The micronutrient selenium has antioxidant and anti-aging properties. Specifically, numerous selenoproteins, in which selenium is an essential component, have antioxidant, anti-inflammatory, and immunostimulating effects [Bjørklund 2022].
Why is this important?
The aging process is characterized by the following inevitable physiological developments [Alehagen 2021]:
- increasing imbalance between antioxidant protection and oxidative damage caused by harmful free radicals
- chronic systemic inflammation
- decline in mitochondrial renewal and function
- stem cell exhaustion
Selenium and selenoproteins and antioxidant protection
One theory of biological aging is that oxidative stress and chronic low-grade inflammation play an important role in aging-related physical and mental decline. Harmful reactive oxygen species – popularly known as free radicals – overwhelm the ability of the available antioxidants to neutralize them. The harmful free radicals cause oxidative damage to the cells and to the DNA, lipids, and proteins in the cells [Bjørklund 2022].
Acting as scavengers of harmful free radicals, antioxidants are indispensable to the prevention and treatment of age-related disorders. Through the action of its selenoproteins, the trace element selenium possesses valuable antioxidant properties. In particular, the selenium-dependent glutathione peroxidases and the thioredoxin reductases directly suppress oxidative stress [Bjørklund 2022].
Selenium and selenoproteins and chronic inflammation
Selenium plays a significant role in regulating different inflammatory processes in the body. Insufficient selenium levels in the cells are associated with manifestations of inflammation in various tissues and organs. Optimal selenium status can mitigate inflammatory processes and reduce complications [Bjørklund 2022].
Selenium and selenoproteins and immune function
Selenium deficiency has a negative effect on the response of the innate and adaptive immune systems. In general, optimal selenium levels stimulate increasing antibody production in the immune system. Overall, selenium’s impact on the immune system is achieved through the modulation of the
activity of neutrophils, macrophages, natural killer cells, and T and B-lymphocytes [Bjørklund 2022]
Deficient, sub-optimal, and optimal selenium concentrations
Optimal plasma/serum selenium concentrations are around 125 mcg/L [Winther 2020, Fig. 3].
Sub-optimal plasma/serum selenium concentrations are between 70 and 100 mcg/L [Al-Mubarak 2021].
Deficient plasma/serum selenium concentrations are below 70 mcg/L [Al-Mubarak 2021].
The estimated range of dietary selenium consumption in European countries is between 30–50 mcg/day. Typical supplemental doses are 50 and 100 mcg/day. Note that daily selenium intakes above 400 mcg/day over time can result in harmful effects [Bjørklund 2022].
Studies of selenium and healthy aging
France
In the 9-year longitudinal EVA study in France involving 1389 community-living participants aged 59–71 years, researchers investigated the relationship between plasma selenium concentrations and longevity. They observed that sub-optimal plasma selenium levels adversely affected the maintenance of optimal health in an aging population. Their comparisons of survival rates among quartiles of plasma selenium levels showed that mortality increased in subgroups with low plasma selenium concentrations at baseline [Akbaraly 2005].
Italy
Studies of nonagenarians and centenarians in Italy have shown that very few long-time survivors have sub-optimal blood selenium concentrations.
This is a possible explanation for the longevity seen in Italian scientists’ nonagenarian–centenarian studies.
A study of individuals living in Sardinia, an Italian island with a higher prevalence of centenarians than in other European countries, showed significant depletion of selenium concentration in the plasma of
nonagenarians (88.9 mcg/L) and centenarians (81.9 mcg/L) compared to 60-year-old controls. However, it is noteworthy that the individuals surviving into their nineties and one hundreds had managed to stay well above the selenium deficiency level of < 70 mcg/L [Bjørklund 2022].
Sardinia is one of five blue zones in the world – regions in the world where people are known to live longer than average. The other blue zones are Okinawa, Japan; Nicoya, Costa Rica; Icaria, Greece; and Loma Linda, California, United States.
If we accept that genetics plays a role of no more than 30% in survival to high old age, then nutrition (including selenium intake) and exercise and lifestyle (including stress) must play a role. It is well known that selenium intakes vary considerably from region to region in the world in accordance with the selenium content of the soil and the foodstuffs [Stoffaneller & Morse 2015].
Sweden
After 12 years (four years of daily supplementation and eight years of follow-up), researchers could see significantly reduced cardiovascular mortality in the elderly community living citizens supplemented with a combination of selenium and Coenzyme Q10. Selenium supplementation at a dose of 200 mcg/day raised the serum selenium concentrations of the study participants, average age 78 years, from a baseline mean value of 67.1 mcg/L to a mean value of 210.3 mcg/L [Alehagen 2018; Alehagen 2020 ].
Spain
A cohort study of 227 older adults residing in 14 nursing homes in Asturias has revealed that study participants in the upper tertile of serum selenium concentration had more than twice as much probability of reporting good health status, good chewing ability, and doing more than 60 minutes of exercise per day.
Conclusion: Selenium and anti-aging and a long and healthy life
Deficient (< 70 mcg/L) and sub-optimal (70-100 mcg/L) selenium
status may accelerate the aging process, increase vulnerability
to various disorders, and reduce life expectancy [Bjørklund 2022].
One estimate is that selenium deficiency affects one billion people world-wide and has adverse health effects [Bjørklund 2022].
Damage to cells, lipids, proteins, and DNA caused by an imbalance between protective antioxidants and harmful reactive oxygen species are a characteristic of aging. Selenium in the form of selenoproteins has a critical role in anti-aging processes [Bjørklund 2022].
Selenium deficiency is a factor in some disorders caused by pathogenic bacteria and viruses. Selenium supplementation can stimulate
the immune system against infectious diseases [Bjørklund 2022].
Health effects of selenium are dose-dependent. The margin between essential selenium intakes and intakes associated with toxicity is narrow. Basically, the daily selenium intake should maintain a serum selenium concentration of about 125 mcg/L [Winter 2020].
Sources
Akbaraly NT, Arnaud J, Hininger-Favier I, Gourlet V, Roussel AM, Berr C. Selenium and mortality in the elderly: results from the EVA study. Clin Chem. 2005 Nov;51(11):2117-23.
Al-Mubarak AA, van der Meer P, Bomer N. Selenium, Selenoproteins, and Heart Failure: Current Knowledge and Future Perspective. Curr Heart Fail Rep. 2021 Jun;18(3):122-131.
Alehagen U.; Opstad, T.B.; Alexander, J.; Larsson, A.; Aaseth, J. Impact of selenium on biomarkers and clinical aspects related to ageing: a review. Biomolecules 2021, 11, 1478.
Alehagen U, Aaseth J, Alexander J, Johansson P. Still reduced cardiovascular mortality 12 years after supplementation with selenium and coenzyme Q10 for four years: A validation of previous 10-year follow-up results of a prospective randomized double-blind placebo-controlled trial in elderly. PLoS One. 2018 Apr 11;13(4):e0193120.
Alehagen U, Aaseth J, Alexander J, Johansson P. (2020). Supplemental selenium and coenzyme Q10 reduce glycation along with cardiovascular mortality in an elderly population with low selenium status. Journal of Trace Elements in Medicine and Biology, 61: 126541.
Bjørklund G, Shanaida M, Lysiuk R, Antonyak H, Klishch I, Shanaida V, Peana M. Selenium: An antioxidant with a critical role in anti-aging. Molecules. 2022;27:6613.
Stoffaneller R, Morse NL. A review of dietary selenium intake and selenium status in Europe and the Middle East. Nutrients. 2015 Feb 27;7(3):1494-537.
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.
15 February 2023