Understanding Mercury in Tuna
Mercury is a naturally occurring element that is released into the environment through both natural processes and human activities, such as industrial pollution. In water, it is converted into methylmercury, a potent neurotoxin that can accumulate in the food chain. Larger, older predatory fish like albacore tuna tend to have higher concentrations of mercury due to a process called biomagnification, while smaller, shorter-lived species like skipjack have lower levels.
Species Matters: The Albacore vs. Light Tuna Divide
The most significant factor influencing a can of tuna's mercury content is the species of fish it contains. Canned 'light' tuna is most commonly made from skipjack tuna, a smaller, faster-growing species. Canned 'white' tuna is exclusively albacore, a larger and longer-lived species. The difference in mercury levels is substantial. According to FDA data, canned albacore averages 0.350 parts per million (ppm) of mercury, nearly three times higher than the 0.126 ppm average for canned light tuna. This fundamental difference makes canned light tuna a universally safer, low-mercury choice, regardless of the brand. However, individual cans within a brand can still show unpredictable spikes in mercury levels, as highlighted by Consumer Reports.
A Comparison of Low-Mercury Tuna Brands
Beyond just choosing light tuna, several brands stand out for their specific commitments to providing low-mercury options, often through proprietary testing or sourcing smaller fish.
Safe Catch
Safe Catch markets itself as having the "lowest mercury of any brand" by testing every single fish they process. Their proprietary technology allows them to test each tuna to a strict mercury limit, ten times stricter than the FDA's action limit for their Elite Wild Tuna (0.1 ppm). For their Wild Albacore, the limit is 2.5 times stricter (0.38 ppm). This process eliminates the uncertainty of random mercury spikes found in other brands. This meticulous, individual-fish testing is their primary differentiator, though it does come at a higher price point compared to standard canned tuna.
Wild Planet
Wild Planet also takes proactive steps to ensure low mercury levels by catching smaller, younger, surface-dwelling tuna. They use annual third-party testing to verify their products' average mercury content. Their average levels are impressively low: Skipjack tuna averages 0.067 ppm, while their Albacore averages 0.17 ppm. Both figures are significantly lower than the FDA's action limit of 1.0 ppm. However, unlike Safe Catch, they do not test every single fish, meaning some variability in mercury levels may still occur within their products.
American Tuna
This brand utilizes a sustainable pole-and-line fishing method, which targets smaller, younger tuna with inherently lower mercury levels. They regularly employ independent third-party testing and state that their mercury content is consistently well below U.S. safety standards. Their FAQ specifically mentions levels below 0.3 ppm. Their commitment to American-sourced seafood and transparent testing makes them another strong contender for low-mercury choices.
Conventional Brands: Bumble Bee, StarKist, and Chicken of the Sea
For budget-conscious consumers, sticking to the chunk light options from conventional brands like Bumble Bee, StarKist, and Chicken of the Sea is still a relatively safe bet. These brands predominantly use skipjack tuna, which is naturally lower in mercury. A Consumer Reports analysis included their chunk light products among the safer choices for limited weekly consumption. However, relying solely on brand and species without per-can testing means consumers accept the risk of occasional mercury spikes, which some studies have found.
Brand Comparison Table
| Brand | Primary Tuna Species | Mercury Control Method | Mercury Claim/Level | Price Point (relative) |
|---|---|---|---|---|
| Safe Catch | Skipjack (Elite), Albacore | Tests every single fish | Elite: <0.1 ppm; Albacore: <0.38 ppm | High |
| Wild Planet | Skipjack, Yellowfin, Albacore | Third-party annual testing of averages | Skipjack: ~0.067 ppm; Albacore: ~0.17 ppm | Mid-High |
| American Tuna | Albacore, Skipjack | Independent third-party batch testing | <0.3 ppm reported for Albacore | Mid-High |
| Bumble Bee Chunk Light | Skipjack | FDA limits | Average for Canned Light: ~0.126 ppm | Low |
| StarKist Chunk Light | Skipjack | FDA limits | Average for Canned Light: ~0.126 ppm | Low |
| Chicken of the Sea Chunk Light | Skipjack | FDA limits | Average for Canned Light: ~0.126 ppm | Low |
Tips for Choosing Low-Mercury Tuna
Here are some practical strategies to minimize your mercury exposure from canned tuna:
- Choose Canned Light or Skipjack: As a rule of thumb, always opt for light or skipjack tuna over albacore or yellowfin.
- Limit Consumption of Albacore: If you prefer albacore, consume it less frequently. The FDA suggests limiting it to one 4-ounce serving per week for most adults.
- Vary Your Seafood Intake: Incorporate other low-mercury, high-omega-3 fish into your diet, such as salmon, sardines, and anchovies.
- Research Specific Brands: For the lowest possible mercury levels, consider brands with strict testing protocols like Safe Catch, though it's important to weigh cost against risk.
- Don't Drain the Tuna for Mercury Reduction: Mercury is stored in the muscle tissue of the fish, so draining the water or oil will not reduce the mercury content.
Conclusion
While all commercial canned tuna products on the market are generally considered safe under FDA guidelines for moderate consumption, mercury levels can vary significantly. For those most concerned about minimizing mercury, such as pregnant women or young children, choosing canned light (skipjack) tuna is the most effective strategy. Brands like Safe Catch offer the highest level of assurance through their individual-fish testing protocol, albeit at a higher cost. Brands like Wild Planet and American Tuna also provide consistently lower average levels by sourcing younger fish. For the average consumer, moderation and selecting light tuna from any brand offer a good balance of nutritional benefits and minimal mercury exposure.
Important Resources
For the latest advice on eating fish, consult the official guidelines from the U.S. government. The FDA provides comprehensive advice, including guidance for vulnerable populations. FDA/EPA Fish Advice
