What foods have mercury in them?

December 29, 2025 •

4 min read

According to the World Health Organization, mercury is one of the top ten chemicals of major public health concern. Understanding what foods have mercury in them is crucial for making safer dietary choices and protecting against the toxic effects of this heavy metal.

Quick Summary

This guide details which foods contain mercury, focusing on marine life and other less common sources. It provides practical advice on minimizing exposure for all consumers, with special consideration for vulnerable groups.

Key Points

High-risk fish: Large, predatory species such as shark, swordfish, king mackerel, and Gulf of Mexico tilefish contain the highest levels of mercury.
Safe choices: Smaller, low-mercury fish like salmon, sardines, shrimp, and canned light tuna can be enjoyed regularly as part of a healthy diet.
How mercury accumulates: Mercury, released into the environment, converts to methylmercury and builds up in the fatty tissues of marine life through bioaccumulation, concentrating at higher levels in larger, longer-lived fish.
Other food sources: While fish is the main dietary source, trace amounts of mercury can be found in other foods like rice, wine, and certain vegetables, particularly in contaminated areas.
Prioritize vulnerable groups: Pregnant women, breastfeeding mothers, and young children are most susceptible to the effects of mercury and should be particularly cautious by limiting high-mercury fish.
Enjoy the benefits: The nutritional benefits of fish, including omega-3 fatty acids, often outweigh the risk of mercury exposure, provided you choose low-mercury varieties most often.
Cooking doesn't help: The mercury in fish is bound to its protein and cannot be removed by cooking or any standard preparation method.

How Mercury Enters the Food Chain

Mercury is a naturally occurring element that is also released into the environment by industrial pollution, such as coal-fired power plants and mining. When it settles in bodies of water, microorganisms convert it into methylmercury, the organic and highly toxic form that accumulates in the food chain. Fish and shellfish absorb this methylmercury as they feed, and the concentration increases dramatically in larger, predatory fish through a process called bioaccumulation. This explains why fish higher up the food chain typically contain higher mercury levels than smaller fish or shellfish.

High-Mercury Foods: Fish to Limit or Avoid

For most people, the highest dietary exposure to mercury comes from fish and seafood. The FDA and EPA provide specific guidance on which fish are safest to eat and which should be limited, especially for vulnerable populations like pregnant women and young children. The fish with the highest levels of mercury are large, long-living predatory species. The following should be avoided or consumed very rarely:

Shark: As a top predator, shark meat contains very high levels of mercury.
Swordfish: Like sharks, swordfish are large predators that have accumulated significant amounts of mercury over their long lifespan.
King Mackerel: This large variety of mackerel is consistently listed as having high mercury content.
Bigeye Tuna: This type of tuna is known for its high mercury levels and should be limited, especially compared to canned light tuna.
Tilefish (Gulf of Mexico): This specific variety of tilefish contains exceptionally high mercury levels and should be avoided.
Marlin: A large, predatory fish with a significant mercury load.
Orange Roughy: A long-lived deep-sea fish, orange roughy accumulates substantial levels of mercury.

Medium-Mercury Fish: A Matter of Moderation

Some fish contain moderate levels of mercury and should be consumed in moderation, particularly by sensitive groups. These include:

Albacore (White) Tuna: Albacore tuna has higher mercury levels than canned light tuna. Pregnant women should limit their intake, while other adults should moderate their consumption.
Grouper: This large predatory reef fish falls into the medium-mercury category.
Halibut: Depending on the source, halibut can have moderate to high levels of mercury.
Mahi Mahi: This popular sport fish has medium levels of mercury.

Other Sources of Mercury in the Diet

While seafood is the primary source, minor mercury exposure can come from other foods, though it's typically a much smaller amount. Some studies have found that low levels of mercury may be present in:

Rice: Depending on the soil it is grown in, rice can contain traces of mercury. This is more of a concern in populations with very high rice consumption.
Wine and Liquor: Some studies have noted a link between alcohol consumption and blood mercury levels, possibly due to environmental contamination in some regions.
Vegetables and Grains: In areas with contaminated soil, plant products like vegetables and other grains can contain traces of inorganic mercury.
Herbal Medicines and Supplements: Some herbal products and supplements have been found to contain mercury.

