About selenium status in the elderly, not much is known. Therefore, data from the recently published Newcastle 85+ study are of interest. The researchers assessed the selenium status of 85-year-olds living in the Northeast of England. They measured serum selenium concentrations, selenoprotein P (SELENOP) concentrations, and glutathione peroxidase 3 (GPx3) activity levels [Perri 2024 Mar].
In addition, the researchers studied the relationships between each of those three biomarkers of selenium status. They observed that there was a linear relationship between serum selenium and serum SELENOP concentrations. On the other hand, they found nonlinear relationships between serum selenium levels and GPx3 activity and between serum SELENOP levels and GPx3 activity [Perri 2024 Mar].
Note: SELENOP levels in the blood matter because SELENOP is the primary selenium transport protein distributing selenium to the tissues and organs.
Note: GPx3 activity matters because GPx3 reduces oxidative stress and protects against the development of chronic diseases.
Selenium Status in Elderly English Men and Women
Altogether, the researchers investigated the selenium status of 757 participants (60% women, 40% men) in the Newcastle 85+ Study. They compared the biomarker concentrations with pre-selected cut-off points as follows [Perri 2024 Mar]:
- Sub-optimal levels = 70 mcg/L serum selenium and 4.5 mg/L serum SELENOP
- Deficiency levels = 45 mcg/L serum selenium and 2.6 mg/L serum SELENOP
Note: Serum selenium is measured in mcg/L while serum SELENOP is measured in mg/L. This is because the SELENOP compound is much larger than the selenium element.
Sub-optimal and Deficient Selenium Status in the Elderly
The Newcastle 85+ investigations yielded the following data [Perri 2024 Mar]:
- Median serum selenium: 53.6 mcg/L
- Median serum SELENOP: 2.9 mg/L
- Median GPx3 activity: 142.1 U/L
The study showed that 82% of the elderly study participants had sub-optimal serum selenium levels, i.e., below 70 mcg/L. Nearly one-third (31%) had deficient serum selenium levels, i.e., below 45 mcg/L.
Similarly, 83 % of the participants had sub-optimal serum SELENOP levels, i.e., below 4.5 mg/L. Fully 40 %of participants had deficient serum SELENOP levels, i.e., below 2.6 mg/L.
Determinants of Low Selenium Status in the Elderly
The researchers found that protein intake has a significant influence on selenium status. The investigations revealed that BMI, physical activity, and sex also influenced GPx3 activity [Perri 2024 Mar].
Selenium Supplementation of Elderly Citizens
In southeastern Sweden between 2003 and 2010, Prof. Urban Alehagen et al enrolled 443 community-dwelling elderly individuals in the KiSel-10 Study, a randomized double-blind placebo-controlled trial. Over a 48-month period, the elderly study participants received either 200 mcg/day of selenium and 200 mg/day of Coenzyme Q10 or matching placebos. The average age of the study participants was 77 years. The average serum selenium level at the start of the study was quite low: 67.1 mcg/L [Alexander 2024].
Sub-analysis of data from KiSel-10 Study showed that serum GPx3 activity was dependent upon selenium status and upon renal function at serum selenium concentrations below 100 mcg/L. Selenium supplementation induced an increase in GPx3 that was associated with improvement in renal function. Low GPx3 activity was associated with an increased relative risk of cardiovascular disease mortality and all-cause mortality [Alexander 2024].
Further sub-analysis of KiSel-10 Study data showed that an inverse relationship existed the level of SELENOP at the start of the study and biomarkers for inflammation. Lower SELENOP meant more inflammation. At follow-up, the researchers saw shorter telomere lengths in study participants who had had low levels of SELENOP at their inclusion in the study. By contrast, higher levels of SELENOP were associated with better quality of life and decreased mortality [Alehagen 2024].
Daily selenium supplementation induced higher levels of circulating SELENOP. The KiSel-10 study participants achieved SELENOP saturation at a serum selenium level of 146 mcg/L. The saturation level for GPx3 was reached at 99 mcg/L [Alehagen 2024].
The KiSel-10 Study researchers concluded that there were significant associations between SELENOP concentration and inflammation, telomere length, quality of life, and mortality. The selenium supplementation improved SELENOP expression, thereby facilitating systemic selenium bioavailability.
Conclusions: Selenium Status and the Elderly
The findings in the Newcastle 85+ study show that most participants had sub-optimal selenium status.
The elderly study participants’ serum selenium levels were too low to saturate circulating SELENOP.
Thus, higher dietary intakes of selenium and/or selenium supplementation are necessary for elderly individuals to achieve satisfactory SELENOP and GPx3 activity.
The KiSel-10 study outcomes show multiple health benefits of selenium supplementation in elderly community living citizens low in selenium.
Sources
Alehagen U et al. Selenoprotein P increases upon selenium and coenzyme Q10 supplementation and is associated with telomere length, quality of life and reduced inflammation and mortality. Free Radic Biol Med. 2024 Sep;222:403-413.
Alexander J et al. Circulating glutathione peroxidase-3 in elderly-association with renal function, cardiovascular mortality, and impact of selenium and Coenzyme Q10 supplementation. Antioxidants (Basel). 2024 Dec 19;13(12):1566.
Perri G et al. Selenium status and its determinants in very old adults: insights from the Newcastle 85+ Study. Br J Nutr. 2024 Mar 14;131(5):901-910.
The information presented in this review article is not intended as medical advice. It should not be used as such.