Is Cod Fish High in Heavy Metals?

November 8, 2025 •

3 min read

According to the U.S. Food and Drug Administration (FDA), cod is categorized as a "Best Choice" for consumption, indicating its low mercury content compared to many other seafood varieties. This makes cod fish a safe and healthy option for regular consumption, even for sensitive populations like pregnant women and young children. However, concerns about heavy metals persist, and understanding the nuances of contamination is key to making the best choices.

Quick Summary

Cod fish is generally low in heavy metals like mercury and cadmium, making it a safe seafood choice for most people. Heavy metal accumulation varies by species, location, and diet, with larger, longer-lived predatory fish posing a greater risk. Key factors influencing contamination include the fish's trophic level and its specific habitat. Regulatory bodies provide consumption guidelines to help minimize exposure while maximizing nutritional benefits.

Key Points

Low Mercury Content: Cod is consistently ranked as a "Best Choice" by the FDA due to its low mercury concentration, making it one of the safer fish to consume regularly.
Position on the Food Chain: Because cod is not a high-level predator and is relatively short-lived, it does not accumulate heavy metals at the same rate as larger fish like tuna, shark, or swordfish.
Cadmium and Lead are Low: Studies show that levels of toxic metals such as cadmium and lead in cod muscle are at safe, low concentrations and pose minimal risk to consumers.
Consider Geographic Origin: Contamination levels can vary slightly depending on the specific species (e.g., Atlantic vs. Pacific cod) and its water source, with some research indicating minor differences.
Be Cautious with Cod Liver Oil: While cod muscle is safe, cod liver can be more contaminated with other pollutants like dioxins and PCBs; thus, cod liver oil products should be consumed with awareness of regulatory guidelines.
Diversify Your Seafood: To minimize overall exposure to any single contaminant, health authorities recommend eating a variety of lower-mercury fish, including cod, salmon, and sardines.

Understanding Heavy Metal Accumulation in Fish

Heavy metals, such as mercury, cadmium, and lead, can find their way into our oceans and waterways through natural processes and industrial pollution. Fish and other aquatic life then absorb these metals, which can accumulate over time through a process called bioaccumulation. For consumers, this poses a potential health risk, particularly concerning for high-mercury species.

The Role of the Food Chain

One of the most significant factors in determining a fish's heavy metal content is its position in the food chain. This is a phenomenon known as biomagnification.

Lower Trophic Level: Fish that feed on plankton or smaller organisms at the lower end of the food chain, like sardines and anchovies, generally have lower heavy metal concentrations.
Higher Trophic Level: Larger, predatory fish that eat smaller, contaminated fish accumulate more heavy metals over their lifespan. These include species like shark, swordfish, and some types of tuna.

Why Cod Is a Safer Choice

Cod is a lean, white fish that sits lower on the food chain than many of its larger, predatory counterparts. This, combined with a relatively short lifespan compared to top predators, significantly limits the amount of heavy metals it can accumulate. The FDA consistently lists cod as a good option for people seeking a low-mercury fish.

Mercury Levels in Cod vs. Other Fish

Numerous studies and governmental data confirm that cod has one of the lowest average mercury concentrations among commercially sold fish. This low level makes it a smart choice for maintaining a healthy diet.

Comparison of Mercury Levels in Common Fish Species


Fish Species	Trophic Level	Average Mercury (ppm)	Consumption Category	Notes
Cod	Lower-Mid	0.111	Best Choice	Safe for frequent consumption.
Canned Tuna (Light)	Mid	0.126	Best Choice	A good alternative to higher-mercury tuna.
Canned Tuna (Albacore)	Mid-High	0.350	Good Choice	Higher mercury than light tuna; limit intake.
Halibut	Mid	0.241	Good Choice	Moderate levels; consume in moderation.
Swordfish	High	0.995	Avoid	High mercury content; limit or avoid.
King Mackerel	High	0.730	Avoid	Very high mercury content; avoid entirely.

Contaminants in Cod: Beyond Mercury

While mercury often gets the most attention, other heavy metals and contaminants are sometimes present in seafood. Research has shown that the levels of toxic metals like cadmium and lead in cod muscle are generally low and pose no significant health risk to consumers. However, studies have identified issues with cod liver products, which can have higher concentrations of dioxins and polychlorinated biphenyls (PCBs). For example, the German Federal Institute for Risk Assessment recommends limiting tinned cod liver consumption to minimize exposure to these contaminants.

Geographic and Species Variations

The levels of heavy metals in cod can also depend on its specific species and fishing location. For instance, some studies have found variations in mercury levels between Atlantic and Pacific cod. This is because different bodies of water have varying levels of environmental pollution. Being aware of the source of your fish can be a good additional safety measure, though overall cod remains a low-risk option.

Guidelines for Healthy Fish Consumption

Enjoying the nutritional benefits of fish while minimizing heavy metal exposure is easily achievable by following a few simple guidelines:

Diversify your fish intake: Don't rely on a single species. Eating a variety of fish, especially lower-mercury choices, helps spread out your exposure.
Follow official advice: Heed recommendations from agencies like the FDA and EPA, which provide specific consumption guidelines, especially for sensitive groups.
Prioritize smaller fish: Opt for fish that are lower on the food chain, such as cod, salmon, sardines, and shrimp.
Limit predatory fish: Reduce or eliminate the intake of larger, longer-lived predatory species that accumulate more toxins.
Choose muscle meat: When eating fish, consume the muscle meat (fillet) and avoid organs, as some contaminants can accumulate in other parts of the fish.

Conclusion

For those concerned about heavy metal contamination, cod stands out as a safe and nutritious choice. Its position low on the marine food chain and typically low levels of contaminants, including mercury and cadmium, make it a healthy addition to a balanced diet. While it is always wise to be mindful of where your food comes from, consumers can feel confident in choosing cod. By following general seafood safety guidelines and eating a variety of fish, you can enjoy the significant health benefits of seafood with minimal risk. Always choose responsibly sourced fish from reputable suppliers to ensure the highest quality and safety. For more information, the FDA provides a comprehensive guide on mercury levels in various commercial fish species.

Frequently Asked Questions

No, Atlantic cod is generally considered low in heavy metals, particularly mercury. The FDA lists cod as a "Best Choice" for consumption, meaning it's safe for frequent eating, even for sensitive groups like pregnant women.

Both Atlantic and Pacific cod are low in mercury compared to many other fish. However, some older research suggests Pacific cod may have slightly higher mercury levels than Atlantic cod, though both remain well within safe consumption limits for most people.

Many smaller fish species that are lower on the food chain contain the lowest levels of heavy metals. Excellent low-mercury choices include sardines, anchovies, salmon, and shrimp.

Cod liver, and thus cod liver oil, can contain higher levels of certain contaminants, such as dioxins and PCBs, compared to the muscle meat. Reputable brands, however, typically test and filter their products to remove these toxins, but consumers should still be mindful of consumption limits, as advised by some health authorities.

Cod is significantly lower in mercury than most tuna, particularly larger tuna species like Albacore and Bigeye. While light canned tuna is also a good choice, cod remains one of the safest options for regular intake.

No, cooking methods do not reduce the amount of heavy metals, such as mercury, present in fish. These metals are bound within the fish's tissue, so they cannot be cooked out or rinsed away. Choosing fish low in heavy metals is the only effective way to minimize exposure.

Bioaccumulation is the process by which organisms accumulate substances, such as heavy metals, faster than they can excrete them. This is why larger, older predatory fish higher on the food chain tend to have higher concentrations. Since cod is lower on the food chain and is not a top predator, its risk of bioaccumulation is much lower.