Selenium and Longevity and Ageing

There are notable regional variations in the blood selenium concentrations in senior citizens. The differences range from 66 micrograms per liter in Brazil and Turkey to 126 micrograms per liter in Japan.  Below 85 micrograms per liter is poor selenium status.  The desirable range is thought to be 125-135 micrograms per liter.

We want, all of us, to stay as young and healthy as possible as late in life as possible.  Ageing is inevitable.  How can we delay the onset of ageing’s bio-chemical and physiological consequences?

  • Physical exercise?
  • Caloric restriction?
  • Ingestion of micronutrients?

Selenium Status and the Health of Senior Citizens

The authors of a 2019 review article have found that, overall, there is an inverse correlation between age and blood selenium levels. Higher age is associated with lower blood selenium concentrations [Robberecht 2019].

Inadequate dietary intakes of selenium and poor selenium status (< 85 micrograms per liter in blood) may increase the risk of following harmful health outcomes [Robberecht]:

  • oxidative stress (= imbalance of harmful free radicals and protective antioxidants)
  • destruction of nerve cells (neurons)
  • dementia

Selenium Status and Biological and Social Factors

A variety of factors must be taken into consideration when we investigate the relationship between ageing and selenium intake and status.  There are, first of all, considerable regional variations in the availability of selenium in the soil and in foodstuffs [Stoffaneller & Morse].

Then, secondly, the following biological and social factors influence selenium intake and make the factor of age difficult to isolate as a possible cause of lower blood selenium status:

  • education level
  • ethnicity
  • fish consumption
  • gender
  • health status
  • lifestyle
  • occupational status
  • smoking
  • social class
  • supplementation with selenium

These and other factors need to be controlled for when assessing the relationship between selenium status and age.

Interestingly, selenium status is positively associated with alcohol consumption.  Researchers speculate that alcohol either increases selenium bio-availability, or it influences the bio-transformation of selenium in the liver [Robberecht].

Selenium Status and Cancer

A 2016 review of 69 observational studies has shown an inverse relationship between selenium exposure and the risk of various cancers [Cai 2016]:

  • breast cancer
  • esophageal cancer
  • gastric cancer
  • lung cancer
  • prostate cancer

The same inverse relationship did not apply to the following forms of cancer [Cai 2016]:

  • bladder cancer
  • colorectal cancer
  • skin cancer

Current thinking tends towards the U-Shaped Curve relationship between selenium status and the risk of disease [Rayman 2019; Rayman 2012, fig. 3].

In this conception, too low selenium status and too high selenium status are both associated with increased risk of disease. Keeping one’s selenium status in the bottom of the U is thought to be better than having a selenium status too low or too high.  The bottom of the U for serum/plasma selenium status seems to be in the range from 125 to 135 micrograms per Liter [Rayman 2019; Rayman 2012, fig. 3].

The lower level of serum/plasma selenium status — the level at which the risk of overall mortality and cancer mortality seems to increase — is a selenium status of less than 87 micrograms per Liter.  This is the level seen in the Epidemiology of Vascular Ageing (EVA) study of 1389 community dwelling French senior citizens [Akbaraly 2010].

The upper level of serum/plasma selenium status at which the increased risk of disease may become significant is a selenium status greater than 150 micrograms per Liter [Rayman 2012, fig. 3].

Note: Commercial laboratories can carry out the assay of blood selenium status.

Selenium Status and Cardiovascular Diseases

Results from the Epidemiology of Vascular Ageing (EVA) study in France showed that obesity and adverse cardiovascular events were major outcomes associated with an age-related decline in plasma selenium concentrations [Arnaud 2007].

In the KiSel-10 Study, healthy community dwelling Swedish senior citizens (aged 70 – 88 years at baseline) were administered either a selenized yeast preparation (200 micrograms/day) together with a Coenzyme Q10 preparation (2 times 100 milligrams/day) or matching placebos for four years.  The senior citizens on the selenium and CoQ10 regimen showed significantly reduced
cardiovascular mortality, improved heart function, and better health-related quality of life compared to placebo [Alehagen 2013].

