CAMBRIDGE, UNITED KINGDOM. Although not related to lone atrial fibrillation (AF), I found a recent study linking a higher plasma level of vitamin C to a lower risk of heart failure to be of sufficient interest to include in this issue of the newsletter.

The recently reported study involved 9,187 men and 11,112 women aged between 39 and 79 years and apparently healthy when enrolled in the European Prospective Investigation into Cancer and Nutrition between 1993 and 1997. During a follow-up period of 12.8 years, 154 fatal and 1,104 non-fatal cases of heart failure were reported involving 724 men and 534 women (incidence 0.5%/person-year). The researchers involved in the study discovered a clear correlation between the incidence of heart failure and a low plasma level of vitamin C. An increase of 20 micromol/L in plasma vitamin C concentration was associated with a 17% relative reduction in risk of heart failure. They believe the plasma level of vitamin C reflects intake of fruits and vegetables, but found no correlation between self-reported intake of fruit and vegetables and the risk of heart failure.

The study clearly showed the benefits of high plasma vitamin C levels. An average level of 70 micromol/L (quartile 4) was associated not only with a decreased risk of heart failure, but also with a statistically highly significant lower body mass index, waist-hip ratio, systolic blood pressure, diastolic blood pressure, total cholesterol, glucose level, and C-reactive protein (an important marker of inflammation) level when compared to an average plasma level of 23 micromol/L. A high vitamin C plasma level was also associated with a significantly reduced risk of hypertension and diabetes.

A higher occupational social class, greater physical activity, and a higher level of education were all associated with a higher plasma vitamin C level indicating that these factors are important in living a healthy lifestyle, which would tend to include an increased intake of vitamin C both in the form of fruits and vegetables, and in the form of vitamin C supplements. NOTE: 12% of the group constituting quartile 4 was supplementing with vitamin C as compared to only 1% in quartile 1.

The researchers conclude that every 20 micromol/L increase in plasma vitamin C concentration is associated with a 9% relative risk reduction in the risk of heart failure after adjusting for age, sex, smoking, alcohol consumption, physical activity, occupation social class, educational level, systolic blood pressure, diabetes, cholesterol level, body mass index, and interim coronary heart disease.

Pfister, R, Khaw, KT, et al. Plasma vitamin C predicts incident heart failure in men and women in European Prospective Investigation into Cancer and Nutrition – Norfolk prospective study. American Heart Journal, Vol. 162, No. 2, August 2011, pp. 246-53

Editor's comment: This study adds to the already abundant evidence that an adequate intake of vitamin C is essential for the maintenance of health and the avoidance of disease. See Vitamin C: Your Ultimate Health Insurance and IHN Database on Vitamin C. Unfortunately, the average daily intake of vitamin C in the USA and Canada is only about 60 mg, which is unlikely to yield an optimum plasma level. A daily intake of 200 mg/day, on the other hand, would likely result in a plasma level of 90 micromol/L corresponding to an almost 30% decrease in the risk of heart failure. By supplementing with 1250 mg/day (in divided doses) a peak plasma vitamin C level of 187 micromol/L can be achieved. See Linus Pauling Vindicated.