Global Improvement of Vascular Function and Redox State With Low-Dose Folic Acid: Implications for Folate Therapy in Patients With Coronary Artery Disease

@article{citeulike:2960385, abstract = {Background-- Although dietary folate fortification lowers plasma homocysteine and may reduce cardiovascular risk, high-dose folic acid therapy appears to not alter clinical outcome. Folic acid and its principal circulating metabolite, 5-methyltetrahydrofolate, improve vascular function, but mechanisms relating folate dose to vascular function remain unclear. We compared the effects of folic acid on human vessels using pharmacological high-dose versus low-dose treatment, equivalent to dietary folate fortification. Methods and Results-- Fifty-six non-folate-fortified patients with coronary artery disease were randomized to receive low-dose (400 {micro}g/d) or high-dose (5 mg/d) folic acid or placebo for 7 weeks before coronary artery bypass grafting. Vascular function was quantified by magnetic resonance imaging before and after treatment. Vascular superoxide and nitric oxide bioavailability were determined in segments of saphenous vein and internal mammary artery. Low-dose folic acid increased nitric oxide-mediated endothelium-dependent vasomotor responses, reduced vascular superoxide production, and improved enzymatic coupling of endothelial nitric oxide synthase through availability of the cofactor tetrahydrobiopterin. No further improvement in these parameters occurred with high-dose compared with low-dose treatment. Whereas plasma 5-methyltetrahydrofolate increased proportionately with treatment dose of folic acid, vascular tissue 5-methyltetrahydrofolate showed no further increment with high-dose compared with low-dose folic acid. Conclusions-- Low-dose folic acid treatment, comparable to daily intake and dietary fortification, improves vascular function through effects on endothelial nitric oxide synthase and vascular oxidative stress. High-dose folic acid treatment provides no additional benefit. These direct vascular effects are related to vascular tissue levels of 5-methyltetrahydrofolate rather than plasma levels. High-dose folic acid treatment likely confers no further benefit in subjects already receiving folate supplementation. 10.1161/CIRCULATIONAHA.106.679084}, author = {Shirodaria, Cheerag and Antoniades, Charalambos and Lee, Justin and Jackson, Clare E. and Robson, Matthew D. and Francis, Jane M. and Moat, Stuart J. and Ratnatunga, Chandi and Pillai, Ravi and Refsum, Helga and Neubauer, Stefan and Channon, Keith M. }, citeulike-article-id = {2960385}, doi = {http://dx.doi.org/10.1161/CIRCULATIONAHA.106.679084}, journal = {Circulation}, keywords = {aging, cu, cvd, edd, vessel}, month = {May}, number = {17}, pages = {2262--2270}, posted-at = {2008-07-03 20:22:06}, priority = {0}, title = {Global Improvement of Vascular Function and Redox State With Low-Dose Folic Acid: Implications for Folate Therapy in Patients With Coronary Artery Disease}, url = {http://dx.doi.org/10.1161/CIRCULATIONAHA.106.679084}, volume = {115}, year = {2007} }

TY - JOUR ID - citeulike:2960385 L3 - citeulike-article-id:2960385 TI - Global Improvement of Vascular Function and Redox State With Low-Dose Folic Acid: Implications for Folate Therapy in Patients With Coronary Artery Disease JF - Circulation VL - 115 IS - 17 SP - 2262 EP - 2270 N2 - Background-- Although dietary folate fortification lowers plasma homocysteine and may reduce cardiovascular risk, high-dose folic acid therapy appears to not alter clinical outcome. Folic acid and its principal circulating metabolite, 5-methyltetrahydrofolate, improve vascular function, but mechanisms relating folate dose to vascular function remain unclear. We compared the effects of folic acid on human vessels using pharmacological high-dose versus low-dose treatment, equivalent to dietary folate fortification. Methods and Results-- Fifty-six non-folate-fortified patients with coronary artery disease were randomized to receive low-dose (400 {micro}g/d) or high-dose (5 mg/d) folic acid or placebo for 7 weeks before coronary artery bypass grafting. Vascular function was quantified by magnetic resonance imaging before and after treatment. Vascular superoxide and nitric oxide bioavailability were determined in segments of saphenous vein and internal mammary artery. Low-dose folic acid increased nitric oxide-mediated endothelium-dependent vasomotor responses, reduced vascular superoxide production, and improved enzymatic coupling of endothelial nitric oxide synthase through availability of the cofactor tetrahydrobiopterin. No further improvement in these parameters occurred with high-dose compared with low-dose treatment. Whereas plasma 5-methyltetrahydrofolate increased proportionately with treatment dose of folic acid, vascular tissue 5-methyltetrahydrofolate showed no further increment with high-dose compared with low-dose folic acid. Conclusions-- Low-dose folic acid treatment, comparable to daily intake and dietary fortification, improves vascular function through effects on endothelial nitric oxide synthase and vascular oxidative stress. High-dose folic acid treatment provides no additional benefit. These direct vascular effects are related to vascular tissue levels of 5-methyltetrahydrofolate rather than plasma levels. High-dose folic acid treatment likely confers no further benefit in subjects already receiving folate supplementation. 10.1161/CIRCULATIONAHA.106.679084 KW - aging KW - cu KW - cvd KW - edd KW - vessel AU - Shirodaria, Cheerag AU - Antoniades, Charalambos AU - Lee, Justin AU - Jackson, Clare AU - Robson, Matthew AU - Francis, Jane AU - Moat, Stuart AU - Ratnatunga, Chandi AU - Pillai, Ravi AU - Refsum, Helga AU - Neubauer, Stefan AU - Channon, Keith PY - 2007/05/01/ UR - http://dx.doi.org/10.1161/CIRCULATIONAHA.106.679084 ER -