Low-Mercury Foods: Safe and Nutritious Choices

Many types of fish and seafood are low in mercury and are excellent sources of nutrients like protein and omega-3 fatty acids. These are generally safe to consume regularly, even for sensitive populations. Healthier options include:

Salmon: A great source of omega-3s with consistently low mercury levels.
Shrimp: This popular shellfish has very low mercury content.
Canned Light Tuna (Skipjack): This comes from smaller, younger tuna species and contains significantly less mercury than albacore or bigeye tuna.
Sardines: A small fish low on the food chain, sardines are an excellent low-mercury choice.
Anchovies: Tiny, short-lived fish that have very low mercury levels.
Tilapia: A commonly farmed fish with minimal mercury.
Catfish: A freshwater fish that is low in mercury.

Comparing High- and Low-Mercury Fish


Feature	High-Mercury Fish	Low-Mercury Fish
Species	Shark, Swordfish, King Mackerel, Bigeye Tuna, Gulf Tilefish	Salmon, Shrimp, Canned Light Tuna, Sardines, Tilapia
Size	Typically larger and longer-lived	Generally smaller and shorter-lived
Food Chain Position	Apex predators	Lower on the food chain
Mercury Accumulation	High levels due to bioaccumulation	Low levels
Consumption Recommendation	Limit or avoid, especially for pregnant women and children	Can be consumed regularly as part of a healthy diet
Nutritional Benefits	Still contain protein and omega-3s, but outweighing the risks is key	Excellent source of protein and beneficial omega-3 fatty acids

Protecting Yourself from Mercury Exposure

While a completely mercury-free diet is virtually impossible due to environmental factors, minimizing exposure is a practical goal. The key strategy is to eat a variety of fish and prioritize those known to be lower in mercury. Pregnant women and young children are most vulnerable to the neurotoxic effects of methylmercury and should be particularly vigilant. The FDA and EPA provide detailed, regularly updated advice for different groups. You can check their websites for the most current guidelines.

The Importance of Fish in a Healthy Diet

Despite mercury concerns, the health benefits of eating fish are significant and should not be overlooked. Fish is an excellent source of protein, vitamin D, and crucial omega-3 fatty acids (EPA and DHA), which support brain development and heart health. The goal is not to eliminate fish but to make informed choices. By selecting low-mercury varieties and consuming higher-mercury species sparingly, you can enjoy the health benefits of seafood while managing your mercury intake effectively.

Conclusion

Understanding what foods have mercury in them empowers consumers to make informed decisions that balance the nutritional benefits of seafood with the risks of mercury exposure. The primary concern lies with large, predatory fish like shark, swordfish, and king mackerel, which should be limited. Conversely, smaller fish and shellfish, such as salmon, sardines, and shrimp, offer excellent nutritional value with low mercury levels. By following official recommendations and diversifying your seafood choices, you can safely incorporate fish into a healthy diet and minimize your risk of mercury-related health issues. For more details on species-specific mercury levels, consult official sources like the FDA. [https://www.fda.gov/food/consumers/advice-about-eating-fish]

Frequently Asked Questions

The fish with the highest mercury levels are large, predatory species like shark, swordfish, king mackerel, and tilefish from the Gulf of Mexico. These fish are at the top of the food chain and accumulate more mercury over their lifetime.

Yes, while fish and seafood are the primary dietary sources of mercury, trace amounts can be found in other foods. Studies have detected low levels in some rice, vegetables, wine, and liquor, depending on environmental factors in the region where they were produced.

Canned tuna can be a safe choice, but mercury levels vary by type. Canned light tuna, which is usually skipjack, is lower in mercury than canned albacore (white) tuna. It's safe for most adults to eat light tuna in moderation, but sensitive groups like pregnant women should limit their intake of all tuna.

No, cooking fish does not reduce its mercury content. Methylmercury is tightly bound to the protein in fish muscle and cannot be removed by washing, cooking, or marinating.

Developing fetuses and young children are the most vulnerable to mercury exposure. Pregnant women, women who may become pregnant, and breastfeeding mothers are advised to be cautious about their seafood choices to prevent neurological damage in the developing baby.

Methylmercury is the organic form of mercury that is most dangerous to humans. Microorganisms in water convert inorganic mercury into this form, which then accumulates in fish. Inorganic and elemental mercury have different exposure routes and toxicological effects.

Some studies suggest that farmed fish may contain less mercury than their wild-caught counterparts, primarily because their diet is more controlled. However, opting for smaller species that are lower on the food chain is a more reliable way to minimize mercury exposure.

Fish is a great source of lean protein and is rich in essential nutrients like vitamin D and omega-3 fatty acids, which are important for brain development and heart health. The benefits of consuming fish, especially low-mercury varieties, often outweigh the risks associated with mercury.