A healthy pregnancy. Selenium is an essential trace element needed to support a healthy pregnancy. However, to date, studies of the mother’s selenium status and the child’s growth and development are scarce. Data from the Odense Child Cohort study in Denmark give researchers an opportunity to investigate the possible effects of the mother’s low selenium intake and low selenium status on the child’s neuro-development [Demircan 2023; Demircan 2024].
We humans need an adequate dietary supply of selenium. Like iron and iodine, our bodies need this essential trace element in sufficient amounts from food for normal physiological functioning.
The content of selenium in food varies according to the selenium content of the soil in any particular region [Stoffaneller & Morse 2015]. Unfortunately, in most areas of the Nordic and Baltic countries, the soil is poor in selenium. Accordingly, the local crops and fruits tend to have low selenium content. An exception is Finland, which enriches soil fertilizers with selenium. Import of wheat from regions with high contents of selenium in the soil has earlier been an important source of selenium in Norway [Alexander & Olsen 2023].
Heart disease. The evidence from clinical studies is increasing. Selenium deficiency is associated with an increased risk of heart trouble [Bomer 2020]. Selenium supplementation of elderly individuals who have low selenium status is associated with improved survival, improved heart function, and improved quality of life [Alehagen 2013].
Especially in northern Europe, clinical studies show the relationship between the need for selenium and the risk of heart disease. This makes sense because the dietary selenium intake in northern Europe is considerably lower than the dietary selenium intake in much of the United States. Consequently, the mean plasma selenium concentrations in Europe tend to be well below 80–90 mcg/L. In the USA, on the other hand, the mean plasma selenium concentrations are generally above 120 mcg/L [Alehagen 2022].
Good thyroid health depends, in part, upon the bio-synthesis of selenium-dependent seleno-enzymes called deiodinases. These seleno-enzymes are key factors in thyroid hormone metabolism and regulation. Thyroid hormones regulate the body’s metabolism (think: energy expenditure, body weight, body temperature, digestion, heart rate, etc.).
There are three types of deiodinase enzymes. In normal thyroid function, these deiodinases regulate the activation and inactivation of the T4 and T3 thyroid hormones, as needed. Abnormal thyroid hormone function is closely associated with diminished health-related quality of life and with increased risk of cardiovascular morbidity and mortality.
In many selenium-poor regions of the world, including much of Europe and the Middle East, low selenium intake and status may cause sub-optimal synthesis of deiodinase enzymes and, consequently, sub-optimal thyroid gland function. Selenium is an essential trace element found in soil, and humans must get it from their food.
Thyroid disease. What is the role of the micronutrient trace element selenium in thyroid disease? The thyroid gland is the organ in the body that contains the greatest amount of selenium per gram of tissue [Wang 2023]. Even in times of low dietary selenium intakes, the thyroid gland has high priority for the supply of selenium in the body [Schomburg 2020].
Dietary selenium intakes vary considerably from region to region in the world. There are large differences in the soil content of selenium and in the factors that influence the bioavailability of selenium to plants. As a consequence, individuals’ plasma/serum selenium status varies accordingly [Winther 2020]. Thus, widespread sub-optimal selenium status has been reported throughout Europe, the United Kingdom, and the Middle East [Stoffaneller & Morse 2015].
Metabolic syndrome – according to the American Heart Association, metabolic syndrome is a medical condition that can lead to heart disease, diabetes, stroke, and other health problems. The diagnosis of metabolic syndrome is met whenever a patient has three or more of the following five risk factors [What 2023]:
High blood pressure
In particular, metabolic syndrome puts the patient at increased risk of developing atherosclerosis, the condition in which the build-up of fatty deposits on the inner walls of arteries impedes blood flow and eventually restricts the flow of blood to the heart [What 2023].
Less systemic inflammation. Better immune function. Selenium is an essential trace element. Our cells cannot synthesize it. We must get it as a part of our diets. Adequate intakes are necessary for optimal immune system function.
Unfortunately, many of us live in regions with selenium-poor soil and selenium-poor crops and fruits. We do not get sufficient selenium from our food [Stoffaneller & Morse 2015]. Adequate selenium intake and status are vital. There are increased health risks associated with selenium deficiency.
Data from the BIOSTAT-CHF observational cohort study indicate that serum selenium concentrations under 70 mcg/L constitute a deficiency status. Serum selenium concentrations under 100 mcg/L constitute a sub-optimal status [Bomer 2020].
In the CATALYST study, researchers found that selenium supplements and placebo supplements improved the quality of life of patients with hypothyroidism to an equal extent. Accordingly, the researchers have now emphasized a need for more research into the effect of selenium supplementation on immune system function, on oxidative stress, and on low-grade inflammation in patients with thyroid diseases [Larsen 2024].
The CATALYST study was a multi-center randomized, double-blinded, placebo-controlled clinical trial conducted in Denmark. The study participants were patients aged 18 or more years with serum thyroid peroxidase antibody (TPOAb) levels equal to or greater than 100 IU/mL. 82% of the study participants were women [Larsen 2024].
The absorption of dietary and supplemental selenium has an important and positive influence on human longevity. Selenium researchers have called selenium a “longevity element.” The selenoenzymes and selenoproteins of which selenium is an essential component have antioxidant, anti-inflammatory, and anti-cancer activity in humans [Li 2024].
Maintaining selenium absorption and metabolism at an optimal physiological state seems to be one of the primary factors for good health and longevity of the elderly people. In particular, scientific studies have shown that selenium intake and status play an important role in the incidence and progression of some chronic diseases [Li 2024]:
Bama Yao Autonomous County is the only longevity township in China that is globally recognized as having a continuously growing longevity population. In 2020, Bama had 102 residents over 100 years old. The number had increased from the 2000 census (74 residents over 100 years of age) and the 2010 census (82 residents over 100 years of age). Bama has relatively stable genetic and geographic factors and a relatively stable dietary culture [Li 2024]. The proportion of centenarians is nearly six times greater than the international standard proportion [Zhang 2023].
Reduced risk of heart disease and reduced risk of some cancers. Increasing the daily intake of selenium among individuals with low selenium status may reduce the risk of cardiovascular disease and some cancers. The available data seem to show that most adults in the Nordic and Baltic countries, with the exception of adults in Finland, have low selenium intakes and low selenium status [Alexander & Olsen 2023].
Selenium is an essential trace element. The human body cannot synthesize it. It must come from the diet and supplements. Selenium is a vital component of selenoproteins that are critical to normal health and physiological functioning. This is the fundamental message from a 2023 selenium scoping review conducted for the Nordic Nutritional Recommendations 2023 [Alexander & Olsen 2023].
