VEGANALYZE

Selenium Deficiency - Symptoms, Causes, Therapy

Selenium is an essential trace element that should be obtained through daily nutrition to prevent selenium deficiency. In the body, selenium has several important functions as a component of enzymes, such as protecting cells from free radicals and converting thyroid hormones into their active form (T4 to T3).

Selenium deficiency is rare. Nevertheless, selenium supply to the body in Europe is rather suboptimal 1.

Low selenium concentrations in the body have been associated with impaired immune function, cognitive decline, and even increased mortality risk 2.

At-Risk Groups

Some groups can be particularly affected by a lack of selenium. These include:

People who consume foods grown in selenium-deficient soils. So, vegetarians and vegans are also considered at risk. 3 4 5 6 7 8 9 10 11 12 13. For example, selenium consumption with a vegan diet is on average 11 µg in Sweden and 29 µg in Denmark 14 15. These intake amounts would fall significantly below the selenium recommendations for adults in the United States (men: 55 µg; women: 55 µg). However, other studies from England show higher intake amounts for selenium (men: 62.1 μg; women: 51.7 μg) 16. In this study, 48.9% of vegan women were affected by deficiency.

If selenium absorption is reduced or impaired in individuals with gastrointestinal disorders such as Crohn's disease or ulcerative colitis, selenium deficiency is also highly likely. 17 18.

Smokers have lower selenium levels compared to non-smokers. 19. Consumption of alcohol also negatively affects selenium levels.

Elderly individuals are also at a greater risk of selenium deficiency.

Individuals with severe trauma and burns 20.

Study results indicate that patients who are parenterally nourished (bypassing the intestine) or undergo hemodialysis have lower selenium levels when selenium is not supplied 21 22 23.

Individuals with phenylketonuria, an inherited metabolic disorder, may also be prone to selenium deficiency 24.

Patients with severe cirrhosis may be affected by mild selenium deficiency 25.

Causes

A selenium deficiency can be attributed to inadequate selenium supply to the body and an unbalanced diet. Selenium-rich foods can be found in this list. Soil composition plays a crucial role 26. Thus, soils in Burundi, China, Denmark, Finland, the United Kingdom (depending on the region), Croatia, New Zealand, Slovakia, Turkey, as well as in eastern and central Siberia, have low selenium levels 27 28 29. Therefore, consuming plant-based foods grown in regions with selenium-deficient soil can quickly lead to selenium deficiency. Generally, the lowest selenium levels are found in people living in China.

If the intestinal function is severely impaired, it may result in inadequate absorption of selenium from food, leading to a deficiency.

Cholesterol-lowering medications such as statins can also contribute to selenium deficiency 30 31.

Symptoms

Common symptoms of selenium deficiency can include 32 33 34 35 36:

• Swelling of the thyroid gland, goiter formation, to compensate for selenium deficiency (cretinism)
• Fatigue
• Mood swings
• Depression
• Dry skin
• Thinning hair
• Constipation
• Muscle and joint pain
• Brittle nails / white nail beds
• Spots on fingernails and toenails (leukonychia)
• Cold sensitivity
• Hoarseness
• Infertility
• Weight gain or difficulty losing weight

Since selenium deficiency is involved in the conversion of thyroid hormones, it can lead to an underactive thyroid (hypothyroidism) with corresponding symptoms. 37. The symptoms of hypothyroidism have been included in the list.

Consequences

Selenium is required for the proper functioning of the immune system. A selenium deficiency generally reduces the effectiveness of immune cells 38.

Numerous enzymes such as glutathione peroxidases (GPX), deiodinases, and thioredoxin reductases require selenium as an essential component. These enzymes are needed for the formation and functions of the thyroid gland, as well as for protecting cells against free radicals and oxidative damage 39. A deficiency in selenium leads to reduced GPX activity, which can result in oxidative damage 40. If deiodinases are affected by a selenium deficiency, it can lead to reduced thyroid activity and abnormal thyroid processes 41. Furthermore, a deficiency causes autoimmune processes that result in the destruction of the thyroid gland. Thus, a selenium deficiency can cause autoimmune diseases like Hashimoto's thyroiditis (autoimmune thyroiditis) and Graves' disease 42 43 44 45. Additionally, reduced selenium concentrations in the thyroid can contribute to the development of thyroid cancer.

