Are Tomato Sauce & Ketchup Low FODMAP?

Are Tomato Sauce and Tomato Ketchup Low FODMAP?

As a child we used to go to the beach and mum would buy a huge newspaper parcel of hot potato chips. We would smother them in tomato sauce before devouring them and licking our fingers clean. However, these days, tomato sauce is a fickle friend of mine and unless I watch my portion size I pay the price.

This brings us to the question is tomato sauce (ketchup) low FODMAP?

The FODMAP content of tomato sauce (ketchup) seems to vary by serving size and country, as well as being dependent on the type and quantity of ingredients used.

USA Tomato Ketchup

So far two types of ketchup from the United States have been tested. Surprisingly, the FODMAP content did not vary greatly between ketchup sweetened with high fructose corn syrup and ketchup sweetened with sucrose. Both types of ketchup were low FODMAP at a 1 sachet (packet, which is about 2 teaspoons) sized serve and became high FODMAP at 2 sachets (packets, which is about 4 teaspoons) serve (1). At larger serving sizes the ketchups contained high levels of oligosaccharides, specifically fructans (1). This means large serving sizes of tomato ketchup should be avoided during the elimination phase. However, a small low FODMAP serve of ketchup should be well tolerated by many individuals (1).

Australian Tomato Sauce

Australian tomato sauce is low FODMAP at a 2 sachets (packets, which is about 2 teaspoons) sized serve and contains moderate levels of FODMAPs when you increase the serve to 4 sachets (packets, which is about 4 teaspoons) (1). At the larger serving size of 4 sachets (packets) the tomato sauce contains moderate levels of oligosaccharides, specifically fructans (1). This means in the elimination phase of the diet, you should limit your serve to 2 sachets to stay within the low FODMAP limits.

Tomato Sauce Outside the USA and Australia

Tomato sauces from other countries have not yet been tested and the ingredients may vary. This means if you want to try tomato sauce (ketchup) you will need to test your tolerance levels. You could start by trying a 1 teaspoon serve and increase up to 2 teaspoons to test your tolerance levels.

FODMAP Content of Tomato Sauce & Ketchup

(Table Content Sourced from: Monash Blog, 2014; Monash University App, 2014)

Was only one brand of tomato sauce or ketchup tested by Monash University for each category?

No, Monash would have tested several brands of tomato sauce (ketchup) for each category. In accordance with the Food Standards Australia New Zealand (FSANZ) guidelines, Monash University would have tested 3 samples from different manufacturers of the processed food (tomato sauce or ketchup) (3).

What ingredients in the tomato sauce/ketchup are likely to cause FODMAP issues?

We know that ½ cup (92g or 3.25oz) of canned tomatoes is low FODMAP and that canned tomatoes become high FODMAP for excess fructose at 180g (6.7oz) (2). This means it might not be the tomato content causing the tomato sauce (ketchup) to become high FODMAP. Instead it is could be the dried onion and garlic powder that is often added to the sauce (ketchup), as these ingredients contain fructans. Additionally, if the tomato sauce contained a high FODMAP sweetener with excess fructose, then this could also cause issues as the serving size increases.

Can I make my own low FODMAP tomato sauce (ketchup)?

Yes you can make your own low FODMAP tomato sauce and leave out the onion and garlic powder. Providing you only use low FODMAP ingredients you might be able to increase your serving size. Just keep in mind that homemade tomato sauce will only last for about a week in the fridge, or 3 months in the freezer, before it loses its flavour or becomes a health risk.

Final Thoughts

It is worth testing to see if you can enjoy small serving sizes of commercially made tomato sauce or ketchup. If you are not sure you can tolerate the commercially made sauces then try making your own homemade tomato sauce.