In the KiSel-10 study, 443 Swedish citizens aged 70 to 88 received either a combined daily supplementation of high-selenium yeast and Coenzyme Q10 or matching placebos. The elderly Swedish citizens who received the active treatment of selenium and Coenzyme Q10 had significantly reduced risk of death from heart disease, significantly better heart function as recorded on echocardiograms, and significantly lower levels of a bio-marker indicating an increased risk of heart failure.