Corn Flour

Dry mills turn corn into grits, meal and flour. Flour is the fine product. A mill may keep the whole kernel or separate the bran and germ before grinding.^6,7

1. 01 // Source Dried corn kernels Mature kernels enter a dry mill that separates and grinds corn into different products.
2. 02 // Process Keep or separate Whole grain flour keeps the bran and germ; refined flour loses much of both.
3. 03 // Process Grind finely The mill grinds corn more finely than cornmeal to make flour.
4. 04 // Output Corn flour A dry powder reaches the food plant, where its starch cooks with the other ingredients.

1. 01

   Supplies cooked energy

   Extrusion cooks starch so dogs can digest it. Dog trials found starch in corn based diets was almost completely digested, though those results do not isolate corn flour.^1,2

2. 02

   Holds kibble together

   Heated starch thickens and binds the food mix as kibble forms. Corn flour supplies starch, but the binding effect of this flour alone has not been measured.^5,8

3. 03

   Fits a large supply

   Researchers have described corn as less expensive than rice for dog food. The large US corn harvest gives manufacturers a broad supply for starch heavy recipes.^2,10

How much A dog trial used corn as its main cereal, but it does not tell us a typical amount of corn flour in commercial kibble.²

1. Brands say

   Cooked corn flour gives dogs digestible energy

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   A 36 dog trial (6 dogs per diet) found starch digestibility above 98% across diets including corn, and an 18 dog trial found complete fecal starch digestion on a corn diet. Both are small, short feeding trials, and neither isolates corn flour from the rest of a corn based kibble.^1,2

2. Brands say

   Corn flour helps bind kibble

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   NC State describes cooked starch as the binder in extruded foods. Corn flour supplies that starch, but no dog trial tested its binding effect separately. This is a manufacturing claim, not a health benefit.^5,8

3. Brands say

   Corn flour gives slow, steady energy

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   In a 36 dog trial, corn based kibble produced a larger early glucose and insulin response than sorghum, pea or lentil diets. The study did not isolate corn flour or show harm in healthy dogs.¹

4. Owners say

   Corn flour commonly causes food allergies

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   A review found corn reactions in 13 of 297 dogs with identified food reactions. A laboratory study found antibodies that recognized corn flour proteins, but the dogs' clinical corn allergy status was unknown. Corn is a possible allergen, not a common one.^3,4

5. Critics say

   Corn flour is just filler

   Outruns the evidence

   Evidence

   1. Strong
   2. Some
   3. Thin
   4. None

   Low fiber maize flour averages 79.7% starch on a dry matter basis, and an 18 dog trial found complete digestion of starch in a cooked corn diet. A starch this digestible supplies real energy, not nothing, whatever the label calls it.^2,5