Selenium Ascorbate
Also known as: Selenium ascorbate, selenium combined with Vitamin C
Overview
Selenium ascorbate is a synthetic compound that combines selenium, an essential trace element, with ascorbate, the ionized form of ascorbic acid (Vitamin C). While selenium is naturally found in foods like Brazil nuts and seafood, and Vitamin C is abundant in fruits and vegetables, selenium ascorbate is a less common, engineered form designed to potentially leverage synergistic antioxidant effects. Selenium is crucial for the function of selenoproteins, which play a vital role in reducing oxidative damage, supporting immune function, and regulating thyroid hormone metabolism. Vitamin C is a potent water-soluble antioxidant that also supports collagen synthesis and immune cell function. Individually, both selenium and Vitamin C are well-researched for their health benefits, particularly their antioxidant properties. However, specific high-quality clinical research on selenium ascorbate as a distinct combined supplement form is currently limited, with most evidence derived from studies on selenium and Vitamin C taken separately or as part of broader antioxidant mixtures.
Benefits
Selenium supplementation, often in combination with antioxidants like Vitamin C, has demonstrated several evidence-based benefits. Meta-analyses suggest that moderate selenium intake (e.g., 10 μg/day increments) is associated with a reduced risk of all-cause mortality, with some studies showing up to a 21% lower risk. Selenium also shows potential in reducing cancer incidence and mitigating chemotherapy side effects, particularly when combined with other antioxidants. For instance, a systematic review found that antioxidant supplementation, including selenium and Vitamin C, had favorable effects on reducing treatment-related side effects in oncology patients. Antioxidant mixtures containing selenium have also been linked to decreased mortality in cardiovascular disease contexts. These benefits are most pronounced in adults at risk of selenium deficiency, cancer patients undergoing treatment, and individuals with cardiovascular disease risk. While the benefits of selenium and Vitamin C are well-established individually, the specific efficacy of selenium ascorbate as a combined form lacks dedicated high-quality clinical trials.
How it works
Selenium's primary mechanism of action involves its incorporation into selenoproteins, such as glutathione peroxidases and thioredoxin reductases. These enzymes are critical components of the body's antioxidant defense system, working to neutralize reactive oxygen species (ROS) and free radicals, thereby reducing oxidative damage. Selenium also plays a role in immune function and thyroid hormone metabolism. Ascorbate, or Vitamin C, acts as a direct antioxidant, scavenging free radicals and regenerating other antioxidants like Vitamin E. It also supports collagen synthesis and the proper functioning of immune cells. The combination in selenium ascorbate is theorized to provide enhanced antioxidant capacity by combining these two distinct yet complementary antioxidant pathways. While the specific bioavailability of selenium ascorbate is not fully characterized, the solubility and transport properties of ascorbate may potentially influence the absorption of selenium.
Side effects
Selenium supplementation is generally safe at recommended doses, but high intakes can lead to toxicity. The upper intake level for selenium is 400 μg/day; exceeding this can cause selenosis, characterized by symptoms such as hair loss, nail brittleness, fatigue, and neurological issues. Vitamin C is generally safe at typical doses, though very high intakes may cause gastrointestinal upset like diarrhea or nausea. Common side effects for selenium are primarily gastrointestinal discomfort at higher doses. Rare side effects include allergic reactions. Selenium may interact with certain chemotherapy agents, and antioxidant supplementation during cancer treatment should always be supervised by a healthcare professional. Vitamin C can also affect the absorption of some drugs. High-dose selenium is contraindicated in individuals already experiencing selenium toxicity, and caution is advised for patients with certain cancers or thyroid disorders. Special populations, including pregnant women, children, and those with renal impairment, require careful dosing due to increased sensitivity or altered metabolism.
Dosage
For adults, the recommended daily intake of selenium is 55 μg/day. Benefits, particularly in reducing all-cause mortality, have been observed with moderate intake levels, with increments of 10 μg/day linked to positive outcomes. The optimal dosage range for selenium supplementation typically falls between 55–200 μg/day. It is crucial not to exceed the maximum safe dose, which is an upper intake level of 400 μg/day, as higher doses significantly increase the risk of selenium toxicity (selenosis). Selenium supplements are generally recommended to be taken daily with meals to enhance absorption and minimize potential gastrointestinal discomfort. While organic forms of selenium, such as selenomethionine, are often preferred for their higher bioavailability, there are no specific dosing guidelines or absorption factors unique to selenium ascorbate. Adequate intake of other antioxidants, such as Vitamin E, may synergize with selenium's effects.
FAQs
Is selenium ascorbate more effective than selenium alone?
Currently, there is no high-quality clinical evidence to suggest that selenium ascorbate is superior in efficacy compared to other forms of selenium supplementation.
Is it safe to take selenium with Vitamin C?
Yes, combining selenium and Vitamin C supplementation is generally considered safe when taken within their respective recommended daily dosages.
How long does it take to see benefits from selenium supplementation?
Benefits, particularly those related to mortality reduction or cancer risk, typically require long-term supplementation, often observed over months to years.
Can selenium cause toxicity?
Yes, excessive intake of selenium, particularly above the upper intake level of 400 μg/day, can lead to a toxic condition known as selenosis.
Should selenium be taken with food?
Yes, taking selenium supplements with food is generally recommended as it can improve absorption and help reduce potential gastrointestinal side effects.
Research Sources
- https://pubmed.ncbi.nlm.nih.gov/37321210/ – This systematic review analyzed 24 studies on antioxidant supplementation in oncology patients, including selenium and Vitamin C. It found that such supplementation could favorably reduce treatment-related side effects with limited adverse effects, though it highlighted the need for large-scale randomized controlled trials to confirm these findings.
- https://pubmed.ncbi.nlm.nih.gov/33053149/ – This meta-analysis of randomized controlled trials investigated selenium supplementation and its impact on all-cause mortality. It concluded that antioxidant mixtures containing selenium were associated with reduced all-cause mortality, underscoring selenium's significant role in these beneficial outcomes.
- https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2023.1263853/full – This umbrella review, encompassing 76 meta-analyses, examined the relationship between selenium intake and various health outcomes. It provided dose-response evidence that moderate selenium intake (e.g., 10 μg/day increments) reduces the risk of all-cause mortality, but cautioned that the highest supplemental doses did not consistently yield additional benefits.
