Author
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Hawkes, Wayne |
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LASLETT, LAWRENCE - UCDAVIS, CARDIOVASCULARER |
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Submitted to: Journal of Cell Biology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 11/22/2008 Publication Date: 11/26/2008 Citation: Hawkes, W.C., Laslett, L.J. 2008. Selenium Supplementation Does Not Improve Vascular Responsiveness in Healthy North American Men. Journal of Cell Biology. 296: H256-H262, 2009. Interpretive Summary: Risk for cardiovascular disease is influenced by many dietary factors. Populations with higher selenium intakes have lower rates of cardiovascular disease than populations with lower selenium intakes and animals treated with selenium are protected against atherosclerosis, or "hardening of the arteries". Since selenium deficiency is extremely rare in the United States, the relevant issue is whether selenium supplementation offers any further improvement in cardiovascular health. We tested the effects of taking 300 micrograms of selenium in high-selenium yeast tablets for one year in 42 healthy, free-living men who were already getting an average of 135 micrograms per day from their usual diets. We found that selenium supplementation had no effect on the responsiveness of subjects' veins, a major predictor of heart attacks. Our research shows that selenium supplementation does not improve vascular responsiveness in men receiving adequate dietary selenium and suggests that selenium affects cardiovascular health through a different mechanism. Technical Abstract: Selenium is an essential trace element that is an integral part of many selenoproteins, such as glutathione peroxidase and thioredoxin reductase, which may be important in inflammation and cardiovascular disease. In animal studies, selenium deficiency is associated with cardiomyopathy and sudden death. In humans, selenium deficiency has been implicated in the etiology of cardiovascular disease and other conditions in which oxidative stress and inflammation are prominent features. To test whether an increased intake of dietary selenium affects endothelial function, we conducted a randomized, placebo-controlled trial of selenium supplementation in free-living men. Forty-two men were administered 300 micrograms of selenium a day as high-selenium Baker’s yeast, or low-selenium placebo yeast for 48 weeks. Tests of brachial artery responsiveness to transient occlusion were performed at baseline and after 24 and 48 weeks of supplementation. After 48 weeks of supplementation, selenium concentration increased 50% in blood plasma and erythrocytes. There was no effect of selenium on arterial diameter or blood flow rate before or after transient ischemia, or on the maximum dilated diameter after administration of nitroglycerin. This study suggests that selenium supplementation is not likely to improve peripheral arterial responsiveness in healthy North American men and that other mechanisms are responsible for selenium’s beneficial effects on cardiovascular health. |
