Corn / Maize
Corn appears in cat food as whole ground corn, corn meal, corn gluten meal, and corn protein meal. Each form varies in digestibility and nutritional value, but all share the same fundamental problem: cats are obligate carnivores with a limited capacity to handle high-starch diets.
Why manufacturers use it
Corn is one of the cheapest available calorie sources. Corn gluten meal is also used as a protein extender — it has a high crude protein percentage on paper, which allows manufacturers to meet minimum protein requirements at lower cost than animal ingredients. Corn also helps kibble bind and maintain shape during extrusion.
What the evidence says
Cats have a low activity of salivary and intestinal amylase, the enzyme that breaks down starch. Research by Kienzle (1994) established that cats have a limited but functional capacity to digest cooked starches, but that digestibility decreases as starch inclusion rises. Cats fed high-carbohydrate diets show higher postprandial blood glucose and reduced protein utilisation compared to those on meat-based diets (Hewson-Hughes et al., 2011). Corn gluten meal provides protein that is lower in taurine and arginine — amino acids that are critical for cats and found almost exclusively in animal tissue.
How it affects a product's score
Products where corn is among the first three ingredients score lower on the protein ranking pillar. When corn appears as the first or second ingredient, a product typically receives the grain-filler and low-animal-protein flags. Corn gluten meal used as a protein extender does not directly increase the animal protein ranking.
Reviewed products containing corn or maize (15)