Are Canned Tomatoes Low in FODMAP? A Guide to Safe Serving Sizes

November 27, 2025 •

4 min read

According to Monash University, a leading authority on the low FODMAP diet, plain canned tomatoes are considered low in FODMAPs within specific serving sizes. This can come as a surprise to many, as other concentrated tomato products can be problematic, but with careful portion control and label reading, canned tomatoes can be safely included.

Quick Summary

Plain canned tomatoes can be low FODMAP if consumed in recommended portion sizes, though larger servings can become high in fructose. Choosing plain varieties without added high-FODMAP ingredients like onion or garlic is essential. Portions for Roma/plum tomatoes (100g) differ from other varieties, so check reputable sources like the Monash app for precise amounts.

Key Points

Portion Control is Key: A typical low FODMAP serving of plain canned tomatoes is 100g (about ½ cup), as larger servings can be high in fructose.
Read the Label: Always choose plain canned tomatoes and check ingredients to ensure no high-FODMAP additives like onion or garlic.
Variety Matters: Canned Roma/plum tomatoes have a higher tolerance threshold for moderate FODMAPs than canned common round tomatoes.
Dilute Your Sauce: If a recipe needs more volume than your low FODMAP tomato portion, use low FODMAP broth or water to stretch it.
Know Other Tomato Products: Tomato paste is low FODMAP at 28g (2 tbsp), but concentrated products like sun-dried tomatoes have smaller safe serving sizes.
Flavor Safely: Use low FODMAP-friendly ingredients like garlic-infused oil, chives, or the green tops of spring onions to add flavor.

Understanding FODMAPs in Canned Tomatoes

FODMAPs are a group of carbohydrates that can cause digestive distress in individuals with Irritable Bowel Syndrome (IBS). Tomatoes, despite being a fruit, contain FODMAPs, specifically fructose, a monosaccharide. While the FODMAP content in fresh tomatoes is generally lower, the canning process can concentrate these carbohydrates, making serving size a critical factor. The good news is that plain, canned tomatoes can be safely incorporated into a low FODMAP diet if you follow specific guidelines for portion control.

The Importance of Monash University Guidelines

Monash University in Australia developed the low FODMAP diet and maintains the most comprehensive and up-to-date database of tested foods. Their research provides the traffic light system, indicating low, moderate, and high FODMAP serving sizes. For canned tomatoes, this is especially important because the FODMAP levels increase significantly past the green-light portion. Relying on the Monash app or other reputable sources for the latest serving sizes is the best practice for managing symptoms effectively. The app also accounts for variations between different types of tomatoes and products, providing crucial details for careful meal planning.

Choosing the Right Canned Tomatoes

When shopping for canned tomatoes, vigilance is key. Many store-bought products contain added high-FODMAP ingredients that can trigger symptoms. To ensure a safe choice, follow these tips:

Opt for plain varieties: Always choose canned tomatoes that are plain, with no added flavorings.
Read the ingredient label carefully: Look for a short ingredient list. Common additions like onion, garlic, or high-fructose corn syrup are high in FODMAPs and should be avoided.
Check the type of tomato: As Monash research shows, different tomato varieties have different FODMAP thresholds. Plain canned Roma or plum tomatoes are often a safer bet, with a slightly higher tolerable serving size than canned common (round) tomatoes.

Comparison Table: Canned Tomato Serving Sizes


Product Type	Low FODMAP Serving (Approx.)	Notes
Canned Roma/Plum Tomatoes	100g (½ cup)	Becomes high FODMAP at 244g (approx. 1 ¼ cup).
Canned Whole Round Tomatoes	100g (½ cup)	Becomes high FODMAP at 178g (approx. 1 cup).
Plain Tomato Paste	28g (2 tbsp)	Small amount provides concentrated flavor with low FODMAPs.
Un-tested Canned Tomatoes	100g (½ cup) or less	Use the most conservative guideline (100g) for un-tested crushed or diced varieties.

Low FODMAP Tomato Products Beyond the Can

While canned products are convenient, other low FODMAP options exist. Tomato passata (strained tomato puree) with no added ingredients can be used in small servings (around ¼ cup). Low FODMAP certified pasta sauces, such as Rao's Sensitive Formula Marinara, are also available and specifically formulated without common high-FODMAP additives like onion and garlic. Making your own sauce from plain canned tomatoes is the safest way to control all ingredients.

What About Tomato Paste and Sun-Dried Tomatoes?

Tomato paste is a concentrated source of tomato flavor and is low FODMAP at a small serving size of 28g (about 2 tablespoons). This is an excellent way to add richness to a dish without exceeding your FODMAP threshold. Sun-dried tomatoes, however, are higher in concentrated fructose, making their low FODMAP serving size much smaller, at around 8g (3 pieces). Overconsuming either of these could lead to symptoms, so precise measurement is necessary.

Practical Tips for Cooking with Canned Tomatoes

Stick to the Serving Size: The easiest way to stay safe is to measure out your canned tomato serving. If a recipe calls for a large amount, use a lower portion and make up the volume with low FODMAP broth or water.
Avoid High-FODMAP Add-ins: Be cautious of pre-made sauces and seasoned canned tomatoes. These often include onion and garlic powder, which are high in FODMAPs.
Boost Flavor Safely: To enhance the flavor of your tomato dish, use garlic-infused oil instead of fresh garlic and the green parts of spring onions or chives instead of onions.
Listen to Your Body: Everyone's tolerance is different. The Monash guidelines are a starting point. If you find even a low FODMAP serving size triggers symptoms, it might be due to other compounds in tomatoes like salicylates, not just FODMAPs.

Conclusion: Enjoy Canned Tomatoes with Caution

The verdict on are canned tomatoes low in FODMAP is a definitive 'yes,' but with important conditions. By choosing plain varieties, adhering strictly to the portion sizes recommended by reliable sources like Monash University, and being mindful of added ingredients, those on a low FODMAP diet can continue to enjoy the versatility of canned tomatoes in their cooking. It's a matter of informed choices and careful preparation that allows for both delicious food and digestive comfort.

For an in-depth explanation of Monash testing protocols, see this article from FODMAP Everyday.

Frequently Asked Questions

The canning process concentrates the natural sugars, including fructose, in tomatoes. This means that a larger portion of canned tomatoes will have a higher concentration of FODMAPs compared to the same weight of fresh tomatoes.

The most reliable way is to check the Monash University FODMAP Diet App. Additionally, read the ingredient list carefully and only choose products that list plain tomatoes, water, salt, and safe additives like citric acid, without any onion or garlic.

Plain canned diced tomatoes should be safe in the low FODMAP serving size of 100g (about ½ cup), similar to whole canned tomatoes. Just be sure to check the ingredients for any high-FODMAP additions.

Monash University has tested both, finding subtle differences in their FODMAP thresholds at higher servings. For a low FODMAP serving of 100g (½ cup), both are safe, but canned plum tomatoes tolerate a larger moderate-FODMAP portion before becoming high FODMAP.

Yes, tomato paste is considered low FODMAP in a serving size of 28 grams (about 2 tablespoons). It is an excellent way to add rich tomato flavor without exceeding your FODMAP intake.

To stay within the safe serving size, use the recommended amount of canned tomatoes and bulk up the recipe with low FODMAP liquid, such as low FODMAP broth or water. You can also add other safe vegetables like carrots or zucchini to increase volume.

Yes, canned and drained tomatillos have been tested by Monash and contain only trace amounts of FODMAPs, allowing for larger serving sizes (up to 500g per person). This makes them a great option for a low FODMAP salsa.