How much selenium was being used in SELECT? What risks were involved with taking selenium?
The amount of selenium (provided as l-selenomethionine) was 200 micrograms (μg) daily. Although the initial results of the NPC trial showed an overall decrease in cancer incidence from selenium, a 2003 update reported 17 percent more new non-melanoma skin cancers in the selenium group compared with the placebo group (8). It is not clear how these results would apply to men who did not already have skin cancer when they enrolled in SELECT, or to men who are not at increased risk for skin cancer. Since the start of SELECT, four studies have been published looking at the effect of selenium on blood glucose and risk of diabetes: two studies suggested that higher levels of selenium taken from supplements or received naturally were associated with an increased risk of diabetes. One study showed no association between the two, and one showed that people with higher levels of selenium in their blood had a reduced risk of diabetes (9-12). Starting in early 2007, the SELECT DSMC was specifically
