Selenium is a trace mineral obtained from soil, water, and certain foods. It is a component of proteins known as selenoproteins, which are involved in reproduction, DNA production, and protecting against infection. The thyroid gland contains the highest concentration of selenium in the body, where it supports hormone production and metabolism. This mineral also functions as an antioxidant, helping to protect cells from damage.
Symptoms of Selenium Deficiency
One of the most common indicators of selenium deficiency is persistent fatigue and muscle weakness. Individuals might experience mental fog or difficulty concentrating. These cognitive symptoms may accompany other physical changes, such as hair loss or the appearance of thin, colorless hair.
A weakened immune system is another frequent sign of insufficient selenium, leading to an increased susceptibility to infections. Skin and nail changes can also occur. Some people may notice their nails becoming brittle or developing white spots, while their skin may become pale and dry.
Health Conditions Linked to Deficiency
A sustained selenium deficiency is connected to medical conditions affecting the thyroid gland. Selenium is directly involved in the metabolism of thyroid hormones, specifically the conversion of thyroxine (T4) into its more active form, triiodothyronine (T3). A chronic shortage can impair this process and may contribute to the development of hypothyroidism, a condition characterized by an underactive thyroid.
In regions with extremely low selenium content in the soil, severe deficiencies have been linked to specific endemic diseases. One such condition is Keshan disease, a form of cardiomyopathy that affects the heart muscle. Another is Kashin-Beck disease, a type of osteoarthritis that results in joint pain and deterioration, leading to reduced mobility. These conditions are rare and typically occur when the deficiency is combined with other nutritional or environmental stressors.
Low selenium levels have also been associated with challenges in reproduction for both men and women. In pregnancy, insufficient selenium is linked to a higher risk of miscarriage and potential damage to the fetus’s nervous and immune systems.
Causes and Risk Factors
The primary cause of selenium deficiency is inadequate dietary intake, which is often directly linked to the selenium content of the soil where food is grown. People living in geographical areas with selenium-poor soil are at a higher risk because the crops and livestock raised there will also be low in this mineral.
Certain health conditions can also increase the risk of developing a deficiency by impairing the body’s ability to absorb nutrients. Individuals with gastrointestinal disorders such as Crohn’s disease, celiac disease, or colitis may have difficulty absorbing selenium from their food. Similarly, patients undergoing kidney dialysis are at risk, as the process can remove selenium from the blood.
People with specific viral infections, such as HIV, may also exhibit lower levels of selenium. The deficiency in these cases can be related to both reduced dietary intake and metabolic changes associated with the illness. Another at-risk group includes individuals receiving parenteral nutrition, a method of feeding that bypasses the digestive system, as these intravenous solutions can sometimes lack sufficient amounts of the mineral.
Diagnosis and Treatment
Diagnosing a selenium deficiency typically involves a medical evaluation and laboratory tests. A healthcare provider may order a blood test to directly measure the concentration of selenium in the serum or plasma. Another diagnostic method involves measuring the activity of glutathione peroxidase, a selenium-dependent enzyme, as low levels can indicate a deficiency.
Treatment focuses on correcting the deficiency by increasing selenium intake, primarily through diet. Foods rich in selenium include Brazil nuts, seafood like tuna and sardines, organ meats, poultry, and enriched grains.
In cases of a diagnosed deficiency, a doctor might recommend supplementation. It is important that supplementation is guided by a healthcare professional, as excessive selenium intake can lead to toxicity, known as selenosis. Symptoms of toxicity can include hair loss, fatigue, nausea, and nerve damage.