# Another article about the all mighty corn



## Unosmom (May 3, 2009)

I get weekly emails from a vet tech journal and they had a new article today. I'm not sure if you'll be able to see the website, so I'll post it here. 

https://www.vetlearn.com/_preview?_...2-0050568d3693&WT.mc_id=evnewsletter;VT110711

*Pet food myths abound among consumers, especially myths concerning the nutritional value and digestibility of corn as an ingredient in pet food. Corn is commonly thought to be a low-quality food ingredient (i.e., a filler) that has minimal nutritional value. This article addresses common nutrition myths regarding corn in pet food and explains why this diverse grain is valuable as an excellent source of protein, carbohydrate, and essential fatty acids.
Myth 1

Myth 1: The primary ingredient in many dry commercial pet foods is not protein, but cereal. Corn and wheat are the most commonly used grains, but as with meat sources, the nutritious parts of the grain are generally present only in trace amounts.

Protein quality is based on the bioavailability (digestibility) of protein, the content of essential amino acids, and the amino acid requirement of the animal consuming the protein.1,2 Based on these criteria, corn has a high protein value. The digestibility of corn is discussed in myth 2 below. Cells of the body use amino acids from multiple sources, including food proteins, single amino acids, and amino acids synthesized in the body.

There are two groups of amino acids:

• Essential amino acids cannot be synthesized by the body in sufficient quantities and, therefore, must be supplied in the diet.

• Nonessential amino acids are synthesized by the body if sufficient “building material” is available, which is usually the case if a pet receives a balanced diet.

The amino acid requirement for dogs and cats includes arginine, methionine, histidine, phenylalanine, isoleucine, threonine, leucine, tryptophan, lysine, and valine. In addition, cats need taurine.

Corn has been determined to have a protein content of 16.1%, with respectable levels of essential amino acids. According to Kemmerer and Acosta,3 corn is “approximately optimum in histidine, leucine, phenylalanine, and valine.” In comparison, broccoli has a 29.4% protein content, cauliflower has 24.3%, and carrots have 6%. The authors state that “carrot protein is deficient in all the essential amino acids.”3

Cells cannot distinguish between amino acids obtained from plant or animal protein. Combining animal and plant proteins in the diet can provide a complete source of essential amino acids. Therefore, protein sources that have a low biologic value alone can be combined with other protein sources, resulting in a high biologic value.4,5 This process is called protein complementation. Quality pet foods complement highly digestible animal protein with a natural plant protein source, such as corn, to deliver all the essential amino acids that pets need4,5 (FIGURE 1).

Protein concentrations

Figure 1. Protein concentrations in common pet food ingredients (as fed).1,2
Myth 2

Myth 2: Plant-based proteins (e.g., soy, corn, by-products) are difficult to digest.

This statement can be valid if grains are not processed properly. However, plant protein sources that are properly processed can provide highly digestible, high-quality dietary protein for dogs and cats. For example, using a wet milling process for corn maintains its protein quality. In this process, the corn kernel is separated into starch, fiber, and protein. The protein component becomes corn gluten meal—a source of highly digestible protein for dogs and cats.

In a balanced diet, the digestibility of nutrients is as important as appropriate nutrient levels; therefore, the processing of ingredients can be the rate-limiting factor in the total bioavailability of a food.1,2 TABLE 1 indicates the superior digestibility of corn gluten meal compared with meat products. Therefore, corn is an excellent source of digestible energy.

Digestibility of Key Ingredients

Table 1. Digestibility of Key Ingredients (Dry Matter)3,4
The nutrient and energy needs of dogs and cats must be met completely through their daily food intake. Because cats are obligate carnivores, they have greater protein needs per body weight than dogs. A cat requires approximately 2 g/lb/d of protein, whereas a dog requires approximately 1 g/lb/d. It is important for the ingredients in canine and feline diets to be balanced to provide an optimal amount of nutrients in the daily ration. Corn contributes a wide range of nutrients while offering balanced energy. In addition, corn has highly digestible (>90%) protein and a moderate amount of fat.
Myth 3

Myth 3: Corn causes many allergy problems.

Corn has been thought to be highly antigenic and to cause food allergies. However, in a study6 that examined the frequency with which specific food ingredients cause a reappearance of pruritus during a food elimination trial, corn had the lowest frequency among the ingredients evaluated1,2 (FIGURE 2).

food ingredients causing pruritus

Figure 2. Frequency of specific food ingredients causing pruritus in food-allergic dogs.5
Myth 4

Myth 4: The corn gluten meal and soybean meal added to pet foods have little nutritional value because they are leftovers from processing grain for human use.

