Sodium Bisulfate

It needs care. Over the long term it can lead to acid buildup in the blood, so the balance should be set carefully for older cats and cats with kidney disease.

Sodium bisulfate is an acid salt used in cat food to make urine more acidic and to help preserve the food. The Merck Veterinary Manual notes that struvite stones form more easily in neutral to alkaline urine, while calcium oxalate stones are favored in acidic urine, so the right level of acidity depends on the cat. If your cat has a urinary or kidney condition, ask your veterinarian about the food.

Source: merckvetmanual.com

Sodium bisulfate lowers the pH of urine, which helps keep struvite crystals from forming. It also lowers the pH of the food itself, which slows spoilage and can make coatings taste better to cats. Many cat foods that mention urinary tract support use an acidifier like this one. It is used in small amounts.

They are different compounds whose names differ by one letter. Sodium bisulfate is an acid salt used mainly to lower pH. Sodium bisulfite is a sulfite preservative, which FDA lists separately on its GRAS list for animal feed. A label listing sodium bisulfate does not mean the food contains sulfites.

Source: ecfr.gov

Overly acidic urine is linked to calcium oxalate stones. The Merck Veterinary Manual says calcium oxalate forms more readily at acidic pH, and that oxalate stones have become more common in cats while struvite has declined. For cats prone to oxalate stones, Merck describes targeting a neutral urine pH. A veterinarian can test urine and choose a food for that cat.

Source: merckvetmanual.com

Pettings gives sodium bisulfate 2 out of 5 and lists it as a phosphate or acid additive. It appears on 24 of the 149 dry cat foods we list. The score reflects an ingredient that helps against struvite but needs a careful balance with calcium oxalate risk. Each food's page shows how it scores overall.