Dietary mercury poses risks to the human nervous system.

And intake should be minimized, especially when it comes to protecting growing brains.

This is why experts advise children and pregnant or nursing mothers to avoid high-mercury fish.

However, a new study from Johns Hopkins University's School of Public Health holds reassuring news for older adults.

The researchers tested the blood mercury levels of 474 Baltimore residents aged 50 to 70, and tested the participants' performance on 12 brain-function measures, including memory, manual dexterity, intelligence, behavior, and verbal skills.

As the investigators concluded, “Overall, the data do not provide strong evidence that blood mercury levels are associated with worse neurobehavioral performance in this population of older urban adults.”

Results offer reassurance to younger fish-lovers, too
The study's encouraging results indicate that diets that include frequent enjoyment of fish present no serious risk of increased cognitive decline to middle-aged and older adults.

The study also support findings by the Centers for Disease Control and Prevention (CDC), which show that even the upper range of mercury levels found in Americans' bodies don't come near the levels known to cause health problems.

Study bolsters seafood benefits
Thanks to an extensive body of research, it's clear that the omega-3 fatty acids in fish reduce the risk of both sudden death and death from coronary heart disease in adults, reduce the risk of blood clots and stroke, protect against certain cancers, exert therapeutic effects on autoimmune diseases, and may help prevent and relieve depression.

Accordingly, the USDA's 2005 Dietary Guidelines recommend that Americans eat two eight-ounce servings a week of foods rich in the omega-3 fatty acids EPA and DHA... and the only such foods are fatty fish.

As the Environmental Working Group has said, “"The risk of mercury in salmon appears to be minimal. In fact, the FDA states that limiting consumption is unnecessary for salmon.”

  • Weil M, Bressler J, Parsons P, Bolla K, Glass T, Schwartz B. Blood mercury levels and neurobehavioral function. JAMA. 2005 Apr 20;293(15):1875-82.