Corn

Field corn is grown as a feed grain. Its kernels are the intended crop product, not a processing leftover. Drying allows storage, and grinding prepares the starch to cook when the recipe is extruded.^1,6

1. 01 // Source Field corn kernels Mature kernels are separated from the cob; dent corn is the type most often used for feed.
2. 02 // Process Dried The kernels are dried so the grain keeps in storage before it enters a food recipe.
3. 03 // Process Ground Milling breaks the kernels into smaller particles, which affects how thoroughly their starch cooks during extrusion.
4. 04 // Output Ground corn The dry, ground grain is weighed into the recipe before the kibble is cooked.

1. 01

   Supplies digestible energy

   Starch makes up most of the kernel. In a controlled comparison of extruded dog foods, starch digestibility exceeded 98% across the tested grain and legume diets.^2,5

2. 02

   Helps form kibble

   Heat, water and pressure cook the ground starch in an extruder. Cooked starch helps the food expand and hold its shape.^1,9

3. 03

   Keeps grain costs down

   Corn is a major feed grain. Researchers comparing grain diets described corn as considerably less expensive than rice, giving manufacturers a lower-cost starch source.^3,6

How much One controlled dog study tested recipes containing 56.2% corn on a dry matter basis; that is a study amount, not a typical recipe amount.¹

1. Brands say

   Cooked corn gives dogs usable energy

   Evidence

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

   In a 36-dog comparison of extruded diets, starch digestibility exceeded 98% across all diets, including corn. An 18-dog grain comparison also found complete fecal starch digestibility. Cooked corn is a usable energy source.^2,3

2. Critics say

   Corn raises blood sugar faster than legumes

   Outruns the evidence

   Evidence

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

   In a 36-dog trial, corn, rice and cassava diets produced a larger early glucose and insulin response than pea and lentil diets. That short meal test did not show a health problem in healthy dogs.²

3. Brands say

   Corn's resistant starch improves gut health

   Outruns the evidence

   Evidence

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

   A 12-dog study compared differently cooked corn diets and measured stool, fermentation products and gut bacteria. More resistant starch did not improve the measured fermentation profile; the extruded diet gave the best stool quality.¹

4. Owners say

   Corn is a common dog food allergen

   Outruns the evidence

   Evidence

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

   A review found corn implicated in 13 of 297 dogs with reported food reactions, fewer than beef, dairy, chicken or wheat. Those selected cases cannot tell us how common corn allergy is among dogs generally.⁴

5. Critics say

   Corn is only cheap filler

   Outruns the evidence

   Evidence

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

   Corn was cheaper than rice in an 18-dog grain study, but its cooked starch was readily digested. Price explains part of its appeal; calling an energy source useless ignores what the dog gets from it.^3,5