TL;DR Summary: How Fast Does Selenium Work?
In most people, selenium supplements start working within 30-60 minutes of ingestion, depending on several factors, including the type of selenium you are taking, your metabolism, and how you take it (with or without food). Selenium supplements absorb the fastest, but topical selenium gels and creams are not too far behind in terms of efficacy. Keep in mind, however, that you are unlikely to notice any effects from selenium supplementation itself. Selenium is more of a multivitamin-type of a compound, where you take it for general health support and to cover any nutrient deficiency.
What is Selenium?
Selenium is a mineral that is naturally found in plant and animal products. It has been studied for the past several decades for its potential benefits. 
Selenium has been touted as an important nutritional supplement, with many people touting it to be able to reduce inflammation caused by arthritis and other diseases. Selenium has been studied in some very impressive ways, and we know that it is beneficial.
The issue arises when consumers are looking to try products that might help them with their arthritis and other diseases, they just don’t have a way to know what is the best quality selenium product.
- Selenium supplements are often marketed as a way to reduce inflammation caused by arthritis and other diseases. They are able to do this because they can block the production of certain cytokines that cause inflammation.
There is no uniform regulation on what makes a selenium supplement “good” or “bad.” This means it is tough to know if a selenium supplement is just doing what it says it can do, or if the product has other side effects.
It’s hard to say how much selenium is enough for any given person, but for most people, 200 to 300 mcg per day is a safe dosage according to current evidence. More than that can be pro-diabetic and causing increased oxidative stress.
What are the benefits of Selenium?
Selenium is a trace mineral that is important for human health and the antioxidant properties of selenium help to protect cells and tissues.  Selenium can be obtained through the diet, but it may be difficult to achieve the optimal dose depending on your diet. Supplementation provides a more reliable source of selenium than dietary intake – if your diet is lacking. If you’re already eating foods like pork, beef, and Brazil nuts, you don’t need a selenium supplement.
Selenium supplementation may reduce the risk of colorectal cancer, heart disease, and infections. It also affects the regulation of many vital cellular processes. Furthermore, it works as an antioxidant and protects cells against free radicals which can damage DNA and cause cancer in some cases. In the context of this article, Selenium is also a solid joint health supplement because it helps to improve the elasticity of joints and reduce cartilage inflammation. This is why you’ll often see selenium in the best joint supplements.
How does it work?
Selenium may help protect against heart disease and infections by helping the body process cholesterol and reducing inflammation and oxidative stress. However, too much selenium can have a contra effect, so it’s crucial to have a healthy balance.
Additionally, selenium has been shown to protect against certain other cancers by working as an antioxidant. Selenium also affects many vital cellular processes such as cell growth, gene expression, and protein synthesis.
How fast does Selenium work?
Selenium typically starts working within 30-45 minutes, depending on how you took the supplement and whether you consumed any food with it. It can be taken by mouth or applied to the skin as an ointment or cream at a dose of 200 micrograms per day.
Selenium is a supplement that you can take to support your immune system. The selenium supplement is a natural substance found in small amounts in certain foods.
Selenium helps fight free radicals, and boosts the production of glutathione, which is the body’s natural antioxidant.
How fast does Selenium leave the body?
Selenium is a trace mineral, there is no set half-life for it. The half-life of selenium can differ from person to person. It also depends on the situation and on what type of selenium you are taking. If you are taking a supplement, you should consult your doctor who should know more about this topic.
According to the National Institutes of Health, the selenium half-life varies from person to person: Selenium generally has a short half-life in humans, which is why it is not recommended that people take amounts greater than 400 μg per day. 
- Rayman MP. Selenium intake, status, and health: a complex relationship. Hormones (Athens). 2020 Mar;19(1):9-14. doi: 10.1007/s42000-019-00125-5. Epub 2019 Aug 6. PMID: 31388899; PMCID: PMC7033057.
- Nessel TA, Gupta V. Selenium. [Updated 2022 Apr 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK557551/