Methylmercury contamination is a concern for many seafood consumers, particularly for sensitive groups like pregnant women and young children. As a result, choosing the right type of canned tuna is essential for balancing nutritional benefits with the potential risks associated with mercury exposure. The key to finding the lowest-mercury option lies in understanding the species of tuna used and the size of the fish caught.
Understanding Mercury in Tuna
Mercury enters marine ecosystems through both natural processes and industrial pollution, eventually being converted into highly toxic methylmercury by bacteria. As methylmercury is consumed by small marine organisms and travels up the food chain, its concentration increases in larger, longer-lived predatory fish—a process known as bioaccumulation. Tuna, being a large predator, can accumulate significant levels of mercury, but levels vary dramatically by species and age. Smaller, younger tuna species like skipjack have much less time to accumulate mercury compared to their larger and older counterparts, such as albacore and bigeye.
The Top Choice: Light and Skipjack Tuna
For consumers seeking the lowest mercury levels, canned light tuna is the definitive choice. This product is most often made from skipjack tuna, a smaller and faster-maturing species. Its shorter lifespan means it has less time to accumulate methylmercury. Data consistently shows that light tuna varieties contain less mercury on average than albacore.
Commonly available low-mercury brands:
- Bumble Bee Chunk Light
- Chicken of the Sea Chunk Light
- StarKist Chunk Light
Higher Mercury Varieties: Albacore and Yellowfin
Often labeled as "white" tuna, albacore has substantially higher mercury levels than canned light tuna, typically three times as much. This is because albacore are larger, older fish. Similarly, fresh or frozen yellowfin tuna also contain higher mercury concentrations, similar to or exceeding albacore. The FDA advises that sensitive populations, such as pregnant women, should limit albacore consumption to no more than one 4-ounce serving per week. For reference, bigeye tuna, often used in sushi, has the highest mercury levels of all tuna varieties.
Brand Spotlight: Mercury-Tested Options
While most brands offer canned light tuna with low average mercury levels, some go a step further with specific testing protocols.
- Safe Catch: This brand uses proprietary technology to test every single fish for mercury to ensure it meets a specific purity standard. For example, their Elite Wild Tuna (skipjack) is tested to a limit 10 times stricter than the FDA's action limit. This offers a high degree of confidence for consumers, especially those with increased health concerns.
- Wild Planet: Focusing on smaller, younger, and sustainably caught tuna via pole and line, Wild Planet's products consistently demonstrate lower average mercury levels. Their skipjack tuna averages significantly below the FDA's action limit.
Comparing Canned Tuna Varieties
| Feature | Canned Light Tuna (Skipjack) | Albacore Tuna (White) | Fresh/Frozen Yellowfin Tuna |
|---|---|---|---|
| Average Mercury (ppm) | Low (approx. 0.126) | Higher (approx. 0.350) | High (approx. 0.354) |
| Fish Size | Smaller, younger species | Larger, longer-lived species | Large, predatory species |
| FDA Recommendation for Vulnerable Groups | 2-3 servings (up to 12 oz) per week | 1 serving (up to 4 oz) per week | 1 serving (up to 4 oz) per week |
| Texture/Flavor | Softer, flakier, richer flavor | Firmer texture, milder flavor | Meaty, firmer texture, often used for steaks |
The Importance of Serving Size and Frequency
Even with lower-mercury options, moderation is key. The FDA and EPA recommend that women who are pregnant, trying to become pregnant, or breastfeeding, as well as young children, limit their fish consumption according to specific guidelines. For healthy adults, eating a variety of low-mercury seafood, including up to 12 ounces of canned light tuna weekly, is generally considered safe. Individual cans of tuna can have unpredictable spikes in mercury, so sticking to a variety and recommended serving sizes is the most prudent approach.
Safe Fish Alternatives to Tuna
For those looking to diversify their low-mercury seafood intake, many other excellent options exist.
- Salmon: Canned or fresh salmon is rich in omega-3s and is consistently low in mercury.
- Sardines: These small, oily fish are very low in mercury and packed with nutrients.
- Shrimp and Scallops: Both are safe and low-mercury options for regular consumption.
- Tilapia: A mild white fish that is low in mercury.
Conclusion: Making the Best Choice for Your Health
When asking what canned tuna has the least amount of mercury, the answer is consistently canned light tuna, typically made from the smaller skipjack species. For maximum assurance, opt for brands like Safe Catch or Wild Planet that explicitly test their fish for mercury and practice sustainable fishing methods. By prioritizing species and following recommended serving guidelines, you can safely enjoy the health benefits of canned tuna while minimizing your mercury exposure. For more information on mercury levels in seafood, consult the official guidelines from the FDA.
Frequently Asked Questions
What type of canned tuna is highest in mercury? Albacore, or "white" tuna, typically has the highest mercury levels among common canned options because it is a larger, older species. Bigeye tuna, often used in fresh or frozen form for sushi, has even higher levels.
Can draining the liquid from canned tuna reduce mercury? No, draining the liquid (water or oil) from canned tuna does not significantly reduce the mercury content. Mercury is stored in the fish's tissue, not the packing liquid.
How much canned light tuna is safe to eat in a week? The FDA generally recommends that most adults can safely consume 2 to 3 servings (up to 12 ounces total) of canned light tuna per week. Sensitive populations should adhere to specific, more cautious guidelines.
Is it safe for pregnant women to eat canned tuna? Yes, but with caution. Pregnant women are advised to choose low-mercury options like canned light or skipjack tuna and limit their total intake to 8–12 ounces per week from a variety of low-mercury fish.
Do all canned light tunas have the same mercury level? No, mercury levels can vary from can to can, even within the same brand of light tuna. While the average is low, brands like Safe Catch that test each individual fish can offer more consistent results.
Are tuna pouches different from canned tuna in terms of mercury? Tuna pouches contain the same species of tuna as the cans, so the mercury content depends on the type (e.g., light/skipjack vs. albacore), not the packaging.
How does Wild Planet ensure low-mercury tuna? Wild Planet sources smaller, younger tuna caught via pole and line, which naturally have lower mercury levels. They also conduct annual third-party testing to verify that their products consistently meet low average mercury standards.
