Dartmouth: There is an important association between eating fish and seafood with higher levels of mercury and being at a higher risk of developing amyotrophic lateral sclerosis (ALS), according to a preliminary study released this week. Results of the study will be shared during the 69th annual meeting of the American Academy of Neurology, which will be held in Boston April 22 to 28, 2017. “For most people, eating fish is part of a healthy diet,” said study author Elijah Stommel, MD, PhD, a professor of neurology at Dartmouth’s Geisel School of Medicine, a neurologist at Dartmouth-Hitchcock Medical Center, and a fellow of the American Academy of Neurology. “But questions remain about the possible impact of mercury in fish.”
While a growing body of evidence from previous studies has pointed to
mercury as a risk factor for ALS—in the U.S., primarily through eating
fish contaminated with the neurotoxic metal—the exact cause of the
disease is still unknown.
Commonly referred to as Lou Gehrig’s disease, ALS is a progressive
and lethal neurodegenerative disorder affecting nerve cells in the brain
and spinal cord. As of yet, no cure has been found and no effective
treatments have been developed for the disease.
In the case-control study, researchers used questionnaires to assess
fish and seafood consumption among 518 study participants (294 who had
ALS and 224 who did not) and determine estimated annual exposure to
mercury. Participants reported on the amount and type of fish and
seafood they consumed, and whether they were bought in stores or caught
by fishing. Researchers also measured mercury levels found in toenail
samples obtained from ALS patients and compared them to those from
participants without ALS.
The results of the study showed that among participants who consumed
fish and seafood on a regular basis, those in the top 25 percent of
estimated annual mercury levels, based on fish-related intake or toenail
clippings, were at a two-fold higher risk of ALS.
“It’s important to emphasize that these results don’t negate the fact
that eating fish provides many health benefits,” says Stommel.
“However, they do suggest that people may want to choose species that
are known to have a lower mercury content and avoid consuming fish
caught in waters where mercury contamination is well-documented. More
research needs to be done before fish-consumption guidelines for
neurodegenerative illness can be made.”
Consumers are encouraged to consult current U.S. Food and Drug
Administration health recommendations on fish and seafood consumption,
and to check water body specific fish advisories before eating fish
caught by angling.
The study was supported by the Diamond Endowment Fund, the ALS
Association, the Centers for Disease Control and Prevention, the Agency
for Toxic Substances and Disease Registry, the Dartmouth SYNERGY
Clinical and Translational Science Institute, and donor funds from the
French and Scheuer Families.