Canned Tuna Species to Avoid
Not all canned tuna is created equal. The species of tuna inside the can is the most significant factor determining its mercury level. Larger, longer-living tuna accumulate more mercury throughout their lifespan through a process called biomagnification, making them a less desirable choice for frequent consumption.
Bigeye Tuna (Ahi)
Bigeye tuna, sometimes marketed as 'ahi,' consistently contains the highest levels of mercury among canned and fresh tuna varieties. The FDA and EPA explicitly list this as a 'choice to avoid' for pregnant women and children. While not as common in standard grocery store cans, it can be found in some specialty 'gourmet' or 'tonno' products. If you see 'bigeye' or 'ahi' on the label, it is best to avoid it, particularly for sensitive populations.
Canned White Albacore Tuna
Albacore tuna, known for its lighter color and milder flavor, has mercury levels that are typically almost three times higher than light tuna. The FDA advises that pregnant women, nursing mothers, and young children should limit their intake to no more than one serving per week. For most adults, moderate consumption is generally safe, but those who consume a lot of fish should be mindful of their mercury intake.
Certain Yellowfin Tuna
Yellowfin tuna, often found in light tuna products, has moderately higher mercury levels than skipjack. While typically less of a concern than albacore, some 'gourmet' yellowfin products or 'tonno' use larger, more mature yellowfin that can contain mercury levels comparable to canned white tuna. Consumers who regularly eat tuna should check the can's label for the specific species and aim to diversify their seafood choices.
Packing Liquid and Additives
The liquid in which the tuna is packed can also influence your purchasing decision based on nutritional and dietary needs.
Tuna Packed in Oil vs. Water
There are nutritional tradeoffs between tuna packed in oil versus water. Tuna packed in oil, while often richer in flavor and moister, contains more calories and fat. For those watching their fat or calorie intake, water-packed tuna is the better choice. Additionally, some healthy omega-3 fatty acids in the tuna can leach into the oil, and if you drain it, you lose a portion of these benefits. With water-packed tuna, the omega-3s are retained in the fish itself.
High-Sodium Brine
Standard canned tuna is often packed in a brine with high sodium content, which can be a concern for people with high blood pressure or other heart conditions. It is best to choose products with 'no salt added' or 'low sodium' on the label if you are monitoring your sodium intake.
Ethical and Environmental Concerns
Beyond personal health, the environmental impact of your tuna choice is a significant factor. Not all fishing methods are sustainable, and some contribute to overfishing and harm to other marine life.
Tuna Caught via Purse Seines with FADs
Purse seines are large nets used to encircle entire schools of fish. When these nets are used with Fish Aggregating Devices (FADs), they attract a variety of marine animals, leading to high levels of bycatch—the unintended capture of other species like dolphins, turtles, and sharks. While the 'dolphin-safe' label exists, some sources say it can be misleading and does not guarantee the safety of all ocean wildlife. For a more ethical choice, look for labels indicating 'pole-and-line caught' or 'FAD-free'.
Packaging Considerations
BPA-Lined Cans
Bisphenol A, or BPA, is an industrial chemical once commonly used to line food cans. BPA can leach into food and has been linked to health issues, particularly concerning reproductive and developmental systems. While many manufacturers now offer BPA-free packaging, some may use alternatives that have not been as extensively studied. Choosing tuna that explicitly states 'BPA-free' on the label is a proactive step for consumer safety.
Comparison of Canned Tuna Types
| Feature | White Albacore Tuna | Light/Skipjack Tuna | Bigeye (Ahi) Tuna |
|---|---|---|---|
| Mercury Content | Higher | Lower | Highest |
| FDA/EPA Recommendation | Limit 1 serving/week for at-risk groups | Best Choice (2–3 servings/week) | Avoid for at-risk groups |
| Flavor | Milder | Richer, 'tuna-y' flavor | Rich, intense flavor |
| Texture | Firmer, 'steak-like' | Softer, flakier | Firm and meaty |
| Common Use | Salads, sandwiches, casseroles | Casseroles, sauces, budget-friendly dishes | Gourmet recipes, often not canned |
Conclusion
When navigating the canned tuna aisle, exercising caution and reading labels are key to making a healthy and ethical choice. Avoid varieties known for high mercury levels, such as bigeye and albacore tuna, and opt for lighter, lower-mercury options like skipjack. Pay attention to how the tuna was caught and avoid products from unsustainable fishing practices involving FADs. Be mindful of added sodium and choose BPA-free packaging whenever possible to minimize exposure to potentially harmful chemicals. By prioritizing species diversity, sustainable sourcing, and ingredient transparency, you can enjoy canned tuna as part of a balanced diet while safeguarding both your health and the marine environment. For additional information on sustainable seafood, consider referencing the Monterey Bay Aquarium Seafood Watch guide.
