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Thursday, February 11, 2016

Clarifying Cat Nutrition

I recently received an email from George with some questions about cat foods and cat nutrition.  At the same time I just this week read an article on the issue of carbohydrates in cats, so all of this ties together quite well.  If this is your first time reading one of my blog posts on nutrition I would highly encourage you to go to the search box on the top left of the blog and put in "nutrition".  I've written quite a lot on this subject over the years and you'll find a lot of answers about corn, byproducts, grain-free, etc. in these older posts.  I'll try to avoid repeating myself too much in today's post.
I'll break George's email into sections and respond to each part individually.  I am also going to be quoting the article I read, which is by Cailin Heinze, MS, VMD, DACVN (Diplomate of the American College of Veterinary Nutrition), an assistant professor of nutrition at Tufts University.  Her opinion weighs stronger than mine because of her specialty in nutrition, so if you don't believe me, maybe you will believe her.
Hello Chris i read your article regarding cat food. You say that these nutritionist tell you that Hills, Purina, Iams, and royal canin are what they feed there cats. That is amazing to me. My research tells me that firstly dry foods have no real moisture content. So cat are already semi dehydrated due to there lack of thirst drive.
Yes, board-certified veterinary nutritional specialists routinely recommend these foods and feed them to their own pets.  It is also true that dry foods have a lower moisture content than canned or soft foods.  However, that doesn't mean that there is no moisture.  A dry food may have 10-20% moisture by volume while a canned food may have 80%.  Yes, a considerable difference, but not a harmful one.  It is true that in the case of urinary disease we want as much fluid passing through the kidneys and bladder as possible, so we recommend canned foods for these pets.  But dry food is fine for most other cats.  Also, cats are NOT semi-dehydrated.  Trust me on this as a vet, a dehydrated cat is a sick cat, and a healthy cat should never be dehydrated at all (even "semi-dehydrated"...which is a term that we don't use in medicine and has no real definition).  Cats also very much have a "thirst drive".  When they are thirsty they will drink.  You may not notice it as much as with dogs because cats are more likely to eat and drink privately.  Their original ancestors were desert cats, so our modern house cat is virtually a desert animal.  Their kidneys are very efficient so a cat has to drink less than a dog of the same size.
From Dr. Heinze's article:  "I never criticize owners for feeding dry diets...Some health conditions will dictate that a cat ideally be fed a canned diet later in life, so it's best to have flexibility."
More from George:
Then take into consideration that the first ingredients of these foods are 1. poultry by product, corn meal, corn gluten meal , brewers rice, soy fiber, animal fat. The first ingredient should be turkey, chicken, venison, duck or what ever the protein source is. Am i wrong here?
No offense, George, but unfortunately you are wrong.  The first listed ingredient does not mean that it carries the most protein or other nutrients.  Ingredients are listed by pre-cooked weight, not by nutritional quality or density.  So an ingredient is first just because it weighs more, not because it's "better".  It is very possible for a manufacturer to manipulate the ingredients so that "real meat is first", even if it doesn't give the most protein.  I wrote extensively about it this past December so I'll link you to that post.  Click on that link for a much longer explanation as to why the first ingredient is somewhat irrelevant.
Please educate me on this because i am spending alot of money on these brand name foods. My disagreement with what you say is this. Cats and dogs do not need gluten, soy, corns, wheats, etc in there foods. And it has been debated that these grains are harmfull.
Unfortunately there is a ton of misinformation in these sentences.  There is absolutely, positively NOTHING wrong with gluten, soy, corn, wheat, etc. in dog and cat food!
Dr. Heinze:  "Misconceptions about cats and carbs stem from the popular belief that, since cats are obligate carnivores and don't really eat carbohydrates in the wild, they shouldn't eat them, period.  A healthy cat doesn't require carbs, but can digest them." 
There are a lot of great reasons why these ingredients are found in pet foods.  Dogs and cats absolutely have an ability to digest and utilize carbohydrates from many different sources.  Here's a link to a post I wrote in January of last year
The people debating about whether or not grains are harmful are not the nutritional specialists.  I have never read or heard a veterinary nutritionist say anything against grains.  The recommendations for grain-free diets have to do with fad and misinformation, and have nothing to do with scientific facts. 
Dr. Heinze:  "Another misperception among owners is that grain-free diets are inherently healthier than diets with grains.  Grain-free does not equal carbohydrate-free.  Ingredients substituted for grain, such as peas, tapioca, lentils or potatoes, are no more part of a 'wild' cat diet than grains.  However, it is likely that the type of carbohydrate matters.  Tapioca starch is a very simple carbohydrate, not too different from glucose.  Whole grains and complex carbohydrates are likely better choices, because they are less likely to trigger dramatic changes in blood glucose."
Wow, grains may actually be beneficial to cats!  Maybe we should listen to a board-certified nutritionist. 
Dr. Heinze continues:  "Diets both with and without grains can be very healthful.  Corn, for instance, is highly nutrition and not a so-called dietary 'filler'.  If clients have concerns about feeding their cats diets that contain grain along with meat protein, I remind them that grains provide a high-quality source of protein....On a related note, gluten is a big bad word these days.  If people are forgoing gluten themselves, it's very hard to convince them in most cases there's no real benefit to feeding their pet a gluten-free diet.  I emphasize that feeding too many calories and allowing cats to become obese is the real cause of health problems in cats, not feeding gluten."
I don't know about you, but reading Dr. Heinze's words seems to be pretty convincing against the fad of grain-free, gluten-free diets.  Which brings us to the last part of George's email.
This is why every cat food company has jumped onto the Grain Free Foods.
Do you want to know why pet food companies have started making grain-free foods?  Because customers want them!  It's supply and demand, nothing more.  Some people without any scientific basis started talking about grain-free foods, and it somehow became wide-spread among pet owners.  Pet food companies are out to make money and sell foods.  If clients want a particular flavor, ingredients, shape, and so on, they'll absolutely make that food as a way to sell product.  As more and more people are "convinced" that their pets should eat grain-free diets the food manufacturers are merely making products to meet that demand.  Customers are willing to pay a premium price for these newer diets, even though there is absolutely no evidence that they are nutritionally better than other foods.  The plethora of grain-free diets is not about science or nutrition, it's about meeting customer demand.  Unfortunately those customers are misinformed.  And have you noticed that while there are many grain-free diets on the market, the companies haven't stopped making diets containing grains?
If you really want to know why nutritional specialists recommend brands like Iams, Purina, Science Diet, and Royal Canin, you can call these companies and ask them yourself.  A few months ago during a nutrition series I listed questions that nutritionists use to assess a company's ability to produce high quality foods.  None of that information is found anywhere on the labels!  These questions are agreed on by most veterinary nutritionists and are what they consider when making food brand recommendations.
George, I hope this has been enlightening and informative.  Hopefully you can see a different perspective from what you have learned so far, and know a bit more why specialists recommend these foods.  If you still disagree, then you can reach out to Dr. Heinze and other members of the nutrition specialty, as all of my information comes from them.


