Mercury in Seafood: Tips for Safe and Healthy Eating
Seafood is a delicious and nutritious part of many diets. While concerns about mercury levels can arise, it's important to know that the vast majority of seafood is safe to eat for most of the population. In fact, the bigger issue is that most people are not eating enough seafood. According to Johns Hopkins University, almost 90% of Americans don’t eat the recommended 2 or more servings of seafood per week.
This guide is perfect for those with specific concerns or anyone wanting to learn more about mercury in seafood. By understanding why some fish have mercury and identifying low-mercury seafood options, you'll be equipped with the knowledge to enjoy seafood confidently and safely.
- What is Mercury?
- Should I Be Concerned About Mercury in Seafood?
- Why Do Some Fish Have Mercury?
- Are There Safe Levels of Mercury?
- Which Seafood Is Low in Mercury?
- Which Fish Are High in Mercury?
What is Mercury?
Mercury is a naturally occurring element found in the earth's water, air, and soil. It can also come from industrial sources like coal burning, mining, and waste incineration. Mercury exists in several forms, with a commonly problematic one in select foods being methylmercury. Methylmercury is an organic compound that forms when bacteria in water bodies react to mercury, a process known as bacterial methylation. This methylmercury can accumulate in water sources and, ultimately, in some seafood species.
Should I Be Concerned About Mercury in Seafood?
Most likely not. In fact, the biggest issue is that most people do not eat enough seafood. While mercury levels in seafood might raise some questions, it's reassuring to know that the vast majority of seafood is safe to eat, containing either no mercury or trace amounts that our bodies can handle comfortably. Most people can enjoy seafood without worry. It's important for some at-risk populations, such as pregnant or breastfeeding women and young children, to monitor their mercury intake while also ensuring they consume the recommended amounts of seafood and take advantage of all its health benefits!
Mercury becomes a consideration primarily with larger predatory fish that have more time to accumulate it. These include shark, swordfish, king mackerel, golden tilefish, bluefin tuna, and bigeye tuna. Eating these fish occasionally is fine for most people, but it's wise to moderate the frequency and quantity, particularly for vulnerable groups.
Why Do Some Fish Have Mercury?
Mercury from both natural and industrial sources makes contact with bodies of water like lakes, rivers, and oceans, eventually settling into the water itself. Once mercury is in the water, bacteria can convert it into methylmercury. This toxic form of mercury then enters the aquatic food chain through a process known as bioaccumulation. Small organisms, such as plankton, absorb methylmercury from the water. When small fish eat these plankton, they struggle to process the methylmercury, allowing it to accumulate in their bodies. Larger fish then eat these smaller fish, leading to further accumulation of methylmercury in their bodies. This gradual process is called biomagnification.
As a result of biomagnification, larger fish higher up the food chain tend to have higher levels of mercury. Species such as shark, swordfish, king mackerel, golden tilefish, and bluefin tuna are examples of fish that accumulate more mercury due to their position in the food chain and their longer lifespans. Smaller or shorter-lived seafood, such as salmon and various shellfish, tend to have lower mercury levels because they have shorter lifespans and are lower on the food chain, meaning they accumulate less mercury over a shorter time despite consuming plankton or other food that may contain mercury.
What Is Mercury Poisoning?
Mercury poisoning occurs when a person is exposed to extreme levels of mercury over time. This condition can have serious health implications, primarily affecting the nervous system, especially for vulnerable groups such as pregnant women, nursing mothers, and young children. Therefore, it's important to be mindful of mercury levels in seafood and make informed choices to minimize exposure.
Are There Safe Levels of Mercury?
Absolutely, there are safe levels of mercury in seafood! Not only do most species have little to no mercury in them at all, but the human body can also naturally eliminate methylmercury over time, making most seafood consumption both safe and attainable.
