Canned fish is a convenient, long-lasting source of protein and heart-healthy omega-3 fatty acids. However, not all canned seafood is created equal. From potential heavy metal exposure to excessive sodium, certain products are best consumed sparingly or avoided entirely, especially for vulnerable groups like pregnant women and children.
High Mercury Fish to Limit or Avoid
Mercury is a neurotoxin that accumulates in the bodies of fish, especially larger, longer-living predatory species. For most people, trace amounts in food aren't a concern, but high levels can be harmful, particularly to developing brains.
Tuna
Different types of canned tuna contain varying mercury levels. While all tuna can accumulate mercury, some varieties are riskier than others.
- Albacore (White) Tuna: Often canned as solid white tuna, this species is larger than skipjack and typically contains three times more mercury. Limiting consumption is advisable for most adults, and it should be limited to one can per week for children and pregnant individuals.
- Bigeye and Yellowfin Tuna: These species, though less common in canned form, contain very high mercury levels and are recommended for avoidance by the FDA.
Other high-mercury species
While less frequently canned, the FDA recommends avoiding other high-mercury fish, including king mackerel, marlin, swordfish, and tilefish. If you encounter canned versions of these, they are best left on the shelf.
Excessive Sodium and Additives
Salt is a primary preservative in canned fish, but many products contain exceptionally high levels that are concerning for those with high blood pressure or other health conditions.
Anchovies
Anchovies are notoriously high in sodium due to the curing process. A small 43-gram serving can contain over 1,650 milligrams of sodium, nearly 70% of the daily recommended upper limit. While rinsing can help, it is still a high-sodium product.
Other salty culprits
Canned shellfish like crab and mussels can also be packed with high levels of sodium. A single can of blue crab can contain around 700 mg of sodium, a significant portion of the recommended daily intake. Choosing products packed in water or unsalted options is crucial for managing intake.
Bisphenol A (BPA) in Can Linings
For decades, many metal food cans were lined with epoxy resins containing Bisphenol A (BPA), a chemical that can leach into food and has been linked to hormonal disruption and other potential health issues.
The shift to alternatives
While most manufacturers have moved to BPA-free linings due to consumer demand, it's not a universal standard, and some substitutes may have their own risks. To be safe, look for explicit "BPA-free" labeling on the packaging. The best way to avoid this risk is to opt for alternative packaging like glass jars or pouches, or stick with fresh or frozen seafood.
Other Contaminants and Poor Sourcing
Beyond mercury and BPA, other contaminants and farming practices can affect the quality and safety of canned fish.
Farmed fish issues
Some farmed fish, particularly Atlantic salmon, have been shown to contain higher levels of certain pollutants like PCBs and dioxins due to their crowded living conditions and feed. This practice is less common for canned salmon than fresh, but checking the sourcing is wise.
Shellfish toxins and bacterial risks
Certain canned shellfish, such as clams or mussels, can carry specific bacterial or paralytic toxins if harvested from contaminated waters. Buying from reputable brands that can verify their sourcing is the best defense against these less common risks.
Key Considerations for Choosing Canned Fish
To make the healthiest choice, evaluate the species, sodium content, and packaging. Here is a guide to navigating the canned fish aisle.
Safer Canned Fish Options
- Sardines and Mackerel: These smaller, shorter-lived fish are lower on the food chain and therefore have significantly lower mercury levels. They are also rich in omega-3s and calcium.
- Skipjack (Light) Tuna: This variety is a smaller species of tuna and has considerably lower mercury content than albacore. It is a safer choice for more frequent consumption.
- Salmon: Canned salmon, especially wild-caught varieties, is a great low-mercury option. The canning process softens the bones, making them a source of calcium.
Reading labels is vital
Always read the ingredient and nutritional information. Opt for products packed in water or olive oil rather than processed vegetable oils. Look for "low sodium" or "no salt added" versions, which allow you to control the seasoning yourself.
Comparison of Common Canned Fish Varieties
| Feature | Albacore Tuna | Light/Skipjack Tuna | Sardines | Wild Salmon |
|---|---|---|---|---|
| Mercury Level | High | Low | Very Low | Very Low |
| Sodium Concern | Moderate (varies) | Moderate (varies) | High (can be rinsed) | Moderate (choose low-sodium) |
| Omega-3s | Moderate | Moderate | High | High |
| Sourcing Risk | Moderate | Low | Low | Low (wild-caught is best) |
| BPA Risk | Possible (check can) | Possible (check can) | Possible (check can) | Possible (check can) |
What to look for on the label
- Look for a "BPA-free" certification on cans.
- Prioritize products packed in spring water or 100% olive oil.
- Choose "low sodium" or "no salt added" options.
- Opt for smaller, younger species like sardines, mackerel, or skipjack tuna.
- Check for certifications indicating sustainable sourcing, such as the Marine Stewardship Council (MSC) label.
Conclusion
While canned fish can be a nutritious part of a balanced diet, making mindful choices is key to minimizing potential health risks. By avoiding high-mercury species like albacore tuna and being aware of high-sodium options and BPA-lined cans, consumers can ensure they are getting the benefits of seafood without the unnecessary drawbacks. Reading labels carefully and opting for smaller, sustainably sourced fish like sardines and skipjack tuna is the safest approach.
For more detailed guidance on mercury levels, consult the FDA and EPA's advice: https://www.fda.gov/food/consumers/advice-about-eating-fish.
