Selenium

What it is


Selenium is a trace element that is essential for human health, but required only in small amounts. It was first discovered in 1817 by a Swedish chemist, Jöns Jakob Berzelius, but it was not until the mid-20th century that its potential health benefits began to be explored. One of the primary ways in which selenium is believed to benefit human health is through its role in neurocognition.


Selenium is a key component of several enzymes that are involved in the production of neurotransmitters, which are chemical messengers that play a crucial role in brain function. There is some evidence to suggest that selenium supplementation may improve cognitive function in older adults, particularly in those who are selenium deficient. In one study, selenium supplementation was found to improve mental processing speed, verbal learning, and verbal fluency in older adults with mild cognitive impairment.


There are several forms of selenium available on the market, including selenium yeast, selenium sulfide, and selenomethionine. Selenium yeast is a form of selenium that is produced by growing yeast in a selenium-rich medium. It is considered to be a more bioavailable form of selenium, meaning that it is more easily absorbed by the body. Selenium sulfide is a form of selenium that is commonly used in shampoos and other topical products for the treatment of dandruff and seborrheic dermatitis. Selenomethionine is a form of selenium that is found naturally in some plant-based foods, such as Brazil nuts and whole grains.



How it works


Selenium is involved in a number of important processes in the body. It is a key component of several enzymes, including glutathione peroxidase, which helps to protect cells from oxidative stress. Selenium is also involved in the production of thyroid hormones and in the functioning of the immune system. In addition to its role in enzyme function, selenium has been shown to have antioxidant properties, meaning that it can help to protect cells from damage caused by free radicals. It has also been linked to a reduced risk of certain types of cancer, although the evidence for this is mixed and more research is needed.


The felt effects of selenium supplementation can vary depending on the individual and the dosage. At appropriate doses, selenium supplementation may produce little to no noticeable effects. However, some people may experience an improvement in cognitive function, particularly if they are deficient in selenium. It is important to note that while selenium has been shown to have potential health benefits, it is also possible to have too much selenium in the body, which can lead to toxicity. Symptoms of selenium toxicity may include nausea, vomiting, and hair loss. In severe cases, selenium toxicity can lead to neurological problems such as tremors and difficulty walking.



How it is taken


The typical way that most people use selenium as a supplement is by taking a daily dose in the form of a capsule, tablet, or liquid. The recommended daily intake of selenium for adults is 55 mcg for men and women. It is generally considered safe to consume up to 400 mcg of selenium per day, although higher amounts may cause negative side effects such as nausea, vomiting, and hair loss. As with any supplement, it is important to speak with a healthcare provider before starting a selenium supplement regimen to determine the appropriate dosage. Factors such as age, sex, and overall health can all impact the optimal dose of selenium.


In terms of the best time of day to take selenium, it can be taken at any time of day as long as it is consistently taken at the same time each day. Some people find it convenient to take their selenium supplement in the morning with breakfast, while others prefer to take it in the evening with dinner. It is ultimately a matter of personal preference and what works best for the individual.




References and further reading:

  1. Whanger PD. Selenium in the treatment of heavy metal toxicity and chemical carcinogenesis: a review. Journal of Trace Elements in Experimental Medicine. 1992;5(1):43-51.

  2. Combs GF Jr. Selenium in global food systems. British Journal of Nutrition. 2001;85(2):517-47.

  3. Rayman MP. The importance of selenium to human health. Lancet. 2000;356(9225):233-41.

  4. Schrauzer GN, Shrestha KP. Selenium in the environment and human health. Environmental Pollution. 2002;116(1):9-19.

  5. Beck MA, Levander OA. Selenium in human health and disease. Annual Review of Nutrition. 2002;22:517-41.