Serum vitamin C concentration was inversely associated with subsequent 20-year incidence of stroke in a Japanese rural community - The Shibata study

Background and Purpose-Epidemiological evidence suggests that vitamin C may decrease the risk of stroke, The purpose of the present study was to exami ne the association of serum vitamin C concentration with the subsequent inc idence of stroke. Methods-In a Japanese rural community, a cohort of 880 men and 1241 women a ged 40 years and older who were initially free of stroke was examined in 19 77 and followed until 1997. The baseline examination included a measurement of serum vitamin C concentration. The incidence of stroke was determined b y annual follow-up examinations and registry. Results-During the 20-year observation period, 196 incident cases of all st roke, including 109 cerebral infarctions and 54 hemorrhagic strokes, were d ocumented. Strong inverse associations were observed between serum vitamin C concentration and all stroke (sex- and age-adjusted hazard ratios were 0. 93, 0.72, and 0.59, respectively, for the second, third, and fourth quartil es compared with the first quartile; P for trend=0.002), cerebral infarctio n (0.71, 0.59, and 0.51; P for trend= 0.015), and hemorrhagic stroke (0.89, 0.75, and 0.45; P for trend = 0.013), Additional adjustments for blood pre ssure, serum total cholesterol, body mass index, physical activity, smoking , alcohol drinking, antihypertensive medication, atrial fibrillation, and h istory of ischemic heart disease did not attenuate these associations marke dly. Conclusions-Serum vitamin C concentration was inversely related to the subs equent incidence of stroke. This relationship was significant for both cere bral infarction and hemorrhagic stroke. Additional mechanistic hypotheses m ay be required to explain our findings.