What makes selenium and Coenzyme Q10 a good heart health combination supplement? Here, of course, we are talking about supplementation of individuals who have low selenium and CoQ10 blood levels.
Selenium and Selenoproteins and Health
A 2025 review summarizes the biological activities and health functions of important selenoproteins. The selenoproteins play a role in antioxidant and anti-inflammation defense, cancer prevention, cardiovascular health, fertility, immune system regulation, and defense against viral infections including COVID-19 [Shahidin 2025].
Selenium deficiency leads to insufficient synthesis of the selenoproteins. Generally, selenium researchers regard serum selenium concentrations under 70 mcg/L as deficiency levels. Serum selenium concentrations below 45 mcg/L indicate severe selenium deficiency [Winther 2020; Schomburg 2021].
The point is that selenium deficiency and insufficient selenoprotein synthesis can impair antioxidant and anti-inflammation defense, weaken immune function, and disturb thyroid hormone metabolism. Likewise, selenium deficiency can contribute to neurological and endocrine disorders. Selenium deficiency can have a detrimental effect on cardiovascular health. Selenium deficiency is associated with increased incidence of Keshan disease and Kashin–Beck disease [Shahidin 2025].
Selenoprotein P and Heart Health
Low serum concentrations of selenoprotein P (SELENOP) are an indication of increased heart health risks. Low serum SELENOP is strongly associated with the following risks:
- increased risk of a first cardiovascular event
- increased risk of cardiovascular mortality
- increased risk of all-cause mortality
This is the conclusion from a relatively large study of adults in Sweden. The study participants had no history of cardiovascular disease at the beginning of the study [Schomburg 2019].
There were 3,531 non-smokers and 835 smokers enrolled in the study in Sweden. At the end of the study, the study participants at increased risk of cardiovascular disease had a mean serum SELENOP level below 4.3 mg/L SELENOP. This serum concentration of SELENOP corresponds to serum selenium concentrations of less than 70 mcg/L [Schomburg 2019].
Selenium and Sports Nutrition
In sports, in exercise, and in training, selenium is a frequently overlooked micronutrient. Selenium’s fundamental importance to human health is not well known. Researchers are beginning to conduct studies of selenium in sports nutrition and skeletal muscle health. Their studies show that selenium and selenoproteins play an important role in maintaining skeletal muscle function. Studies show that selenoproteins delay exercise fatigue and muscle aging [Wang 2025].
Optimal selenium intake from food and from supplements (when necessary) can mitigate aging-related muscle decline. Selenium can help to prevent exercise-associated musculoskeletal injuries. There is a need for more clinical studies of the effect of selenium supplementation on skeletal muscle health in selenium-poor regions [Wang 2025].
Selenium Essential for Human Health
Selenium is a trace element that is essential for good human health. Essential means that selenium is a micronutrient that the body must have but cannot synthesize for itself. Its supply must come from food and, if necessary, from supplements. What the body does synthesize when it has an adequate supply of the element selenium is first the amino acid selenocysteine and then selenoproteins into which the selenocysteine molecules are incorporated [Bai 2024].
Accordingly, selenium is an indispensable component of selenoprotein P and numerous other selenoproteins. Among these selenoproteins are several vital selenoenzymes, e.g., the glutathione peroxidases (GPxs), the thioredoxin reductases (TrxRs), and the iodothyronine deiodinases (DIOs). Through the activity of the selenoproteins, selenium has many biological functions, i.e., antioxidant activity, anti-inflammatory effects, enhanced immune system function, enhanced reproductive capacity, protection of the cardiovascular system, and regulation of thyroid function. In figure 6 of their paper, Bai et al list the best documented selenoproteins and their known functions [Bai 2024].
Selenium for Adjuvant Cancer Treatment
Cancer treatment. What do we know at the present time about the effectiveness of selenium as an adjuvant treatment in cancer patients?
In a 2024 systematic review, researchers have evaluated the existing evidence from data from 12 studies with 2,483 adult patients undergoing cancer treatment. The types of cancer included non-Hodgkin lymphoma, head and neck cancer, thyroid cancer, acute myeloid or acute lymphocytic leukemia, stage I non-small lung cancer, breast cancer, cervical and endometrial cancer, prostate cancer, and non-invasive urothelial carcinoma [Krannich 2024].
The researchers’ analysis of the available data does not give a clear picture of the efficacy of selenium administration to adult cancer patients. One reason is that several of the evaluated studies did not report measurements of the patients’ serum selenium levels at the beginning or the end of the study. The studies that did report serum selenium levels used different ways to measure selenium levels. Moreover, the duration of the selenium administration and the type of selenium preparation and the dosage varied from study to study [Krannich 2024].
Selenium and Healthy Aging
Greater hand grip strength is associated with greater probability of healthier aging and living longer. The explanation for this positive association may be, in part, the action of proteins in the blood circulation. In particular, proteins that affect inflammation and immunity responses may be at work. One of the leading proteins positively associated with the chance for a longer and healthier life is Selenoprotein P (SELENOP) [Liu 2025].
SELENOP is known to be the primary transporter of selenium in the blood. It carries selenium in the form of selenocysteine from the liver to the body’s tissues and organs. In times of scarcity of selenium, SELENOP distributes the selenium in a hierarchical priority manner. The brain and the testes and the thyroid gland are high-priority recipients of selenium [Schomburg 2022].
Selenium and the Risk of Heart Disease
The association between the risk of heart disease and dietary intakes of selenium remains unclear. Here we report the results of some of the recent observational studies on this topic.
Risk of Cardiovascular Disease
Selenium and the Elderly
About selenium status in the elderly, not much is known. Therefore, data from the recently published Newcastle 85+ study are of interest. The researchers assessed the selenium status of 85-year-olds living in the Northeast of England. They measured serum selenium concentrations, selenoprotein P (SELENOP) concentrations, and glutathione peroxidase 3 (GPx3) activity levels [Perri 2024 Mar].
In addition, the researchers studied the relationships between each of those three biomarkers of selenium status. They observed that there was a linear relationship between serum selenium and serum SELENOP concentrations. On the other hand, they found nonlinear relationships between serum selenium levels and GPx3 activity and between serum SELENOP levels and GPx3 activity [Perri 2024 Mar].
Selenium and Good Health
Selenium is an essential trace element for good health. If we are to survive and reproduce, we need some selenium in our diets. Not much but some. The reason is that our bodies cannot synthesize the selenium we need. Many of us live in a region of the world with low selenium content in the soil and in the regionally grown food products. Accordingly, it is difficult for us to get enough selenium in our diet.
For example, Alexander et al point out that mainland Europe and Scandinavia are regions with a low intake of selenium. North America, by contrast, is a region with much higher selenium intake. There is considerable variation in the selenium content of locally cultivated food products around the world. Consequently, daily selenium intake varies considerably. Depending upon the region we live in, we may be at risk of sub-optimal selenium intakes or selenium deficiency [Alexander 2024].