Selenium and mercury and eating fish

Ocean fish – salmon, herring, mackerel, and sardines – are good sources of the omega-3 fatty acids EPA and DHA that have been associated with healthy fetal development, healthy cardiovascular function, and healthy ageing.  Whatever mercury there is in these fish has bound with the selenium in the fish.   This chemical binding has rendered the mercury harmless but has also depleted the amount of selenium available for absorption.

Too many of us are missing out on the health benefits of the omega-3 fatty acids available to us from eating certain types of fish a couple of times a week.  Why are we avoiding fish?  Because many of us are afraid of “eating mercury” in the fish.

It turns out, there is research to show that this is a misconception.  Professor Nick Ralston and his colleagues at the University of North Dakota’s Energy and Environmental Research Center have measured and evaluated the molar ratios of selenium in fish to the mercury in fish [Ralston 2007, 2016].

Their studies show that many of the edible ocean fish have an abundance of selenium in relation to mercury.  So, not only are we missing out on the omega-3 fatty acid benefits, we are also missing out on a good source of dietary selenium [Berry 2008].

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Selenium and Alzheimer’s disease and cognitive decline

Pictured: A healthy brain and a brain suffering from severe Alzheimer’s disease. The question: what is the role of the selenium-dependent antioxidant seleno-enzymes in the prevention of Alzheimer’s disease? Professors Aaseth and Alehagen offer an explanation.

There is no reliable method to prevent the development and progression of Alzheimer’s.  There is no known cure for Alzheimer’s.  The approaches that we have tried over the past 20-25 years have not prevented or inhibited the decline in cognitive function that is associated with Alzheimer’s.

Now, Professor Jan Aaseth (Norway) and Professor Urban Alehagen (Sweden) propose selenium supplementation as a prophylactic measure to inhibit the decline of cognitive function, especially in the selenium-poor regions of the world.  They hypothesize that the optimal functioning of the selenoproteins SEPP, GPx, and TrxR is necessary to protect against the cognitive decline associated with Alzheimer’s disease.

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