What fish should I eat to avoid mercury?

According to the World Health Organization, mercury is one of the top ten chemicals of public health concern. Choosing the right seafood is key to reaping the benefits of fish while minimizing exposure to harmful methylmercury. This guide will explain what fish should you eat to avoid mercury, highlighting the best options for safer consumption.

Quick Summary

This guide provides recommendations for selecting low-mercury fish and avoiding high-mercury options, detailing specific seafood choices based on FDA and EPA guidelines. It explains how mercury accumulates in the food chain and the importance of diversification for safer consumption, covering best practices for all consumers, including sensitive populations.

Key Points

• Choose Low-Mercury Fish: Prioritize species like salmon, sardines, and tilapia, which are low in mercury and high in healthy fats.

• Limit High-Mercury Fish: Significantly reduce or completely avoid large predatory fish such as shark, swordfish, king mackerel, and bigeye tuna.

• Follow FDA Guidelines: Use the FDA and EPA's Best Choices, Good Choices, and Choices to Avoid categories to make informed decisions.

• Vary Your Seafood: Diversify your fish consumption by eating different low-mercury species to minimize exposure from a single source.

• Mind Portion Sizes: Adhere to recommended serving sizes, especially if you are in a sensitive group like pregnant women, nursing mothers, or young children.

• Pregnant Women and Children Need Extra Caution: These groups are most vulnerable to mercury's effects on the nervous system and should be especially careful with their seafood choices.

• Don't Avoid Fish Entirely: The health benefits of fish, including omega-3s, are important, and the risks of mercury are low with smart, informed choices.

Understanding Mercury in Fish and Its Health Implications

Mercury, a naturally occurring element, enters our waterways through both natural and industrial sources. In aquatic ecosystems, bacteria and other microorganisms convert it into methylmercury, a highly toxic organic form. This compound accumulates in the fatty tissues of fish and moves up the food chain in a process called biomagnification. Larger, longer-lived predatory fish tend to have the highest concentrations of mercury because they consume many smaller fish that also contain mercury.

For most people, the nutritional benefits of eating fish—such as high-quality protein and beneficial omega-3 fatty acids—outweigh the risks associated with mercury. However, certain groups, especially pregnant women, nursing mothers, and young children, are more vulnerable to mercury's harmful effects on the developing nervous system. Exposure to high levels can lead to a range of neurological issues. Making informed seafood choices is therefore a crucial part of a healthy diet.

Best Choices: Fish to Eat Frequently

To reduce mercury exposure, focus on eating a variety of fish that are lower on the food chain. The U.S. Food and Drug Administration (FDA) and Environmental Protection Agency (EPA) offer extensive guidelines to help consumers make safe choices. The following list includes options classified as "Best Choices," meaning it is safe to consume two to three servings per week.

Low-mercury fish and seafood options include:

• Salmon: A fatty fish rich in omega-3s, salmon is a top choice for its health benefits and low mercury content.
• Sardines: These small, oily fish are packed with nutrients and are consistently low in mercury.
• Shrimp: One of the most consumed types of seafood, shrimp has very low mercury levels.
• Tilapia: This popular, fast-growing farmed fish is a reliable low-mercury option.
• Cod: A versatile white fish, cod has low to moderate mercury levels and is safe for regular consumption.
• Trout: Freshwater trout is a low-mercury option that provides excellent nutrition.
• Catfish: Generally low in mercury, especially farmed varieties, making it a safe choice.
• Flounder and Sole: These flatfish species are known for their low mercury concentration.
• Oysters and Clams: Most shellfish, including oysters and clams, are very low in mercury.
• Canned Light Tuna: Made primarily from skipjack, canned light tuna is a much safer option than albacore or bigeye tuna.

Good Choices: Fish to Eat Less Often

Some fish fall into a moderate category and should be consumed in moderation, particularly by sensitive groups. The FDA advises limiting these to one serving per week.

Moderate-mercury fish options include:

• Mahi Mahi: Also known as dolphinfish, this fish has moderate mercury levels.
• Halibut: A popular white fish, halibut typically has higher mercury than cod but is lower than high-mercury predators.
• Snapper: While some varieties are higher, snapper is generally in the moderate category.
• Canned Albacore Tuna: Albacore ("white") tuna contains more mercury than canned light tuna and should be limited.
• Grouper: This is a larger fish and thus tends to have higher mercury levels.

Choices to Avoid: High Mercury Fish

Fish at the top of the marine food chain and longer-lived species accumulate the highest levels of mercury and should be avoided or eaten very infrequently. The FDA and EPA strongly recommend that pregnant women, nursing mothers, and young children avoid these altogether.

