Selenium Delays Cognitive Decline

In the Swedish KiSel-10 clinical trial, the study participants had an average age of 78 years at the start of the study [Alehagen 2013]. Their serum selenium concentration at baseline was at a deficiency level (mean: 67.1 mcg/L).

Woman meditating
Diet, exercise, and meditation are all important to good brain health. Dietary and supplemental selenium crosses the blood-brain barrier. Supply of selenium to the brain has a higher priority than supply to other organs. Low selenium status is associated with cognitive decline.

Moreover, the low selenium status of the elderly Swedish citizens was significantly associated with relatively high mortality risk [Alehagen 2016]. Daily supplementation with 200 mcg of a selenium-enriched yeast preparation together with 200 mg of Coenzyme Q10 raised the study participants’ serum selenium levels to 210 mcg/L and reduced the risk of cardiovascular mortality [Alehagen 2022a].

The four years of joint supplementation were associated with the following positive health outcomes: read more

Blood Sugar Control and Selenium Supplementation

Blood sugar levels. Insulin sensitivity. Risk of diabetes. What, if anything, is the likely effect of selenium supplementation on glycemic control?

Blood sugar monitor
To maintain blood sugar levels within the normal range, the CDC recommends eating at regular times, not skipping meals, eating foods lower in calories, saturated fat, trans fat, sugar, and salt, drinking water instead of juice or soda, limiting alcohol intake, and exercising. Adequate intakes of selenium are also important.

Glycemic control is the maintenance of blood sugar levels within an acceptable range to prevent the adverse effects of low blood sugar and high blood sugar.

The best measure of glycemic control is the HbA1c test. This blood test HbA1C gauges the average glucose level in the blood over a period of approximately three months. It is considered a good predictor of diabetic complications.

Checking Blood Sugar

The US Center for Disease Control and Prevention suggests that logical times for testing blood sugar levels are as follows [CDC 2022]:

  • When first awake and before eating or drinking anything
  • Before a meal
  • Two hours after a meal
  • At bedtime
Target Blood Sugar Levels

The CDC suggests the following desirable blood sugar levels [CDC 2022]: read more

Selenoprotein P – Selenium Transport Protein and Biomarker of Selenium Status

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.

Selenium researcher Professor Urban Alehagen
Professor Urban Alehagen realized that the low selenium content of the soil in Sweden and in much of Europe results in wide-spread low dietary selenium intake and selenium deficiency. In the Swedish KiSel-10 Study, the average serum selenium concentration was a quite low 67 mcg/L.

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].

  • The best estimate for serum selenium status that is sufficient for good health is around 125 mcg/L [Winther 2020, fig. 3].
  • Serum selenium levels below 70 mcg/L are indicative of selenium deficiency [Bomer 2020].
  • Serum selenium levels below 100 mcg/L are indicative of sub-optimal selenium status [Al-Mubarak 2021].
Selenoprotein P as the Major Selenium Transport Protein

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]. read more

Selenium Deficiency and Thyroid Disorders

Selenium plays an important role in optimal immune and endocrine system function. The role that selenium plays with respect to thyroid function is complex [Chmura 2022]:

Thyroid system
Good thyroid system function promotes improved metabolism, better growth and development, and increased effect of catecholamines. Note: Catecholamines are hormones released in response to emotional or physical stress. (Attribution: Mikael Häggström, Public domain, via Wikimedia Commons.)

The thyroid gland is the organ with the greatest amount of selenium per gram of tissue.

  • An adequate supply of selenium is necessary for synthesizing the enzymes – the iodothyronine deiodinases – that are involved in the metabolism of thyroid hormones.
  • Selenium supplementation may give beneficial effects to patients with autoimmune diseases of the thyroid gland.
  • There is a significant correlation between selenium deficiency and thyroid gland dysfunction. Selenium deficiency is defined as serum or plasma selenium levels below 70 mcg/L. Optimal serum/plasma selenium levels are approximately 125 mcg/L [Winter 2020].
  • Selenium Deficiency and Thyroid Dysfunction

    A 2022 review highlights the following relationships between selenium deficiency and thyroid gland dysfunction [Chmura 2022]: read more

    Selenium Supplementation and Preeclampsia Risk

    Selenium supplementation of pregnant women at a high risk of preeclampsia has shown beneficial effects on 1) serum selenium levels, 2) some metabolic profiles, 3) uterine artery pulsatility index, and 4) mental health, compared to placebo. The study compared the effect in 60 pregnant women of supplementation with 200 mcg/day for 12 weeks with the effect of placebo for the same period.

    Pregnant woman
    Preeclampsia is a serious hypertensive condition of pregnancy. It is associated with high risk of maternal and fetal morbidity and mortality. Selenium intake and status have been linked to the occurrence of preeclampsia.

    The supplementation took place for 12 weeks starting in weeks 16 to 18 of pregnancy. No side effects related to the intake of 200 mcg of selenium per day by pregnant women at high risk of preeclampsia were reported throughout the duration of the study  [Mesdaghinia 2022].

    Selenium Supplementation Compared to Placebo

    How did the selenium supplementation compare with the placebo supplementation in the pregnant women? read more