ORLANDO – Low vitamin C intake may worsen heart failure and put patients at a higher risk for cardiac events, according to a study conducted in three U.S. clinics.
The findings showed that patients who had low intakes of vitamin C were 2.4 times as likely to have higher levels of high-sensitivity C-reactive protein (hsCRP) – a marker for inflammation – compared with those who had high vitamin C intake. They also had shorter intervals without cardiac events.
In other words, "adequate intake of vitamin C was associated with longer survival in patients with heart failure," said Eun Kyeung Song, Ph.D., of the University of Ulsan (South Korea), who is the lead author of the study and a registered nurse.
The study, which is the first of its kind, was "provocative," and could lead to more investigations and larger studies to verify the findings, said Dr. Roger S. Blumenthal, director of preventive cardiology at Johns Hopkins University, Baltimore. He was not involved in the study.
"We generally attribute high CRP to increased weight in the midsection," said Dr. Blumenthal. "But this study suggests that it may be dietary inadequacies that may also increase inflammation and may be even a stronger predictor than just the CRP blood test by itself."
After taking a detailed, 4-day food diary, the authors measured the serum hsCRP of 212 patients at three outpatient heart failure clinics in Kentucky, Indiana, and Georgia during a 12-month follow-up.
Of the cohort, 82 patients (39%) had low vitamin C intake, as defined by the Institute of Medicine’s guidelines. In all, 98 (46%) had hsCRP greater than 3 mg/L, which is the cut-off point for being at high risk of having cardiac events. The patients with low vitamin C were 2.4 times more likely to have a high hsCRP level.
During the follow-up, 61 patients (29%) had cardiac events. After the authors controlled for age, sex, body mass index, New York Heart Association class, ejection fraction, comorbidities, total caloric intake, and medications, the results showed that the patients with low vitamin C levels were exactly twice as likely as those with adequate levels to have shorter cumulative cardiac event–free survival. Furthermore, those with hsCRP levels of at least 3 mg/L were 1.9 times as likely to have that outcome. Both differences were significant.
"Adequate intake of vitamin C was associated with longer survival in patients with heart failure."
"The data suggest that one possible mechanism by which vitamin C deficiency contributed to poor health outcomes is through inflammatory pathways in [heart failure] patients," they concluded.
"Diet is the best source of vitamin C," said Terry Lennie, Ph.D., one of the study authors and an associate dean at the University of Kentucky in Lexington. "Eating the recommended five servings of fruits and vegetables a day provides an adequate amount."
Dr. Blumenthal added that "sometimes we just talk to our patients about avoiding fast foods, and we don’t give as much positive reinforcement for things that are good for them to eat. ... We should go back to what our mothers and grandmothers told us, and try to have a more balanced diet and have more fruits and vegetables."
Dr. Lennie has received research grant from multiple extramural funders in the research area. Dr. Song and Dr. Blumenthal had no disclosures.