Corn gluten is the protein portion of corn. Corn gluten meal (the dried form) provides protein that is complementary to many meat sources of protein. The digestibility of corn gluten meal is as high as that of many meat meals (TABLE 1).1,2 Corn gluten meal has an amino acid profile that is quite different from those of meat-based protein sources. Corn gluten meal is especially high in the amino acids cystine and methionine, which are particularly important for skin and haircoat health.

In addition to providing energy and protein, corn provides other essential nutrients, including vitamins (B complex, E, and A), minerals, and insoluble fiber, which are important to digestive and immune health. Corn also provides fatty acids (e.g., linoleic acid) and antioxidants (e.g., β carotene, lutein, zeaxanthin), which protect the entire body from oxidative cellular damage and support eye health.

A particular benefit of using corn in pet food is that it is the only commonly used grain that contains linoleic acid—an omega-6 essential fatty acid required for healthy skin and hair in dogs and cats.

Antioxidants help to reduce cell damage. Vitamin E is a major fat-soluble antioxidant, and corn oil, a common ingredient in pet food, is a major source of vitamin E. In a human study conducted by the Institute of Nutritional Science at the University of Vienna, Austria, a diet containing corn oil was found to reduce DNA damage more effectively than a diet containing an olive/sunflower oil combination.7

It is commonly thought that processed ingredients have a lower nutritional value than fresh ingredients. However, a study conducted by Cornell University found that cooking corn at 150°C (302°F) for 50 minutes increased its antioxidant levels by as much as 53%.8

Energy requirements can be met with carbohydrate, fat, or protein; therefore, providing a portion of the energy from a carbohydrate such as corn permits the overall diet formula to be lower in fat and/or protein. Corn is a very useful ingredient in pet food because it is a high-quality source of carbohydrate and protein. Cornmeal, a major source of carbohydrate in pet food, contains approximately 75% carbohydrate6 (FIGURE 3).

Carbohydrate concentration

Figure 3. Carbohydrate concentration in cornmeal versus corn gluten meal.2
Conclusion

Many pet food myths circulate among consumers every day. Do not be misled by myths about corn in pet diets. Good nutrition involves not only the list of ingredients but also the right balance of nutrients. Corn has proven to be a very useful ingredient because of its high digestibility, low allergenic tendency, and excellent nutrient content, including antioxidants, protein, carbohydrate, and essential fatty acids. When properly processed and provided in a balanced manner, corn is healthy for pets.*



Ironically the sources listed as just as laughable as the article itself. First study compares raw meat to rendered byproduct (raw is more digestible), 3 studies claiming the benefits of corn are done on people, not dogs/cats. Another study links to a livestock weekly bulletin and another one is from department of agriculture (can you say biased?)

*

1. Murray SM, Patil AR, Fahey GC Jr, et al. Raw and rendered animal by-products as ingredients in dog diets. J Nutr 1998;128(12 suppl):2812S-2815S.

2. University of Alberta. Department of Agricultural, Food and Nutritional Science Web site. Home - Agricultural Food and Nutritional Science - University of Alberta.

3. Kemmerer AR, Acosta R. The essential amino acid content of several vegetables. J Nutr 1949;38(4):527-533.

4. Hand MS, Thatcher CD, Remillard RL, et al, eds. Small Animal Clinical Nutrition. 4th ed. Topeka, KS: Mark Morris Institute; 2000:141.

5. Oklahoma State University. OSU Offering Weekly Feed Commodity Bulletin on Web. November 1997. Welcome to Livestock Weekly!.

6. Jeffers JG. Results of dietary provocation in dogs with food hypersensitivity. Vet Dermatol 1994;5(3):127-144.

7. Elmadfa I, Park E. Impact of diets with corn oil or olive/sunflower oils on DNA damage in healthy young men. Eur J Nutr 1999;38(3):286-292

8. Dewanto V, Wu X, Liu RH. Processed sweet corn has higher antioxidant activity. J Agric Food Chem 2002;50(17):4959-4964.*


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## Tobi (Mar 18, 2011)

Completely biased, these sources are laughable at best. I can't imagine that they aren't trying to promote their infinite superfood corn! :lol:


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## biancaDB (Nov 3, 2011)

I agree with what Tobi said and whats even funnier is that all people have to do is do some research and they would learn the truth about dog nutrition. It is kind of annoying to know that some people read this and believe it though  I know because so many of those people come into my work and buy Science Diet and preach about their know it all vet who recommended that "great" food. sigh.


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## DaViking (Sep 27, 2011)

Corn and it's many uses is one of the most studied food sources, making it actually easy to evaluate and take a stand.

