July 26, 2019—College students may be unwittingly exposing themselves to potentially harmful levels of mercury by eating too much tuna in campus dining halls, a new study suggests.
Nearly all fish contain trace amounts of mercury. This toxic metal can harm the brain and nervous system at high levels. Tuna, especially large species, contains fairly high amounts of mercury.
Researchers surveyed students at University of California, Santa Cruz, about their tuna consumption and knowledge of mercury's risks. They also measured the mercury levels in student hair samples.
The researchers found that:
- About a third of the students ate tuna weekly—mostly in dining halls.
- Half of the tuna eaters ate the fish three or more times weekly.
- The amount of mercury in the student's hair closely correlated with how much tuna they ate. And for some students, those measurements were above what is considered a "level of concern."
- Most of the students in the study weren't aware that eating too much tuna could be a health risk.
The amount of tuna that students ate isn't necessarily enough to trigger toxic effects, the researchers said. But it does potentially exceed what the U.S. Environmental Protection Agency considers safe.
Since college students' nervous systems are still developing, they should be especially careful to limit the amount of tuna they eat, the researchers cautioned.
They also warned that overeating tuna could be an issue at many places with dining halls, particularly ones that serve children, such as boarding schools. People often help themselves in these settings.
How much tuna is safe?
Consumers are typically advised to eat either:
- No more than three servings a week of tuna with lower levels of mercury. Good choices include skipjack and tongol (often labeled "chunk light") tuna.
- One serving a week of tuna with higher levels of mercury. Options include albacore and yellowfin tuna.
Fish overall is an important part of a healthy diet. It's packed with high-quality protein. And regularly eating it helps protect your heart.
The U.S. Food and Drug Administration generally advises adults to eat two to three 4-ounce servings of a variety of fish every week. Ask your doctor what's right for you.
The study appeared in Environmental Toxicology and Chemistry.