CAMBRIDGE, UNITED KINGDOM. A couple of recent test tube experiments widely reported by the popular press have managed to create doubt as to the benefits of vitamin-C. A report just released by researchers at Cambridge University will hopefully lay these doubts to rest. The study measured blood plasma concentrations of ascorbic acid (vitamin-C) in 8,860 men and 10,636 women. The study participants were followed for approximately four years. During this period a total of 692 men and women died - a total of 268 from cardiovascular disease, 189 from ischemic heart disease (angina or heart attack) and 284 from cancer. After adjusting for age, systolic blood pressure, cholesterol, body mass index, smoking, diabetes and the use of supplements the researchers concluded that men with an ascorbic acid level of 72.6 micromol/L or higher had a 36 per cent lower risk of dying from cardiovascular disease than did men with a level of 20.8 micromol/L or lower. The decrease in risk for death from ischemic heart disease, cancer and all causes was 37 per cent, 24 per cent and 23 per cent respectively. Women with a plasma level of 85.1 micromol/L had a 19 per cent lower cardiovascular disease mortality, a 44 per cent lower ischemic heart disease mortality, and a 15 per cent lower all-cause mortality than did women with an ascorbic acid level of 30.3 micromol/L. There was no correlation between cancer mortality and vitamin-C level among the women.
The researchers conclude that a 20 micromol/L rise in plasma ascorbic acid level can reduce all-cause mortality rate by 20 per cent independent of age and other risk factors. A 20 micromol/L increase can be obtained by increasing fruit and vegetable intake by 50 grams per day. The researchers also noted that higher vitamin-C levels were associated with lower systolic blood pressure and body mass index as well as with a higher level of "good" (HDL) cholesterol.
Khaw, Kay-Tee, et al. Relation between plasma ascorbic acid and mortality in men and women in EPIC-Norfolk prospective study: a prospective population study. The Lancet, Vol. 357, March 3, 2001, pp. 657-63