Is Tuna Full of Mercury? What You Need to Know

December 31, 2025 •

5 min read

According to the Food and Drug Administration (FDA), all fish and shellfish contain at least trace amounts of mercury. While tuna is a nutritious source of protein and omega-3s, its position in the food chain means it can accumulate higher levels of mercury than other seafood, raising concerns for frequent consumers, pregnant women, and children.

Quick Summary

Tuna contains varying levels of mercury, with larger, longer-lived species accumulating more of the heavy metal. Consumers can minimize exposure by choosing lower-mercury varieties like canned light or skipjack tuna. Recommendations from health authorities help guide safe consumption, balancing the fish's nutritional benefits against potential risks, particularly for vulnerable populations.

Key Points

Mercury Levels Vary by Species: Larger, longer-lived tuna like albacore and bigeye accumulate more mercury than smaller, shorter-lived species like skipjack and canned light tuna.
Moderation is Key: While occasional tuna consumption is safe for most, regular, high intake, particularly of high-mercury varieties, is not recommended and can pose health risks.
Benefits vs. Risks: Tuna provides significant health benefits, including omega-3s, lean protein, and vitamins. The key is balancing these benefits with an awareness of mercury content.
Vulnerable Groups Need Caution: Pregnant or breastfeeding women and young children should adhere to stricter consumption guidelines for tuna to protect developing nervous systems from methylmercury.
Diversify Your Fish Intake: To minimize exposure to a single contaminant, it is best to eat a variety of fish, including other low-mercury options like salmon and sardines.

The Mercury Paradox: Balancing Benefits and Risks

For decades, tuna has been a pantry staple and a nutritional heavyweight, celebrated for its high-quality protein, essential omega-3 fatty acids, and key vitamins and minerals like B12 and selenium. However, this convenience and nutritional value come with a notable health concern: mercury contamination. The perception that tuna is "full of mercury" is rooted in science, but a deeper understanding of species, preparation, and consumption guidelines reveals a more nuanced reality. By understanding where the mercury comes from, which species contain the most, and how to moderate your intake, you can confidently include tuna as a healthy part of your diet.

Where Does Mercury in Tuna Come From?

Mercury is a naturally occurring heavy metal that enters the ocean through both natural processes, such as volcanic activity, and human activities like coal-burning and industrial waste. Once in the marine environment, bacteria convert inorganic mercury into a more toxic, organic form called methylmercury, which is the primary form found in fish. This methylmercury then begins to move up the food chain through a process known as bioaccumulation and biomagnification.

Bioaccumulation: As a fish feeds, its body absorbs mercury faster than it can excrete it. The mercury builds up in its tissues over its lifetime.
Biomagnification: This process describes the increasing concentration of mercury as it moves up the food chain. For example, a small fish has a low level of mercury. A larger predator fish, like tuna, eats many of these smaller fish, accumulating and concentrating the mercury from all of its prey. As a result, larger, longer-lived predatory fish like tuna have the highest levels of mercury.

Comparing Mercury Levels Across Tuna Species

Not all tuna is created equal when it comes to mercury. The size and lifespan of the specific tuna species are the biggest factors influencing its mercury content. Here is a general comparison of mercury levels based on FDA data:


Tuna Species	Average Mercury (PPM)	Notes
Canned Light (Skipjack)	0.126	This is the smallest and shortest-lived tuna species, making it the safest option for regular consumption, including for children and pregnant women.
Canned Albacore (White)	0.350	Albacore tuna are larger than skipjack, leading to significantly higher mercury levels. Health experts advise limiting intake, especially for vulnerable groups.
Fresh/Frozen Yellowfin	0.354	Often used for steaks and sushi, yellowfin has mercury levels comparable to canned albacore and should be consumed in moderation.
Fresh/Frozen Bigeye	0.689	A larger species of tuna, bigeye has the highest mercury concentration of the commonly consumed varieties and should be eaten sparingly or avoided by sensitive individuals.

Navigating Safe Tuna Consumption

Health authorities offer clear guidelines to help you reap the benefits of seafood while managing mercury intake. For the general population, the FDA and EPA recommend eating 2 to 3 servings of fish per week (approximately 8-12 ounces) from their list of "Best Choices," which includes light canned tuna. The type of tuna you choose matters greatly.

Here are some practical tips for choosing and preparing tuna wisely:

Prioritize Canned Light (Skipjack): If you are a frequent tuna eater or belong to a vulnerable group, canned light tuna is the best option due to its low mercury content.
Limit Albacore and Yellowfin: For canned albacore or fresh/frozen yellowfin, stick to smaller portion sizes and fewer weekly servings to stay within safe mercury limits.
Check Local Advisories: If you catch your own fish, be sure to consult local advisories from environmental agencies, as regional contamination can vary.
Consume a Variety of Fish: To further minimize mercury exposure, vary your seafood choices. Low-mercury alternatives include salmon, sardines, and shrimp, which also offer excellent nutritional benefits.
Avoid High-Mercury Fish: Some fish, like swordfish and king mackerel, are known to have very high mercury levels and should be avoided entirely, especially by children and pregnant women.

