Put down those chopsticks; your sushi might not be safe… again? A study published Thursday in the Journal of the American Society of Nephrology finds that a seafood toxin known to cause brain damage, is also harmful to your kidneys but at much lower concentrations. "We have found that domoic acid damages kidneys at concentrations that are 100 times lower than what causes neurological effects," said Dr. P. Darwin Bell from the Medical University of South Carolina. "This means that humans who consume seafood may be at an increased risk of kidney damage possibly leading to kidney failure and dialysis."

Red Tide

Sometimes the ocean turns a deep red color, commonly called "red tide" by surfers, yet referred to by scientists as "harmful algal blooms" or HABs.  The cause of HABs is an uncontrollable growth of algae colonies, the simple plants which live in both the sea and freshwater. Though beautiful to behold, HABs produce chemicals and toxins that may have a harmful effect on fish, shellfish, marine mammals, birds, and even people. Illnesses caused by HABs may be rare, but they may also be debilitating or even fatal to humans. One chemical common to red tide is domoic acid, a neurotoxin that is becoming more prevalent in coastal regions, likely due to environmental changes. Sadly, domoic acid is known to cause amnesic shellfish poisoning (ASP), a life-threatening syndrome that caused the death of four people in 1987. Symptoms of ASP affect both the gastrointestinal tract as well as the brain and may include nausea, vomiting, abdominal cramps, diarrhea, dizziness, headache, seizures, disorientation, and coma. True to its name, ASP might also involve short-term memory loss.

Domoic acid can accumulate in mussels, clams, scallops, and fish, yet because of its potentially harmful neurological effects, the FDA set a legal limit of domoic acid in seafood. What the FDA apparently didn't account for is the fact that this neurotoxin clears from the body through the kidneys. Understanding this, Bell and his co-researchers, including Dr. Jason Funk, hypothesized the toxin might have detrimental effects not only on the brain, but on the kidney as well. To test their theory, they gave mice incremental doses of domoic acid and assessed the animals' health at each dose. Perhaps unsurprisingly, the team discovered the kidney was much more sensitive to the toxin than the brain. In their published research, the scientific team notes that their findings need to be verified in humans, yet in the meantime, they would like to see increased awareness of domoic acid. Additionally, they suggest the FDA and other public health agencies might need to reconsider legal limits of domoic acid in food.

 

Source: Bell PD, Funk J, Janech M, Dillon J, Bissler J,  Siroky B. Characterization of Renal Toxicity in Mice Administered the Marine Biotoxin Domoic Acid. Journal of the American Society of Nephrology. 2014.