What Inhibits Selenium? Understanding Absorption Blockers

January 8, 2026 •

4 min read

Selenium levels in crops are directly influenced by soil composition, which varies dramatically worldwide, leading to variable dietary intake. Understanding what inhibits selenium is crucial for maintaining optimal levels, as several factors can prevent proper absorption and utilization by the body.

Quick Summary

Numerous factors can impede selenium uptake and utilization. These include interactions with heavy metals, certain medications, specific nutrient imbalances, and poor gut health conditions.

Key Points

Heavy Metals Inhibit Selenium: Mercury, arsenic, and cadmium can bind to selenium, rendering it biologically unavailable for absorption.
Certain Medications Affect Absorption: Drugs like corticosteroids, statins, and PPIs can interfere with selenium metabolism and increase its excretion.
Gut Health is Critical for Absorption: Inflammatory bowel diseases like Crohn's and celiac disease compromise the gut's ability to absorb selenium.
Sulfur Competes with Selenium: High dietary intake of sulfur can compete with selenium for absorption, particularly when selenium status is low.
Soil Content Dictates Food Levels: The geographic location where food is grown directly impacts its selenium concentration due to variations in soil content.
Kidney Dialysis Increases Excretion: The long-term process of kidney dialysis can remove significant amounts of selenium from the blood, requiring careful management.
Chronic Illness Raises Demand: Conditions like HIV and other systemic infections increase oxidative stress and the body's demand for selenium, potentially causing deficiency.

Environmental Factors that Inhibit Selenium

Inadequate Soil Content

One of the most foundational inhibitors of selenium levels is the geographic concentration of the mineral in the soil. The selenium content of crops and the animals that feed on them is a direct reflection of the soil where they originated. Regions like parts of Europe, China, and New Zealand have naturally low-selenium soil, making it challenging to obtain sufficient amounts through diet alone without importing food from other regions. In contrast, areas like the Great Plains of the United States are known for having higher soil selenium concentrations. This variability highlights why relying solely on locally sourced produce can sometimes be problematic for selenium status, especially for those in deficient regions following plant-based diets.

Heavy Metals and Toxic Exposure

Heavy metals represent a significant inhibitory factor for selenium. Metals such as mercury, arsenic, and cadmium can directly interact with selenium, effectively neutralizing its biological activity and preventing absorption. Mercury, in particular, has a strong binding affinity for selenium. When ingested together, they form a biologically inert mercury-selenium compound that the body cannot absorb, leading to its excretion. This interaction is particularly relevant when considering the consumption of certain types of fish, which can contain both selenium and mercury. Other metals like cadmium and arsenic also compete with selenium, impacting its availability.

Dietary and Nutritional Interactions

Sulfur Competition

Due to their chemical similarities, sulfur and selenium can compete for absorption pathways in the body. While sulfur is an essential mineral, excessive intake, often from a high-sulfur diet or specific supplements, can lead to increased urinary excretion of selenium, reducing overall body retention. Conversely, adequate selenium can help balance sulfur metabolism. This complex relationship suggests that dietary balance, rather than simply increasing one mineral, is critical for optimal nutrient status.

Alcohol and Oxidative Stress

Chronic, excessive alcohol consumption can deplete selenium stores in the body in several ways. Alcohol increases oxidative stress, which increases the body's demand for selenium, a crucial component of antioxidant enzymes. Prolonged alcohol abuse also damages the liver and digestive system, impairing nutrient absorption and increasing the body's excretion of trace minerals.

Medical Conditions and Medications

Gastrointestinal Disorders

Conditions that affect the health of the digestive tract significantly inhibit the absorption of selenium. Diseases like Crohn's disease, celiac disease, and ulcerative colitis cause inflammation and damage to the gut lining, which severely compromises the body's ability to absorb nutrients like selenium efficiently. Chronic diarrhea associated with these or other conditions can also lead to nutrient loss and lowered selenium levels.

The Impact of Medications

Several prescription and over-the-counter drugs have been shown to interfere with selenium metabolism or increase its excretion.

