HANOVER, N.H. — Amyotrophic lateral sclerosis, or ALS, took center stage in American culture in the summer of 2014 when the “Ice Bucket Challenge” brought viral awareness to the disease. More than $100 million was donated to help shed light on the mysterious, incurable ailment, and though its cause remains a mystery in the vast majority of cases, a new study finds high levels of mercury in fish could lead to development of the disease in some people.
ALS, also commonly referred to as Lou Gehrig’s Disease, is a progressive neurological disease that often starts with mild twitching and weakness in a limb, before it winds up causing complete body paralysis, and later, death.
The study, led by researchers at Dartmouth University, looked into the impact of fish consumption on developing the disease. Seafood is the primary source of Americans’ exposure to mercury, a chemical suggested to be a risk factor for the disease by previous studies.
“For most people, eating fish is part of a healthy diet,” study author Elijah Stommel, MD, PhD, of Dartmouth and a Fellow of the American Academy of Neurology, says in a release from the academy. “But questions remain about the possible impact of mercury in fish.”
This new research examined 518 individuals— 294 had ALS, while the rest did not. Participants would log the amount of fish they ate, along with the source of the fish (i.e. if it was personally caught, purchased, etc.)
Researchers were able to determine one’s exposure to mercury by multiplying typical mercury levels encountered in a given amount of fish with the consumption rates examined. Toenail samples were also used to more empirically determine an individual’s exposure.
Ultimately, those in the 25th percentile of exposure to mercury through fish consumption were found to have double the risk of developing ALS, whether the exposure was self-reported or determined through the toenail clippings. In fact, 61% of the individuals examined with ALS ended up being in the top quartile of fish eaters.
The study’s researchers did emphasize that while eating fish may lead to an increase in exposure to mercury, it still has many health benefits, playing “part of a healthy diet,” when consumed in moderation.
One can lessen their consumption of mercury by avoiding seafood with higher rates of mercury, such as shark and swordfish.
Though release in February, the study will be presented at the American Academy of Neurology’s 69th Annual Meeting in Boston, April 22 to 28, 2017.