What Causes Low Selenium in the Body?

October 8, 2025 •

4 min read

Worldwide, it is estimated that up to one billion people are affected by insufficient selenium intake due to various factors, including geographical location and diet. Understanding the primary drivers is crucial for addressing what causes low selenium levels and preventing potential health complications.

Quick Summary

Low selenium results from poor soil quality affecting food sources, restrictive diets, impaired nutrient absorption due to certain health issues, or increased physiological demand. The article explores these causes and identifies at-risk populations.

Key Points

Soil Quality and Location: The primary cause of low selenium is often the low mineral content in the soil of specific geographic regions, impacting the selenium levels in local foods.
Dietary Restrictions: Vegan and vegetarian diets or reliance on highly processed foods can result in inadequate selenium intake, as plant-based sources vary widely based on soil quality.
Malabsorption Conditions: Gastrointestinal disorders like Crohn's disease, Celiac disease, and chronic diarrhea can severely impair the body's ability to absorb selenium, even with sufficient dietary intake.
Increased Physiological Demand: Factors such as pregnancy, lactation, or chronic infections can significantly increase the body's need for selenium, potentially leading to deficiency if intake is not adjusted.
Medical Treatments: Patients undergoing long-term kidney dialysis or total parenteral nutrition (TPN), or taking certain medications like statins, are at higher risk for selenium deficiency.
Serious Health Consequences: Long-term, severe selenium deficiency is linked to conditions like Keshan disease (a type of cardiomyopathy) and Kashin-Beck disease (osteoarthritis).

Environmental and Agricultural Factors

One of the most significant reasons behind low selenium intake globally is the concentration of this trace mineral in the soil where food is grown. Soil selenium content varies dramatically by region, with certain areas, such as parts of Europe, China, and New Zealand, being naturally low in the element.

How Soil Quality Impacts Food

Soil Depletion: Intensive modern farming and specific fertilizers can further strip soil of trace minerals, reducing the nutrient density of crops over time.
Regional Variation: Food grown in selenium-poor regions will inherently contain less of the mineral, directly impacting the diets of local populations who rely on locally sourced produce and livestock. While extensive food transport can mitigate this in some countries, it remains a major factor for others.
Soil pH: The bioavailability of selenium to plants is affected by soil pH. Selenite ($Se^{4+}$) is less available in neutral and acidic soils, while selenate ($Se^{6+}$) is more available in alkaline soils.

Dietary Habits and Restrictions

What you eat plays a crucial role in maintaining adequate selenium levels, as the body cannot produce this mineral on its own. Certain dietary patterns can increase the risk of deficiency.

Vegetarians and Vegans

Individuals following strict vegetarian or vegan diets may have a higher risk of selenium deficiency. Selenium content in plant-based foods is highly dependent on soil quality, and levels are often lower compared to animal products like fish, meat, and eggs.

Reliance on Processed Foods

Diets high in processed foods and low in whole, nutrient-dense ingredients can fall short of meeting the body's selenium needs. Processing can also strip minerals from food.

Medical Conditions Affecting Absorption

Even with sufficient dietary intake, certain health issues can impair the body's ability to absorb and utilize selenium effectively, leading to deficiency.

Gastrointestinal Disorders

Chronic inflammatory bowel conditions, including Crohn's disease and Celiac disease, can damage the intestinal lining and severely reduce nutrient absorption. Prolonged, severe diarrhea also leads to significant nutrient loss.

Other Conditions and Treatments

Kidney Dialysis: Long-term hemodialysis can remove selenium from the blood, and associated dietary restrictions can limit intake.
HIV/AIDS: Low selenium concentrations are common in individuals with HIV, possibly due to malabsorption or inadequate intake.
Total Parenteral Nutrition (TPN): Patients on long-term intravenous feeding may be at risk if selenium is not included in the nutrient solution.
Chronic Oxidative Stress: Conditions involving high oxidative stress, like infections, can increase the body's demand for selenium, depleting reserves.