Corticosteroids: Long-term use of anti-inflammatory corticosteroids, such as prednisone, can increase the urinary excretion of selenium, gradually depleting body stores over time.
Statins: These cholesterol-lowering drugs may reduce the activity of selenium-dependent enzymes, possibly increasing oxidative stress.
Proton Pump Inhibitors (PPIs): Medications used to reduce stomach acid can alter the gastrointestinal environment, potentially hindering selenium absorption.
Chemotherapy Agents: Some cancer treatments, like cisplatin, can deplete selenium levels dramatically.
Anticonvulsants: Certain antiepileptic drugs can also negatively impact selenium status through altered metabolism.

Chronic Illness and Medical Procedures

Kidney Dialysis

Patients undergoing long-term kidney hemodialysis frequently have significantly lower selenium concentrations. This is due to the removal of micronutrients during the dialysis process and dietary restrictions that limit the intake of selenium-rich foods. Monitoring and potentially supplementing selenium is crucial for these individuals.

Other Inflammatory Conditions

Systemic inflammation, such as that caused by HIV or other infections, increases the body's demand for selenium due to its antioxidant and immune-modulating roles. If dietary intake does not match this increased demand, a functional deficiency can occur.

Comparison Table: Inhibitors of Selenium


Inhibitor Type	Examples	Mechanism of Action	Impact on Selenium	Mitigation Strategy
Heavy Metals	Mercury, Cadmium, Arsenic	Binds directly to selenium, forming biologically inert compounds that are poorly absorbed and increase excretion.	Reduces absorption and bioavailability, leading to potential deficiency and reduced antioxidant capacity.	Limit exposure to heavy metals. Ensure adequate selenium intake to help sequester and excrete metals.
Medications	Corticosteroids, Statins, PPIs	Alter absorption pathways, increase excretion, or reduce the activity of selenium-dependent enzymes.	Decreases overall selenium status, increases oxidative stress.	Consult a healthcare provider regarding medication effects and potential supplementation.
Dietary Factors	High Sulfur Intake, Contaminated Fish	Sulfur competes with selenium; mercury in fish binds selenium.	Can reduce retention and absorption. Mercury contamination depletes selenium's protective effects.	Maintain balanced diet. Choose fish lower in mercury. Address dietary extremes.
Health Conditions	Crohn's Disease, Celiac Disease, Kidney Dialysis	Damages the intestinal lining, impairing absorption. Dialysis removes minerals from the blood.	Reduces body's ability to take up and retain selenium from food sources.	Treat underlying condition. Work with a doctor and dietitian to manage nutrition. Monitor levels closely.

Conclusion

While inadequate dietary intake due to soil deficiencies is a common cause of low selenium levels, various other factors can profoundly inhibit selenium absorption and utilization. Medical conditions affecting the gut, heavy metal exposure, and certain medications can all disrupt the body's delicate mineral balance. A balanced diet, awareness of potential medication interactions, and addressing underlying health issues are critical steps toward maintaining healthy selenium levels. For a comprehensive overview of essential nutrients, visit the National Institutes of Health website.

Frequently Asked Questions

Heavy metals such as mercury, arsenic, and cadmium are known to interfere with selenium absorption by binding to it and forming inactive compounds that are then excreted by the body.

Yes, gastrointestinal disorders like Crohn's disease, celiac disease, and chronic diarrhea can damage the intestinal lining, impairing the body's ability to absorb and utilize selenium effectively.

Yes, certain medications can block selenium or increase its excretion. These include long-term use of statins, corticosteroids (like prednisone), and proton pump inhibitors (PPIs).

The selenium content of crops and animal products depends directly on the selenium concentration of the soil they are grown or raised in. Many parts of the world have naturally low-selenium soil, which can result in lower dietary intake.

Because of their chemical similarity, high dietary sulfur can compete with selenium for absorption pathways in the body, particularly when overall selenium intake is low.

The body readily absorbs both organic (e.g., selenomethionine) and inorganic (e.g., selenite) selenium, but their metabolic pathways differ. Organic forms are often incorporated into protein, while inorganic forms are used more directly for selenoprotein synthesis.

Excessive and chronic alcohol consumption can deplete selenium levels by increasing oxidative stress and impairing nutrient absorption due to damage to the digestive system.

Yes, long-term kidney hemodialysis can remove significant amounts of selenium from the blood. Patients undergoing this procedure often have lower selenium levels and may require supplementation.