Dr Felicity’s topics: Sulphites, so what?

By January 23, 2017Dr Felicity

Dr Felicity discusses sulphite sensitivity and the effects of preservatives on our pets

Sulphites are commonly used food preservatives. They prevent food from spoiling, increase shelf life and in many cases are very useful.

The addition of preservatives, however, is questionable when it is used to mask the age of a food that is otherwise marketed as ‘fresh’. Preservatives should probably not be fed to anyone in the main part of their food every day. Why?

It is well known that sulphite preservatives in pet food can cause depletion of the essential nutrient thiamine from food. Veterinary cases of thiamine deficiency causing severe illness and death have been documented.

Theoretically, re-supplementing depleted thiamine in sulphite-containing foods should prevent this particular problem. But are we sure this is the only potential issue that sulphites present, especially if they are found in most or all of an animal’s daily diet?

There has been little investigation into sulphite sensitivity in dogs. In humans, the condition has only been recently recognised, despite papers being published on the topic since the 1970s.

What we do know is that dogs suffer from many diseases and sensitivities similar to humans. Dogs, for example, commonly suffer from allergies to inhaled airborne particles like pollen, as do humans. In humans the main sign is upper respiratory tract irritation, hayfever or asthma, while dogs tend to get conjunctivitis, itchy skin, dermatitis and occasional upper respiratory tract signs.

Sulphite sensitivity in humans is complicated and often dose-dependent. Exposure can be via skin contact, inhalation or through the diet. A reaction to sulphites can present in a number of ways – more acute cases can have wheezing, shortness or breath, nausea, stomach cramps, diarrhea, itching, swelling, hives, throat swelling, tingling sensations, skin flushing, low blood pressure and even shock and loss of consciousness in extreme cases.

Chronic cases can present with dermatitis or chronic respiratory problems. The good news is that humans with sulphite sensitivity usually maintain excellent health once sulphites are eliminated from the diet.

There are plenty of anecdotal stories of pets with a range of health problems that improve once the pet is moved onto a preservative free diet. I have witnessed these changes in my own patients and always recommend a preservative-free diet, like 4Legs.

Could sulphite sensitivity in pets be more prevalent that currently documented? Until more is known about this topic, is it really worth taking the risk and feeding them sulphites in every meal, every day?



Albert F. Gunnison, Donald W. Jacobsen, and Howard J. Schwartz (1987) Sulfite Hypersensitivity. A Critical Review, CRC Critical Reviews In Toxicology 17:3

Vally, H., Misso, N. L. A. and Madan, V. (2009), Clinical effects of sulphite additives. Clinical & Experimental Allergy, 39: 1643–1651. doi:10.1111/j.136


Leave a Reply