Low blood selenium levels may be not linked to higher risk of lung cancer

Low blood selenium concentrations may not be an independent risk factor for lung cancer in men, according to a new Danish study.

In the observational study, serum selenium concentrations and cases of lung cancer were monitored in 3,333 males aged 53 to 74 years over the course of 16 years (1). The study results showed no difference in the rate of lung cancer among men with low selenium levels (0.4-1.0 ?mol/l) versus those with high selenium levels (1.3-3.0 ?mol/l). After taking all potential confounders into account, such as alcohol, fat, and salt intake, high serum selenium was associated with a significantly increased risk of lung cancer mortality among heavy smokers.

The researchers commented that these findings could not prove whether selenium affects the risk of cancer over a very long period of time. The reason for the observed increase in the risk of lung cancer was unknown and may have had nothing to do with selenium itself. More studies involving selenium and a range of health outcomes would be needed to determine that. The best advice for smokers who want to decrease their risk of lung cancer is to stop smoking.

Selenium is a trace element which aids the body's antioxidant defenses, helping to limit the cell damage that can lead to diseases like cancer. Some studies have found that people with relatively high selenium levels have a lower risk of certain cancers, including lung cancer, while others have failed to find a link. In the U.S., the recommended dose of selenium for adults is 55 micrograms per day (and 60 and 70 micrograms per day during pregnancy and breastfeeding, respectively). The tolerable upper intake limit for selenium is set at
400 micrograms per day for adults. Too much selenium can cause selenosis, causing symptoms like gastrointestinal problems, hair loss, fatigue, and mild nerve damage.

1. Suadicani P. et al. Serum selenium level and risk of lung cancer mortality. Eur Respir J. Online publication November 2011.