Calcium Iodate (Iodine)

Both too little and too much iodine can upset the thyroid, which is why the amount in cat food is adjusted to the cat's needs.

Calcium iodate is a mineral compound used to add iodine to animal feed. FDA lists calcium iodate under 21 CFR 582.80, its GRAS list of trace minerals added to animal feeds. Cats need iodine to make thyroid hormones. If your cat has hyperthyroidism or is on an iodine-restricted diet, follow your veterinarian's guidance on which foods to feed.

Source: ecfr.gov

Calcium iodate is in cat food to supply iodine. Cornell Feline Health Center notes that iodine is required for the production of the thyroid hormones T3 and T4. Calcium iodate is a stable iodine source that holds up well in dry food, which is why many recipes use it.

Source: vet.cornell.edu

It varies widely. A study of 112 commercial cat foods from three regions of the USA, published in the Journal of Feline Medicine and Surgery in 2013, found dramatic variation among canned foods in estimated daily iodine intake, from about 49 to 9,639 micrograms a day. The authors encouraged manufacturers to ensure adequate iodine supplementation across all products and areas of the USA.

Source: pubmed.ncbi.nlm.nih.gov

Both are iodine sources listed by FDA in 21 CFR 582.80 for animal feeds. Calcium iodate pairs iodine with calcium and is more stable in heat and storage. Potassium iodide pairs it with potassium. In cat food they serve the same purpose, and Pettings scores each on its own page.

Source: ecfr.gov

Pettings gives calcium iodate 3 out of 5 and lists it as a mineral. It appears on 123 of the 149 dry cat foods we list. It is the most common iodine source in the dry foods we track. Each food's page shows how it scores overall.