The protective action of the combined high-selenium yeast and Coenzyme Q10 supplementation extended beyond the intervention period and persisted during a follow-up of 12 years [Alehagen 2018].  The researchers suggested the following biological mechanisms as possible explanations for the heart health benefits of the supplementation:

  • reduced oxidative stress
  • reduced inflammation
  • reduced fibrosis

Selenium Status and Neurological Disorders

The scientific evidence seems to show that decreased expression of several selenoproteins is associated with the development of age-related diseases including Parkinson’s disease and Alzheimer’s disease [Robberecht 2019].

Most studies show that patients diagnosed with Alzheimer’s disease or related dementias generally have low selenium status or selenium status no higher than the selenium status of healthy controls. Randomized controlled trials of selenium supplementation are needed to test the preventive and/or therapeutic effects of selenium [Robberecht 2019; Aaseth 2016].

The antioxidant role of selenium in delaying the onset of Parkinson’s disease is not clearly established.  The results from completed studies are contradictory. Again, randomized controlled trials of selenium supplementation are needed [Robberecht 2019].

Supplementation with compounds containing selenium have shown potential for stimulating cognitive improvement [Aaseth 2016].

Summary: Selenium and Longevity and Ageing

Researchers have concluded that selenium status plays a role in health maintenance during the ageing process; however, the exact mechanisms are not known with certainty [Robberecht 2019].  To the extent that lower selenium intake and lower selenium bio-availability affect the overall health of senior citizens, there may be an explanation in the following biological effects of selenium [Alehagen 2018]:

  • improved heart function
  • reduced low-grade systemic inflammation
  • reduced oxidative stress
  • reduced fibrosis

Sources

Aaseth, J., Alexander, J, Bjørklund, G, Hestad, K, Dusek, P, Roos, P & Alehagen, U. (2016).
Treatment strategies in Alzheimer’s disease: a review with focus on selenium supplementation.
Biometals; 29(5): 827–839.

Akbaraly TN, Arnaud J & Rayman MP. (2010). Plasma selenium and risk of dysglycemia in an elderly French population: results from the prospective Epidemiology of Vascular Ageing Study. Nutr Metab; 7: 21.

Alehagen, U., Johansson, P., Björnstedt, M., Rosén, A., & Dahlström, U. (2013). Cardiovascular mortality and N-terminal-proBNP reduced after combined selenium and Coenzyme Q10 supplementation: a 5-year prospective randomized double-blind placebo-controlled trial among elderly Swedish citizens. International Journal of Cardiology, 167(5), 1860-1866.

Alehagen, U., Aaseth, J., Alexander, J., & Johansson, P. (2018). 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, 13(4), e0193120.

Arnaud J, Akbaraly TN, Hininger I, Roussel AM & Berr C. (2007). Factors associated with longitudinal plasma selenium decline in the elderly: the EVA study. J Nutr Biochem 2007; 18(7): 482-7.

Cai X, Wang C, Yu W, Fan W, Wang S, Shen N, & Wang F. (2016). Selenium exposure and cancer risk: an updated meta-analysis and meta-regression. Scientific Reports, 619213.

Rayman, MP. (2019). Selenium intake, status, and health: a complex relationship.  Hormones, doi: 10.1007/s42000-019-00125-5. [Epub ahead of print].

Rayman MP.  (2012). Selenium and human health.  Lancet, 379: 1256-68.

Robberecht H, De Bruyne T, Davious-Charvet E, Mackrill J & Hermans N. (2019).  Selenium status in elderly people: Longevity and age-related diseases.  Current Pharmaceutical Design, 25; 1694-1706.

The information contained in this review article is not intended as medical advice and should not be used as such.

16 November 2019

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