title: Vascular endothelial function and oxidative stress are related to dietary niacin intake among healthy middle-aged and older adults.
abstract: We tested the hypothesis that vascular endothelial function and oxidative stress are related to dietary niacin intake among healthy middle-aged and older adults. In 127 men and women aged 48-77 yr, brachial artery flow-mediated dilation (FMD) was positively related to dietary niacin intake [%change (Δ): r = 0.20, P < 0.05; mmΔ: r = 0.25, P < 0.01]. In subjects with above-average dietary niacin intake (≥ 22 mg/day, NHANES III), FMD was 25% greater than in subjects with below-average intake (P < 0.05). Stepwise linear regression revealed that dietary niacin intake (above vs. below average) was an independent predictor of FMD (%Δ: β = 1.8; mmΔ: β = 0.05, both P < 0.05). Plasma oxidized low-density lipoprotein, a marker of systemic oxidative stress, was inversely related to niacin intake (r = -0.23, P < 0.05) and was lower in subjects with above- vs. below-average niacin intake (48 ± 2 vs. 57 ± 2 mg/dl, P < 0.01). Intravenous infusion of the antioxidant vitamin C improved brachial FMD in subjects with below-average niacin intake (P < 0.001, n = 33), but not above-average (P > 0.05, n = 20). In endothelial cells sampled from the brachial artery of a subgroup, dietary niacin intake was inversely related to nitrotyrosine, a marker of peroxynitrite-mediated oxidative damage (r = -0.30, P < 0.05, n = 55), and expression of the prooxidant enzyme, NADPH oxidase (r = -0.44, P < 0.01, n = 37), and these markers were lower in subjects with above- vs. below-average niacin intake [nitrotyrosine: 0.39 ± 0.05 vs. 0.56 ± 0.07; NADPH oxidase: 0.38 ± 0.05 vs. 0.53 ± 0.05 (ratio to human umbilical vein endothelial cell control), both P < 0.05]. Our findings support the hypothesis that higher dietary niacin intake is associated with greater vascular endothelial function related to lower systemic and vascular oxidative stress among healthy middle-aged and older adults.
authors: Department of Integrative Physiology, University of Colorado, Boulder, Colorado.
authors: Rachelle E
authors: RE
authors: Kaplon
authors: Lindsey B
authors: LB
authors: Gano
authors: Douglas R
authors: DR
authors: Seals
mesh_terms: D000368:Aged; D000975:Antioxidants / Q000008:administration & dosage; D001205:Ascorbic Acid / Q000008:administration & dosage; D001916:Brachial Artery / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D004032:Diet; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D005260:Female; D006801:Humans; D008077:Lipoproteins, LDL / Q000097:blood; D008297:Male; D008875:Middle Aged; D019255:NADPH Oxidases / Q000378:metabolism; D009525:Niacin / Q000008:administration & dosage*; D018384:Oxidative Stress / Q000187:drug effects* / Q000502:physiology; D012039:Regional Blood Flow / Q000187:drug effects; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology; D014665:Vasodilator Agents / Q000008:administration & dosage*; D014803:Vitamin B Complex / Q000008:administration & dosage*
chemical_list: D000975:Antioxidants; D008077:Lipoproteins, LDL; D014665:Vasodilator Agents; D014803:Vitamin B Complex; D009525:Niacin; C002744:3-nitrotyrosine; D014443:Tyrosine; D019255:NADPH Oxidases; D001205:Ascorbic Acid
keywords: NADPH oxidase; flow-mediated dilation; oxidized low-density lipoprotein