Selenium is a trace element that is naturally found in a variety. Since selenium is naturally found in food, it qualifies as a dietary ingredient, and therefore, it may also be sold as a dietary supplement.
In the U.S., selenium deficiency is rare because the food supply contains plenty of selenium. In fact, selenium is also found in the water supply in some regions, and the Environmental Protection Agency has issued toxicity guidelines for those who may be exposed to too much selenium (such as those who live close to coal burning power plants or other mines). Despite this, there are plenty of selenium supplements on the market. Selenium can be purchased by itself or as an ingredient in a multivitamin.
In 2008, the FDA investigated adverse events related to selenium overdose from a dietary supplement. Consumers experienced hair loss, changes in the shape and texture of their fingernails, stomach upset and diarrhea, headache, nausea, and memory problems. It turned out the overdose was caused by a manufacturing error which led to the consumers ingesting more than 200 times the recommended amount of selenium.
There is certainly a time and place for supplementing selenium, for instance when someone has a gastrointestinal disorder that causes them to not absorb selenium well from their food, or in countries like China where food is grown in soil poor in selenium. There are also some indications that people who have the correct amount of selenium in the blood are less likely to develop certain diseases.
In the U.S., however, most people are not deficient in selenium. So, why would they take more? Often, it is because they wanted to do something good for their health. There are plenty of companies that tout the health benefits of selenium, and there are plenty of products on supermarket and nutrition store shelves. So, many people assume it must be safe and decide to give it a try. Others may have purchased a multivitamin without having a full understanding of what all the ingredients are and what they do in the body, whether or not they need to supplement that specific element, or whether there were any risks associated with using them.
In the example here, a manufacturing error caused a number of consumers to receive toxic doses of selenium. The consumers probably had no idea there were any risks associated with selenium, and they probably never thought there could be a manufacturing problem that would cause such illness (it’s hard to imagine that something that is supposed to be healthy for you could actually make you sick).
In deciding whether or not to use a dietary supplement, it is important to fully understand and evaluate the pros and cons. The benefits should outweigh the risks. If they don’t, is it really worth it?
For food sources of selenium, read the National Institute of Health Fact Sheet on Selenium
To read more about how the Environmental Protection Agency protects consumers from too much selenium in their drinking water, click here.
To read more about the FDA investigation into the selenium overdose, click here.
To learn more about the toxicity of selenium, read the fact sheet written by the Agency for Toxic Substances and Disease Registry (US Department of Health and Human Services)