Red 40

Red 40, or FD&C Red No. 40, is a synthetic dye. FDA's color additive rule allows it for coloring foods generally at levels consistent with good manufacturing practice, and each batch must be certified by FDA. Long-term studies of Red 40 in cats are rare, and it adds no nutrition. If your cat has a medical condition or reacts to its food, ask your veterinarian.

Source: ecfr.gov

Red 40 is added so kibble pieces look red or meaty to the person buying the bag. Cats pick food mostly by smell and taste, so the color is aimed at people. Red 40 has no nutritional purpose. Many cat foods meet the same AAFCO nutrient profiles without any dye.

No, Red 40 is not banned in US pet food. FDA lists it among certified color additives allowed in foods, and it appears on 18 of the dry cat foods Pettings tracks. In 2026 FDA said it would use enforcement discretion for certain voluntary claims on animal foods made without FD&C certified colors, which gives makers a way to market dye-free foods.

Source: fda.gov

Red 40, or FD&C Red No. 40, is a synthetic azo dye. FDA's color additive rule identifies it chemically as the disodium salt of a sulfonated azo naphthalene compound, so it is a manufactured chemical rather than a plant or insect extract. Every batch of Red 40 and of its lakes must be certified by FDA before use. On a label it may appear as Red 40 or as Red 40 Lake.

Source: ecfr.gov

Pettings gives Red 40 0 out of 5 and lists it as an artificial color. It appears on 19 of the 149 dry cat foods we list. Synthetic dyes get our lowest score because they change only how the food looks and add nothing for the cat. Each food's page shows how it scores overall.