Effects of Selenium Supplementation in Patients with Mild Cognitive Impairment or Alzheimer’s Disease: A Systematic Review and Meta-Analysis
What this study found
Selenium supplementation significantly increased selenium levels in plasma (about 4.09x), serum (about 1.88x), erythrocytes (about 3.73x), and CSF (about 2.18x). Erythrocyte GPX activity rose by about 0.95x (p<0.001). Malondialdehyde (MDA) levels increased by about 0.95x (p=0.0002), indicating no reduction in lipid peroxidation with Se alone. Cognitive tests improved in some MCI cases (e.g., verbal fluency and constructive praxis) and in some AD cases (MMSE), with Se plus other nutrients regimens also showing cognitive benefits in AD and MCI, though MMSE/ADAS-Cog improvements were not…
- Study & population
- Adults with Alzheimer's disease or mild cognitive impairment (older adults; age ~68–88).
- Intervention
- Se regimens varied: Brazil nut (1 nut daily) for 24 weeks; inorganic Se as sodium selenate at 320 µg/day (three times daily) for 24 weeks; supranutritional sodium selenate at 10 mg/day (three times daily) for 24 weeks; Formulation F ampoule containing 27.5 µg Se daily for 24 weeks; Souvenaid delivering 60 µg Se daily…
- Key limitation
- Small sample sizes; heterogeneity in selenium regimens (dose, form, duration); varied outcome measures and reporting (some medians); risk of bias in several studies; short follow-up limits assessment of long-term cognitive effects and safety.
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Open PDFOriginal abstract
Elevated levels of oxidative stress could cause and aggravate Alzheimer’s disease (AD). Selenium (Se) is a trace element with antioxidant and anti-inflammatory activity with neuroprotective effects. To evaluate the effects of Se supplementation in patients with AD or mild cognitive impairment (MCI) through a systematic review and meta-analysis, data were searched and collected from four electronic databases, including clinical trial studies published until December 2020, following the PRISMA guidelines. Statistical analysis was performed by RevMan, and the risk of bias was assessed using the Rob 2 tool. A total of 1350 scientific papers were collected, and following evaluation 11 papers were included in the systematic review and 6 of these were used in the meta-analysis. Studies that evaluated only Se supplementation observed an improvement in Se levels, glutathione peroxidase (GPX) activity, and in some cognitive tests in MCI patients; similarly, improvement in Se levels and mini-mental score was also observed in AD patients. Regarding supplementation of Se plus other nutrients, improvement in cognitive tests was observed in both AD and MCI patients. Therefore, Se supplementation is a good alternative for patients with AD and MCI for improving Se levels and GPX activity. More detailed studies are required to further evaluate the effects of Se on the cognitive deficit and oxidative stress associated with AD and MCI.