Selenium is growing in popularity, but is it safe for all patients?

By Lisa Marie Basile | Fact-checked by Davi Sherman
Published May 18, 2023

Key Takeaways

  • More people are taking selenium supplements to help them sleep.

  • Most people get enough selenium through their food, but some may need to take supplements for their health.

  • Taking too much selenium can cause adverse symptoms like nausea and hair loss.

It’s no secret that the COVID-19 pandemic has had a serious impact on mental health, leading to a rise in depression, anxiety, and insomnia. As a physician, you know how inextricably linked mental health and sleep hygiene are, so it’s also not surprising that people who don’t sleep well are more likely to experience mental health issues, such as depression.[] 

In fact, the National Sleep Foundation's 2023 Sleep in America Poll found that adults who sleep less than seven hours per weekday night were three times as likely to have moderate to severe depressive symptoms compared to those who sleep at least seven hours (the amount recommended by the American Academy of Sleep Medicine and the Sleep Research Society) each night.[][] 

All of this may explain why so many people are trying to find ways to improve their sleep hygiene. Your patients may even be reporting sleeping struggles, hoping to find a way to solve the issue—from trying social media trends like the “sleepy girl mocktail” to taking selenium supplements. 

Related: What is the “sleepy girl mocktail”—and should your patients drink it?

Selenium has been making the rounds in recent news reports for its potential sleep-inducing qualities—but is it safe?

What you should know about selenium 

Selenium is a trace element found in a few rare minerals, and it is naturally present in many foods, including organ meats, eggs, poultry, cereals and grains, Brazil nuts, and seafood. It is essential for human health, as it plays a role in “reproduction, thyroid hormone metabolism, DNA synthesis, and protection from oxidative damage and infection,” according to the National Institutes of Health (NIH).[] 

The recommended dietary allowance (RDA) for adult men and women is 55 mcg(except for pregnant and lactating women, who should have 60 mcg and 70 mcg per day, respectively). 

Currently, most people in the United States get enough selenium, as the food they eat is grown or raised in areas with selenium-rich soil, according to the NIH. That said, researchers say this may not always be the case, with predictions that one out of seven people will struggle to get enough selenium in the future. In fact, Environment International says that 39% to 61% of Chinese residents have a low daily intake of selenium. 

Certain groups of patients may also not get enough selenium, including people with HIV, people undergoing kidney dialysis, and people whose food is not grown in selenium-rich soil, the NIH also says. Certain medications may also lower selenium levels.[]  

However, it is possible to reach the upper limit of selenium intake (400 mcg per day for adults) by eating a lot of selenium-rich foods, like Brazil nuts, the NIH warns. Your patients should be warned against overconsuming these foods in an effort to gain better sleep. 

According to a 2023 study published in Nutrients, selenium is gaining popularity, especially in biology and medicine, since “[t]he antioxidant role of [selenium] is important to improve sleep quality and sleep duration.” The study, which looked at a Chinese population that was getting less than the RDA of selenium, found that “[s]elf-reported optimum sleep duration and [selenium] intake were positively correlated” and that “people who consumed large amounts of [selenium] experience the best sleep.”[] 

Why is this the case? The researchers posited that since poor sleep is associated with oxidative stress and antioxidant imbalance, the selenoenzymes in selenium could act as a defense against oxidative stress. 

The study also states that “[a]ntioxidant consumption may influence sleep because sleep duration can be affected by pro-inflammatory cytokines,” which are “associated with increased body temperature, reduced nREM sleep duration, and increased wakefulness, thereby proving that having insomnia is connected to increased plasma cytokine levels.” Thus, the antioxidants, the researchers explained, could inhibit the pro-inflammatory cytokines' expression, which promotes healthy sleep. 

The study noted that the consumption of selenium had the most impact on people with a high body mass index. 

Selenium may also help patients with obstructive sleep apnea, says Amanda Frick, ND, a trained naturopathic doctor and Vice President of Medical Affairs at Thorne. “An individual who is deficient in selenium might experience sleep abnormalities. Research … has found that individuals who consume sufficient selenium are able to fall asleep more quickly and stay asleep longer, particularly when they suffer from sleep apnea (OSA).”

The journal Sleep and Breathing found that increased selenium concentrations in patients with OSA who do not have any other comorbidities “may be important defense mechanisms” and that “[a]ntioxidant nutrients or supplements may be implemented as a complementary treatment of OSA to support antioxidant defense.”[]

While selenium’s benefits are clearly demonstrated, patients need to take the right amount. Consuming selenium in excess quantities, particularly for an extended period of time, can cause selenium toxicity,” Frick adds. 

Toxicity is rare, but it can occur—and has happened in cases where supplements were improperly manufactured. Symptoms of selenium toxicity can include nausea, vomiting, nail discoloration or brittleness, hair loss, foul breath, or fatigue, according to the Archives of Internal Medicine.[]

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