Briefly, the data from the meta-analysis show that selenium decreases the risk of cancer at the highest daily intake levels of the included studies.
This outcome is consistent with the outcomes of a previous study showing a protective effect of selenium at high doses compared to low doses [Cai 2016]. A 2018 meta-analysis used different methods to assess selenium exposure and showed a null association between selenium at high doses compared to low doses [Vinceti 2018].
Adequate intakes of selenium, zinc, and vitamin D are essential to ensure resistance to viral infections, to promote strong immune function, and to reduce levels of inflammation. A team of Norwegian, Swedish, and Russian researchers recommends the initiation of adequate supplementation with these micronutrients in high-risk areas and in cases of suspected exposure to SARS-CoV-2 [Alexander 2020].
The team of researchers concluded from its review of the available medical literature that an adequate selenium intake/status can protect against the hyper-inflammation associated with corona viral infections.
Consequently, individuals at high risk who have a selenium status below 100 micrograms per liter should consider daily supplementation at a dose of 100–200 micrograms of selenium per day [Alexander 2020].
Selenium is an essential antioxidant trace element that is necessary for key activities in human metabolism [Djalalinia 2019]. Meta-analyses of randomized controlled trials of selenium supplementation reveal that selenium supplementation is a cost-effective and simple-to-use intervention that can play an important role in the prevention of heart disease risk factors [Hasani 2018; Hasani 2019; Mahdavi 2019; Tabrizi 2017].
These results from meta-analyses of randomized controlled trials reaffirm the outcomes in the Bomer multinational observational cohort study. In that study, heart failure patients with serum selenium concentrations below 70 micrograms per liter were more likely to have the following characteristics [Bomer 2019]:
Quote: “Pluck almost any cell from your body, and it will have a million or more selenium atoms in it, yet until recently nobody had any idea what they were there for. We now know that selenium makes two vital enzymes, deficiency in which has been linked to hypertension, arthritis, anaemia, some cancers, and, even, possibly reduced sperm counts. So, clearly, it is a good idea to get some selenium inside you (it is found particularly in nuts, whole meal bread, and fish), but at the same time, if you take too much, you can irremediably poison your liver. As with much of life, getting the balances right is a delicate business.” End Quote.
The above lines are quoted from Bill Bryson’s book The Body: A Guide for Occupants. ISBN-13: 978-0385539302. I can recommend the book highly. Bryson writes an English that is a pleasure to read, and the book is full of facts and relationships. You may already know him from his earlier book about science and technology, The Short History of Almost Everything.
In a 2015 review of the research literature, the selenium researchers Holger Steinbrenner and Helmut Sies from the Heinrich-Heine-University in Düsseldorf, Germany, give an overview of the effect of selenium status and supplementation in infectious diseases caused by viruses (e.g. HIV, influenza A virus, hepatitis C virus, polio virus, West Nile virus) and bacteria (e.g. M. tuberculosis, Helicobacter pylori) [Steinbrenner 2015].
In her 2012 review article in The Lancet, the selenium researcher Margaret P. Rayman points out that selenium intakes average 40 micrograms/day in Europe compared with 93 micrograms/day for women and 134 micrograms/day for men in the United States. Nutritional supplements can provide an additional 50–200 micrograms of selenium per day [Rayman 2012].
Approximately 50% of the problems in couples unable to conceive are caused by male infertility. Something like two percent of all men have sub-optimal sperm parameters [Kumar and Singh 2015]:
The role of selenium in male infertility has not been fully explained. However, some data show that selenium plays a role in the protection of sperm cells against oxidative stress [Buhling 2019].
In particular, the selenoproteins glutathione peroxidase GPx4 and selenoprotein P are essential to the process of sperm development and male fertility [Rayman 2012].
Selenium is a trace mineral that is essential for many important processes in the human body. Selenium is incorporated into enzymes that function as antioxidants. The balance between protective antioxidants and harmful free radicals in cells plays a decisive role in the prevention of disease [Rayman 2002].
China and Corona Virus will be forever linked in our minds. However, there is another important connection that we should be making: selenium status and its effect on COVID-19 virus in China.
Let me explain. Chinese and American and British researchers have published a letter in the American Journal of Clinical Nutrition in which they report evidence of a significant association between regional selenium status and the reported cure-rate of COVID-19 infected patients in China [Zhang 2020].
The researchers’ data show a statistically significant association between the reported cure-rates for COVID-19 virus infections and selenium status in China [Zhang 2020].
Beginning in mid-February 2020, the researchers collected data from the Baidu website, which they describe as a non-governmental website that provides daily updates of reports from the health commission of each province in China.
Selenium and selenoproteins have a role to play in the protection of humans against viral infections [Méplan & Hughes 2020].
Viruses and viral infections are scary enough in and of themselves. Witness the effects of the current corona virus pandemic COVID-19.
Even more scary are the effects of nutritional deficiencies such as selenium deficiency on the body’s ability to fight off a viral infection.
Low selenium status, defined variously as serum selenium status below 70 micrograms per liter or below 85 micrograms per liter, is associated with the following deleterious effects of viral contagion [Méplan & Hughes 2020]:
Re selenium deficiency: Bomer et al reported more severe signs and symptoms of heart failure and poorer exercise capacity and poorer quality of life in heart failure patients with serum selenium concentrations below 70 mcg/L. Rayman reported that serum and plasma levels below 85 mcg/L are associated with decreased survival in HIV-infected patients [Bomer 2019; Rayman 2012].
Fish should be an important part of our diets. Professor Nick Ralston at the University of North Dakota has drawn our attention to the webpages entitled Fish, Mercury, and Nutrition: The Net Effects. The URL is http://net-effects.und.edu/factsheets.aspx
On these webpages, Professor Ralston and his colleagues explain why the benefits of regularly eating fish, especially ocean fish, are often overlooked. Too many of us have cut back on our fish consumption because we have been worried about exposure to toxic mercury.
However, we have been receiving insufficient information about the relative benefits and risks of eating ocean fish. In fact, our avoiding fish meals may be having negative health consequences in some cases.
A 2017 summary of the research literature supports the idea that optimal selenium levels are needed for antioxidant protection against harmful free radicals in the thyroid gland and for the normal metabolism of thyroid hormones [Ventura 2017].
A 2018 research literature review shows that selenium supplementation can reduce anti-thyroperoxidase antibody levels and can improve thyroid ultrasound features. In addition, selenium supplementation is associated with improved symptoms and improved quality of life in patients with Graves orbitopathy [Santos 2018].
Note: Anti-thyroperoxidase antibody levels that are too high (>500 IU/ml) are associated with an increased risk of hypothyroidism in autoimmune thyroiditis, which is the most common form of thyroid disorder [Ehlers 2016].
