Selenium deficiency
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Selenium Deficiency: Essential Trace Element and Health Risks
Selenium is a vital trace element required for many biological processes, including antioxidant defense, immune function, thyroid hormone metabolism, and cardiovascular health. Deficiency in selenium is a global health concern, especially in regions with low selenium content in soil and food sources, and can lead to a range of health problems 510.
Selenium Deficiency and Oxidative Stress
Selenium is incorporated into selenoproteins, which are crucial for protecting cells from oxidative stress. Deficiency disrupts the glutathione antioxidant system, leading to redox imbalance and increased oxidative damage in tissues such as the liver 110. This redox imbalance can trigger metabolic reprogramming, inflammation, and dysfunction in various organs .
Immune Dysfunction and Inflammation
Selenium deficiency impairs immune cell differentiation and function, leading to both cellular and humoral immune dysfunction. It disrupts the balance of Th1/Th2 immune responses, weakens dendritic cell function, and causes spleen damage by activating inflammatory pathways like NF-κB and inducing endoplasmic reticulum stress 78. These immune disturbances can increase susceptibility to infections and may trigger or worsen autoimmune diseases, especially during pregnancy, severe illness, or COVID-19 36.
Cardiovascular and Metabolic Effects
Low selenium status is linked to increased risk of cardiovascular diseases, including cardiomyopathy, heart failure, and hypertension. Selenium deficiency can cause hypertension by increasing oxidative stress and upregulating renal angiotensin II type 1 receptor expression, leading to sodium retention and elevated blood pressure 24. Selenoproteins are also essential for maintaining heart muscle function and protecting against oxidative damage in the cardiovascular system 46.
Gastrointestinal and Microbiota Changes
Chronic selenium deficiency alters the composition of gut microbiota, increases inflammation, and disrupts intestinal barrier function. These changes can lead to chronic diarrhea, autophagy, apoptosis, and abnormal smooth muscle contraction in the intestines . The gut flora shifts, with increases in certain bacteria and decreases in others, contributing to intestinal and systemic health problems .
Endocrine and Neurological Impacts
Selenium is necessary for thyroid hormone metabolism and neuroprotection. Deficiency is associated with thyroid dysfunction, cognitive decline, and increased risk of mortality . The narrow margin between selenium deficiency and toxicity makes maintaining optimal selenium intake critical for health 510.
Prevention and Supplementation
Adequate selenium intake through diet or supplementation can reduce the risk of deficiency-related diseases. However, because selenium has a narrow safety window, supplementation should be targeted to those with low baseline selenium levels to avoid toxicity 36. Population-wide measures, such as food fortification, have been effective in regions with low selenium intake .
Conclusion
Selenium deficiency is a preventable cause of significant health problems, including immune dysfunction, cardiovascular disease, metabolic disturbances, and gastrointestinal issues. Ensuring adequate selenium intake is essential for maintaining overall health, especially in vulnerable populations and regions with low environmental selenium. Personalized approaches and public health strategies are needed to address selenium deficiency while avoiding the risks of excess intake.
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