Vitamin C and Coronary heart disease
Many studies have analyzed the relationship between vitamins C intake from supplements or diet and coronary heart disease risk. Two reviews of these studies pooled the results. The first, pooled together nine prospective studies that included information on intakes of vitamin E, carotenoids, and vitamin C in 293,172 subjects who were free of coronary heart disease at baseline. During ten years of follow-up, 4647 major incident coronary heart events occurred. Subjects who used supplemental vitamin C had a lower coronary heart disease incidence when compared with subjects who did not take supplemental vitamin C. Those who took greater than 700 mg supplemental vitamin C a day had a relative risk of coronary heart disease incidence of 0.75 (0.60, 0.93; P for trend <0.001).[i]
A meta-analysis of fifteen cohort studies including 374,488 participants, reported 7415 incidences of coronary heart disease over a mean follow-up of 10-years. This study found a relative risk of 0.84 (95% CI, 0.73-0.95) when comparing the top third with those in the bottom third of baseline values. This study found that dietary intake of vitamin C was responsible for the response and not supplementation.[ii] A more recent study has shown a similar reduction in coronary heart disease in women with high vitamin C intakes, but not in men.[iii]
[iii] Kubota Y, Iso H, Date C, Kikuchi S, Watanabe Y, Wada Y, Inaba Y, Tamakoshi A; JACC Study Group. Dietary intakes of antioxidant vitamins and mortality from cardiovascular disease: the Japan Collaborative Cohort Study (JACC) study. Stroke. 2011 Jun;42(6):1665-72. PMID: 21512181.