Selenium is one of the most important dietary minerals human body needs. But the amount we need is very small. Selenium is incorporated in a small cluster of important proteins, each of which plays a critical role in our health. Scientists named these selenium-containing proteins “selenoproteins.” And, like all nutrients, selenium can reach a point where enough becomes too much and it begins to hurt rather than help. Your body needs what it needs; more isn’t necessarily better. In fact, if you consume too much selenium, you can experience selenium toxicity, also known as selenium poisoning. As you might guess, this is the presence of too much selenium in the body.
Selenium toxicity is actually more common in livestock than people. This is particularly true in the areas where the soil is rich in selenium. High selenium content in soil is absorbed by plants and passed on to livestock. But humans in those areas are also affected due to high selenium levels in water. And it is also passed from livestock to humans through meat.
Symptoms of Selenium Toxicity
Research suggests that the adult human body can tolerate up to 600 micrograms (µg) of selenium per day for 18 months without experiencing adverse health effects.
- Gastrointestinal Distress and Diarrhea— reported in over 75% of those observed suffering from selenium toxicity.
- Fatigue— reported by roughly 75% of those observed. Not surprising, as one of the key roles of selenium is as a helper for specific enzymes that regulate certain bodily functions related to energy production.
- Hair Loss— reported by over 70% of observed parties.
- Joint Pain— reported by about 70% of those observed.
- Nail Discoloration or Brittleness— reported by 61% of participants. Likely related to the hair loss.
- Nausea— reported in over half of those observed.
- Selenosis— a selenium-induced toxicity across multiple organs.
Selenium’s Role in Health Support
Anti- oxidant Protection
Selenium is required for the proper activity of a group of enzymes called glutathione peroxidases. These enzymes play a key role in the body’s detoxification system and they also provide protection against oxidative stress. Of the eight known glutathione peroxidase enzymes, five of them require selenium.
Supports Thyroid Function
A selenium-containing enzyme is responsible for transforming a less active thyroid hormone called T4 into the more active T3. As you’ll see below in the Relationship with Other Nutrients section, selenium and iodine work together to keep thyroid function strong and consistent.