Get Your Personalized Supplement StackSupplement Stack Quiz

Selenio

Also known as: Selenium, Se, Selenio

Overview

Selenium is an essential trace element vital for various physiological functions, including antioxidant defense and immune support. It is naturally found in foods such as Brazil nuts, seafood, and organ meats. As a component of selenoproteins, selenium plays a critical role in protecting cells from oxidative damage. It is available in both organic (e.g., selenomethionine) and inorganic forms, with organic forms generally exhibiting better bioavailability. Selenium is primarily used to support immune function, reduce oxidative stress, and potentially lower the risk of certain diseases. While extensive research has been conducted, the results are often inconsistent, highlighting the importance of considering dosage and form. The quality of evidence varies, with systematic reviews and meta-analyses providing the most reliable insights into its effects.

Benefits

Selenium offers several evidence-based benefits. It enhances immune function by increasing natural killer cell activity, although it does not significantly affect immunoglobulin or white blood cell counts. In antioxidant mixtures, selenium is associated with reduced all-cause mortality and cardiovascular disease mortality. Selenium supplementation can also lower TSH and thyroid antibodies in patients with Hashimoto's thyroiditis. Furthermore, dietary selenium may reduce the risk of certain cancers. Parenteral selenium supplementation has been shown to reduce mortality in septic patients. The effect sizes vary widely depending on the outcome and population, with benefits typically observed within several months of supplementation. The quality of evidence supporting these benefits ranges from moderate to high, based on systematic reviews and meta-analyses.

How it works

Selenium functions primarily through selenoproteins, which act as antioxidants to protect cells from oxidative damage. These selenoproteins, such as glutathione peroxidase, neutralize free radicals and reduce oxidative stress. Selenium supports immune function by modulating immune cell activity and reducing inflammation. It also plays a crucial role in thyroid health by participating in the synthesis and metabolism of thyroid hormones. Selenium is well-absorbed from dietary sources, although bioavailability can vary depending on the form, with organic forms generally being better absorbed than inorganic forms. Its interaction with various body systems underscores its importance in maintaining overall health and well-being.

Side effects

Selenium is generally safe when consumed within recommended dietary intake levels. Common side effects are rare at recommended doses. Uncommon side effects, occurring in 1-5% of users, may include gastrointestinal upset and a metallic taste. Rare side effects, occurring in less than 1% of users, include selenosis, which can result from excessive intake and cause symptoms such as hair loss and skin lesions. Selenium may interact with certain medications, such as blood thinners. High doses are contraindicated due to the risk of toxicity. Pregnant women and individuals with kidney disease should consult healthcare providers before taking selenium supplements. It is crucial to adhere to recommended dosage guidelines to avoid adverse effects.

Dosage

The minimum effective dose of selenium is approximately 50-100 μg/day for general health. Optimal dosage ranges from 50-200 μg/day for specific health benefits. The maximum safe dose for adults is 400 μg/day. There are no specific timing recommendations for selenium supplementation. Organic forms of selenium, such as selenomethionine, may be better absorbed than inorganic forms. Absorption is generally good but can vary based on dietary factors. No specific cofactors are required for selenium absorption or utilization. It is important to ensure that intake does not exceed safe limits to avoid toxicity.

FAQs

How much selenium should I take daily?

The recommended daily intake is 50-200 μg/day for adults. Do not exceed 400 μg/day to avoid potential toxicity. Consult a healthcare provider for personalized advice.

Is it safe to take selenium supplements?

Selenium is generally safe within recommended limits. High doses can be harmful. Consult a healthcare provider if you have concerns or pre-existing conditions.

When is the best time to take selenium?

There is no specific timing recommendation. Selenium can be taken at any time of day. Consistency is more important than timing.

What are the expected benefits of selenium?

Benefits may include improved immune function, reduced oxidative stress, and support for thyroid health. Individual results can vary.

Can selenium cure diseases?

Selenium is not a cure-all. It supports overall health and may reduce the risk of certain conditions when used within recommended limits.

Research Sources

https://pubmed.ncbi.nlm.nih.gov/36789948/ – A systematic review and meta-analysis of 9 trials found that selenium supplementation in healthy individuals increased natural killer (NK) cell activity but did not significantly affect other immune parameters. The study highlights the potential of selenium to modulate specific aspects of immune function, though results were inconsistent across trials, indicating moderate quality due to trial heterogeneity.
https://pubmed.ncbi.nlm.nih.gov/33053149/ – A comprehensive systematic review and meta-analysis of 43 RCTs revealed that selenium, when included in antioxidant mixtures, reduced all-cause mortality. This study underscores the potential benefits of selenium in combination with other antioxidants for improving overall health outcomes. The high quality of the analysis strengthens the evidence for this effect, despite variability in study designs.
https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2023.1263853/full – This systematic review and meta-analysis explored the impact of selenium supplementation on thyroid health in patients with Hashimoto's thyroiditis, analyzing data from 35 RCTs. The findings indicate that selenium supplementation effectively lowered TSH and thyroid antibody levels in these patients. However, the study acknowledges heterogeneity among the included studies, resulting in a moderate quality assessment.
https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0054431 – A systematic review and meta-analysis of 12 trials focused on critically ill patients found that parenteral selenium administration reduced mortality in septic patients. This study highlights the therapeutic potential of selenium in specific clinical settings. The high quality of the study is attributed to clear outcomes, although the findings are limited to critically ill populations.
https://www.liebertpub.com/doi/10.1089/thy.2023.0556 – This study investigates the effects of selenium supplementation on thyroid function and autoimmunity. It provides evidence supporting selenium's role in reducing thyroid antibody levels and improving overall thyroid health, particularly in individuals with autoimmune thyroid disorders. The research contributes to the understanding of selenium's therapeutic potential in managing thyroid-related conditions.