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


METHODS
Double-blind, placebo controlled, randomised crossover study.


METHODS
Community dwelling vegetarians.


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


METHODS
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).


METHODS
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.
Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong SAR, China.
T
T
Kwok
P
P
Chook
M
M
Qiao
L
L
Tam
Y K P
YK
Poon
A T
AT
Ahuja
J
J
Woo
D S
DS
Celermajer
K S
KS
Woo
D000328:Adult; D001158:Arteries / Q000473:pathology / Q000503:physiopathology*; D015415:Biomarkers; D001916:Brachial Artery / Q000000981:diagnostic imaging / Q000503:physiopathology; D002339:Carotid Arteries / Q000000981:diagnostic imaging / Q000473:pathology; D059168:Carotid Intima-Media Thickness; D018592:Cross-Over Studies; D014676:Diet, Vegetarian / Q000009:adverse effects* / Q000208:ethnology; D019587:Dietary Supplements; D004311:Double-Blind Method; D004730:Endothelium, Vascular / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D006710:Homocysteine / Q000097:blood; D006723:Hong Kong; D006801:Humans; D008297:Male; D008875:Middle Aged; D014664:Vasodilation; D014805:Vitamin B 12 / Q000097:blood / Q000627:therapeutic use*; D014806:Vitamin B 12 Deficiency / Q000178:diet therapy* / Q000208:ethnology / Q000209:etiology / Q000503:physiopathology
D015415:Biomarkers; D006710:Homocysteine; D014805:Vitamin B 12