The risk of developing cancer (colon, rectum, prostate, lung, bladder, skin, esophagus, and stomach) in the human body could also be increased by a deficiency in selenium 46. However, the study results are not yet sufficient to make a conclusive assessment.

The negative effects of iodine deficiency could possibly be exacerbated by selenium deficiency 47. Selenium deficiency combined with iodine deficiency is associated with the occurrence of Kashin-Beck disease (nutritive joint cartilage degeneration) 48 49. This leads to joint deformities, shortened fingers and bones, and osteoarthritis, causing pain, swelling, and loss of mobility in the joints (osteochondropathy). The disease primarily occurs in East Asia. Children aged 5 to 13 years are affected 50.

In addition, the disease myxedematous cretinism is also associated with a combined deficiency of selenium and iodine 51. The consequences can manifest as intellectual disabilities and growth delays in children.

Muscle diseases (myopathy) and heart muscle diseases (cardiomyopathy) are also associated with a deficiency 52 53 54 55. Especially in patients receiving parenteral nutrition, selenium deficiency can lead to muscle weakness, muscle wasting, and cardiomyopathy 56. One cardiomyopathy condition in which selenium deficiency is the main cause is Keshan disease, which involves inflammation and damage to the heart muscle 57. In older individuals, low serum selenium levels are associated with poor skeletal muscle strength 58.

A selenium deficiency is associated with poor cognitive development in children and faster cognitive decline in adults. 59 60 61 62. A deficiency could lead to impairment of cognitive functions and neurological disorders 63 64. Alzheimer's, Parkinson's, epilepsy, and Huntington's chorea (inherited) are possible consequences.

Low selenium levels (≤1 μmol/l) are associated with a significantly increased risk of ischemic heart disease 65. This refers to a circulation disorder of the heart muscle.

Infertility in men may be caused by selenium deficiency, as it impairs sperm quality and sperm motility 66 67.

During pregnancy, a selenium deficiency can lead to complications, miscarriage, and damage to the nervous and immune systems of the fetus 68. Additionally, a deficiency can negatively affect psychomotor skills and language development 69. A low selenium level in early pregnancy is a predictor of low birth weight in newborns 70.

A selenium deficiency may also play a role in the development of asthma 71.

Diagnosis

A selenium deficiency can be determined through a blood test. This test measures erythrocyte levels, serum levels, and tissue levels of glutathione peroxidase, which provide information about a possible deficiency. To measure selenium levels over a past period, hair or nail samples can also be examined.

The following serum values provide information about the selenium status in the body: 72 73:

Treatment

The treatment of selenium deficiency is carried out by a doctor depending on the cause.

For a mild selenium deficiency, a short-term administration of dietary supplements with a selenium-rich diet is usually sufficient. A dietary supplement with high bioavailability is selenomethionine. Selenomethionine is absorbed by the body almost twice as well as the alternative dietary supplement form, sodium selenite 74 75. Therefore, selenomethionine is also more effective in increasing serum selenium levels.

Especially in thyroid diseases, supplementation with selenium seems to be beneficial 76 77. Here, selenium has a significant impact on inflammatory activities in specific autoimmune diseases 78.

If there is a severe selenium deficiency, the doctor must take immediate further steps to prevent irreversible health damage. Intravenous administration of selenium is a possible solution.

Preventive measure

To prevent selenium deficiency in healthy individuals, a balanced diet rich in selenium-containing foods contributes to good nutrient supply. Just two Brazil nuts per day are sufficient to improve selenium levels in the body 79 80.