Canned tuna is a convenient and affordable source of protein and omega-3 fatty acids, but concerns over mercury contamination often leave consumers wondering about its safety. The primary risk comes from methylmercury, a neurotoxin that can accumulate in larger, longer-lived fish. Fortunately, understanding the different types of canned tuna available can help you minimize exposure while still enjoying its nutritional benefits.
Understanding the Mercury Risk in Canned Tuna
Mercury enters our oceans from both natural and industrial sources. As it moves up the food chain, it becomes more concentrated in larger fish—a process known as bioaccumulation. This means that bigger predatory tuna species accumulate more mercury over their lifetime than smaller ones. This distinction is the most important factor when choosing the safest canned tuna.
Comparing Tuna Species
Different species of tuna are used in canned products, and their mercury levels vary significantly. Canned light tuna typically comes from the smaller, younger skipjack species, which is known for its relatively low mercury content. In contrast, canned white or albacore tuna is sourced from the larger albacore species, which has higher mercury levels. Bigeye tuna, often used in sushi and some gourmet canned products, has the highest mercury concentration and should be avoided, especially by vulnerable populations.
The Importance of Packing Liquid
The liquid the tuna is packed in—water or oil—also affects its nutritional profile. Tuna packed in water contains fewer calories and less fat, making it a better option for those watching their weight. Some people prefer tuna packed in oil for its richer flavor and texture, but this adds more calories and fat. It's important to note that the packing liquid does not affect the mercury content of the fish.
Making an Informed Decision
When at the store, checking the label is the best way to ensure you are buying a safe and responsibly sourced product. Look for phrases like "light" or "skipjack" if minimizing mercury is your primary goal. For those seeking sustainability, certifications and fishing method labels are key.
The Role of Sustainable Fishing
Sustainable fishing methods can further ensure a safer product. Techniques like "pole-and-line" or "troll-caught" are more selective, reducing bycatch and often targeting smaller, younger tuna, which naturally contain less mercury. Many consumers look for products certified by organizations like the Marine Stewardship Council (MSC) for rigorous standards.
A Look at Specialty Brands
Some brands, such as Safe Catch, have taken extra steps to address consumer concerns about mercury by testing every individual fish before canning. These brands often market themselves as having the "lowest mercury" levels and are sometimes endorsed by health organizations like the American Pregnancy Association. While these products may come at a higher price point, they offer added peace of mind for those with the greatest concerns, such as pregnant women or young children.
Comparison of Canned Tuna Types
| Feature | Canned Light Tuna (Skipjack) | Canned Albacore Tuna (White) |
|---|---|---|
| Average Mercury Level | Lower (approx. 0.13 ppm) | Higher (approx. 0.35 ppm) |
| Flavor Profile | Richer, meatier | Milder, lighter |
| Typical Texture | Flaked or chunk | Solid or chunk |
| FDA Recommended Serving | 2-3 servings per week for adults | 1 serving per week for adults |
| Suitable for Sensitive Groups | Yes (in recommended portions) | No (avoid for pregnant/nursing/children) |
Tips for Choosing the Safest Canned Tuna
- Read the Label: Look for "light tuna" or "skipjack" to ensure lower mercury. Avoid "bigeye" tuna completely.
- Prioritize Sustainability: Choose tuna labeled "pole-and-line caught" or with MSC certification to support responsible fishing practices.
- Consider Brand Reputation: Look for brands like Safe Catch that test each individual fish for mercury for maximum safety.
- Opt for Water-Packed: Choose tuna packed in water for a lower calorie and fat option.
- Diversify Your Seafood: Incorporate other low-mercury options like salmon and sardines to get a variety of nutrients.
- Moderate Your Intake: Stick to the FDA's recommended serving sizes to prevent long-term mercury buildup, especially with albacore tuna.
Conclusion
While all canned tuna contains some level of mercury, making informed choices about the species and quantity consumed can significantly reduce any potential health risks. For most people, canned light tuna, typically derived from skipjack, is the safest and most practical choice for regular consumption. It offers a great balance of nutritional value and low mercury levels. By paying attention to species, packing liquid, and fishing methods, you can confidently choose the safest canned tuna to incorporate into your healthy diet.
For more detailed information on fish consumption recommendations, consult the FDA/EPA advice on eating fish.