  1. Excellent article Chris!

    And, of course, you didn't mention that PRESCRIPTION diets, which are, of course, fed to animals with special dietary needs, ALSO usually (always?) contain grains. If any animals needed a grain-free diet, it would be those animals; yet grains remain in those foods since vets are going to be less likely to pay attention to fads vs. consumers.

  2. Awesome Chris - very well explained. I'll be sharing this one with the Vetanswers Community & hopefully they in turn will share it with their own clients. The more expert information we can get out there regarding our pet's diet the more pet owners are able to make informed choices - rather than wildly misinformed!

  3. Thanks for clarifying because this whole OMG you are killing your pet with grains thing is crazy-making. I have found it confusing, too, just like poor George.

    Can you clarify something for me on satiety though? I find my cat seems to want more kibble than is actually going to keep his weight down. He eats Hill's t/d because he is only two and already going to need two teeth looked at, as I think they have caries. We got him from a shelter last year. (Seeing our vet on Tuesday about the teeth.) I do give him a bit of wet food too (Ziwipeak; I live in Australia), but in your experience, are cats less easily sated eating kibble? He is 21 inches long, without including the tail, and big built; but since he is neutered, also prone to weight gain. When we got him, he was a bit too thin for his build, at ten pounds, but now weighs twelve and we don't think he should get any heavier as he is losing his waist tuck a bit. Thanks for your blog. I really enjoy reading it. Cheers.

    1. I'll tell you the same thing I tell clients virtually every day. Some dogs and cats just like to eat! We have that same problem in humans, too. How many of us have eaten at a restaurant and been relatively full, but then the server brings out the dessert menu and we just can't help ourselves. Many pets are the same way. They just like the taste of food! You can't keep feeding a dog or cat based on whether or not they want to keep eating! I have several of my own pets that would eat themselves into morbid obesity of I let them.

      That being said, studies have shown that cats seem to do a bit better and have better satiety on high protein, low carbohydrate diets. You can still get this kind of a diet with dry foods.