For a health professional’s point of view, we reached out to Dr. Lori Greene, PhD, RDN, LDN at the University of Alabama’s Department of Human Nutrition. According to Dr. Greene, “While one may hear on social media to avoid certain foods, we can consume most foods and food components in moderation with no harm. Mercury in fish is a good example of this principle.” She continues, “We know there are many benefits to seafood, but most individuals do not consume enough seafood and are missing out on those benefits. Be an informed consumer of your food and aware of the amount of mercury in the fish varieties you consume, but it is not necessary to entirely avoid fish due to the mercury content.”
For pregnant and nursing women, the FDA advises limiting mercury intake to ensure the safety of both the mother and the baby. According to FDA guidelines, you should aim for no more than 0.1 micrograms of mercury per kilogram of your body weight per day.
Consult this chart as a quick reference for your own daily mercury limit by weight if you are in one of the vulnerable groups:
| Recommended Daily Mercury Limit for Vulnerable Groups 1 serving = 3.5oz Source: FDA |
|||||||||
|---|---|---|---|---|---|---|---|---|---|
| Your Weight (lbs) | 25 lbs | 50 lbs | 75 lbs | 100 lbs | 125 lbs | 150 lbs | 175 lbs | 200 lbs | 225 lbs |
| Daily Mercury Limit (micrograms, µg) |
1.13 µg | 2.27 µg | 3.41 µg | 4.54 µg | 5.68 µg | 6.80 µg | 7.95 µg | 9.07 µg | 10.20 µg |
| Equivalent in Salmon (Low Mercury) |
56 servings |
113 servings |
170 servings |
227 servings |
284 servings |
340 servings |
397 servings |
453 servings |
510 servings |
| Equivalent in Golden Tilefish (High Mercury) |
0.3 servings |
0.6 servings |
0.9 servings |
1.2 servings |
1.4 servings |
1.7 servings |
2 servings |
2.3 servings |
2.5 servings |
How Can I Minimize Mercury Exposure?
Minimizing mercury exposure is straightforward when you consume low-mercury seafood that is sourced responsibly. At Fulton Fish Market, we take pride in doing the hard work for you, ensuring that you can savor your favorite seafood dishes without worrying about mercury overexposure. Other types of seafood can also be enjoyed, but it’s wise to moderate the frequency and amount of consumption for those higher in mercury. As with any health concerns, always consult your doctor for personalized recommendations.
Which Seafood Is Low in Mercury?
Choosing seafood that is low in mercury is a great way to enjoy the health benefits of fish while minimizing exposure. Opting for wild species lower on the food chain and responsibly sourced farmed fish is a safe bet.
Here are some excellent low-mercury seafood options you can try today, each of which contains less than 5% of your daily mercury limit per 3.5oz serving:
| % of Daily Mercury Limit in 3.5oz Serving Source: FDA |
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|---|---|---|---|---|---|---|---|---|---|
| Your Weight (lbs) | 25 lbs | 50 lbs | 75 lbs | 100 lbs | 125 lbs | 150 lbs | 175 lbs | 200 lbs | 225 lbs |
| American Red Snapper | 3.1% | 1.5% | 1.0% | 0.8% | 0.6% | 0.5% | 0.4% | 0.4% | 0.3% |
| Anchovies | 0.5% | 0.3% | 0.2% | 0.1% | 0.1% | 0.1% | 0.1% | 0.1% | 0.1% |
| Atlantic Cod | 3.1% | 1.5% | 1.0% | 0.8% | 0.6% | 0.5% | 0.4% | 0.4% | 0.3% |
| Branzino | 0.9% | 0.4% | 0.3% | 0.2% | 0.2% | 0.1% | 0.1% | 0.1% | 0.1% |
| Pollock | 0.9% | 0.4% | 0.3% | 0.2% | 0.2% | 0.1% | 0.1% | 0.1% | 0.1% |
| Salmon | 1.8% | 0.9% | 0.6% | 0.4% | 0.4% | 0.3% | 0.3% | 0.2% | 0.2% |
| Sardines | 0.4% | 0.2% | 0.1% | 0.1% | 0.1% | 0.1% | 0.1% | 0.1% | 0.1% |
| Scallops | 0.1% | <0.1% | <0.1% | <0.1% | <0.1% | <0.1% | <0.1% | <0.1% | <0.1% |
| Shrimp | 0.3% | 0.1% | 0.1% | 0.1% | 0.1% | <0.1% | <0.1% | <0.1% | <0.1% |
- American Red Snapper (wild)(up to 3.1% of your daily limit per serving): Flaky and boasting a sweet and nutty flavor, red snapper is ideal for grilling or baking with a medley of spices, providing a flavorful and low-mercury meal.
