Tuna with mayo is a reasonable source of protein and omega-3 fats, but the healthiness depends heavily on which mayo you use and how much. A standard tuna salad made with two tablespoons of regular mayonnaise adds roughly 180 calories and 20 grams of fat, most of it from soybean or canola oil. The tuna itself is nutritious. The mayo is where things get complicated.
What Tuna Brings to the Mix
Canned tuna is one of the most affordable sources of lean protein and marine omega-3 fatty acids. A single 4-ounce serving of light tuna packed in water delivers around 25 grams of protein with minimal fat. The omega-3s in tuna, specifically EPA and DHA, help reduce inflammation by counteracting the effects of omega-6 fatty acids that dominate most modern diets. These marine omega-3s work by dialing down the same inflammatory pathways that drugs like ibuprofen target, just through diet instead of medication.
Tuna also provides selenium, vitamin D, and B vitamins. Canned light tuna (typically skipjack) sits in the FDA’s “Best Choices” category for mercury, meaning you can safely eat two to three servings per week. Albacore (white) tuna contains roughly three times more mercury than light tuna, so the FDA recommends limiting it to one serving per week with no other fish that week. Bigeye tuna should be avoided entirely.
The Problem With Standard Mayonnaise
Most commercial mayonnaise is made primarily from soybean oil, which is high in omega-6 fatty acids. This matters because omega-6s, when consumed in excess, promote low-grade inflammation, oxidative stress, and can contribute to arterial damage over time. The irony of a tuna-mayo sandwich is that you’re pairing a food rich in anti-inflammatory omega-3s with a condiment loaded with pro-inflammatory omega-6s. The omega-3s in tuna work partly by suppressing the inflammatory compounds that omega-6 metabolism produces. Adding a heavy dose of soybean oil mayo partially undermines that benefit.
Two tablespoons of regular mayo also contain around 180 to 200 calories, nearly all from fat. If you’re generous with the mayo (and most people are), a single bowl of tuna salad can easily cross 400 calories before it touches bread or crackers. That’s not inherently bad if it fits your daily intake, but it shifts tuna salad from “lean protein” to something closer to a fat-heavy meal.
Healthier Ways to Make It
You don’t have to ditch mayo entirely. Small adjustments make a meaningful difference.
- Use less mayo. One tablespoon instead of two or three cuts the added fat and calories roughly in half. Stretch it with a squeeze of lemon juice or a splash of pickle brine for moisture.
- Choose avocado oil mayo. Avocado oil is about 70% monounsaturated fat, the same heart-healthy type found in olive oil. It contains far less omega-6 than soybean oil. Several brands now make avocado oil mayonnaise that tastes nearly identical to the original.
- Try olive oil mayo. Similar logic: more monounsaturated fat, less omega-6. Check the label, though. Some “olive oil” mayonnaises still list soybean or canola oil as the first ingredient, with olive oil added in small amounts.
- Swap in Greek yogurt. Mixing half mayo and half plain Greek yogurt adds protein, cuts fat, and keeps the creamy texture. Full Greek yogurt with a little mustard and lemon works too if you want to skip mayo altogether.
Canned Tuna: Water vs. Oil
Tuna packed in water is the leaner option, with significantly fewer calories and less total fat than tuna packed in oil. Sodium is another factor worth watching. A single ounce of regular canned tuna in water contains around 70 mg of sodium in low-sodium versions, but standard versions run much higher. If you eat tuna regularly, choosing “no salt added” varieties keeps your sodium intake in check, especially once you add mayo (which contributes its own sodium).
Draining tuna packed in oil doesn’t remove all the added fat, because the fish absorbs some during processing. If you’re trying to keep the meal lean, water-packed tuna gives you more control over exactly how much fat you’re adding through your choice of mayo or dressing.
How Often You Can Eat It
For most adults, tuna salad two to three times a week is perfectly fine as long as you’re choosing light (skipjack) tuna. If you prefer albacore for its milder flavor and firmer texture, limit it to once a week. A standard serving is 4 ounces measured before mixing in other ingredients.
Pregnant or breastfeeding women and young children should follow these limits more carefully, since mercury accumulates over time and affects developing nervous systems more than adult ones. For everyone else, the nutritional benefits of eating tuna regularly, including the omega-3s, protein, and selenium, outweigh the mercury risk at these serving levels.
The Bottom Line on Tuna With Mayo
Tuna itself is one of the healthiest, most convenient proteins you can eat. The mayo is the variable. A modest amount of avocado oil or olive oil mayo keeps the omega-6 load low and preserves most of tuna’s anti-inflammatory benefits. Two tablespoons of soybean oil mayo won’t ruin the meal, but it does dilute the nutritional advantage you’re getting from the fish. If tuna salad is a regular part of your diet rather than an occasional lunch, the type and amount of mayo you use adds up over weeks and months.