stands for diseased, down, or dead. A renderer can buy these cows and then sell them to be used in pet foods. This is perfectly legal, so the company you choose is very important. Reputable companies get their ingredients from reputable sources, not form renderers.
Now that we’ve gotten all the boring legal and terminology aspects covered, let’s talk about specific ingredients. Think about this logically, say chicken is the first ingredient on the list, do you really think that a whole chicken or just the chicken breast is what goes into that food? The Blue Buffalo commercial (I’m not suggesting that Blue is bad, it’s not) that is out at the moment comes to mind. They show a whole chicken being washed under a faucet while talking about the ingredients that go into their food. That is an outright lie and is intentionally presented in a way as to deceive you. Beef is an even better example. Think about how expensive a good cut of beef is. Do you really think that a filet, rib eye, or brisket cut is what is used in pet foods? Pet food companies would certainly have you believe so, but it’s just not true. Remember the USDA slaughterhouse where human food goes one way and pet food goes another? What goes to the pet food side are the cuts, trimming would actually be more accurate, that are not consumed by humans. Very few people would be able to afford pet foods made with the best cuts of meat and producers would make far less money if they sold these cuts to food companies. This is the simple truth.
So, what exactly goes into pet foods as far as meat is concerned? Meat is legally defined as striated muscle (filet mignon, rib eye, chicken breast, etc..) tongue, esophagus, and diaphragm. These are all good sources of protein, just not what we (some of us anyway) typically think of as appetizing.
Anything left over after the meat is removed is called a by-product. Today’s marketing gurus would have you believe that by-products are the devil, but that is not the case. By-products, when talking about pet foods, includes the intestines, skin, organs, and in the case of chickens, feet, and rib bones. Intestines are made of smooth muscle and are, on a cellular level, just as good as striated muscle as far as nutrition goes. Organ meat is also very nutritious.
When you see chicken as the first ingredient, it is not the entire chicken, or even the chicken breast. Those go to the human side of the house. The AAFCO definition of chicken is “the clean combination of flesh and skin with or without accompanying bone, derived from the parts or whole carcasses of chicken or a combination thereof, exclusive of feathers, heads, feet, and entrails. Basically, it’s what is left over after the human food is removed, the rib cage and whatever meat is left over (stuck to the ribs) after the breast is removed. So, I ask you, what is more nutritious? The little bit of meat that’s left over after processing, or the “by-products”?
Another note on by-products is that they can, and do, vary in quality. The way to tell is by looking at the ash content, 5% is acceptable. Ash in a pet food comes from bones, both in the chicken feet and ribs/breast bone. Food made with by-products that has a high ash content has a lot of feet and ribs and is not of good quality.
Remember the water weight issue? If the water weight is not remove before processing the protein source will surely be first on the ingredient list. If the water weight is removed from the protein source before processing, it is known as meal. So, if you see chicken meal, or chicken by-product meal as the first ingredient you have a food truly has a protein source as it’s first ingredient. Plus, if chicken (without any bones) is the first ingredient, bone, more more like bone meal, will have to be added because this is an important source of minerals in the diet.
Lets talk about fat and fiber next. Fat can be derived from animals (saturated fats) or plants and they provide an excellent source of energy in your pets diet. They also provide the important vitamins A, D, K, and E. Also, fat tastes good! So it plays an important role in palatability (acceptable taste). While fat does all these good things, it does have a down side. Too much fat will cause your pet to become overweight or obese (so will too many unused calories from carbs and protein). Obesity in pets carries all of the same detrimental health issues that it does in people. Fat will also spoil easily and needs to be preserved. Historically this has been done with 2 chemicals, BHT and BHA. Neither of them is very healthy as they are known to cause cancer, but they are cheap. Today, tocopherols, which are natural antioxidants and a source of vitamin E, are used in many foods as a preservative. Foods preserved with tocopherols have a shorter shelf life, but are usually of much higher quality.
Fiber is an important component of a diet. Fiber can be soluble or insoluble and is derived from plants. Rice millings, grain hulls, (wheat, corn, rice), bran, peanut hulls, and beet pulp are examples. They help to regulate glucose uptake, provide an important source of pre-biotics (healthy GI bacteria that aid in digestion), and helps maintain normal gut motility. It also helps our pets, and us, feel full.
And last, but certainly not least, lets talk about carbohydrates. This includes all grain sources, like corn, barley, oats, and rice, as well as potatoes. It is not possible to make dry foods without them (except for a couple prescription diets that use soy instead). Carbohydrates are what cause the kibble to stick together and it would be impossible (for dogs) to have a nutritionally balanced diet without a carbohydrate source. Cats are carnivores and they do not need ANY carbohydrates in their diets. 35-50% of most pet food calories come from a carbohydrates source. These are commonly referred to as “filers”, but they are anything but. They are an important source of energy in any diet (except for cats, of course).
Corn has been in the media a good bit and many people feel that it is a bad ingredient to have in pet food. There are numerous claims about why it is bad, one of which is that it is poorly digested. This is true if you, or your pet, were to swallow a whole kernel. However, if you chew the kernel, it is actually highly digestible. Most diets contain cornmeal (remember what meal means, think powered) or corn gluten meal. These forms of corn are highly digestible. Corn should not be the first ingredient on the list, but having it in the diet is not a bad thing. Another claim is that of allergies. Dogs and cats, as well as people, are MUCH MORE likely to develop allergies to a protein, rather than to a carbohydrate. Gluten, corn or wheat, is the protein component of these grains. It is extracted from these grains and is much more concentrated than how nature originally created it. When you see corn gluten on an ingredient list, it is there as a protein source, not a carb source. This is why some people have trouble eating gluten, because it is protein! If an individual does not have an allergy to gluten, it is nutritious and is not a bad thing to have in a diet.
Now the big question, what food do I feed my dogs and cats and what foods do I recommend. I feed my dogs Science Diet Healthy Advantage and my cats Hill’s M/D dry (this is one of the foods that uses soy vs corn to hold the kibble together). There are MANY foods out there that are considered premium foods, here are a few: Eukanuba, Royal Canin, Blue Buffalo, certain lines of Science Diet (Healthy Advantage and Ideal Balance), Innova, EVO, Canine Caviar, Wellness, Solid Gold, and Eagle Pack. There are many others. A general rule of thumb is pricing. If you are looking at a food that is in the same price range as the above-mentioned foods, chances are it is a good food.
So there you have it, the truth about pet food diets. This is a highly competitive market and the companies that make these foods will try very hard to convince you to buy their product. As with any other purchase, buyers beware. The most dangerous thing to many of these companies is an educated consumer. Now you know the truth about pet foods. Armed with this knowledge, you will be much more able to sift through all the marketing and manipulation.