Here's some quick pointers. I'll list some negatives first, the ones important for my NO take on corn products ;

- Corn Gluten Meal have in study after study been shown to be inferior to Meat Meal and Chicken Meal. Study, There are many more

- As a main ingredient and in corn meal form it ads tons of unnecessary carbs

- Our corn can no longer reproduce and have also become a cultigen

- GMO everywhere you look

- Fat cells duplicate in reaction to corn lectins. Science on how corn lectins affect dogs is scarce but I do not like it. Info on lectins


Now, you can make some cases for corn too (personally I look away tho) ;

- Ultra low ash source and urine acidifier

- Can balance calcium/ phosphor levels

- As corn gluten meal it is low in carbs

- Cheap, many can't even pay $1/lbs for food. Or, if you have lots of high performance dogs it is a cheap source of energy


If I was forced to pick one corn ingredient in my food I would go for corn gluten meal in smaller amounts. Not as the first or second source of proteins. Funny how things work, Blue Buffalo are all over my TV with ads ridiculing corn gluten meal. What they should do instead is attack corn in general. But I guess that wouldn't resonate as well with their target audience. Marketing 101, find something scientific sounding and attack it even if it makes less sense than attacking the real problem.

Personally I don't want corn in my foods, my reasoning is both scientific and social. Would your average dog suffer from smaller amounts of corn gluten meal in the diet? Probably not but I choose to make the better choice imho.


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## Scarlett_O' (May 19, 2011)

I cant believe, or really understand, how many people(ESPECIALLY the ones who write the studies and produce the "food") forget(or forgot long ago) that dogs are CARNIVORES!!!!

I do NOT understand it!!!hwell:hwell:


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## Caty M (Aug 13, 2010)

Scientific studies are so incredibly biased it's ridiculous yet people still shun anecdotal evidence..


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## DaViking (Sep 27, 2011)

Caty M said:


> Scientific studies are so incredibly biased it's ridiculous yet people still shun anecdotal evidence..


No one is dismissing anecdotal evidence but you have to grant everyone the same right to submit their anecdotal findings then. Meaning you will have millions and millions of owners from all camps and levels of knowledge ready to submit anecdotal evidence that their corn protein based (used as an example since this is a corn thread) foods works great for their pets. Anecdotal evidence is a starting point to learn more. If there is enough of it on a certain topic it will grow into something more.


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## kevin bradley (Aug 9, 2009)

DaViking said:


> No one is dismissing anecdotal evidence but you have to grant everyone the same right to submit their anecdotal findings then. Meaning you will have millions and millions of owners from all camps and levels of knowledge ready to submit anecdotal evidence that their corn protein based (used as an example since this is a corn thread) foods works great for their pets. Anecdotal evidence is a starting point to learn more. If there is enough of it on a certain topic it will grow into something more.


As much as it might piss us off, I do NOT want a world where "anecdotal" evidence is flying all over the place. Hell, I had a 130lb Rottweiler live to 15 years old... also had a stray I found live to around 20 years old(not sure how old she was when I found her). They both ate Pedigree for their entire lives. I suppose some could use that as "anecdotal."

I keep corn out of all of the foods I rotate in my Dogs diets now. However, I'm also open minded enough to listen to folks who don't believe corn is the devil that its made out to be. In fact, the lady who wrote the Dog Food Project actually doesn't diminish corn as an ingredient that should never be present in food. She just doesn't like it to be the FIRST or primary ingredient. What the hell do I know? The lady has done extensive work in canine nutrition and I have zero right to challenge her. 

But logically, I just have a feeling that our Dogs need meat. For what my opinion is worth


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## Unosmom (May 3, 2009)

I dont necessarily think corn is any worse then any other grain, but it shouldnt make up 70% of the food. I also noticed time after time that when dogs are switched from a grocery store brand (or SD for that matter), that stinky corn chip dog odor disappears and their poops are 1/2 the size(so much for the high digestibility claim). 

On the funny note, I left a comment under the article and it disappeared shortly after. Typical.


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## DaViking (Sep 27, 2011)

kevin bradley said:


> However, I'm also open minded enough to listen to folks who don't believe corn is the devil that its made out to be. In fact, the lady who wrote the Dog Food Project actually doesn't diminish corn as an ingredient that should never be present in food. She just doesn't like it to be the FIRST or primary ingredient. What the hell do I know? The lady has done extensive work in canine nutrition and I have zero right to challenge her.


I have great respect for Sabine. She is an awesome source of knowledge and is very balanced and level headed.


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## swolek (Mar 31, 2011)

.............

lol


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## kevin bradley (Aug 9, 2009)

DaViking said:


> I have great respect for Sabine. She is an awesome source of knowledge and is very balanced and level headed.


me too. She also places a TON of importance on the ethics and practices of where the food comes from. From what I've seen, she doesn't tolerate anything that doesn't give total transparency on ingredient sourcing and quality of ingredients. IE-she doesn't like any BS from companies.


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