Canned tuna is a convenient, high-protein source of beneficial omega-3 fatty acids, but mercury contamination is a common concern for many consumers. This guide will explain how mercury levels in tuna vary, highlight brands known for their low-mercury products, and provide practical tips for making safer, more informed choices.
Understanding Mercury in Tuna
Mercury is a naturally occurring heavy metal that finds its way into oceans through both natural events, like volcanic eruptions, and human activities, such as industrial pollution. Once in the water, bacteria convert it into a more toxic form called methylmercury.
The Bioaccumulation Process
Fish higher up the food chain and those that are larger and older tend to accumulate higher concentrations of mercury in their tissues, a process known as bioaccumulation. When we eat these fish, we also ingest the accumulated mercury. This is a key reason why tuna species, particularly larger ones, can be a significant source of mercury exposure for humans.
Species Matter: Albacore vs. Light Tuna
Not all canned tuna is created equal when it comes to mercury. The two most common types you'll find are 'white' albacore and 'light' tuna. The difference is significant:
- Albacore (White) Tuna: This comes from larger, older tuna species and therefore contains significantly more mercury than light tuna. The FDA classifies it as a "Good Choice" but recommends limiting consumption for most adults to one 4-ounce serving per week.
- Light Tuna (Skipjack): This typically comes from smaller, younger skipjack tuna, which have had less time to accumulate mercury. The FDA categorizes it as a "Best Choice" and suggests it can be safely consumed by most adults 2-3 times per week.
Top Brands with Low Mercury Canned Tuna
When searching for the canned tuna with the least mercury, some brands stand out due to their commitment to specific sourcing and testing methods. Here's what the research shows:
Safe Catch: The Mercury Tester
Safe Catch is unique in the industry because it's the only brand that tests every single fish for mercury contamination before canning.
- Proprietary Technology: The company developed a special technology to rapidly test each fish for mercury, ensuring a strict limit is met.
- Very Low Levels: The brand's Elite Wild Tuna has mercury levels that are on average 25x lower than the FDA's action limit and 8x lower than albacore tuna.
- Recommended for Sensitive Groups: Its rigorous testing is why Safe Catch Elite Tuna is the official tuna of the American Pregnancy Association, a key factor for pregnant women and young children.
Wild Planet: Sustainable and Lower Mercury
Wild Planet prioritizes sustainability and uses fishing methods that also help to lower mercury levels. They catch younger, smaller, migratory tuna using pole-and-line and troll methods.
- Naturally Lower Levels: Because the fish are younger, they have had less time to accumulate mercury.
- Independent Testing: Wild Planet's own third-party testing protocols show that their skipjack and albacore tuna are well below FDA action limits.
- Variable Results: Consumer Reports has noted that despite the brand's low-mercury average, unpredictable spikes can still occur in individual cans, so vigilance is still warranted.
American Tuna: US-Processed with Low Levels
This brand supports US fishing communities and conducts its own mercury and radiation testing.
- Untraceable Mercury: American Tuna claims its products have "untraceable levels of mercury".
- High Selenium: They also highlight the naturally high selenium levels in their tuna, which binds to mercury and helps the body eliminate it.
Standard Brands (Bumble Bee, StarKist, Chicken of the Sea)
For standard grocery store brands, the type of tuna is the most important factor in determining mercury levels. When choosing these brands:
- Stick to Chunk Light: Always opt for the 'Chunk Light' or 'Skipjack' varieties to minimize mercury intake.
- Avoid Albacore: The Albacore tuna from these brands tends to have higher mercury levels.
Comparison of Popular Tuna Options
To help you visualize the differences, here's a comparative table based on data and general industry practices:
| Tuna Type | Typical Species | Mercury Level | Fish Size | Recommended Consumption (Adults) |
|---|---|---|---|---|
| Light Tuna | Skipjack | Lowest (Best Choice) | Smaller, younger | 2-3 servings per week |
| Albacore Tuna | Albacore | Higher (Good Choice) | Larger, older | 1 serving per week |
| Safe Catch Elite | Wild Skipjack | Consistently lowest | Smaller, younger | Approved for sensitive populations |
| Wild Planet Skipjack | Wild Skipjack | Lower than Albacore | Smaller, younger | Varies by can, follow guidelines carefully |
| American Tuna | Albacore | Very low (tested) | Smaller, younger | Safe for pregnancy (tested low) |
How to Choose the Right Canned Tuna for Your Diet
Check the Label
Don't just assume 'light' tuna is safe. To be certain, look for specific species on the label, such as "Skipjack". Also, check for sustainable fishing method labels like "pole-and-line caught," which typically harvest smaller, younger fish with lower mercury levels.
Prioritize Your Health Needs
For sensitive populations like pregnant women and young children, low-mercury intake is especially critical. While Safe Catch is approved by the American Pregnancy Association due to its strict testing, some groups like Consumer Reports advise against tuna altogether for pregnant women due to unpredictable can-to-can mercury spikes. Consider lower-mercury alternatives like sardines, salmon, and mackerel instead.
Read Third-Party Certifications
Look for certifications from reputable organizations like the Marine Stewardship Council (MSC). These certifications not only indicate sustainable practices but also provide assurance that brands meet certain standards. Some brands also specify "FAD-free" (fish aggregating device-free), indicating less bycatch and potentially better ecological practices.
Water vs. Oil
The packing liquid does not affect the mercury content of the tuna. The primary difference is nutritional. Tuna packed in oil will have more fat and calories, while tuna in water is leaner. Choose based on your dietary goals, but know that it won't impact your mercury intake.
Conclusion: Making an Informed Choice
Making a conscious effort to choose low-mercury canned tuna involves a simple yet effective strategy: know your species and know your brands. By opting for skipjack (light) tuna over albacore, you are already making a substantial reduction in mercury exposure. For those who want the highest degree of confidence, selecting a brand like Safe Catch, which tests every single fish, offers the greatest assurance of low mercury content. When shopping, remember to read the labels for species and certifications to ensure your tuna consumption is as safe and healthy as possible. While tuna is a nutritious food, incorporating a variety of other low-mercury fish like salmon and sardines is the best way to ensure you're reaping health benefits without over-exposing yourself to mercury. For further reading on safe seafood consumption, consult the official FDA guidelines.
Comparison of Popular Tuna Options (Continued)
To help visualize the differences between popular tuna varieties and brands regarding mercury content, here is a more comprehensive breakdown:
- Wild Planet Skipjack Wild Tuna: While considered a lower-mercury option due to younger fish, Consumer Reports testing found some cans had higher mercury spikes, closer to albacore levels. Consumers should be aware that even 'best choice' tuna can have some variation.
- Standard Chunk Light Tuna (e.g., Bumble Bee, StarKist): Made from smaller skipjack tuna, these generally have low mercury levels, making them a safer choice for regular consumption compared to albacore.
- Safe Catch Albacore Tuna: This brand also offers an albacore option that is individually tested for mercury to a limit of 0.38ppm, which is significantly stricter than FDA guidelines for the species. This makes it a safer albacore choice for those who prefer the flavor.
Ultimately, a combination of factors—including species, brand testing practices, and catch method—determines the mercury content. Regular consumption of canned tuna should focus on the lowest-mercury varieties, like skipjack, to maximize benefits while minimizing risk.
