When it comes to COVID-19 and other seasonal virus infections most of the focus is concentrated on vitamin D deficiency. According to a Belgian study, however, lack of selenium and zinc additionally increases the risk of infections, complications, and death, especially among patients who already suffer from chronic diseases. The scientists conclude that supplementation with selenium and zinc may help improve treatments. Selenium and zinc deficiencies are rather common and that is a problem for public health. Even with a healthy diet, it is practically impossible for Europeans to get enough selenium because of the nutrient-depleted farmland. There are also many people with zinc deficiencies due to unhealthy diets, ageing, chronic diseases, and other contributing factors. We must be much more focused on getting enough selenium and zinc, not least for the sake of preventing virus infections and other problems.
Selenium and zinc are trace elements, each of which is important for a well-functioning immune defense, cell signaling, and virus defense. Both nutrients are also vital constituents of some important antioxidants (GPX and SOD) that protect the cells against oxidative stress caused by free radicals.
We humans produce free radicals as a natural byproduct of energy metabolism and other metabolic processes, but the free radicals must be kept on a tight leash. The free radical burden is increased tremendously by factors such as stress, ageing, infections, overweight, poisoning, and smoking. Oxidative stress is a phenomenon that occurs when there is an imbalance between harmful free radicals and protective antioxidants and where free radicals can attack healthy cells and tissues. This sets the stage for a host of different chronic diseases. It also turns out that complicated COVID-19 infections involve oxidative stress.
Blood levels of selenium and zinc are linked to COVID-19 severity
Scientists at two Belgian hospitals in the Ghent area have looked closer at whether blood levels of selenium and zinc in hospitalized COVID-19 patients were linked to disease severity and mortality risk. A total of 138 patients with or without other chronic diseases participated in the study. The scientists measured blood levels of selenium, zinc, iron, and copper.
With regard to selenium, they specifically measured selenoprotein P because this particular selenoprotein is used to gauge the body’s selenium status. Via various enzyme processes, selenoprotein P is converted into many other selenoproteins, including the powerful GPX antioxidants. That way, the different selenoproteins are of vital importance for the body’s immune defense, metabolism, inflammatory response, and defense against oxidative stress.
The COVID-19 patients were aged 18-100 years. Fifty-two percent of them were older than 65.
At one hospital, the researchers concurrently collected data about any other chronic diseases that the patients had such as type 2 diabetes, overweight, and cancer.
They found that having insufficient levels of selenium and/or zinc was significantly related to life-threatening the course of COVID-19 infections and it also increased mortality.
This was especially true for older people, overweight people, and patients suffering from cancer, type 2 diabetes, and other chronic illnesses. In contrast, cancer patients with higher blood selenium levels had better odds of surviving. The scientists also noted that the patients had sufficient levels of copper and that men had higher levels of iron than women did.
Optimization of selenium and zinc levels for better treatment and prevention
According to the scientists behind the Belgian study, blood levels of selenoprotein P and zinc are useful for predicting whether a COVID-19 infection turns out to be mild or is likely to become life-threatening. Optimization of selenium and zinc levels in the blood by means of supplementation may be used to improve treatments for COVID-19 infections and similar virus infections.
Selenium and zinc deficiencies are widespread so it is relevant to have more focus on these trace elements in the actual prevention of COVID-19 and other infections where low levels of the nutrients are observed.
The new Belgian study is published in Nutrients and supports several earlier studies of selenium’s and zinc’s important role in helping the immune defense fight COVID-19 and other respiratory infections.
Selenium supplementation and reasons why people lack selenium
The natural selenium content in soil can vary by several hundred percent from one part of the world to another. Intensified farming methods cause additional nutrient depletion and this affects the entire food chain. According to WHO, more than 40 countries lack selenium and the lowest soil content has been observed in Europe, Africa, China, India, and South America.
Our diets have changed. We eat less fish and offal and that contributes to the widespread lack of selenium. The reference intake (RI) level in countries like Denmark is 55 micrograms per day but according to research, this is not enough to properly saturate selenoprotein P, the selenoprotein that is used as a marker of the blood’s selenium status. It takes around 100 micrograms of selenium daily for effective saturation of this selenoprotein.
Selenium yeast with a variety of different natural selenium types is best for supplementation as it emulates the natural selenium spectrum in a balanced diet with many different selenium sources. The European Food Safety Authority (EFSA) has set 300 micrograms of selenium per day as the safe upper intake level.
Make sure to eat a balanced diet in any case because the different selenoproteins also need vitamin D to function properly.
Zinc supplementation and reasons why people lack zinc
Zinc is mainly found in oysters, meat, eggs, dairy products, nuts, seeds, kernels, and beans. Zinc from animal food sources is absorbed better than zinc from plant sources.
Zinc deficiency is typically a result of unhealthy diets and lack of animal protein. Other factors that contribute are excessive intake of iron, calcium, and alcohol. Ageing, celiac disease, diabetes, various types of medicine, and birth control pills may also increase the need for zinc.
The daily reference intake level is 10 mg. Many zinc supplements contain inorganic zinc types such as zinc sulphate and zinc oxide that have poor absorbability. On the other hand, organic zinc sources like zinc gluconate and zinc acetate are easy for the body to absorb. Always look at the label before buying supplements.
EFSA has established a 25 mg per day safe upper intake level for zinc (for adults).
Gijs Du Laing et al. Course and Survival of COVID-19 Patients with Comorbidities in relation to the Trace Element Status at Hospital Admission. Nutrients September 2021
Lutz Schomburg. Selenium Deficiency Due to Diet, Pregnancy, Severe Illness or COVID-19 – A Preventable Trigger for Autoimmune Disease. International Journal of Molecular Sciences. 2021
Qiyuan Liu et al. Selenium (Se) plays a key role in the biological effects of some viruses: Implications for COVID-19. Environmental Research. 2021
Outzen M, et al. The effect on selenium concentrations of a randomized intervention with fish and mussels in a population with relatively low habitual dietary selenium intake. Nutrients. 2015;7(1):608-24.
Ozlem Equils et al. Proposed mechanism for anosmia during COVID-19: The role of local zinc distribution. Oat. 2020
Nikki Hancocks. Diet and supplements: Swiss panel publishes COVID-19 recommendations. 2020
Luke Maxfield, Jonathan S. Crane. Zinc Deficiency. NCBI March 18, 2019
University of Helsinki. Zink acetate lozenges may increase the recovery rate from the common cold by three-fold. ScienceDaily May 11, 2017
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