For the most part, we know that eating fish is an essential element of a healthy diet. Rich in fat-soluble vitamin D, omega-3 fatty acids, and DHA, and heart healthy brain-boosting nutrients, even touted as the healthiest food on the planet by some.

But what occurs when your fish has mercury in it? Multiple studies have been done suggesting that our once healthy fish now has levels of mercury possibly too unsafe to eat.

A recent study conducted at Dartmouth College suggests that eating fish and seafood with higher levels of mercury; specifically, shark and swordfish may be linked to an increased risk of amyotrophic lateral sclerosis (ALS).

Study author, Elijah Stommel, MD, Ph.D., of Dartmouth College in Hanover, H.H., and a Fellow of the American Academy of Neurology said:

“for most people, eating fish is a part of a healthy diet.” “But questions remain about the possible impact of mercury in fish.”

You may remember the “ALS Challenge” that went viral in the late summer of 2014.  Individuals were filming themselves dumping large buckets of ice water over their heads to bring awareness to the disease, ALS. By the end, supporters were able to raise over $115 million dollars, and in turn, scientists were able to make a few breakthrough discoveries, like finding a new gene linked to ALS, NEK1.

Brian Frederick, executive vice-president of the communications and development at the ALS Association, said, “the discovery is significant because it helps us understand what is triggering this and can help us find a treatment.”

Sometimes confused with Lou Gehrig’s disease, ALS is a progressive neurological disease that stops your nerve cells from interacting with your body’s muscles. Including symptoms such as muscles twitching, weakness in limbs and can develop into a complete paralysis of the body, this also includes the muscles that allow you to speak, eat and even breathe.

mercury laden fish

For this study 518 people were surveyed, 294 of them had ALS, and 224 did not. The participants were asked how much fish they typically ate and whether they purchased their fish from a local grocery store, or caught their fish.

Swordfish and shark rank among highest in mercury-laden fish, with salmon and sardines, are typically on the lowest scale.

The study found that the participants who ate fish and seafood regularly were at double the risk of ALS vs. those who ate fish less regularly.  A total of 61 percent of people who had ALS were in the top 25 percent of mercury intake, compared to 44 percent of individuals who did not have ALS. Mercury levels in the toenail clippings had an increased risk of ALS out of the top 25 percent based on fish related intake.

The study does not dispute that eating fish does offer a broad range of health benefits; however, the study does suggest that choosing the type of seafood you decide to eat is crucial.

Avoiding high mercury-rich fish like shark and swordfish and choosing fish with the lowest levels is the best.