- Anchovies (up to 0.5% of your daily limit per serving): These bold and briny fish add a punch to pizzas, salads, or sauces, while their low mercury content lets you enjoy them without worry.
-
Atlantic Cod (wild)(up to 3.1% of your daily limit per serving): Light and flaky, cod is a fantastic low-mercury baking choice. Feeling indulgent? Try them when making classic fish and chips.
- Branzino (up to 0.9% of your daily limit per serving): With its delicate, mild flavor, branzino is an excellent low-mercury fish that is delicious, especially when roasted or grilled whole with herbs.
- Pollock (up to 0.9% of your daily limit per serving): Mild and flaky, pollock works beautifully in fish tacos or when baked with herbs and lemon, offering a low-mercury option for seafood lovers and novices alike.
- Salmon (farmed and wild) (up to 1.8% of your daily limit per serving): Known for their rich, buttery flavor, salmon are versatile, low-mercury fish that are perfect for grilling, baking, or broiling.
- Sardines (up to 0.4% of your daily limit per serving): Robust and flavorful, sardines are perfect for grilling or adding to dishes as a low-mercury protein.
- Scallops (up to 0.1% of your daily limit per serving): Sweet and delicate, scallops are best enjoyed seared to a perfect golden-brown hue. Scallops are a reliable low-mercury seafood option.
- Shrimp (up to 0.3% of your daily limit per serving): Sweet and tender, shrimp are ideal for quick sautéing or grilling, and their low mercury levels make them a great addition to your diet.
As you can see, eating seafood while remaining under your daily mercury limit is extremely attainable. For more detailed recommendations, refer to the FDA's advice on mercury in seafood.
Which Fish Are High in Mercury?
Mercury levels tend to be higher in larger, predatory fish that occupy the top of the food chain. They pose a higher risk for mercury poisoning when consumed frequently or in large quantities. Here are some high-mercury seafoods to reconsider if you are in a vulnerable group such as nursing or pregnant, and recommended alternatives to help you safely enjoy seafood:
| % of Daily Mercury Limit in 3.5oz Serving Sources: FDA & NIH |
|||||||||
|---|---|---|---|---|---|---|---|---|---|
| Your Weight (lbs) | 25 lbs | 50 lbs | 75 lbs | 100 lbs | 125 lbs | 150 lbs | 175 lbs | 200 lbs | 225 lbs |
| Bluefin/Bigeye Tuna | 213% | 106% | 71% | 53% | 42% | 35% | 30% | 27% | 24% |
| Golden Tilefish | 349% | 174% | 116% | 87% | 69% | 58% | 50% | 43% | 39% |
| King Mackerel | 227% | 113% | 75% | 56% | 45% | 38% | 32% | 28% | 25% |
| Shark | 304% | 151% | 101% | 76% | 60% | 50% | 43% | 38% | 34% |
| Swordfish | 309% | 154% | 102% | 77% | 62% | 51% | 44% | 39% | 34% |
- Bluefin or Bigeye Tuna (up to 213% of your daily limit per serving): These coveted tuna species are often enjoyed in various global dishes, from sushi to tuna steaks. So how much tuna is safe to eat? While the average adult can safely eat an occasional 3.5oz serving of bluefin or bigeye tuna, high-risk groups may want to opt for yellowfin tuna (up to 48% of your daily limit) as a lower mercury alternative with a comparable taste and texture.
