Around 1 in 3 people in the Europe, including pregnant women, are consuming potentially unsafe amounts of fish containing high mercury levels, according to a new European Food and Safety Authority (EFSA) report. EFSA defines “unsafe” as eating three or more portions per week of fish containing ≥ 1 mg of methylmercury (MeHg) per kilogram of fish wet weight.

The report found a sharp rise in frequent consumption of high-mercury species between 2023 and 2024. By EFSA’s account, the proportion of respondents saying they consumed three or more portions per week of high-mercury fish rose from 26% in 2023 to 50% in 2024.

Increases in fish consumption were similar in countries with and without updated consumption advice, indicating that other factors may be driving dietary changes. According to the report, taste, price, and perceived health benefits often outweigh safety concerns.

“There is a need for tailored communication strategies: frequent consumers may require targeted risk messages, while infrequent consumers may benefit from information emphasizing health benefits and safe fish and seafood choices,” EFSA said in its report.

Most EU national authorities advise limiting consumption of high-mercury fish (≥ 1 mg/kg MeHg) to one to two portions per week or three to four portions per week for species with lower MeHg (< 0.5 mg/kg). Large predatory species such as shark, swordfish, and large tuna typically have the highest mercury concentrations; smaller species such as salmon, mackerel, trout, sardines, and anchovies tend to have much lower levels.

Mixed Messaging

EFSA surveyed adolescents, adults, and pregnant women across all 27 EU member states by telephone in 2023 and again in 2024, conducting nearly 15,000 interviews in the first wave and about 8000 in the second. Participants were asked about consumption of 38 fish species and about their awareness of contaminants and national dietary advice.

The surveys found that consumers are far more likely to be aware of fish’s health benefits than of its risks: up to 60% were fully aware of benefits such as omega-3s, whereas only 10%-14% were aware of contaminant risks.

“Recent increases in frequent fish consumption may reflect strong health messaging around omega-3 benefits, sometimes without enough emphasis on choosing appropriate species and practicing moderation,” Xavier Coumoul, PhD, professor of biochemistry and toxicology at Université Paris Cité, Paris, France, told Medscape News Europe.

Advice for Patients

“The most vulnerable populations to mercury in food are the fetus, infants, children up to 6 years, and pregnant/ breastfeeding women, or those planning pregnancy, due to risks of impaired neurodevelopment,” Tony Smith, EFSA spokesperson, told Medscape News Europe.

Lars Barregård, professor at the School of Public Health and Community Medicine at the University of Gothenburg, Gothenburg, Sweden, told Medscape News Europe that pregnant women or those planning pregnancy should skip high-mercury fish out of caution.

“For the rest of us, the potential for other risks like a suspected increased cardiovascular risk, is the problem, but that possible risk requires much higher MeHg doses. Consumption of those high MeHg species should be limited to a few times per month,” he said.

Barregård noted, however, that diets including one to five portions of fish per week are beneficial, and that most marine fish species carry no risk for adverse health effects due to low MeHg levels.

Smith agreed, adding that the 2015 EFSA’s scientific committee concluded that one to two servings of fish per week, or up to three to four during pregnancy, is linked to better neurodevelopmental outcomes in children and lower heart disease mortality in adults provided specific high-mercury species are avoided.

Alternatives

“An easy way to know for consumers which types of fish to eat is to consider the size. For example, tuna is big and accumulates mercury, while sardines generally have lower levels,” said Coumoul.

The main concern, he stressed, is not fish consumption overall, but consumption of large, predatory fish that accumulates mercury over time.

“Regular consumption of smaller species such as sardines, anchovies, and herring generally presents lower risk. If people do not like their strong taste, you can prepare them with yoghurt, garlic, and coriander and serve with bread. It’s quite good,” he said.

Barregård noted that the guidance doesn’t necessarily apply to all types of tuna.

“It is the big tuna that may have a high content of MeHg. If you like tuna, then you could still eat a lot of canned tuna, which is based on the less expensive small tuna fish,” he said.

Ronan Gormley, PhD, adjunct professor at the School of Agriculture and Food Science at University College Dublin, Dublin, Ireland, added “All fish are high in high-quality protein, but tuna is probably the highest. Mainstream fish species like cod, mackerel, and hake deliver 18-20 g/100 g, which is lower than tuna but is still excellent. Canned tuna is usually in brine, which increases the salt content a bit which is a small negative,” he said. “The bottom line is: eat fish 2-3 times per week and you will get plenty of good quality protein and essential fish oils.”

Barregård, Gormley, and Coumoul reported having no relevant financial relationships.

Annie Lennon is a medical journalist. Her writing appears on Medscape, WebMD, and Medical News Today, among other outlets.