Eating fish can provide numerous health benefits, thanks to the omega-3 fatty acids found in most fatty fish, which can lower the risk of heart disease and support cognitive health. Moreover, consuming fish can also reduce the risk of depression and promote mental well-being. Nevertheless, it's crucial to be mindful of the potential for increased exposure to mercury in fish. According to Environmental Health Perspectives, fish consumption is responsible for more than 90% of mercury exposure in the U.S., and tuna is among the top fish types with high mercury content.
Despite awareness of the mercury content in fish, many people wonder if it's possible to experience mercury poisoning from consuming too much of it.
Starting With an Overview of Tuna's Usual Mercury Levels
Consumer Reports recently conducted a study to evaluate the levels of mercury, a harmful neurotoxin, present in five popular brands of canned tuna: Wild Planet, Bumble Bee, StarKist, Chicken of the Sea, and Safe Catch. The study examined various types of tuna, including albacore, light, and skipjack, and found that all five brands contained some level of mercury. On average, albacore varieties across all brands had three times more mercury than light or skipjack.
However, the researchers also discovered unexpected spikes in mercury levels in some cans, raising concerns about the potential dangers of consuming certain brands and types of tuna. In fact, six out of 30 cans (20%) were found to have these toxin spikes. To avoid potential health risks, experts at Consumer Reports recommend that pregnant individuals avoid consuming tuna altogether, and that other adults consume it in moderation.
According to James E. Rogers, PhD, and director of Food Safety Research and Testing at Consumer Reports, "Mercury levels can spike in unpredictable ways that might jeopardize the health of a fetus." While certain types of tuna may have lower mercury levels, the unpredictability of the spikes in toxin levels means that all varieties and brands can pose a risk.
Despite these findings, it remains unclear whether consuming too much tuna can actually lead to mercury poisoning in the average adult.
What Causes Tuna to Have Mercury in it?
Consumer Reports states that it's nearly impossible to consume seafood without ingesting some level of mercury, as it is pervasive in the oceans. This is due to its presence as a natural mineral as well as its contribution from man-made pollution. Larger fish typically have higher levels of mercury because they consume smaller fish, which also contain mercury.
In addition to acquiring mercury through their diet, tuna also accumulates the mineral in its tissues over time. A report published in Biological Trace Element Research explains that tuna's inability to easily eliminate mercury from their bodies exacerbates this accumulation. As a result, mercury is a significant concern when it comes to consuming tuna.
What Are the Adverse Effects of Mercury on Your Health?
The Environmental Protection Agency (EPA) classifies mercury as a neurotoxin that can cause harmful health effects when consumed in high amounts. These effects include loss of motor skills and brain cells, impaired memory, increased anxiety, and a higher risk of heart disease. Methylmercury, the type of mercury found in seafood and fish like tuna, can cause poisoning at high levels.
Symptoms of methylmercury poisoning may include hearing or speech impairment, peripheral vision loss, muscle weakness, and a tingling sensation in the body. Unfortunately, it is difficult to determine how much tuna consumption can lead to mercury poisoning, especially given Consumer Reports' recent findings of inconsistent and unpredictable mercury spikes in canned tuna. However, the Food and Drug Administration (FDA) provides some general guidelines to help lower the risk of mercury poisoning.
What the FDA Says
The FDA recommends that adults limit their consumption of low-mercury fish to once or twice a week, while pregnant or breastfeeding individuals should consume fish with low mercury levels and limit their intake to 4 ounces, two to three times a week. It's important to note that Consumer Reports suggests that pregnant individuals avoid tuna entirely due to inconsistencies in mercury levels found in certain cans.
If you frequently consume tuna, be mindful of potential signs of mercury poisoning and consult with your doctor if you have concerns about your consumption levels.
Seafood With Lower Levels of Mercury to Consider
It's important to keep in mind that consuming any type of seafood can result in some level of mercury exposure. However, certain fish and shellfish tend to contain less mercury than others. According to Consumer Reports, seafood options with lower levels of mercury include crab, shrimp, squid, tilapia, cod, salmon, oysters, and lobster. For those who prefer canned options, anchovies and sardines are considered to have lower levels of mercury.
While it's difficult to determine the exact amount of tuna consumption that can lead to mercury poisoning, it's important to note that high levels of mercury can have potentially harmful effects on health. To avoid overexposure, individuals can stay mindful of mercury poisoning symptoms and adhere to the recommended weekly servings of fish.