What Does Sodium Bisulfate Do in Cat Food?

"That sodium bisulfate makes my food taste better."
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What's in a name? Well, if you're a relatively safe chemical that sounds a lot like a substance of more questionable safety, quite a bit. Sodium bisulfate, also known as sodium hydrogen sulfate, is found in many cat and dog foods. It's often mistaken for two similarly-named commercial ingredients.

Sodium Bisulfate

An odorless, white granule, pet grade sodium bisulfate added to cat foods improves palatability, adding flavor enhancement while it helps acidify urine. It does this without affecting the food's calcium-to-phosphorous ratio. It also reduces the pH level in the product and acts as a preservative. Sodium bisulfate has taken the place of phosphoric acid in many cat food brands. In its technical grade, it's used as a bleach for leather and wool, and in cleaning agents.

What It's Not

Sodium bisulfate is not sodium bisulfite, used as a preservative in wine and some processed foods. That's the sort of "sulfite" that some people react to, especially when drinking red wine. In a worst-case scenario, a sulfite allergy can cause death. It's also not menadione sodium bisulfite complex, usually called menadione, which is a synthetic source of vitamin K3. Also found in pet foods, purists decry it as an unnatural ingredient, alleging that it's toxic in high doses. While the jury still is out on the danger of menadione, it's not sodium bisulfate.

Urine Acidity

If you've ever had a cat suffering from struvite crystals or stones in his urinary tract, you know the important of acidic urine. If Puffy's pee is too alkaline, struvite stones can form in the bladder, becoming life-threatening if they obstruct your cat's urethra. While medication sometimes can dissolve these stones, often surgical removal is required, especially in the case of a blockage. After recovery, your vet might recommend a special, highly acidified diet to prevent recurrence.


In a study conducted by the Department of Animal Sciences, University of Illinois in 2003, researchers evaluated sodium bisulfate and phosphoric acid as urine acidifiers in cats. Eighteen cats were used to compare the efficacy of these two urine acidifiers. The study found no difference in urine pH between the two substances, concluding,"Sodium bisulphate and phosphoric acid generally behaved in a similar fashion when incorporated in dry cat diets." Researchers didn't make any conclusions about which product felines preferred in terms of taste.

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