Neurotoxins in Shark Fins, Meat Linked to ALS and Other Neurodegenerative Diseases

University of Miami researchers found high concentrations of toxins associated with neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), in the fins and muscles of 10 different shark species, some of them threatened by extinction due to overfishing. Such findings suggest that restriction of shark meat and fins consumption may have important health benefits.

The research article, “Cyanobacterial Neurotoxin BMAA and Mercury in Sharks,” was published in the journal Toxins.

Sharks, long-lived predators that live higher up in the food chain, are at greater risk for accumulating marine toxins and mercury in their tissues. Shark fins and cartilage also contain β-N-methylamino-l-alanine (BMAA), a cyanobacterial toxin linked to neurodegenerative diseases such as ALS and Alzheimer’s disease.

Currently, several shark species are on the International Union for Conservation of Nature (IUCN) Red List of Threatened Species due to the high demand for shark fin soup, shark meat, and shark cartilage products that are in dietary supplements.

Many studies have cautioned that the consumption of shark meat and fins could lead to human exposure of marine toxins. Here, researchers collected fins and muscle tissue samples from 10 shark species in the Atlantic and Pacific, ranging in threat status from least endangered (bonnethead shark) to most endangered (great hammerhead), and investigated for concentrations of BMAA and mercury.

Results indicated that BMAA was found in all shark species, with only seven of the 55 samples analyzed testing below the limit of detection of the assay. Concentrations of mercury were also worrisome.

The results led researchers to say that people who consume shark parts may be at risk for developing neurological diseases.

“People should be aware and consider restricting consumption of shark parts,” Neil Hammerschlag, a research assistant professor at the UM Rosenstiel School and UM Abess Center for Ecosystem Science and Policy, said in a press release.

“Limiting the consumption of shark parts will have positive health benefits for consumers and positive conservation outcomes for sharks, many of which are threatened with extinction due in part to the growing high demand for shark fin soup and, to a lesser extent, for shark meat and cartilage products,” said Hammerschlag, also the study’s lead author.