Do Canned Tomatoes Contain Sulphites? The Definitive Answer

December 23, 2025 •

3 min read

While it may be surprising, fresh, ripe tomatoes naturally contain a small, minimal amount of sulphites. However, the question of whether canned tomatoes contain sulphites is more complex, depending on the specific product and manufacturing process.

Quick Summary

Canned tomato products may contain varying levels of sulphites, both naturally occurring and added as preservatives. Checking the ingredient label is the most reliable way to determine their presence.

Key Points

Naturally Present: Fresh tomatoes contain minimal, naturally occurring sulphites, which are generally harmless to most people.
Content Varies: The sulphite content in canned tomatoes is not uniform and depends on the specific processing and manufacturer.
Read the Label: The most reliable way to confirm the presence of sulphites is to carefully check the product's ingredient list and "contains" statement.
Watch for Processed Products: Highly processed items like tomato paste, purée, and some sun-dried tomatoes are more likely to contain added sulphites as preservatives.
Look for Specific Names: Be aware of common sulphite names like Sulphur dioxide (E220) and Sodium metabisulphite (E223) on ingredient labels.
Consider Sensitivity: Individuals with a sulphite sensitivity or asthma should be particularly cautious and check labels, as reactions can occur even from small amounts.

The Difference Between Natural and Added Sulphites

Sulphites are a group of chemical compounds that occur naturally in some foods, and tomatoes are one of them, albeit in minimal quantities. For most people, these low, naturally occurring levels are not a concern. However, the presence of sulphites in processed foods, including certain canned tomato products, is often due to their use as food additives.

Manufacturers add sulphites, in forms such as sodium metabisulphite or sulphur dioxide, to serve as preservatives and antioxidants. These additives help to inhibit microbial growth, maintain the product's colour, and extend its shelf life. For individuals with a sensitivity to sulphites, particularly those with asthma, the added amounts found in processed goods can trigger adverse reactions.

The Role of Sulphites in the Canning Process

For standard canned whole or diced tomatoes, the presence of added sulphites is less common than in more processed forms like purées or pastes. The simple heat processing used in canning is often sufficient for preservation. However, other tomato-based condiments and products are different. For example, some brands of sun-dried tomatoes explicitly state that they are made with sulphur dioxide to prevent discolouration and spoilage during the drying process, while others advertise as being sulfite-free. Similarly, tomato paste, purée, and ketchup are listed as foods that are more likely to contain higher levels of sulphites.

How to Check the Label for Sulphites

To be certain whether a particular product contains added sulphites, it is essential to read the ingredient label every time you shop. Food labeling regulations require manufacturers to declare sulphites on the packaging if the concentration exceeds 10 milligrams per kilogram (10 ppm). This declaration can be found in the ingredients list or in a separate "contains" statement. Remember that some products might carry a "may contain sulphites" warning, indicating a risk of cross-contamination.

Common names for sulphites to look for include:

Sulphur dioxide (E220)
Sodium sulphite (E221)
Sodium bisulphite (E222)
Sodium metabisulphite (E223)
Potassium metabisulphite (E224)
Potassium bisulphite (E228)
Sulphurous acid

Sulphite Presence in Different Tomato Products


Tomato Product Type	Potential for Added Sulphites	Common Label Declaration	Notes
Fresh Tomatoes	Minimal (naturally occurring only)	None	Negligible levels, safe for most sensitive individuals.
Canned Whole/Diced Tomatoes	Low to Moderate	Ingredient list: Look for specific sulphite names.	Varies by brand. Many use heat for preservation.
Tomato Paste/Purée	Moderate to High	Ingredient list: Must be declared if over 10ppm.	Sulphites prevent browning and spoilage in concentrated products.
Sun-dried Tomatoes	High	Ingredient list: Often lists Sulphur Dioxide (SO2).	Specifically used to preserve the vibrant colour. Some brands offer sulfite-free options.
Tomato Ketchup/Sauce	Moderate	Ingredient list: Check for various sulphite forms.	A common preservative, found in many processed condiments.

Hidden Sulphites and Considerations

While labeling regulations are designed to protect consumers, some scenarios can lead to a presence of undeclared sulphites. For instance, sulphites can be used as a processing aid or as an ingredient of an ingredient. If the resulting sulphite level is below the 10 ppm threshold, it may not need to be declared on the final product label. This can make avoidance difficult for those with high sensitivity. Cooking can sometimes reduce sulphite levels through the dissipation of sulphur dioxide gas, but this is not a reliable method for complete removal.

For those with concerns about sulphites, it is best to stick to fresh, minimally processed options or purchase products from brands that explicitly state they are sulfite-free, such as the example of sun-dried tomatoes mentioned previously. Always remain vigilant when reading labels, as product formulations can change without notice.

Conclusion

Do canned tomatoes contain sulphites? The answer is not a simple yes or no. While fresh tomatoes contain trace amounts, the sulphite content in canned and other processed tomato products varies significantly. For most consumers, this isn't a health concern, but for sulphite-sensitive individuals, careful label reading is crucial. Added sulphites, which act as preservatives and antioxidants, are more likely to be found in highly processed items like pastes, purées, and certain sun-dried tomatoes. By understanding the different types of tomato products and knowing what to look for on ingredient lists, you can make informed choices about the food you consume. For further information on food sensitivities and reading labels, consult reliable health resources.

Allergy UK provides helpful resources on sulphites and airway symptoms.

Frequently Asked Questions

No, not all canned tomatoes contain added sulphites. The presence of sulphites depends on the product and manufacturer. Simple canned whole or diced tomatoes are less likely to have added sulphites than more heavily processed products like tomato paste or sauce.

Sulphites are added to some tomato products to act as a preservative and antioxidant. This helps to inhibit the growth of microbes, prevent spoilage, and maintain the colour and freshness of the product, especially in concentrates like tomato paste and sun-dried varieties.

The most reliable method is to check the ingredient label on the can. Look for specific names like "Sulphur dioxide," "Sodium metabisulphite," or E-numbers (E220-E228). In many regions, sulphites must be declared if they are present above 10 parts per million (ppm).

For most people, sulphites are safe to consume. However, they can cause adverse reactions, such as asthma-like symptoms, in a subset of sensitive individuals. Sulphites do not cause a true allergic reaction but a sensitivity response.

Yes, many brands produce canned tomatoes without adding sulphites. Some brands, particularly those marketing healthier or more natural products, may even highlight their "sulfite-free" status, like some sun-dried tomato varieties.

Cooking may cause some of the sulphur dioxide gas to dissipate, which could reduce the sulphite level. However, this is not a reliable method for eliminating all sulphites, especially for sensitive individuals.

More processed tomato products tend to have added sulphites. This includes tomato paste, purée, ketchup, and especially sun-dried tomatoes, where preservatives are often used to maintain colour.