What is selenium

Selenium is a dietary supplement. How it works to treat arthritis isn’t well understood, but it might be related to its antioxidant properties. Current evidence, based on published RCTs, suggests that selenium supplements aren’t effective in treating rheumatoid arthritis.

  • Family: Nutritional supplement
  • Scientific name: Selenium
  • Other names: Selenomethionine

Selenium is a trace mineral which is important for many vital functions in your body. For medicinal purposes, the mineral is usually produced from yeast. You can buy selenium supplements over the counter from pharmacies and health food shops, mainly as an ingredient in multivitamin capsules

How does it work?

Some studies have found that people with rheumatoid arthritis have low levels of selenium in their blood compared to people without the disease. How selenium may work to treat rheumatoid arthritis isn’t well understood, but it might be related to its antioxidant properties. Selenium is a crucial part of a number of enzymes, a substance made by your body to help bring about a specific reaction. Some of these enzymes are involved in specific pathways in your body that can prevent cell damage (usually by interacting with harmful molecules known as free radicals which are produced within the cells).

Is it safe?

The daily recommended dietary allowance of selenium is 80–200 micrograms (μg), and it’s well tolerated if no more than this is taken. We don’t yet have a recommended effective and safe does for arthritis and musculoskeletal conditions, but most trials used a dose of 200 μg.

Interactions with other medications are unlikely if selenium is taken in low or moderate doses. Selenium can be toxic if taken in high doses and may cause:

  • gastrointestinal symptoms
  • liver and kidney problems
  • skin changes
  • hair loss.

Trials for rheumatoid arthritis

This review article identified three complete reports of RCTs of selenium treatment in rheumatoid arthritis. The number of participants included in the trials ranged from 40–70 and the trials lasted from three to six months. The active treatment in all trials was selenium capsules (200 μg per day in two trials and 256 μg per day in one trial). The control group in all trials was made up of participants on placebo capsules.

  • In the first trial (40 participants over six months), there was no significant difference between those who were given selenium or placebo in all aspects of disease severity, including pain, morning stiffness and number of swollen joints.
  • In the second trial‡ (55 people over three months), there was no significant difference between participants taking selenium or placebo in pain reduction, morning stiffness and number of swollen joints. Participants on selenium had better arm movement and a perception of better general health.
  • The third trial (70 people over three months) found that there was no significant difference between participants who were on selenium or placebo in terms of pain reduction, morning stiffness, number of swollen joints and non-steroidal anti-inflammatory drug (NSAID) use.

‡ A trial of low quality. Results of this trial were given a lower weighting when we came to our conclusion about the compound.