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Healthy Living

Is Mercury in Fish Bad for You?

Jul. 25, 2024
What you should know about eating fish.

Fish are vital for a healthy diet, providing nutrients essential for brain development. Although there is mercury in fish, if you follow guidelines, fish consumption is safe for all including pregnant people and children. Based on leading studies, researchers at 鶹Ƶexplain the balance of fish benefits and mercury risks.

What are the benefits of eating fish?

Fish are a rich source of important nutrients important to the brain and a healthy diet, including:

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  • Polyunsaturated fatty acids
  • Iron
  • Zinc
  • Iodine
  • Selenium
  • Vitamin D

Recent findings show that the fatty acids in fish enhance developmental and educational outcomes and may even help protect the developing brain from the harmful effects of mercury.

Why is there mercury in fish?

Methyl mercury is generated by industrial pollution and natural events (like volcanoes). It ends up in the oceans and other bodies of water and makes its way up the food chain. Consuming seafood is one of the primary ways humans are exposed to mercury.

Is it safe to eat fish?

For adolescents and adults, there are no real mercury-related health concerns associated with eating a normal diet of seafood. For many people on the planet, fish are the primary source of protein. If you eat a lot of seafood, fish consumption guidelines recommend that your diet has a healthy balance of low mercury fish.

The question gets more complicated when it comes to pregnant and breastfeeding mothers and young children. Loralei L. Thornburg, MD, a professor of Obstetrics and Gynecology at URMC, explains, “Seafoods, and fish in general, are great sources of lean protein, micronutrients, and amino acids that we know that are critical to fetal brain development and a healthy baby.”

Weighing the health benefits of fish with the risks of mercury exposure is complex. Recommendations have evolved over time, which can be confusing. “The key is finding the right balance; too much is problematic, but so is not enough,” said Thornburg.

Too much can be problematic as mercury is a neurotoxicant. This means that it may cause damage to the brain in the early stages of development. There is a growing body of scientific evidence that the benefits of eating fish outweigh the risk of mercury exposure when it comes to brain development. This is reinforced by decades of URMC-led research that find no link between a maternal diet high in fish and deficits in the cognitive development and learning ability of their children.

How much fish should I eat?

A chart that details the safety of eating fish based on mercury levels.

The FDA and EPA recommend that pregnant or lactating people and children under the age of 11 should consume between eight and 12 ounces (about two servings) per week of seafood lower in mercury. Seafood that’s lower in mercury includes salmon, shrimp, cod, and canned (light) tuna (not albacore). For a full list, see .

Omega-3 fatty acid supplements are also a good source of nutrients, but in most instances, are derived from fish oil. Look for the logo, which indicates supplements have safe levels of mercury and other contaminants.

What fish should I avoid?

Seafood should be properly cooked. If you’re pregnant or breastfeeding, you should avoid consuming raw seafood, such as sushi, oysters, and smoked salmon. This is because of the risk of harmful bacteria and viruses.

Large predatory fish like shark and swordfish typically have high concentrations of mercury. If you catch the fish you eat, pay attention to local fish advisories.

How is 鶹Ƶleading the way?

Seychelles Child Development Study

Located in the Indian Ocean, Seychelles' population consumes fish at a significantly higher rate than in the U.S. and Europe, providing a unique setting for this research. Data was collected from over 5,000 mothers and children, looking at diet, nutrition, mercury exposure, and developmental outcomes. The results of the study suggest that the benefits of fish consumption during pregnancy outweigh the risks of mercury exposure.

New Bedford Cohort Study

A recent study by Sally Thurston, PhD, and colleagues is helping create clearer guidance on fish consumption during pregnancy. It considers both fish intake and mercury content, showing that consuming low-mercury fish benefits neurodevelopment while high-mercury fish poses risks. This approach could help balance the benefits and risks of fish consumption.

Long-Term Impact of Methylmercury Study

Researchers in the lab of Matthew Rand, PhD, are studying the long-term impact of methylmercury on motor control, especially when exposure occurs during pregnancy, when it may disrupt the early development of the connections between muscles and the brain.