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Plasma vitamin C: what does it measure?

Published online by Cambridge University Press:  02 January 2007

AR Ness*
Affiliation:
Senior Lecturer in Epidemiology, University of Bristol, Department of Social Medicine, Canynge Hall, Whiteladies Road, Bristol, BS8 2PR, UK
KT Khaw
Affiliation:
Professor of Clinical Gerontology, Department of Clinical GerontologyAddenbrooke's Hospital, Hills Road, Cambridge, CB2 2QQ, UK
S Bingham
Affiliation:
Senior Scientist, MRC Dunn Clinical Nutrition Centre, Hills Road, Cambridge, CB2 2DH, UK
NE Day
Affiliation:
Professor of Public Health, Institute of Public Health, University Forvie Site, Robinson Way, Cambridge, CB2 2SR, UK
*
*Corresponding author: Email Andy.Ness@bris.ac.uk
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Abstract

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Objective:

To examine the association between self-reported consumption of foods and plasma vitamin C levels.

Design:

A cross-sectional analysis of dietary data and plasma vitamin C levels. Subjects placed the following foods into frequency categories: fresh fruit, leafy greens, other vegetables, fatty fish, other fish, chicken, meat, meat products, eggs, cheese and brown bread. The six frequency categories ranged from ‘never’ to ‘at least daily’. Plasma vitamin C was measured by fluorometric assay.

Setting:

A population-based cohort study in Norfolk, UK.

Subjects:

598 men and 566 women aged 45–74 years not taking vitamin supplements.

Results:

Plasma vitamin C was positively correlated with intake of fresh fruit (r = 0.29 in men and r = 0.25 in women, P < 0.001), leafy greens (r = 0.20 in men P < 0.001, r = 0.13 in women P < 0.01), other vegetables (r = 0.20 in men P < 0.001, r = 0.14 in women P < 0.01) and brown bread (r = 0.28 in men, r = 0.17 in women, P < 0.001) and negatively associated with intake of meat products (r = −0.13 in men P = 0.02, r = −0.10 in women P < 0.01). The difference in plasma vitamin C between never and daily eaters of brown bread was 13.6 μmol l−1 in men and 9.9 μmol l−1 in women, P < 0.001

Conclusions:

These data suggest that plasma vitamin C is not only a marker of foods rich in vitamin C but of certain patterns of food consumption. Such patterns are likely to be population specific and might explain inconsistencies in biomarker–disease associations.

Type
Research Article
Copyright
Copyright © CABI Publishing 1999

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