Short answer
Yes — most fresh tomatoes are Low FODMAP at the Monash-tested serves. Common tomatoes (75 g / about half a medium tomato), cherry tomatoes (5 fruits / 75 g), and roma tomatoes (65 g) are all rated Low. Sun-dried tomatoes and tomato paste become High FODMAP quickly because water is removed and fructans concentrate. Canned tomatoes are safe at ½ cup (100 g) per serve.
Monash portion chart for tomatoes
| Type | Low FODMAP serve | Becomes High FODMAP at |
|---|---|---|
| Common (large) tomato | ½ medium (75 g) | 1 whole + (fructans) |
| Cherry tomatoes | 5 fruits (75 g) | 12+ fruits |
| Roma / plum tomato | 1 small (65 g) | 2+ tomatoes |
| Canned tomatoes (chopped, no additives) | ½ cup (100 g) | 1 cup + |
| Tomato passata (pure) | ⅓ cup (92 g) | ½ cup + |
| Tomato paste | 2 tbsp (28 g) | 3+ tbsp |
| Sun-dried tomatoes | 4 pieces (8 g) | 6+ pieces |
| Tomato juice | ½ cup (125 ml) | 1 cup + |
Ingredient watch: many jarred pasta sauces contain onion, garlic, or "natural flavours" on top of the tomato — that's usually what causes symptoms, not the tomato itself. Always check the label.
Why concentrated tomato products are risky
Tomatoes contain a small amount of fructans. In fresh fruit, water dilutes them and portions stay safe. But when tomatoes are dried, reduced, or concentrated (paste, sun-dried, canned soup), the fructans stack up fast. A single tablespoon of tomato paste = the fructans of about 4 fresh tomatoes.
This is a classic case of FODMAP stacking — same food, different form, very different tolerance. See our full FODMAP Stacking Guide for the science.
Safe ways to eat tomatoes on a Low FODMAP diet
- Fresh in salads — 5 cherry tomatoes or ½ common tomato per serve.
- Homemade pasta sauce — use ½ cup canned tomatoes + garlic-infused oil + spring onion greens.
- Bruschetta — dice ½ tomato, add basil and infused oil, serve on Low FODMAP bread.
- Roasted with chicken — halve cherry tomatoes and roast alongside our One Pan Chicken and Rice.
High → Low FODMAP swap chart
| Instead of | Try |
|---|---|
| Jarred pasta sauce (with onion + garlic) | ½ cup canned tomato + garlic-infused oil |
| 3 tbsp tomato paste | 2 tbsp paste + ¼ cup passata |
| Handful of sun-dried tomatoes | 4 pieces sun-dried + fresh cherry tomatoes |
| Bloody Mary mix (2 cups juice) | ½ cup tomato juice + soda + lemon |
Common questions
Are cherry tomatoes Low FODMAP?
Yes — 5 cherry tomatoes (75 g) is Low. Twelve or more becomes High.
Is tomato ketchup Low FODMAP?
It depends. Monash rates 2 sachets (13 g each) of common tomato ketchup as Low, but many brands add onion powder or garlic. Always check the label.
Can I eat tomato soup?
Homemade with ½ cup canned tomatoes per bowl, garlic-infused oil, and lactose-free cream — yes. Store-bought is usually High because of onion.
Are green (unripe) tomatoes Low FODMAP?
Monash hasn't tested green tomatoes specifically. Stick to red, ripe fruit at tested serves.
Bottom line
Fresh tomatoes are one of the easier "Low FODMAP with a caveat" foods — stay under ½ common tomato or 5 cherry tomatoes per serve, and treat concentrated forms (paste, sun-dried, jarred sauces) with respect. Pair with our Low FODMAP Vegetables Guide to plan a full safe plate.
Sources
- Monash University FODMAP App — tomato portion database
- Monash Blog: tomato-based sauces — fructans concentration in paste and passata
Reviewed by Sarah Mitchell, registered dietitian, June 2026. Informational only — not medical advice.