High-mercury fish options to avoid include:

• Shark: As a large predator, shark accumulates very high levels of mercury.
• Swordfish: Another large, predatory species, swordfish is known for its high mercury content.
• King Mackerel: This large mackerel species should be avoided due to high mercury levels.
• Tilefish (Gulf of Mexico): This specific variety is noted for its extremely high mercury concentration.
• Bigeye Tuna: This is the variety of tuna most often found in sushi and has significantly higher mercury than canned light tuna.
• Orange Roughy: A long-lived deep-sea fish, it has high mercury levels and should be avoided.

Comparison of Seafood Choices by Mercury Level

Seafood Type	Mercury Level (Source: FDA)	Typical Recommendation	Nutritional Benefits
Salmon, Sardines, Shrimp	Best Choice (Lowest)	2-3 servings/week	High in Omega-3 fatty acids, protein, and vitamins D & B12.
Canned Light Tuna	Best Choice (Low)	2-3 servings/week	Source of protein and Omega-3s. Economical and convenient.
Cod, Tilapia	Best Choice (Low)	2-3 servings/week	Lean protein source. Versatile and widely available.
Canned Albacore Tuna	Good Choice (Moderate)	1 serving/week	Good protein and Omega-3 source. Must be limited.
Mahi Mahi, Halibut	Good Choice (Moderate)	1 serving/week	Provides protein and nutrients. Should be consumed in moderation.
Shark, Swordfish, Bigeye Tuna	Choices to Avoid (Highest)	Avoid entirely	Potential source of protein, but mercury risk outweighs benefits.

Practical Tips for Reducing Mercury Intake

Beyond choosing the right types of fish, you can take additional steps to manage your mercury intake:

• Vary your fish: Don't rely on just one type of fish. By rotating your seafood choices from the "Best Choices" and "Good Choices" lists, you minimize the risk of accumulating high levels of mercury from a single source.
• Mind portion sizes: For adults, a serving size is typically 4 ounces, measured before cooking. Sensitive populations should adhere to more specific guidelines provided by health authorities.
• Consult local advisories: If you consume fish caught from local waters, check for advisories from your state or local environmental agency, as certain areas can have higher localized contamination.
• Avoid high-risk areas: Be cautious of fish from known polluted or contaminated areas.
• Consider omega-3 supplements: If you're concerned about seafood safety or are unable to consume fish regularly, high-quality omega-3 supplements can offer a safe alternative to get these essential fatty acids.

Conclusion

While mercury in fish is a valid health concern, especially for pregnant women and young children, it should not be a reason to avoid seafood entirely. By being informed and following simple guidelines, consumers can confidently choose lower-mercury fish and enjoy the significant nutritional benefits that seafood provides. Focusing on small, short-lived fish like salmon, sardines, and canned light tuna allows you to maintain a healthy and balanced diet without undue risk. Diversifying your protein sources and being mindful of portion sizes are the key pillars of safe seafood consumption.

An authoritative resource for further details on fish consumption guidelines can be found on the U.S. Food and Drug Administration's website.

Frequently Asked Questions

Which fish have the highest mercury content?

The highest mercury content is typically found in large, predatory fish that are high on the food chain. Examples include shark, swordfish, king mackerel, bigeye tuna, and tilefish from the Gulf of Mexico.

Is it safe for pregnant women to eat fish?

Yes, it is safe and recommended for pregnant women to eat fish. However, they should stick to 8-12 ounces per week of low-mercury fish, such as salmon, shrimp, and canned light tuna, and avoid high-mercury options entirely.

What is the difference between canned light tuna and canned albacore tuna?

Canned light tuna is primarily made from smaller skipjack fish, which have a lower mercury content. Canned albacore ("white") tuna is from a larger tuna species and contains more mercury, so it should be consumed less frequently.

Does cooking remove mercury from fish?

No, cooking does not remove mercury from fish. Mercury is bound to the fish's muscle tissue, not its fat or skin, so trimming and cooking methods have no effect on its concentration.

Which shellfish are low in mercury?

Most shellfish are very low in mercury. Excellent low-mercury options include shrimp, scallops, oysters, and clams, which can be enjoyed regularly as part of a healthy diet.

How often can the average person safely eat fish?

For most people, the FDA recommends eating two to three servings (8-12 ounces) of low-mercury fish per week. The key is to vary your fish choices to minimize consistent exposure.

Why do larger fish have more mercury?

Larger fish, especially predatory ones, are higher up the food chain. They accumulate mercury through a process called biomagnification, where mercury concentrations increase with each successive trophic level.