New research published in the November edition of the American Journal of Clinical Nutrition suggests that postmenopausal women with diabetes, who have a high intake of vitamin C, may have an increased risk of cardiovascular disease mortality.
The researchers from the University of Minnesota in Minneapolis noted that although vitamin C acts as a potent antioxidant, it can also be a prooxidant and glycate protein under certain in vitro circumstances.
"These observations led us to hypothesize that a high intake of vitamin C in diabetic persons might promote atherosclerosis," said the scientists.
They subsequently followed nearly 2000 women for 15 years and studied the relation between vitamin C intake and mortality from total cardiovascular disease, coronary artery disease and stroke.
The patients, at the outset, were free of coronary artery disease.
At the end of the study period, those women who took heavy doses of vitamin C supplements, namely 300 mg or more a day, were about twice as likely to die of heart disease or stroke compared to women who took no supplemental vitamin C.
Vitamin C is an antioxidant, meaning it helps neutralize potentially cell-damaging substances known as oxygen free radicals, which are a normal byproduct of metabolism. The vitamin is obviously necessary for good health, but studies have produced conflicting results on whether supplements help lower the risk of heart disease and stroke.
The current recommended dietary intake for vitamin C is 90 mg a day for men and 75 mg per day for women.