Tuna can deliver a large amount of protein with very little fat, but “tuna” covers several species and products. Canned light tuna in water is not nutritionally or toxicologically identical to albacore, bigeye or an oil-packed product. Species matters especially when tuna is eaten frequently because mercury levels differ.
Protein and calories by product
| Product | Calories/100 g | Protein | Fat |
|---|---|---|---|
| Light tuna in water, no salt added, drained | ~116 | ~25.5 g | ~0.8 g |
| White/albacore tuna in water, drained | ~128 | ~23.6 g | ~3.0 g |
| Tuna in oil, drained | ~190–200 | ~28–29 g | ~8 g |
Brand, species and retained liquid change the exact figures. The broad pattern is stable: water-packed tuna is usually very protein-dense, while retained oil raises energy density.
Does tuna provide omega-3?
Yes. Tuna provides EPA and DHA, but it is usually less omega-3-rich than fattier fish such as salmon, sardines and many types of mackerel. Species and cut matter.
Mercury depends strongly on species
Large, long-lived predatory fish accumulate more methylmercury. FDA/EPA place canned light tuna in the “Best Choices” category, while albacore/white tuna is a “Good Choice.” FDA notes that albacore typically contains about three times as much mercury as canned light tuna.
Bigeye tuna is in the “Choices to Avoid” category for pregnant or breastfeeding people and young children covered by the advisory.
Light tuna is not the same as every tuna steak
Canned light tuna is commonly made from smaller species such as skipjack. Fresh tuna steaks may come from yellowfin, bigeye, bluefin or other species, so “fresh” does not tell you the mercury category.
Water-packed or oil-packed?
If the goal is maximum protein for fewer calories, water-packed tuna is straightforward. At 116 kcal and 25.5 g protein per 100 g, a 120 g drained portion is about 139 calories and 30.6 g protein. A comparable oil-packed product near 198 kcal/100 g would be about 238 calories for 120 g.
Sodium also varies dramatically between salted and no-salt-added cans, so the Nutrition Facts label matters.
Bottom line
Tuna is a highly efficient protein source, but species identification matters more than the protein number when deciding how often to eat it. Rotating tuna with salmon, sardines, trout, pollock and other fish improves variety and reduces reliance on a single mercury profile.
Mercury is not removed by draining or cooking
Mercury is incorporated into fish tissue, so rinsing canned tuna, draining the liquid, grilling a steak, or cooking it more thoroughly does not meaningfully solve the mercury question. The practical control is species choice and how often higher-mercury fish are eaten. That is why public-health advice distinguishes lower-mercury choices from larger predatory species.
For canned tuna, “light” tuna and albacore are not interchangeable categories in U.S. guidance. In Spain and the EU market, species names on the label help clarify what you are buying. People in groups given specific mercury advice should follow their national recommendations rather than assuming every product called tuna has the same profile.
Look at drained weight, sodium, and added oil on canned products
Nutrition panels can be difficult to compare when one can lists values for drained fish and another lists the product as sold. Drained weight gives a better idea of how much tuna you are actually eating. Salt also varies widely: some products are low-salt, while flavored pouches and prepared tuna salads can be much higher in sodium.
Oil-packed tuna may taste richer and can retain more of the added oil depending on how thoroughly it is drained. That does not make it inferior, but it changes calories and fat. Water-packed tuna makes it easier to control added fat elsewhere in the meal.
Use tuna as one fish option, not the only one
Rotating tuna with sardines, salmon, trout, mackerel species that fit local guidance, shellfish, and other fish broadens the nutrient profile and reduces reliance on a single mercury exposure pattern. Small oily fish can be particularly useful when the goal is omega-3 rather than simply lean protein.
Preparation can still matter for the rest of the nutrition profile even though it does not remove mercury. Tuna mixed with mayonnaise, cheese, or salty sauces is a different meal from tuna served with vegetables, beans, or whole grains. The fish provides the protein; the complete dish determines much of the final energy, sodium, fiber, and fat balance.
Sources
- USDA FoodData Central — Composition data for canned light and white tuna and different packing media.
- FDA/EPA — Advice about Eating Fish — Current mercury categories for canned light, albacore, yellowfin and bigeye tuna.
- FDA — Questions & Answers about Eating Fish — Explains species differences and that albacore typically has about three times the mercury of canned light tuna.