Feb 18 2016

Study: Fish Prevents Alzheimer’s; Don’t Sweat Mercury Levels

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SEAFOODNEWS.COM [Atlanta Journal] By Larry Clifton  February 17, 2016

Atlanta – A new study challenges the dietary populism that in the past suggested the consumption of fish poses more of a health risk to the brain than benefit.

According the study, there is not enough toxic mercury to damage our brains in the weekly consumption of seafood. Conversely, the new findings show that the omega-3 fatty acids found in fish had a role in defending our brains against Alzheimer’s and other forms of dementia. Previous studies questioned whether increased mercury levels in the brain would cancel out such benefits, an issue specifically addressed in the new study, published by CNN.

Researchers questioned the study group about their diet every year starting in 1997. Furthermore, they performed brain autopsies on 286 participants who died between 2004 and 2013 to examine the levels of mercury and to determine whether there was neurological damage associated with dementia.

“The findings were very striking,” said Martha Clare Morris, director of nutrition and nutritional epidemiology at Rush University Medical Center.

“Our hypothesis was that seafood consumption would be associated with less neuropathology, but that if there were higher levels of mercury in the brain, that would work against that. But we didn’t find that at all,” said Morris, who is lead author of the study, which was published Tuesday in the Journal of the American Medical Association.

The research only added one caveat; they only observed the benefit among participants who had a strong genetic risk factor for Alzheimer’s. These participants carried a version of the APOE gene called APOE-4, which is associated with higher risk of developing Alzheimer’s. Nevertheless, unless one has been specifically tested for the APOE-4 gene, consuming more fish is decidedly healthy and, according to the study, does not result in the accumulation of toxic amounts of mercury.

Even people who test negative for the APOE-4 gene likely gain some lesser amount of protection from Alzheimer’s by a weekly consumption of seafood, but the current study was not able to confirm or deny that question, Morris said.

“One theory is that seafood consumption may be more beneficial in older age because, as we age, we lose DHA in the brain,” a molecule that is important to maintain brain health, Morris said. DHA is one of the main fatty acids that can be obtained from fish. People with APOE-4 are thought to lose even more DHA in the brain, so seafood consumption could be even more beneficial to them, Morris added.

Still, Morris maintained that individuals sustaining a steady diet of certain kinds of seafood could experience a downside to brain health. “Our findings can’t be generalized to people who are really high consumers of seafood,” Morris said. In the Midwest population in the study, very few ate seafood every day.

The latest study augments findings of previous surveys as well as the professional opinions of doctors who treat patients and study Alzheimer’s disease.

“The evidence is quite clear that people who consume healthier forms of fish [which are baked or broiled rather than fried] are going to end up with healthier brains,” said James T. Becker, professor of psychiatry and associate director of the Alzheimer’s Disease Research Center at the University of Pittsburgh, who was not involved in the current study.

As for whether mercury increases the risk of dementia, “I personally don’t think there’s evidence for it. I think these heavy metals are going to do other things first,” such as causing nerve pain, itching or burning, Becker said.


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