Clinical studies show a clear correlation between Alzheimer’s Disease and low selenium status. Lower selenium status is associated with worse cognitive decline [Aaseth 2016].
In many regions of Europe and the Middle East, there is poor selenium content in the soil and, accordingly, lower intake of selenium from food sources [Stoffaneller & Morse 2015; Winther 2020].
The daily intake of selenium from food in many European countries is well below the amount needed for optimal function of important selenoproteins. The needed intake of selenium from food is estimated to be at least 105 mcg per day [Winther 2020, fig. 2].
Using evidence from human studies in various countries, Prof. Jan Aaseth and colleagues have documented the association between lower selenium status and Alzheimer’s Disease and/or cognitive impairment [Aaseth 2016].
In a study of rural Chinese adults aged 65 years or older, low nail selenium concentration was significantly associated with low cognitive scores in
four of five tests. There was a notable dose-response effect on cognitive function across the selenium quintiles in the study.
Patients diagnosed with mild Alzheimer’s Disease had lower plasma selenium levels than healthy age-matched elderly subjects (82.2 vs. 93.2 mcg/L).
Individuals in the lowest quartile of plasma selenium concentration (less than 75.8 mcg/L) were 58 % more likely to be diagnosed with cognitive decline than were individuals with a plasma selenium concentration of 86.9 mcg/L. Moreover, in the study, cognitive decline was significantly associated with the extent of plasma selenium decline over a nine-year period.
Individuals with low plasma selenium concentrations (less than 66.7 mcg/L) had significantly lower performance-based coordination scores and Mini-Mental State Examination scores compared to individuals with higher (greater than 82.3 mcg/L) concentrations.
Studies in Brazil and Turkey
In the same way, studies done in Brazil and Turkey have shown an association between low selenium status and cognitive decline [Aaseth 2016].
Selenium Supplementation and Cognitive Function
In an evaluation of 11 studies, Pereira et al  observed the following effects of selenium supplementation.
Selenium only studies
- There was improvement in selenium status, glutathione peroxidase activity, and some cognitive test scores in patients diagnosed with mild cognitive impairment.
- There was also improvement in selenium status and mini-mental scores in patients diagnosed with Alzheimer’s Disease.
Studies of selenium plus other nutrients
- Improvement in cognitive test scores was observed in both Alzheimer’s Disease patients and patients with mild cognitive impairment.
- Pereira et al concluded that selenium supplementation is a good adjuvant treatment for patients with Alzheimer’s Disease and patients with mild cognitive impairment [Pereira 2022].
Optimal plasma/serum selenium status
Optimal function of Selenoprotein P and glutathione peroxidase selenoproteins is necessary for protection against the sort of cognitive decline that characterizes Alzheimer’s Disease [Aaseth 2016].
At present, the best estimate for optimal plasma/serum selenium status is approximately 125 mcg/L [Winther 2020, fig. 3].
Combined Selenium and Coenzyme Q10 Supplementation
There exists a biological interrelationship between selenium and Coenzyme Q10 such that there is an advantage in using the two substances in combination if there are deficiencies within the population [Alehagen & Aaseth 2015].
In a study in which researchers administered 200 mcg selenium and 200 mg of Coenzyme Q10 daily for four years to elderly community living citizens, average age: 78 years, the researchers observed improved health-related quality of life and increased vitality as compared to placebo treatment [Johansson 2015].
In the same study, the KiSel-10 study, treatment with selenium and Coenzyme Q10 showed decreased levels of inflammation biomarkers [Alehagen 2015 Sep] and oxidative stress biomarkers [Alehagen 2015 Nov-Dec].
Conclusion: Selenium Supplementation and Alzheimer’s Disease
Human studies show that selenium status is commonly low in patients diagnosed with cognitive impairment and with Alzheimer’s Disease.
The optimal function of selenium-dependent selenoproteins needs
higher selenium intakes than is possible in the selenium-poor regions of much of Europe and the Middle East.
There is, therefore, a role for selenium in the prevention and treatment of Alzheimer’s Disease.
There is also a role for selenium supplementation in the prevention of the development of Alzheimer’s Disease in elderly patients diagnosed with mild cognitive impairment;
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Alehagen U, Lindahl TL, Aaseth J, Svensson E, Johansson P. Levels of sP-selectin and hs-CRP decrease with dietary intervention with selenium and Coenzyme Q10 combined: a secondary analysis of a randomized clinical trial. PLoS One. 2015 Sep 16;10(9):e0137680.
Alehagen U, Aaseth J. Selenium and coenzyme Q10 interrelationship in cardiovascular diseases–A clinician’s point of view. J Trace Elem Med Biol. 2015;31:157-62.
Alehagen U, Aaseth J, Johansson P. Less increase of copeptin and MR-proADM due to intervention with selenium and coenzyme Q10 combined: Results from a 4-year prospective randomized double-blind placebo-controlled trial among elderly Swedish citizens. Biofactors. 2015 Nov-Dec;41(6):443-52.
Johansson P, Dahlström Ö, Dahlström U, Alehagen U. Improved health-related quality of life, and more days out of hospital with supplementation with selenium and Coenzyme Q10 combined: results from a double blind, placebo-controlled prospective study. J Nutr Health Aging. 2015 Nov;19(9):870-7.
Pereira ME, Souza JV, Galiciolli MEA, Sare F, Vieira GS, Kruk IL, Oliveira CS. Effects of Selenium Supplementation in Patients with Mild Cognitive Impairment or Alzheimer’s Disease: A Systematic Review and Meta-Analysis. Nutrients. 2022 Aug 5;14(15):3205.
Winther KH, Rayman MP, Bonnema SJ, Hegedüs L. Selenium in thyroid disorders – essential knowledge for clinicians. Nat Rev Endocrinol. 2020 Mar;16(3):165-176.
The information presented in this review article is not intended as medical advice and should not be used as such.
30 November 2022