The Health Benefits of Eating Tuna

Despite the mercury concerns, the nutritional value of tuna remains significant and shouldn't be overlooked. A balanced approach acknowledges both the risks and the substantial benefits:

Excellent Source of Protein: Tuna is a complete protein, containing all nine essential amino acids necessary for muscle repair and growth.
Rich in Omega-3 Fatty Acids: These healthy fats, particularly EPA and DHA, are crucial for heart health, reducing inflammation, and supporting brain function.
Packed with Vitamins and Minerals: Tuna provides a boost of B vitamins (including B12 and niacin), selenium, and vitamin D, which are important for energy production, immune function, and bone health.
Protective Role of Selenium: Some research suggests that the high selenium content in many types of tuna may offer a protective effect against mercury toxicity, though more study is needed.

Conclusion: Making Informed Choices

While it is true that tuna contains mercury, the statement that it is "full of mercury" is overly simplistic and can lead to unnecessary fear of a healthy food. The key is understanding that mercury levels vary significantly between species. By choosing canned light or skipjack varieties and consuming higher-mercury types like albacore in moderation, most people can safely enjoy the substantial nutritional benefits tuna offers. For pregnant women and young children, following specific, more conservative guidelines from health organizations is the best approach to protect developing nervous systems. The bottom line is to diversify your seafood intake and make informed choices to balance nutritional gains with heavy metal exposure. For more detailed information on specific brands and their mercury levels, reputable sources like Consumer Reports offer in-depth analysis.

Expert Commentary and Further Reading

Note: The following content is illustrative and should be verified with the actual authoritative source if available.

Some research has explored the interaction of selenium and mercury in fish, suggesting that the selenium content in some fish species may mitigate the toxic effects of mercury in the human body. One study, for instance, examined the molar ratio of selenium to mercury in various fish species and found that for many commercially available fish, the selenium content is high enough to neutralize the mercury. This protective effect is an important part of the ongoing conversation about seafood safety. However, this finding does not negate the importance of adhering to consumption limits, especially for sensitive populations. For up-to-date guidance and specific details on your favorite fish, always consult the most current recommendations from reliable public health authorities.

How the FDA Classifies Seafood

The FDA provides a straightforward classification to help consumers make smarter seafood choices. Seafood is categorized based on its average mercury levels into three groups:

Best Choices: These fish can be safely consumed 2–3 times per week. This category includes canned light tuna (skipjack).
Good Choices: These fish can be consumed once per week. Canned or fresh albacore and yellowfin tuna fall into this category.
Choices to Avoid: These fish contain the highest levels of mercury and should be avoided by all, especially pregnant women and young children. This group includes bigeye tuna, king mackerel, and swordfish.

The Importance of Variety in Your Diet

Eating a variety of fish and shellfish from the "Best Choices" list is an excellent strategy for maximizing nutrient intake while minimizing exposure to any one contaminant. This approach ensures you benefit from a wide range of essential vitamins, minerals, and healthy fats that different seafood offers. Switching between canned light tuna, salmon, sardines, and shrimp is a simple and effective way to enjoy seafood safely.

Frequently Asked Questions

For most people, eating canned tuna every day is not recommended. While canned light (skipjack) tuna has low mercury levels, consistently high intake can still increase your overall exposure. The FDA recommends eating a variety of fish and limiting total seafood to 2–3 servings per week for the general population.

Canned light tuna, which is typically made from the smaller skipjack species, contains the lowest levels of mercury. This makes it a safer choice for more frequent consumption compared to larger species like albacore, yellowfin, and bigeye tuna.

For pregnant women, health authorities recommend sticking to low-mercury fish. For canned light tuna, the FDA suggests 2 to 3 servings per week. For canned albacore or yellowfin, intake should be limited to a maximum of one serving per week.

Symptoms of mercury poisoning can include neurological and behavioral issues such as poor coordination, numbness or tingling in the hands and feet, memory loss, anxiety, depression, and tremors. If you suspect you have been exposed to high levels of mercury, consult a doctor immediately.

No, cooking, smoking, or canning tuna does not remove or reduce its mercury content. Draining the liquid from canned tuna also has no effect on the mercury, as it is bound to the proteins in the fish's flesh.

Larger tuna have more mercury due to a process called biomagnification. As a predatory fish, they consume smaller fish that also contain mercury. Because they live longer and eat more, the mercury accumulates and becomes more concentrated in their tissues over time.

Yes, beyond mercury, canned tuna can sometimes contain high levels of sodium, which is a concern for individuals with high blood pressure or heart conditions. Look for "no salt added" varieties to mitigate this risk. There is also a small risk of BPA exposure from the can lining, though many brands now use BPA-free alternatives.