Thanks to Nutrition Science News for this article!
Although vitamin C has long been considered the premier antioxidant,
studies linking the vitamin to increased survival rates have been
inconclusive. However, a major study conducted by researchers at
Cambridge University School of Clinical Medicine in the U.K. and
published in Lancet offers evidence that vitamin C saves lives.
This analysis, part of the nine–country European Prospective
Investigation into Cancer and Nutrition, was conducted on 19,496 men
and women, ages 45 to 79, in Norfolk, U.K., between 1994 and 1997. The
participants described their supplements intake, had their plasma
tested for ascorbic acid, and kept a detailed five–day diet diary.
They were placed in five groups according to their serum ascorbic acid
levels. Because women naturally have higher serum ascorbic acid
levels, men and women were tracked separately.
Prior to December 1999, the researchers observed how many people died
of cardiovascular disease, ischemic heart disease, cancer, and all
causes in each of the serum ascorbic acid quintiles. In every case
(except for women at risk of cancer), death rates were significantly
lower among those with higher serum ascorbic acid levels. People with
the highest ascorbic acid levels had half the risk of dying from all
causes combined. The chances of dying from cardiovascular disease were
reduced by 71 percent in men and 59 percent in women in the group with
the highest ascorbic acid levels compared with the lowest. The results
were virtually the same when smokers and supplements users were
eliminated from the analysis (one–third of the men and half the women
took nutritional supplements).
The researchers suggest that the true protective power of vitamin C is
stronger than they reported because of individual variables. There was
a consistent dose–response relationship across the distribution of
ascorbic acid intake. A change from the 30th to the 70th percentile in
intake was associated with a 30 percent reduction in mortality. Thus,
a practical shift within the normal population could substantially
reduce death rates
Read the abstract:
Relation Between Plasma Ascorbic Acid and Mortality in Men and Women
in EPIC–Norfolk Prospective Study: A Prospective Population Study
Lancet 2001 (Mar 3); 357: 657–663
Summary: Background Ascorbic acid (vitamin C) might be protective
for several chronic diseases. However, findings from prospective
studies that relate ascorbic acid to cardiovascular disease or cancer
are not consistent. We aimed to assess the relation between plasma
ascorbic acid and subsequent mortality due to all causes,
cardiovascular disease, ischaemic heart disease, and cancer.
Methods: We prospectively examined for 4 years the relation between
plasma ascorbic acid concentrations and mortality due to all causes,
and to cardiovascular disease, ischaemic heart disease, and cancer in
19496 men and women aged 45–79 years. We recruited individuals by post
using age–sex registers of general practices. Participants completed a
health and lifestyle questionnaire and were examined at a clinic
visit. They were followed–up for causes of death for about 4 years.
Individuals were divided into sex–specific quintiles of plasma
ascorbic acid. We used the Cox proportional hazard model to determine
the effect of ascorbic acid and other risk factors on mortality.
Findings: Plasma ascorbic acid concentration was inversely related
to mortality from all–causes, and from cardiovascular disease, and
ischaemic heart disease in men and women. Risk of mortality in the top
ascorbic acid quintile was about half the risk in the lowest quintile
(p<0·0001). The relation with mortality was continuous through the
whole distribution of ascorbic acid concentrations. 20 µmol/L rise in
plasma ascorbic acid concentration, equivalent to about 50 g per day
increase in fruit and vegetable intake, was associated with about a
20% reduction in risk of all–cause mortality (p<0·0001), independent
of age, systolic blood pressure, blood cholesterol, cigarette smoking
habit, diabetes, and supplement use. Ascorbic acid was inversely
related to cancer mortality in men but not women.
Interpretation: Small increases in fruit and vegetable intake of
about one serving daily has encouraging prospects for possible
prevention of disease.
AUTHORS: Kay–Tee Khaw, Sheila Bingham, Ailsa Welch, Robert Luben, Nicholas
Wareham, Suzy Oakes, Nicholas Day
Department of Public Health and Primary Care, Institute of Public
Health, University of Cambridge School of Clinical Medicine,
Cambridge, UK (Prof K–T Khaw FRCP, A Welch BSc, R Luben BSc, N Wareham
MRCP, S Oakes, N Day PhD); and MRC Dunn Human Nutrition Unit,
Cambridge (S Bingham PhD)
Correspondence to: Prof Kay–Tee Khaw, Clinical Gerontology Unit, Box
251, University of Cambridge School of Clinical Medicine,
Addenbrooke's Hospital, Cambridge CB2 2QQ, UK