Selenium and good health. How much do we need? How do we get it? Generally speaking, our family and friends do not know just how important selenium is to good health. Our bodies cannot synthesize selenium. We are dependent upon food for an adequate daily intake of this essential trace element.
Selenium and selenoproteins are essential to human health [Rayman 2012]. However, selenium intakes from food vary considerably from region to region in the world, depending on how rich or poor the soil and the foodstuffs are.
For example, widespread suboptimal selenium status has been reported throughout Europe, the UK, and the Middle East [Stoffaneller & Morse 2015]. In contrast, the soil and the foodstuffs in much of the United States and Canada have a much higher selenium content than is the case in Europe. Serum selenium levels of US citizens are generally above 120 mcg/L. In many European countries, the corresponding serum selenium levels are 90 mcg/L on average [Alehagen 2016].
Dietary selenium is incorporated into the amino acid selenocysteine, which becomes an integral component of 25 selenoproteins. The best known selenoproteins are the glutathione peroxidases, thioredoxin reductases, and
iodothyronine deiodinases [Schomburg 2019].
The Swedish cardiologist Dr. Urban Alehagen has written persuasively that there exists a special inter-relationship between selenium and Coenzyme Q10 in the prevention of cardiovascular diseases.
Briefly, Prof. Alehagen, together with the Norwegian professor Jan Aaseth, makes the point that low selenium intakes and status could restrict the cells’ ability to get optimal concentrations of Coenzyme Q10 and that the cells need adequate of Coenzyme Q10 to permit optimal function of selenium [Alehagen & Aaseth 2015a].
The clinical outcomes of the KiSel-10 intervention study in which community living Swedish citizens, average age 78 years, were administered selenium and Coenzyme Q10 daily for four years show that combined selenium and Coenzyme Q10 supplementation, compared to placebo treatment, can be beneficial in populations that have low selenium status:
The proper daily dosage of selenium for normal people? Normal people? How many of us are approximately normal? 68 percent of us, perhaps? Yes, we humans are more the same in many ways than we are different. However, there is considerable biochemical variation amongst us humans. So, it is difficult to say who is average and normal and then suggest an ideal daily dosage of selenium.
What do the numbers from selenium studies say?
Let’s look at the numbers from published research and see what sense we can make of them. Remember: we humans need adequate plasma selenium concentrations for optimal antioxidant and anti-viral and anti-carcinogenic protection [Schrauzer 2009].
Putative beneficial range for plasma selenium status
Hurst and Fairweather-Tait et al, researchers based at Norwich Medical School, University of East Anglia, in the United Kingdom have suggested that the “putative beneficial range” lies between 120 and 150 nanograms of selenium per milliliter of plasma [Hurst 2010].
How much selenium from food and supplements do we need on a daily basis? Which bio-markers of optimal selenium status seem to be most useful to answer this question? Dr. Rachel Hurst and Dr. Susan J. Fairweather-Tait, Norwich Medical School, United Kingdom, and their colleagues set out to find answers. The design of their study is very interesting.
They enrolled 119 healthy British men and women aged 50 – 64 years in a randomized, double-blind, placebo-controlled study that lasted 12 weeks [Hurst]. They excluded the following persons from the study:
The 119 study participants received either placebo or one of the following treatments:
Measurements of selenium
Remember: Selenium is a trace element. We measure its intake in micrograms per day, not milligrams. We measure selenium status in plasma and serum in terms of micrograms per liter (or equivalently, in nanograms per milliliter). Selenium in toenails or hair, then, we measure in micrograms per gram.
