Plasma vitamin C modifies the association between hypertension and risk of stroke.
OBJECTIVE
There are no prospective studies to determine whether plasma vitamin C modifies the risk of stroke among hypertensive and overweight individuals. We sought to examine whether plasma vitamin C modifies the association between overweight and hypertension and the risk of stroke in middle-aged men from eastern Finland.


METHODS
We conducted a 10.4-year prospective population-based cohort study of 2419 randomly selected middle-aged men (42 to 60 years) with no history of stroke at baseline examination. A total of 120 men developed a stroke, of which 96 were ischemic and 24 hemorrhagic strokes.


RESULTS
Men with the lowest levels of plasma vitamin C (<28.4 micromol/L, lowest quarter) had a 2.4-fold (95% CI, 1.4 to 4.3; P=0.002) risk of any stroke compared with men with highest levels of plasma vitamin C (>64.96 micromol/L, highest quarter) after adjustment for age and examination months. An additional adjustment for body mass index, systolic blood pressure, smoking, alcohol consumption, serum total cholesterol, diabetes, and exercise-induced myocardial ischemia attenuated the association marginally (relative risk, 2.1; 95% CI, 1.2 to 3.8; P=0.01). Adjustment for prevalent coronary heart disease and atrial fibrillation did not attenuate the association any further. Furthermore, hypertensive men with the lowest vitamin C levels (<28.4 micromol/L) had a 2.6-fold risk (95% CI, 1.52 to 4.48; P<0.001), and overweight men (> or =25 kg/m2) with low plasma vitamin C had a 2.7-fold risk (95% CI, 1.48 to 4.90; P=0.001) for any stroke after adjustment for age, examination months, and other risk factors.


CONCLUSIONS
Low plasma vitamin C was associated with increased risk of stroke, especially among hypertensive and overweight men.
Kurl
S
S
Research Institute of Public Health, University of Kuopio, Kuopio, Finland.
Tuomainen
T P
TP
Laukkanen
J A
JA
Nyyssönen
K
K
Lakka
T
T
Sivenius
J
J
Salonen
J T
JT
D000328:Adult; D001205:Ascorbic Acid / Q000097:blood*; D015992:Body Mass Index; D002545:Brain Ischemia / Q000097:blood / Q000453:epidemiology; D002543:Cerebral Hemorrhage / Q000097:blood / Q000453:epidemiology; D015331:Cohort Studies; D003710:Demography; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000453:epidemiology; D011446:Prospective Studies; D012306:Risk; D018570:Risk Assessment; D012307:Risk Factors; D020521:Stroke / Q000097:blood* / Q000453:epidemiology
D001205:Ascorbic Acid