Comparison of Risk Factors for Selenium Deficiency


Cause	Mechanism	At-Risk Population	Reversibility	Impact on Health
Geographic Location	Low selenium concentration in local soil affects food supply.	People relying on locally grown foods in regions like parts of China, Europe, and New Zealand.	Reversible with importation of diverse food sources or supplementation.	Can cause severe endemic diseases like Keshan and Kashin-Beck.
Dietary Restrictions	Exclusion of selenium-rich foods, common in vegan or vegetarian diets.	Vegetarians, vegans, and those with poor eating habits.	Reversible through targeted dietary changes and supplementation.	Milder symptoms, but persistent low levels can lead to health issues.
Malabsorption Issues	Damage to intestinal lining or conditions that hinder nutrient uptake.	Individuals with Crohn's, Celiac disease, or chronic diarrhea.	Management of underlying condition and supplementation can help.	Can cause significant deficiency despite adequate intake.
Medical Treatments	Removal of selenium from blood or use of medications that interfere with metabolism.	Patients on kidney dialysis, long-term TPN, or certain chemotherapy.	Requires targeted supplementation and medical supervision.	Can cause severe deficiency and associated symptoms.
Increased Demand	Higher physiological needs due to stress, infection, or pregnancy.	Pregnant or lactating women, those with infections or high oxidative stress.	Temporary supplementation may be needed during high-demand periods.	Can lead to transient deficiency if demand is not met.

Conclusion

Low selenium levels stem from a combination of environmental, dietary, and physiological factors. While geographic location with low soil selenium is a primary cause, especially for specific endemic diseases, modern lifestyle factors like restricted diets, malabsorption conditions, and certain medical treatments are also significant contributors. Understanding these causes is the first step toward prevention and treatment, which can include dietary adjustments to include selenium-rich foods, and in more severe cases, targeted supplementation under medical supervision. A personalized approach that considers individual risk factors is crucial for maintaining adequate selenium status and protecting overall health.

The Role of Selenium in Viral Infections

Severe selenium deficiency has been observed to transform otherwise benign viruses within hosts into highly virulent pathogens, underscoring the link between immune response and selenium status. This was highlighted in regions with low selenium, where factors like Coxsackievirus infection, combined with the deficiency, have been associated with a greater risk of conditions like Keshan disease. Furthermore, studies have shown that individuals with HIV often have low selenium concentrations, and supplementation may improve their immune function. This evidence demonstrates how vital adequate selenium levels are for a robust immune system capable of fighting off infectious agents effectively.

Frequently Asked Questions

The most common cause of selenium deficiency is inadequate dietary intake, which is often tied to geographical factors. People who consume food grown in regions with low-selenium soil are at a higher risk, especially if they rely primarily on locally sourced food.

Several health conditions can lead to low selenium levels, including gastrointestinal disorders that cause malabsorption (e.g., Crohn's disease, celiac disease), kidney dialysis, and HIV/AIDS. These conditions either interfere with the absorption of the mineral or increase its excretion from the body.

Yes, individuals following strict vegan or vegetarian diets may be at higher risk for selenium deficiency. The selenium content in plant foods is dependent on the soil quality, which varies regionally, and these diets often exclude richer animal-based sources like meat and seafood.

Yes, some medications can affect selenium levels. For example, long-term use of certain drugs, including some statins and corticosteroids, may either reduce selenium absorption or increase its excretion, contributing to a gradual depletion of the mineral.

During pregnancy and lactation, the body's demand for selenium increases to support fetal development and milk production. If a mother's dietary intake is not sufficient to meet this increased demand, her selenium levels may drop.

Selenium status is typically evaluated by a healthcare provider through a blood test that measures plasma selenium levels. A comprehensive assessment may also include evaluating symptoms and reviewing your medical and dietary history.

Initial symptoms of low selenium can be subtle and include general fatigue, muscle weakness, and a weakened immune system, leading to more frequent infections. As the deficiency progresses, issues with hair and nail health may also appear.