Studies evaluating the relationship between Se levels and cognitive degeneration suggest that a lack of Se could increase the risk of dementia.
Se is an important trace element for the body and also plays a role as an antioxidant, through selenoprotein P (SeP) and the enzymes glutathione peroxidase (GSH-Px) and thioredoxin reductase (TrxR). In in vitro studies it was observed that neuronal cells exposed to the oxidative effects of amyloid plaques were protected in the presence of SeP. GSH-Px is expressed in neurons and glial cells and its main function is the elimination of peroxides (free radicals). Some studies suggest that cognitive degeneration is associated with a decrease in GSH-Px activity.
Beef, chicken, fish, eggs and wheat are considered good sources for Se. However, the amounts of Se in such foods reflect its concentration in the soil, so the same type of food may have different Se concentrations depending on its origin. Germany is one of the areas where selenium is deficient. Brazil nuts are considered the best source of Se due to their high concentration and high bioavailability. Some studies have shown an improvement in Se status in healthy people after eating two Brazil nuts daily for 12 weeks. Brazil nut consumption may also be effective in improving Se status in patients with AD, and this improvement could be an important therapeutic goal in maintaining cognitive function in patients.
It makes absolutely sense to measure the selenium level. If there is a permanent increase or decrease in selenium intake by a factor of 3 to 10, selenium deficiency or selenium poisoning begins. Both are dangerous and can lead to death.
Cardoso BR, Ong TP, Jacob-Filho W, Jaluul O, Freitas MI, Cozzolino SM. Nutritional status of selenium in Alzheimer’s disease patients. Br J Nutr. 2010;103(6):803–806. https://www.ncbi.nlm.nih.gov/pubmed/19948078
Thomson CD, Chisholm A, McLachlan SK, Campbell JM. Brazil nuts: an effective way to improve selenium status. Am J Clin Nutr. 2008; 87(2):379–384. https://www.ncbi.nlm.nih.gov/pubmed/18258628