Low body mass index is a risk factor forimpaired endothelium-dependent vasodilation in humans: role of nitric oxide and oxidative stress

Objectives The purpose of this study was to evaluate the relationship between body mass index (BMI), including low BMIs, and endothelial function. Background Epidemiologic study has demonstrated that not only obesity but also a low BMI may be a risk factor for cardiovascular disease. Methods The forearm blood flow (FBF) response to acetylcholine (ACh) and isosorbide dinitrate (ISDN) was measured in 87 healthy young men (15 low BMI, 51 normal, 14 obese, and 7 extremely obese). Results Plasma concentrations of 8-hydroxy-2′-deoxyguanosine and serum concentrations of malondialdehyde-modified low-density lipoprotein were higher in low BMI, obese, and extremely obese subjects than in normal subjects and were similar among the low BMI, obese, and extremely obese groups. The FBF response to ACh was greater in the normal group than in the other groups (p < 0.001), and was lower in the extremely obese group as compared with the other groups (p < 0.001). The ACh-stimulated vasodilation was similar between the low BMI group and the obese group. The ISDN-stimulated vasodilation was similar in all four groups. There were no significant differences in ACh-stimulated vasodilation between the four groups after the nitric oxide (NO) synthase inhibitor NG-monomethyl-L-arginine infusion. Co-infusion of vitamin C augmented the FBF response to ACh in low BMI, obese, and extremely obese groups—but not in normal BMI group. Conclusions These findings suggest that not only obesity but also a low BMI may be a risk factor for impaired endothelium-dependent vasodilation through the increased oxidative stress, leading to the reduced bioavailability of NO.