How rare is selenium deficiency?

November 17, 2025 •

4 min read

Over half a billion people worldwide may have insufficient selenium intake, suggesting that answering 'how rare is selenium deficiency?' depends heavily on geographic location. While typically not a widespread issue in Western countries with robust diets, it poses a significant public health concern in regions with low soil selenium levels.

Quick Summary

The global prevalence of selenium deficiency is highly geographical, influenced by soil content and dietary habits. It is uncommon in some regions like the United States but affects millions in parts of Europe, Asia, and Africa.

Key Points

Geographical Variation: The rarity of selenium deficiency is highly dependent on the selenium content of the local soil, which directly affects the mineral content in food.
Not Rare Globally: Globally, selenium deficiency is not rare, with 500 million to 1 billion people estimated to have insufficient intake.
Rare in the U.S.: In the United States, severe selenium deficiency is considered rare, except among high-risk individuals.
High-Prevalence Areas: Deficiency is a major public health concern in parts of China, Sub-Saharan Africa, and Europe where soil is naturally low in selenium.
Risk Factors: Individuals with gastrointestinal disorders, those on long-term TPN or dialysis, vegans, and HIV patients face a higher risk, regardless of location.
Health Impacts: Even mild deficiency can impact the immune system, thyroid function, and cognitive health.
Preventable: Prevention is possible through a balanced diet, agricultural biofortification, or targeted supplementation under medical supervision.

A Global Health Concern with Regional Variations

Determining exactly how rare selenium deficiency is requires a global perspective, as its prevalence varies dramatically from one region to another. While often considered uncommon in areas with sufficient soil selenium and varied diets, it is a significant public health problem in others. The primary cause is inadequate dietary intake, which is directly linked to the selenium content of the soil where food is grown. Up to 1 billion people worldwide are estimated to have inadequate selenium intake.

Global Prevalence: The Big Picture

In regions with sufficient soil selenium, like much of the central and southwestern United States, severe deficiency is considered rare for the general population. However, in regions with historically low soil concentrations, deficiency is much more common and can manifest as serious health conditions.

Key areas with high prevalence of selenium deficiency include:

China: Historically known for endemic deficiency, particularly in provinces like Sichuan and Shaanxi, which led to outbreaks of Keshan disease (a type of cardiomyopathy). While public health efforts have reduced prevalence, a significant portion of the population remains at risk.
Sub-Saharan Africa: A growing public health problem, with some estimates suggesting a high prevalence across the continent due to primarily crop-based diets and low soil content. Studies in countries like Zimbabwe and Ethiopia have shown alarmingly high deficiency rates in vulnerable populations like women and children.
Europe: Selenium levels in many parts of Europe are significantly lower than in the United States, with Eastern Europe often having lower average intake than Western Europe.
New Zealand and Russia: Historically known for low soil selenium levels, though some countries like Finland addressed the issue through fortifying fertilizers.

Individuals at Higher Risk

Even in regions where deficiency is generally rare, certain individuals are at a higher risk due to dietary restrictions or underlying health conditions. Risk factors include:

Long-term Total Parenteral Nutrition (TPN): Patients receiving long-term IV feeding without selenium supplementation are at risk.
Gastrointestinal Disorders: Conditions like Crohn's disease, celiac disease, and ulcerative colitis can impair nutrient absorption, including selenium.
Vegan and Vegetarian Diets: Without careful planning, plant-based diets can be lower in selenium, especially if foods are sourced from low-selenium soil regions.
Dialysis Patients: Individuals on renal dialysis are at increased risk for deficiency.
HIV Infection: Patients with HIV often experience declining plasma selenium levels.

Comparing Selenium Deficiency Across Regions


Feature	Regions with High Prevalence (e.g., Parts of China, Sub-Saharan Africa)	Regions with Low Prevalence (e.g., United States)
Underlying Cause	Primarily low soil selenium content impacting local food supplies.	Typically due to individual risk factors (e.g., medical conditions, specific diets) rather than soil quality.
Impacted Population	Often affects entire communities, particularly women and children, where staple crops are grown in deficient soil.	Isolated cases, not a widespread public health issue affecting the general populace.
Associated Diseases	Severe deficiency has been linked to Keshan disease and Kashin-Beck disease.	These endemic diseases are not observed.
Prevention Strategy	Requires large-scale public health interventions like agricultural biofortification or national supplementation programs.	Focuses on dietary awareness for at-risk individuals and clinical management.

The Health Impact of Selenium Deficiency

Beyond endemic diseases, even sub-optimal selenium status can lead to health issues because selenium is vital for producing selenoproteins, which are crucial for antioxidant defense, thyroid hormone metabolism, and immune function.

Recognized health effects include:

Impaired Immune Response: Weakened immunity, making individuals more susceptible to infections.
Thyroid Dysfunction: Interrupted metabolism of thyroid hormones, which can lead to hypothyroidism.
Cognitive Decline: Low selenium intake is associated with cognitive issues and depressed mood.
Fertility Issues: Impacts reproductive health in both men and women.
Muscle Weakness: Can contribute to muscle pain and wasting.

Prevention and Management

For most people in areas with sufficient soil selenium, a balanced diet is enough to prevent deficiency. The following foods are rich sources:

Brazil nuts
Seafood (e.g., tuna, shrimp)
Meats (e.g., beef, chicken)
Eggs
Whole grains
Mushrooms

In deficient regions, public health strategies like agricultural biofortification have been successful, as seen in Finland. For individuals with specific risk factors, healthcare professionals may recommend supplementation. For more information on selenium, consult the National Institutes of Health Office of Dietary Supplements website.

Conclusion

In summary, the rarity of selenium deficiency is entirely context-dependent. While it is rare in countries like the United States due to high soil content, it remains a significant public health issue for millions in regions of China, Africa, and parts of Europe. Understanding this geographic and demographic variation is key to appreciating the true scope of selenium deficiency as a global health challenge and for targeting effective prevention strategies.

Frequently Asked Questions

No, selenium deficiency is not uniformly common worldwide. While it is rare in some regions, it affects a significant global population, with estimates suggesting up to 1 billion people have insufficient intake, primarily in regions with low soil selenium content.

The primary reason is the selenium content of the soil. The soil in much of the U.S. has adequate selenium levels, which means crops grown there and animals consuming those crops also have sufficient selenium. In contrast, many parts of China, Africa, and Europe have naturally low selenium soil.

Severe deficiency can cause endemic diseases in populations with low intake, such as Keshan disease, a congestive cardiomyopathy, and Kashin-Beck disease, a degenerative joint and bone condition.

Vulnerable groups include those living in low-selenium soil regions, individuals with malabsorption issues from GI disorders, patients on long-term IV feeding or dialysis, vegans and vegetarians, and people with HIV infection.

For most people in areas with sufficient soil selenium, a balanced diet including seafood, meat, eggs, and nuts is adequate. In endemic deficiency areas, public health interventions like soil fortification or dietary diversification may be necessary.

Symptoms can include fatigue, weakened immune function, hair loss, brittle nails, muscle weakness, mood changes, and potential thyroid issues due to impaired hormone metabolism.

Diagnosis can involve measuring selenium levels in blood, hair, or nails. Doctors may also test the activity of selenium-dependent enzymes, such as glutathione peroxidase, which requires selenium to function properly.