Plain tuna is naturally free of FODMAPs, making it one of the safest protein choices on a low-FODMAP diet. The problem is everything else in tuna salad. Mayonnaise, relish, onion, celery, and seasonings can each introduce FODMAPs that turn a safe protein into a trigger food. Whether your tuna salad is low FODMAP depends entirely on how it’s made and which ingredients you control.
Tuna Itself Is FODMAP-Free
All protein foods, including meat, poultry, and fish, are naturally free of FODMAPs. Canned tuna packed in water or oil is no exception. You can eat it in any reasonable portion without worrying about FODMAP content. This applies to fresh tuna steaks, canned chunk light, and canned albacore alike.
Where Store-Bought Tuna Salad Goes Wrong
Pre-made tuna salad is a different story. A look at a popular product like StarKist’s Ready-to-Eat Tuna Salad reveals onion powder listed in the ingredients, which is high in fructans and a clear FODMAP trigger. That same product also contains guar gum, carrageenan, xanthan gum, and “natural flavors,” several of which could be moderate or high FODMAP depending on the source and amount. The Spoonful app flags it as not low FODMAP.
Deli tuna salad from a restaurant or grocery counter is similarly risky. Most recipes include diced raw onion or onion powder, and you typically can’t verify the exact brand of mayonnaise or relish used. Even small amounts of garlic or onion powder mixed into a large batch can push your portion above safe thresholds.
The Mayonnaise Question
Basic mayonnaise, made from oil, egg yolk, vinegar, and a touch of mustard, is low FODMAP. Most full-fat commercial brands stick close to this formula and are safe. The traps show up in two places: flavored varieties and reduced-fat versions.
Light or reduced-fat mayonnaise often compensates for the missing fat with sweeteners like high-fructose corn syrup, honey, or agave nectar, all of which are high FODMAP. Some brands also sneak in garlic powder, onion powder, or “natural garlic flavor” for taste. Before using any mayo, scan the ingredient list for these specific additions. A plain, full-fat mayo from a major brand is almost always the safest choice.
Relish, Pickles, and Other Mix-Ins
Sweet pickle relish is one of the most common tuna salad additions and one of the trickiest. Many major brands, including Heinz, Vlasic, and Coronation, use high-fructose corn syrup as a sweetener, which makes them high FODMAP. The FODMAP level of relish ranges from low to high depending on the recipe, so you need to check labels carefully. A relish sweetened with plain sugar (sucrose) and free of onion or garlic is a safer bet.
Dill pickles themselves are generally low FODMAP in small amounts, but flavored or bread-and-butter pickles often contain garlic and sweeteners. Celery, another classic tuna salad ingredient, is low FODMAP at about half a stalk (roughly 25 grams) but can become moderate at larger servings. A few small dice of celery for crunch is fine for most people.
Replacing Onion Flavor Safely
Onion is the single biggest FODMAP risk in tuna salad, and it’s also what gives the dish much of its flavor. Fortunately, several substitutes deliver that savory bite without the fructans.
- Green scallion tips: Only the green part of scallions (spring onions) is low FODMAP. The white bulb end contains the same fructans as regular onion. The green tips are safe up to about 75 grams, which is a generous handful.
- Chives: Fresh or dried chives have a mild onion flavor and are very low in FODMAPs. Monash University tested fresh chives as low FODMAP up to 500 grams, so you can use them freely.
- Onion-infused oil: When onion is steeped in oil and then strained out, the FODMAPs stay behind in the solids because they’re water-soluble, not fat-soluble. A drizzle of onion-infused oil adds authentic onion flavor with zero FODMAP content, as long as no onion pieces remain.
- Asafetida: This spice, common in Indian cooking, mimics an onion-garlic flavor. Monash tested it as low FODMAP, and FODMAP Friendly found it contains no detectable FODMAPs at all. A small pinch goes a long way.
Building a Low-FODMAP Tuna Salad
Start with canned tuna (in water or oil, drained), then add full-fat plain mayonnaise, a squeeze of lemon juice, salt, pepper, and your choice of safe flavor boosters. Sliced chives or green scallion tips replace onion nicely. A few small pieces of celery add crunch without crossing FODMAP thresholds. Dijon mustard is low FODMAP and gives the salad some sharpness.
If you want relish, look for a brand sweetened with sugar rather than high-fructose corn syrup, or chop your own dill pickles (checking that the jar doesn’t list garlic). Capers, olives, and a pinch of paprika or dried dill are all safe additions that keep the flavor interesting.
Serve it on low-FODMAP bread (sourdough spelt is a common choice), over rice cakes, wrapped in lettuce, or straight from the bowl. The base protein is completely safe, so as long as you’ve vetted each add-in, tuna salad fits comfortably into a low-FODMAP meal plan.
Quick Ingredient Checklist
- Safe: canned tuna, full-fat mayo, lemon juice, Dijon mustard, salt, pepper, chives, green scallion tips, small amounts of celery, plain dill pickles (no garlic), capers, olives
- Risky: relish (check sweetener), flavored mayo, bread-and-butter pickles, “natural flavors” (may contain garlic or onion extracts)
- Avoid: raw onion, onion powder, garlic powder, light or reduced-fat mayo with HFCS or honey, pre-made deli tuna salad with unverified ingredients