Written by Taylor Woosley, Staff Writer. Analysis of a systemic review of 11 studies and a meta-analysis including 6 papers show that selenium supplementation increased MDA levels significantly by an average of 0.95 (0.44, 1.45) times (p = 0.0002). Furthermore, Se only supplementation significantly increased GPX activity by an average of 0.95 (0.59, 1.31) times (p = 0.00001).
Alzheimer’s disease (AD) is the most common cause of dementia, the most common neurodegenerative disease, and one of the most common neurological disorders1. It is estimated that close to 50 million people globally are affected by dementia, including AD, and the prevalence of the disease is projected to double by 20502. AD is characterized by amyloid-β plaques, neurofibrillary tangles and nerve cell death3. It typically manifests through a progressive loss of episodic memory and cognitive function, with later deficiency of language and visuospatial abilities4.
Selenium is an essential micronutrient that plays a crucial role in a variety of physiological processes5. It has been widely researched for its antioxidant and immunological properties, which play a role in anti-inflammatory and free radical scavenging abilities6. Neurodegenerative diseases, such as AD, are characterized by increased oxidative stress and neuroinflammation, with selenium offering protective benefits against oxidative stress and low-grade chronic inflammation7.
Pereira et al. conducted a systematic review and meta-analysis to evaluate the effects of selenium supplementation on selenium levels and oxidative stress, along with verifying whether selenium (Se) supplementation improves subject performance in cognitive tests. The review included studies if they featured patients with AD or mild cognitive impairment (MCI), with available serum levels of Se or Se included with other nutrients. The Cochrane Risk of Bias for Randomized Trials tool was performed for quality assessment. 11 papers were included in the systemic review, with 4 papers being centered on Se supplementation only, and 7 explored Se plus other nutrients supplementation. 6 papers met the criteria to be used in the meta-analysis.
Of the studies measuring only Se supplementation, 40% of the studies measured the MDA levels in plasma to assess oxidative stress activity. Results of the meta-analysis show that after Se supplementation, MDA levels increased significantly by an average of 0.95 (0.44, 1.45) times (p = 0.0002). Studies including Se plus other nutrients supplementation also noted an increase in MDA levels, although it was not statistically significant. Furthermore, blood glutathione peroxidase (GPX) activity was analyzed in 40% of papers for the Se only supplementation. Findings of the meta-analysis show that GPX activity significantly increased by an average of 0.95 (0.59, 1.31) times (p = 0.00001). Cognitive performance assessed in the Se only supplementation groups resulted in an increase in the Mini-Mental State Examination (MMSE) from 10.4-19.7 to 19.5-20.0 after Se supplementation. In the Se plus other nutrients supplemented group, the MMSE score increased from 9.4-23.8 to 10.4-24.3 after supplementation.
Main findings of the systemic review including 11 papers and the meta-analysis of 6 studies show that selenium supplementation improved oxidative stress levels and increased GPX activity. Improvements in MMSE test results, an important screening test to evaluate AD progression, also support the use of selenium to increase cognitive performance. Further research should continue to assess the potential use of selenium to reduce prooxidant molecules and improve antioxidant levels in the brain to increase cognitive performance. Study limitations include the lack of data and disparity between studies in the parameters used made it difficult to analyze in the meta-analysis.
Source: Pereira, Meire Ellen, Júlia Vicentin Souza, Maria Eduarda Andrade Galiciolli, Fernanda Sare, Giovanna Scorsin Vieira, Isabeli Lopes Kruk, and Cláudia Sirlene Oliveira. “Effects of Selenium Supplementation in Patients with Mild Cognitive Impairment or Alzheimer’s Disease: A Systematic Review and Meta-Analysis.” Nutrients 14, no. 15 (2022): 3205.
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Posted September 27, 2022.
Taylor Woosley studied biology at Purdue University before becoming a 2016 graduate of Columbia College Chicago with a major in Writing. She currently resides in Glen Ellyn, IL.
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- Pereira ME, Souza JV, Galiciolli MEA, et al. Effects of Selenium Supplementation in Patients with Mild Cognitive Impairment or Alzheimer’s Disease: A Systematic Review and Meta-Analysis. Nutrients. Aug 5 2022;14(15)doi:10.3390/nu14153205