- Golden Tilefish (up to 349% of your daily limit per serving): A recommended alternative is wild American red snapper (up to 3.1% of your daily limit), which has a similar firm texture and mild flavor.
- King Mackerel (up to 227% of your daily limit per serving): Instead of king mackerel, consider eating Atlantic mackerel (up to 4.4% of your daily limit) to achieve a similar rich taste and flaky flesh.
- Shark (up to 304% of your daily limit per serving): Instead of shark, consider trying Atlantic mackerel (up to 4.4% of your daily limit) to feed your craving.
- Swordfish (up to 309% of your daily limit per serving): A good alternative to swordfish is mahi-mahi (up to 55.8% of your daily limit), which offers a comparable firm texture and mild flavor.
FAQs
Can I eat sushi while pregnant? Does it have safe levels of mercury?
Concerns about consuming sushi while pregnant are valid and require careful consideration. The highest risk for consuming sushi while pregnant isn’t so much in the mercury levels as it is in bacteria or parasites. Improperly handled raw fish can harbor harmful bacteria and parasites, which can pose risks during pregnancy. Opt for sushi made with cooked fish or vegetarian options to reduce the risk of bacteria or parasite exposure. Always ensure that sushi is responsibly sourced and prepared in a clean, reputable establishment.
Some fish used in sushi, such as bluefin and bigeye tuna, have higher mercury levels and should be avoided during pregnancy. Instead, choose sushi made with low-mercury fish like salmon or shrimp. By taking these precautions, you can still enjoy sushi while pregnant, provided you make informed choices and prioritize safety. Always consult your healthcare provider for personalized advice.
Does shellfish have mercury?
Shellfish, like finfish, contain varying levels of mercury. However, they generally tend to have lower mercury levels due to their position lower on the food chain. For example, a serving of shrimp contains up to 0.3% of the recommended daily mercury limit per serving for vulnerable groups, and scallops contain up to 0.1%. Both of these options are safe to consume regularly and provide a nutritious addition to your diet without the risk of mercury overexposure.
Can you cook mercury out of fish?
No, you cannot cook mercury out of fish. Mercury binds tightly to the fish's muscle tissue, and cooking or other forms of preparation do not reduce its levels in your food. Instead, the best approach is to choose fish with less mercury to enjoy without worry.
Are there other contaminants I should be concerned about in my seafood?
Aside from mercury, another contaminant to be aware of is PFAS (per- and polyfluoroalkyl substances). These persistent "forever chemicals" can accumulate in various food and water sources, posing potential health risks to humans. According to the Food and Drug Administration, PFAS in the environment can enter the food supply chain through crops and animals grown, raised, or processed in contaminated areas. PFAS are known for their resistance to breaking down and can remain in the environment and in organisms for extended periods.
A large health opportunity for many people continues to be eating more seafood, packed with essential nutrients. To minimize exposure to PFAS in seafood specifically, it's crucial to source your seafood from reliable and reputable sources. Avoid seafood from contaminated waters, such as irresponsible farms and heavily industrialized coastal areas. By choosing seafood from trusted providers like Fulton Fish Market, you can reduce the risk of contamination and enjoy your seafood with greater peace of mind.
How frequently can I consume seafood that has mercury?
Safely enjoying seafood with mercury largely depends on your individual health circumstances. The FDA recommends that adults eat at least 8 ounces of seafood per week. To make the most of your seafood intake, focus on species with lower mercury levels like those shared above, and be mindful while enjoying higher mercury options like shark, swordfish, king mackerel, and golden tilefish. Higher-risk individuals, such as pregnant or nursing women and young children, should mitigate their intake of higher mercury seafood altogether.
Always consider your individual health circumstances and consult with your doctor for personalized advice. Making informed choices ensures you can savor the rich flavors of seafood while maintaining a safe mercury intake.