Folic acid: a marker of endothelial function in type 2 diabetes?

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Authors: Arduino A Mangoni, Roy A Sherwood, Belinda Asonganyi, Emma L Ouldred, Stephen Thomas, Stephen HD Jackson

Published Date January 2005 Volume 2005:1(1) Pages 79 - 83

DOI: http://dx.doi.org/10.2147/VHRM.S

Arduino A Mangoni¹, Roy A Sherwood², Belinda Asonganyi², Emma L Ouldred³, Stephen Thomas⁴, Stephen HD Jackson³

¹Department of Clinical Pharmacology, Centre for Neuroscience, School of Medicine, Flinders University, Adelaide, SA, Australia; ²Clinical Biochemistry, King’s College Hospital, London, UK; ³Department of Health Care of the Elderly, Guy’s, King’s, and St Thomas’ School of Medicine, King’s College, London, UK; ⁴Department of Diabetic Medicine, King’s College Hospital, London, UK

Objectives: Endothelial dysfunction is a common feature of type 2 diabetes. Recent studies suggest that the B-vitamin folic acid exerts direct beneficial effects on endothelial function, beyond the well known homocysteine lowering effects. Therefore, folic acid might represent a novel “biomarker” of endothelial function. We sought to determine whether plasma levels of folic acid determine endothelial-dependent vasodilation in patients with type 2 diabetes.

Methods: Forearm arterial blood flow (FABF) was measured at baseline and during intrabrachial infusion of the endothelial-dependent vasodilator acetylcholine (15 µg/min) and the endothelial-independent vasodilator sodium nitroprusside (2 µg/min) in 26 type 2 diabetic patients (age 56.5 ± 0.9 years, means ± SEM) with no history of cardiovascular disease.

Results: FABF ratio (ie, the ratio between the infused and control forearm FABF) significantly increased during acetylcholine (1.10 ± 0.04 vs 1.52 ± 0.07, p < 0.001) and sodium nitroprusside (1.12 ± 0.11 vs 1.62 ± 0.06, p < 0.001) infusions. After correcting for age, gender, diabetes duration, smoking, hypertension, body mass index, microalbuminuria, glycated hemoglobin, low-density lipoprotein cholesterol, and homocysteine, multiple regression analysis showed that plasma folic acid concentration was the only independent determinant (p = 0.037, R2 = 0.22) of acetylcholine-mediated, but not sodium nitroprusside-mediated, vasodilatation.

Conclusions: Folic acid plasma concentrations determine endothelium-mediated vasodilatation in patients with type 2 diabetes. These results support the hypothesis of a direct effect of folic acid on endothelial function and the rationale for interventions aimed at increasing folic acid levels to reduce cardiovascular risk.

Keywords: folic acid, homocysteine, endothelium, type 2 diabetes

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