Taurine
An essential sulfur-containing amino acid. Unlike most mammals, cats have a limited ability to synthesise taurine from precursors and must obtain it from their diet. Its absence from cat food has caused epidemics of preventable heart disease and blindness.
Why it matters
Taurine is required for bile acid conjugation, retinal function, heart muscle contraction, immune function, and foetal development. Cats supplemented taurine from meat in their natural diet. When commercial cat food shifted to cereal-heavy formulas in the 1970s and 80s, taurine intake fell dramatically. The result was an epidemic of feline dilated cardiomyopathy (DCM) and central retinal degeneration (FCRD) — both now understood to be taurine deficiency diseases.
The science
Pion et al. (1987) identified taurine deficiency as the cause of feline DCM in a landmark study in Science. Following that finding, AAFCO added minimum taurine requirements (0.1% in dry food, 0.2% in wet food on a dry matter basis) to US standards. The EU followed with similar requirements. Most commercial cat foods now declare taurine on the label and supplement it regardless of meat content, because processing can degrade taurine present in raw ingredients.
What to look for
Taurine should appear in the ingredient list of any complete cat food. Its presence does not tell you how much is included — only the guaranteed analysis does. A high-meat diet will provide some taurine through the meat itself; a grain-heavy diet relies entirely on supplementation. This site does not currently flag taurine absence separately, but products where it is absent from the ingredient list of a complete food are a concern.
Reviewed complete foods without taurine declared (42)