Consuming fish in moderation is a healthy way you can obtain protein and omega-3 fatty acid in your diet, which is good for heart-health. The American Heart Association recommends eating fish twice per week for most people, unless you are a woman who is pregnant, trying to conceive, nursing or a young child. Nearly all fish and shellfish contain some traces of mercury, but safety starts with knowing the amount of mercury in the fish or shellfish you are consuming.
Definition
Mercury is an odorless, invisible element found naturally in the environment or released through industrial pollution, according to the U.S. Food and Drug Administration, or FDA. The mercury released in the air accumulates in and forms into methyl mercury in the water. The fish absorb the methyl mercury through feeding on plankton or other small fish, which is the cause of the fluctuation in different mercury levels in the fish and shellfish.
Significance
Mercury is a contaminant found in fish that can affect brain development and the nervous system. Methyl mercury exits the body naturally, but it may be a year before the levels drop significantly. Methyl mercury is not easily detectable and you cannot avoid it by cutting off the skin or fat of the fish. A higher level of mercury accumulates in older, larger, predatory fish and marine mammals such as swordfish, king mackerel, shark and tilefish, according to the FDA.
Effects
According to the Environmental Protection Agency, mercury is a neurotoxicant and has the potential to cause nervous system damage to developing fetuses. The methyl mercury exposure in the womb from a mother consuming fish or shellfish may have a negative effect on the fetus' cognitive thinking, attention, memory, language, fine motor and visual spatial skills. According to the Natural Resources Defense Council, mental retardation, cerebral palsy, deafness and blindness are conditions prenatal and infant mercury exposure can cause because a child's brain is still developing during the first few years of life.
Warning
The FDA and EPA recommend avoiding the fish and shellfish with the highest level of mercury to young children or if you are pregnant. In addition, since the mercury levels stay in your body for approximately one year, if you are planning on conceiving, monitor the amount of fish to avoid high levels of mercury in your body. If you are pregnant, or planning on conceiving, the FDA recommends consuming no more than 12 oz. per week of lower mercury fish or shellfish. In addition, if you consume high-level mercury fish, limit those servings to three, 6 oz. servings per month.
Considerations
In some situations, eating fish and seafood containing mercury, the benefits of the protein and omega-3 may outweigh the risk of mercury consumption. Dr. Jane Hightower, an internal medicine physician at California Pacific Medical Center in San Francisco, linked fish consumption to elevated mercury levels when she tested her own patients. However, Hightower mentions that you can cut the consumption of mercury-contaminated fish and over time, it will reverse the mercury levels.
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