COMMON NUTRITIONAL MYTHS, PART II
Nutrition oriented questions are some of the most common ones that I get or discuss in general practice. Last month we covered two common nutrition topics from a scientific perspective. This month, we will address a few more to help give you a better general idea of the truth, and not the myth, when it comes to your pet's nutritional needs.
I have heard, more times than I can count, that a dog is allergic to some food item, most commonly a grain (corn is a favorite.) When I begin to probe into this with the owner, I routinely find that this is absent any testing or concrete findings. Instead, they had tried a few foods, one or two of which may have disagreed with their pet, and then they made a determination of an 'allergy' from there. Diagnosing a food allergy is never really that simple. Unpacking if a pet has a food allergy and which food(s) they may be allergic to is a long, complicated process best handled by your veterinarian. That said, I want to cover a few very important things.
Corn allergies are something you read about - especially online - all the time, when in fact the scientific evidence surrounding them is almost non-existent. Is there a dog out there allergic to corn? Probably. There is some animal out there allergic to almost anything. Is that a common allergy? Not by a long shot. Often times what you will read from unchecked sources will make it sound like grain allergies are a dime a dozen. The science shows the exact opposite is true. What are the most common food allergies dogs face? If we review all the scientific literature, what we will find is a 'top ten' list that is, in no particular order: beef, chicken, dairy, egg, fish, pork, lamb, rabbit, soy, and wheat. I don't need to point out that only one grain appears on that list (wheat). The rest are all the major protein sources found in just about every food under the sun, which makes perfect sense from an allergy perspective.
Many owners who may be working with their veterinarian to diagnose a food allergy will often go to the store and find foods that are 'novel protein' diets. This means that they contain an atypical, but perfectly nutritious protein source (think venison, duck, or kangaroo.) While there are prescription diets that are like this as well, and novel proteins can work to control food allergies once they are diagnosed, many owners move towards the store versions simply because they are cheaper. Unfortunately in this case you get what you pay for and these diets commonly fail. What makes a prescription diet with venison better than an over-the-counter diet with venison? The major thing is the steps taken to prevent cross-contamination. If you have food allergies and the restaurant you go to uses those ingredients in the kitchen, they will often have a warning on the menu or tell you outright that they cannot guarantee that what you eat didn't come into contact with those allergens. Pet food is no different. If the novel protein food is not either made on its own production line, or a 'clean' line that is shut down and thoroughly sanitized before the novel protein, and only the novel protein, food is made, then cross-contamination is almost impossible to avoid. Needless to say, this costs the food company a lot of extra money to do this, which is why those foods cost more. But, foods made that way do work compared to the cheaper versions that don't take these steps. The other option - which is actually what we use to diagnose a food allergy - is a hydrolyzed diet. Your veterinarian can best direct you on the ideal options there and why that can often be the best way to go to initially diagnose a food allergy.
Another common advertising trick is to ask you to look at what or where things are on the label as a means to determine how good a food might be. Unfortunately, while it sounds nice, doing so provides no real useful information and has no real scientific merit. This is for two reasons. First, the ultimate nutrition a food has is a product of all the ingredients, in specific combinations, that it possesses and the particular weight of one ingredient doesn't make it better or worse (weight is what puts an ingredient higher on a list.) Second, most all companies use a number of tricks to legally move ingredients around on their label, arguably the most common of which is "ingredient splitting".
The law requires that a food label list ingredients in descending order of weight in the manner that they arrived at the production facility. So, let's say I want to make a food that is only chicken and wheat. I order whole breasts and legs or whatever cut of chicken is most cost effective for my company. Bear in mind that all of that meat contains lots of water, which is quickly cooked out just like it is when we grill out, and artificially increases their weight (pre-cooking, when it arrived at the facility) with no increase in nutrition (By the way, if they simply put a protein source that is dried out and absent the artificial inflation of water weight, it is listed as a meal, such as "chicken meal". This is really no less nutritious than the 'water weight added' version.). The marketing department of my pretend food decides it would be best if the label says "chicken first". So, when we order ingredients, we don't order wheat, but instead order it as three major components: wheat bran, wheat germ and wheat flour. This is ingredient splitting. Each of these will be only 1/3 the total weight of the wheat when they come into the production facility. I decide to make the wheat 2/3 of the total weight of my food. This means each of these (bran, germ and flour) is 22% of the weight of the food (1/3 each of 66% total weight) and the chicken is 33% (1/3) of the total. Guess which is highest on the label? Chicken. Guess what almost all of the food - 2/3 to be exact - really is in one form or another? Wheat. So, you may read that label and see "chicken first", but that actually doesn't tell you anything about what is really going on. How can you tell if a company did this? You can't. That's the tricky part.
I want to end with one of the other major hot button issues that is fully misunderstood and shrouded in myth: by-products. The word itself doesn't sound good, but it is purely a nutritional term that doesn't imply good or bad in an ingredient. Olive oil is a by-product and I bet most of us regularly cook with it and may even consider it 'healthy'. So is the beef liver that costs $60 a plate at some high end restaurant. As a matter of fact, if you've ever watched a nature show and seen a group of predators kill another animal and begin to eat it, what you see most commonly is them fighting over "by products" first: things like the liver or heart. Why? These are the most nutrient dense parts of most animals. They may not sound appetizing, but by-products happen to be great, high-density, fully functional sources of nutrition. Adding in beef or chicken by-products, for example, can actually be a way to greatly enhance, not detract, from the nutrition of a dog or cat food. You may also read that by-products include things like horn, hair, hooves or teeth. This is actually illegal and simply a marketing myth.
I hope the last two months have greatly helped you learn about the true science of nutrition so that you can ignore the reams of marketing hype and nutrition that are fed to all of us on a daily basis. As always, if you have any questions then I strongly encourage you to talk to your veterinarian to help make the best nutrition decisions for your pet. I hope you have a good start to Spring, and we'll talk again in May.
Dr. Brandon Stapleton
Managing Doctor/Medical Director