Vitamin C and the risk of acute myocardial infarction.
BACKGROUND
Low-fat soluble-antioxidant status is associated with an increased risk of heart disease.


OBJECTIVE
The aim of this study was to examine whether low plasma concentrations of vitamin C confer an independent risk of acute myocardial infarction (AMI).


METHODS
Male patients (n = 180) aged <65 y with a first AMI and without an existing diagnosis of angina (>6 mo) who were admitted within 12 h after onset of symptoms were compared with apparently healthy volunteers (n = 177). Plasma concentrations and dietary intakes of vitamin C were determined during hospitalization and 3 mo later.


RESULTS
Compared with the control subjects, the patients had higher total cholesterol and lower HDL-cholesterol concentrations and more of them smoked. The relative risk of AMI for the lowest compared with the highest quintile of plasma vitamin C during hospitalization (14.5 and >60.5 micromol/L, respectively) was 8.37 (95% CI: 3.28, 21. 4) after adjustment for classic risk factors. At 3 mo, mean (+/-SEM) plasma vitamin C concentrations in patients had increased significantly, from 19.6 +/- 1.2 to 35.1 +/- 1.9 micromol/L (P < 0. 001) and no longer conferred a risk of AMI [relative risk: 1.02 (95% CI: 0.51, 2.03)]. Habitual dietary vitamin C intake of patients (before AMI) did not differ significantly from that of control subjects. The increase in plasma vitamin C after recovery from the infarction could not be explained by a similarly large increase in dietary vitamin C.


CONCLUSIONS
A low plasma concentration of vitamin C was not associated with an increased risk of AMI, irrespective of smoking status. The apparent risk of AMI due to a low plasma vitamin C concentration was distorted by the acute phase response.
Riemersma
R A
RA
British Heart Foundation Cardiovascular Research Unit, the Department of Cardiology and Medicine, the Royal Infirmary of Edinburgh, Edinburgh, United Kingdom. rudolph.riemersma@ed.ac.uk
Carruthers
K F
KF
Elton
R A
RA
Fox
K A
KA
D000328:Adult; D001205:Ascorbic Acid / Q000097:blood*; D001794:Blood Pressure; D002784:Cholesterol / Q000097:blood; D008076:Cholesterol, HDL / Q000097:blood; D015331:Cohort Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000097:blood / Q000453:epidemiology / Q000209:etiology*; D012307:Risk Factors; D012606:Scotland / Q000453:epidemiology; D012907:Smoking / Q000453:epidemiology; D012923:Social Class; D011795:Surveys and Questionnaires; D014280:Triglycerides / Q000097:blood
D008076:Cholesterol, HDL; D014280:Triglycerides; D002784:Cholesterol; D001205:Ascorbic Acid