Vitamin B-12 supplementation improves arterial function in vegetarians with subnormal vitamin B-12 status

J Nutr Health Aging. 2012;16(6):569-73. doi: 10.1007/s12603-012-0036-x.


Objective: Vegetarians are more vascular-healthy but those with subnormal vitamin B-12 status have impaired arterial endothelial function and increased intima-media thickness. We aimed to study the impact of vitamin B-12 supplementation on these markers, in the vegetarians.

Design: Double-blind, placebo controlled, randomised crossover study.

Setting: Community dwelling vegetarians.

Participants: Fifty healthy vegetarians (vegetarian diet for at least 6 years) were recruited.

Intervention: Vitamin B-12 (500 µg/day) or identical placebo were given for 12 weeks with 10 weeks of placebo-washout before crossover (n=43), and then open label vitamin B-12 for additional 24 weeks (n=41).

Measurement: Flow-mediated dilation of brachial artery (FMD) and intima-media thickness (IMT) of carotid artery were measured by ultrasound.

Results: The mean age of the subjects was 45±9 years and 22 (44%) were male. Thirty-five subjects (70%) had serum B-12 levels <150 pmol/l. Vitamin B-12 supplementation significantly increased serum vitamin B-12 levels (p<0.0001) and lowered plasma homocysteine (p<0.05). After vitamin B-12 supplementation but not placebo, significant improvement of brachial FMD (6.3±1.8% to 6.9±1.9%; p<0.0001) and in carotid IMT (0.69±0.09 mm to 0.67±0.09 mm, p<0.05) were found, with further improvement in FMD (to 7.4±1.7%; p<0.0001) and IMT (to 0.65±0.09 mm; p<0.001) after 24 weeks open label vitamin B-12. There were no significant changes in blood pressures or lipid profiles. On multivariate analysis, changes in B-12 (β=0.25; p=0.02) but not homocysteine were related to changes in FMD, (R=0.32; F value=3.19; p=0.028).

Conclusions: Vitamin B-12 supplementation improved arterial function in vegetarians with subnormal vitamin B-12 levels, proposing a novel strategy for atherosclerosis prevention.

Publication types

  • Clinical Trial
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Arteries / pathology
  • Arteries / physiopathology*
  • Biomarkers
  • Brachial Artery / diagnostic imaging
  • Brachial Artery / physiopathology
  • Carotid Arteries / diagnostic imaging
  • Carotid Arteries / pathology
  • Carotid Intima-Media Thickness
  • Cross-Over Studies
  • Diet, Vegetarian / adverse effects*
  • Diet, Vegetarian / ethnology
  • Dietary Supplements*
  • Double-Blind Method
  • Endothelium, Vascular / pathology
  • Endothelium, Vascular / physiopathology*
  • Female
  • Homocysteine / blood
  • Hong Kong
  • Humans
  • Male
  • Middle Aged
  • Vasodilation
  • Vitamin B 12 / blood
  • Vitamin B 12 / therapeutic use*
  • Vitamin B 12 Deficiency / diet therapy*
  • Vitamin B 12 Deficiency / ethnology
  • Vitamin B 12 Deficiency / etiology
  • Vitamin B 12 Deficiency / physiopathology


  • Biomarkers
  • Homocysteine
  • Vitamin B 12