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SODIUM SELENATE

Also known as: Selenic acid disodium salt, selenate, Na₂SeO₄, Sodium selenate

Overview

Sodium selenate is an inorganic form of selenium, an essential trace element vital for human health. Unlike organic forms of selenium commonly found in food, sodium selenate is primarily used as a supplement to address selenium deficiency and is particularly noted in research for its ability to deliver selenium to the central nervous system. It is a highly bioavailable, water-soluble compound. While several clinical trials and systematic reviews exist, the evidence base for sodium selenate is considered moderate, with some high-quality studies but also limitations such as small sample sizes or mixed results. Its primary applications are in correcting selenium deficiency and as a research tool to investigate selenium's effects on neurological function and metabolic processes, though its role in glycaemic control in humans remains unclear.

Benefits

Sodium selenate offers several potential benefits, primarily related to its role as a selenium source. It has been shown to effectively deliver selenium to the central nervous system (CNS) in humans, as demonstrated in a randomized controlled pilot trial where supranutritional supplementation significantly increased CNS selenium levels. This suggests a potential role in neurological research or conditions. Selenium, in general, is a crucial component of selenoproteins, which possess significant antioxidant and anti-inflammatory properties, contributing to overall cellular health and protection against oxidative stress. While animal studies have explored its effects on glycaemic control, showing mixed and dose-dependent results (e.g., low doses reducing fasting blood glucose, higher doses having variable effects), human clinical significance for this benefit is not yet established. Furthermore, higher dietary selenium intake is associated with a lower risk of all-cause mortality, though supplementary selenium intake, including sodium selenate, has not consistently shown this specific benefit. Sodium selenate is particularly effective in correcting selenium deficiency.

How it works

Sodium selenate functions by being converted into selenide within the body, which is then incorporated into selenoproteins. These selenoproteins, such as glutathione peroxidases and thioredoxin reductases, are critical for antioxidant defense and regulating redox balance in cells. A unique aspect of sodium selenate is its ability to cross the blood-brain barrier, allowing it to increase selenium levels within the central nervous system. This mechanism makes it a valuable tool for research into neurological conditions. While it may influence insulin sensitivity and glucose metabolism, its precise interaction with the endocrine system and the clinical relevance of these effects are still under investigation. Sodium selenate exhibits high bioavailability, meaning it is efficiently absorbed and distributed throughout the body, including to the CNS.

Side effects

Sodium selenate is generally considered safe when consumed within recommended dosages. However, exceeding the upper intake limit can lead to selenium toxicity, known as selenosis. Common side effects are rare at typical doses, but gastrointestinal upset may occur with higher intakes. Uncommon side effects associated with chronic high intake include nausea, hair loss, changes in nails, and fatigue. Selenosis, a rare but serious condition resulting from very high intake, is characterized by more severe symptoms such as neurological issues (e.g., tremors, irritability) and pronounced gastrointestinal disturbances. There are no major drug interactions reported at typical doses. Sodium selenate is contraindicated in individuals with existing selenium toxicity or known hypersensitivity. Caution is advised for pregnant or lactating individuals, and those with kidney or liver disease, as their ability to process and excrete selenium may be impaired, increasing the risk of accumulation and toxicity.

Dosage

The minimum effective dose for sodium selenate is not well-established, but the general Recommended Dietary Allowance (RDA) for selenium in adults is 55 μg/day. For general health, optimal dosage ranges for selenium (from various forms, including selenate) typically fall between 55–200 μg/day. In research settings, particularly for neurological studies, higher doses of sodium selenate, up to 1 mg/day, have been utilized in clinical trials. However, the long-term safety of these higher doses is not fully established. The established Upper Limit (UL) for selenium intake from all sources in adults is 400 μg/day; exceeding this limit significantly increases the risk of toxicity. Sodium selenate can be taken with or without food, as there is no strong evidence suggesting timing affects its efficacy. As a water-soluble inorganic salt, it is efficiently absorbed, and no specific cofactors are required for its absorption.

FAQs

Is sodium selenate safe to take daily?

Yes, sodium selenate is safe for daily use when taken within recommended dosages, typically up to 200 μg of selenium per day. It's crucial not to exceed the upper limit of 400 μg/day to avoid toxicity.

What is the main benefit of sodium selenate compared to other selenium forms?

Sodium selenate is particularly noted for its ability to effectively deliver selenium to the central nervous system, making it valuable in neurological research. Other forms may not cross the blood-brain barrier as efficiently.

Can sodium selenate help with blood sugar control?

While some animal studies suggest mixed effects on glycaemic control, there is currently no clear evidence to support the use of sodium selenate for blood sugar control in humans. More research is needed.

Are there any common side effects of sodium selenate?

At recommended doses, side effects are rare. However, high doses can lead to gastrointestinal upset, and chronic excessive intake may cause more severe symptoms like hair loss or neurological issues due to selenium toxicity.

Research Sources

https://www.cambridge.org/core/journals/british-journal-of-nutrition/article/effects-of-selenium-supplementation-on-glycaemic-control-markers-in-healthy-rodents-a-systematic-review-and-metaanalysis/4D644455D14B19862F1F8EC26FAA9E06 – This systematic review and meta-analysis investigated the effects of selenium supplementation on glycaemic control in rodents. It found mixed results, with low doses sometimes reducing fasting blood glucose, while high doses showed variable and sometimes detrimental effects, highlighting dose-dependency and the need for caution in translating animal data to humans.
https://pubmed.ncbi.nlm.nih.gov/30215171/ – This randomized controlled pilot trial demonstrated that supranutritional sodium selenate supplementation effectively increased selenium levels in the central nervous system of healthy adults. The study suggests sodium selenate's potential for delivering selenium to the brain, although it was a small-scale pilot study requiring further confirmation.
https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2023.1263853/full – This umbrella review synthesized evidence from 76 meta-analyses on selenium intake and various health outcomes. It concluded that higher dietary selenium intake is associated with a lower risk of all-cause mortality, but supplementary selenium intake did not consistently show this benefit, indicating differences between dietary and supplemental forms.
https://ods.od.nih.gov/factsheets/Selenium-HealthProfessional%20/ – This fact sheet from the Office of Dietary Supplements provides comprehensive information on selenium, including its functions, dietary sources, recommended intakes, deficiency symptoms, and health implications. It serves as a reliable source for general selenium guidelines and safety limits.
https://pubmed.ncbi.nlm.nih.gov/36268733/ – This study, likely the same as the first Cambridge URL, is a systematic review and meta-analysis focusing on the effects of selenium supplementation on glycaemic control markers in healthy rodents. It highlights the variability and dose-dependent nature of selenium's impact on glucose metabolism in animal models, emphasizing the need for careful interpretation.