What could be more convenient than opening a can and getting instant protein? Canned fish, like tuna and salmon, is both nutrient dense and inexpensive. And if you have cans in the pantry, you can open them up when you’re short of time and turn them into a meal, whether it’s tuna salad or salmon cakes. But how safe are they metal cans of fish from a health standpoint? Let’s dig deeper.
Canned Tuna and Mercury
While canned tuna is one of the least expensive sources of protein you can buy, it comes with a drawback. Independent testing by third parties, like Consumer Labs, reveals a dirty secret. Canned tuna contains mercury, a neurotoxin linked to health issues. If you consume canned tuna too often, over time it can build up in your body and potentially cause health issues. Young children and pregnant women are at the highest risk of toxicity from canned tuna.
Not all tuna is the same in terms of risks and how it affects your health. When you scour the label of tuna cans and see white tuna or albacore tuna, think twice. Studies show albacore tuna contains the highest levels of mercury relative to other types of canned fish. Due to concerns about mercury, experts recommend consuming no more than a single serving each week.
When you see “light” tuna on a label, there’s a good chance the product contains Skipjack tuna. On the plus side, it usually contains less mercury than albacore tuna, but the amount of mercury in skipjack products varies quite a bit. Some brands that have undergone testing show levels of mercury high enough to warrant caution. Levels were elevated enough to justify consuming it no more than twice a week.
The type of canned tuna that contains the least mercury is yellowfin tuna. Plus, it has the same high protein content and is rich in omega-3s. On the downside, some samples of yellowfin tuna contain concerning levels of arsenic. So, it may not be the safest choice either.
Another popular canned fish, sardines, has a dark secret too. They may contain inorganic arsenic, a heavy metal linked with a variety of health effects, including effects on the heart and nervous system. One study uncovered a disturbing fact. More than 70% of the sardine samples they tested contained inorganic arsenic. Some samples contain other heavy metals, including cadmium, a heavy metal that is exceedingly difficult to clear from your body. It’s a probable carcinogen and capable of causing kidney damage.
Salmon: A Safer Alternative?
If the mercury content of tuna makes you pause, you might move your cart further down the aisle and explore canned salmon. Like albacore tuna, pink salmon is nutritious and has a mild flavor. Plus, it has a light color like albacore tuna. It may be better for your health too, as its mercury levels are lower. Plus, it’s not known to have high arsenic levels like some samples of yellowfish tuna.
There’s another reason to choose salmon over tuna. It typically contains higher quantities of long-chain omega-3 fatty acids, healthy fats with anti-inflammatory properties. Pink salmon has substantial quantities of omega-3s, but sockeye salmon (also known as red salmon) has even more. Plus, testing of sockeye salmon shows it has low levels of both mercury and arsenic.
Understanding Omega-3 Fatty Acids in Fish
One reason people eat fish is its high protein content. Another is for the omega-3 fats that fatty fish have in abundance. You need long-chain omega-3s to support cell membranes in your brain. Some studies also show eating a diet rich in long-chain omega-3s lowers the risk of cardiovascular disease through its effect on blood pressure and blood triglycerides and its anti-inflammatory benefits.
However, some research also reveals that long-chain omega-3s in supplement form may not lower the risk of cardiovascular disease. However, experts still recommend getting long-chain omega-3s from natural food sources, like tuna and salmon. Of the fish species out there, salmon is the best option. It has more omega-3s than tuna and is less likely to contain concerning quantities of heavy metals.
When choosing canned salmon or tuna, keep this in mind:
- Sockeye salmon is the highest in omega-3s. Second and third in line are coho salmon and pink salmon.
- Albacore tuna is the highest in omega-3s in the tuna family, followed by skipjack and then yellowfin. However, the heavy metal risks of tuna make it a riskier choice.
- Consider switching from albacore tuna to pink salmon for a similar taste with lower contaminant levels and higher omega-3 content.
- If you enjoy the rich flavor of redfish, opt for sockeye salmon instead of tuna for a significant omega-3 boost with minimal contaminant concerns.
Balance the Risk with the Benefits
When choosing and eating fish, balance the nutritional benefits with the growing risk of adding heavy metals to your body. On the plus side, when you put fish on your plate, you’re getting anti-inflammatory, long-chain omega-3s, and a substantial number of vitamins and protein. But you’re also taking in heavy metals like mercury and arsenic.
So, limit your risk. The best approach is to only consume canned tuna or salmon no more than two times per week. Also, choose a type that’s less likely to be contaminated, like pink salmon, one of the most common types of canned fish. Regardless of what type you eat, watch your portion sizes, and keep it to a single serving.
If you give kids canned fish, keep the portion sizes small. Their smaller size and rapidly dividing cells mean they’re at higher risk of toxic effects from heavy metals. If you’re pregnant or breastfeeding, follow your doctor’s guidelines for how much and what type of fish you can eat.
Make Informed Choices
Canned fish is convenient and nutritious. Still, it isn’t a food you should eat daily. By making informed choices, you can enjoy the health benefits of fish while limiting the risks of heavy metal exposure. As always, talk to your doctor about what dietary guidelines they recommend for you.
Sources
- How Worried Should You Be About Mercury in Your Tuna? https://www.consumerreports.org/health/food-safety/how-worried-should-you-be-about-mercury-in-your-tuna-a5041903086/
- Some brands ‘safer’ but mercury levels in canned tuna hard to predict https://www.foodsafetynews.com/2023/02/some-brands-safer-but-mercury-levels-in-tuna-hard-to-predict-shouldnt-be-eaten-during-pregnancy/
- Lead, cadmium, arsenic, and mercury in canned tuna fish marketed … https://pubmed.ncbi.nlm.nih.gov/25443538/
- Omega-3’s and Toxic Heavy Metals in Tuna, Salmon & Sardines https://www.consumerlab.com/news/best-and-worst-tuna-salmon-sardines/07-10-2020/
- Omega-3 Fatty Acid Content in Fish https://seafood.oregonstate.edu/sites/agscid7/files/snic/omega-3-content-in-fish.pdf
- https://www.consumerlab.com/news/best-and-worst-tuna-salmon-sardines/07-10-2020/
- A comprehensive review on the health benefits and risks of fish consumption:
- Mozaffarian, D., & Rimm, E. B. (2006). Fish intake, contaminants, and human health: evaluating the risks and the benefits. Jama, 296(15), 1885-1899.
- S. Food and Drug Administration. (2022). Advice about Eating Fish. https://www.fda.gov/food/consumers/advice-about-eating-fish
- Karimi, R., Fitzgerald, T. P., & Fisher, N. S. (2012). A quantitative synthesis of mercury in commercial seafood and implications for exposure in the United States. Environmental Health Perspectives, 120(11), 1512-1519.
- org.hk. “46 Canned Fish Samples Found to Contain Arsenic, Mercury, Cadmium, Lead and Other Metallic Contaminants Rich in Calcium and Protein Contents but Beware of Excessive Sodium Intake | Consumer Council,” 2020. https://www.consumer.org.hk/en/press-release/525-canned-fish-nutrition-value-safety.