    2. Thank you for your reply; that's very helpful. Cheers.

  4. Good afternoon Chris. I appreciated your article on the comments i made regarding cat food. But to be honest you broke down my questions but did not clearly state your argument. Firstly when we talk about hydration the cat from what i have researched needs 70% moisture in its food to thrive. Dry foods only supply 12% moisture on average. Thus the problem in feeding a dry only based diet. Secondly the issue of by products. Have you ever been to a production plant to see what by products consist of. In the labeling of "by products" no mention is given to what ingredients make up a "by product. . Whole sourced meat that is biologically appropriate seems to be the better choice. If the pet food industry labels there ingredients as a by product there should be a list of all ingredients that go into the making of a "by product". Are you trying to tell me that purina dry cat food is more biologically appropriate for a cats diet than say Origen, Weruva, Innova, Raw, which consist of human grade meats. Or even if we go down the list to less appropriate foods say Nutro, Blue, wellness, what we find is at least these foods list Turkey, Chicken, venison, duck, etc. as there main ingredients. Also they dont appear to use as many fillers. Are human grade meats more nutritionally appropriate for a cat?. Foods like Iams, purina , friskeys, royal canine use by products as fillers to cut cost. That is why a can of friskeys is .55 cents. for a large can. If im wrong in my understanding then i am willing to listen to any proof driven logic. Any fact driven information that will aid me in better understanding how to read between the lies of these greed driven food companies would be appreciated. My research comes from Dr Becker of mercola. Not quoting her just sharing my source of information. George

    1. I think you've gone to some of my other posts and have likely answered some of these questions. But I want to take a brief moment to quickly address a few broader points.

      For cats canned foods are required only for certain health conditions related to the kidneys and urinary tract. Most of them do fine on a dry kibble diet, though most nutritionists agree that a high protein, low carb diet is preferable.

      By-products actually have a very specific definition, but it's not known by the average consumer. It's mostly organ meat, and is absolutely, definitely NOT "filler". Many nutritional specialists consider by-products the most nutritious part of the carcass! At a conference I attended last year, Dr. Angela Witzel, the Chief of Clinical Nutrition Services at the University of Tennessee Veterinary Medical Center, said that she and other nutritionists are very concerned about the current fad against by-products, as eliminating them from the foods also eliminates nutrients you can't find in other parts of a carcass.

      If you read my nutrition series ( you'll see that there is no such thing as "human grade" pet food. That is a term with no real definition and certainly says nothing about nutritional quality.

      A word on Dr. Becker...I don't know her, never heard of her before, and have nothing against her. But I looked her up and looked at her credentials. She lists a lot of them and there is absolutely nothing in her background that gives any indication of her being a nutritional specialist. My information comes from members of the American College of Veterinary Nutrition, as well as text books on nutrition used to teach veterinary students. I would absolutely say that the knowledge of those nutritional specialists trumps hers. I also see that she has a strong tendency towards homeopathic remedies, which is often contrary to traditional Western veterinary medicine. I don't disparage that leaning of hers, but it will make her have a different outlook than I would have, as I firmly embrace Western medical knowledge. Dr. Becker may be a great vet and a smart woman, but in the area of nutrition I will trust a board-certified specialist over her any day of the week.

      George, search "nutrition" on this blog and you will see a lot of posts I've written over the years on this subject. I think that will clear up some of the misunderstandings you have. And feel free to email me any time!

  5. Dr. Bern,
    I just wanted to take this opportunity to THANK YOU again for sharing your expertise and experience with us through the pages of your blog. You give us such valuable insights and information that most of us would never be able to get otherwise. Please never think aren't reading, or learning, or appreciating your time!

    1. Thanks, Lynn! I started all of this many years ago just for fun, and I still continue to write because I enjoy it. People enjoying reading it is just a bonus!

  6. This is certainly a controversy!

    First, I am not a veterinarian and have no training in animal health whatsoever. I have searched for reliable info and found the following references helpful. With all due respect, I am not saying your opinions are wrong in the least, however, these sources did greatly influence the diet of my own my cats. So. . . I am interested in your view, and that of other other experienced vets that follow your blog.

    Please reply if you can--I spent way to much time typing the following. :)

    Zoran, D L. The Carnivore Connection to Nutrition in Cats. Journal of A Veterinary Medicine, Vol 221, No 11, Dec. 2002;

    Online Articles (opinins?)
    Feeding Your Cat: Know the Basics of Feline Nutrition, by Lisa A. Pierson, DVM (she doesn't give any references, but she does explain her position.

    10 Reasons Why Dry Food Is Bad for Cats & Dogs, by Hofve, DVM (same kind of thing as above, no sources mentioned)


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