Pollard J, Wild C P, White K L M, Greenwood D C, Cade J E, Kirk S F L
Nutrition Epidemiology Group, Nuffield Institute for Health, University of Leeds, Leeds, UK.
Eur J Clin Nutr. 2003 Aug;57(8):988-98. doi: 10.1038/sj.ejcn.1601634.
To assess the variability and validity of plasma-based biomarkers of antioxidant vitamin, and fruit and vegetable intake.
Leeds, Wakefield, Huddersfield and Bradford, England.
A total of 54 free-living, nonsmoking women recruited from participants of the UK Women's Cohort Study (UKWCS).
Two fasting blood samples were taken at two time points, 18 months apart. A 4-day food diary was completed prior to the first blood sample and a 24-h recall was conducted at the time of the second blood collection. All blood samples were analysed for ascorbic acid and four carotenoids. Associations between antioxidant vitamin intake from all food sources and supplements, as well as fruit and vegetable intake, and plasma levels of the antioxidant vitamins were assessed.
Using the 4-day diary, positive associations were found between micronutrient intake from all food sources and plasma concentrations of ascorbic acid (P<0.01) and beta-carotene (P<0.01). No associations were seen between plasma micronutrient levels and specifically fruit and vegetable intakes. In general, associations between plasma levels and intakes assessed by the 24-h recall were less marked than those based on the 4-day diary.
Plasma ascorbic acid and beta-carotene are good indicators of previous vitamin C and beta-carotene intake, from all food sources. However, caution is required in extrapolating these results to include individual food groups, rich in these vitamins. The results imply that the practice of using plasma biomarkers simply as a proxy measure of dietary intake is not valid and emphasise that plasma biomarkers are not simply a reflection of dietary intake, but also of a number of physiological processes. Biomarkers in nutrition epidemiological studies are however useful to measure nutrient status at the tissue level.
评估基于血浆的抗氧化维生素生物标志物以及水果和蔬菜摄入量的变异性和有效性。
英国利兹、韦克菲尔德、哈德斯菲尔德和布拉德福德。
从英国女性队列研究（UKWCS）的参与者中招募的54名自由生活、不吸烟的女性。
在两个时间点采集两份空腹血样，间隔18个月。在采集第一份血样之前完成一份4天的食物日记，并在采集第二份血样时进行24小时膳食回顾。对所有血样进行抗坏血酸和四种类胡萝卜素的分析。评估所有食物来源和补充剂中的抗氧化维生素摄入量、水果和蔬菜摄入量与抗氧化维生素血浆水平之间的关联。
使用4天的食物日记，发现所有食物来源的微量营养素摄入量与抗坏血酸（P<0.01）和β-胡萝卜素（P<0.01）的血浆浓度之间存在正相关。血浆微量营养素水平与特定的水果和蔬菜摄入量之间未发现关联。总体而言，通过24小时膳食回顾评估的血浆水平与摄入量之间的关联不如基于4天食物日记的关联明显。
血浆抗坏血酸和β-胡萝卜素是所有食物来源中先前维生素C和β-胡萝卜素摄入量的良好指标。然而，在将这些结果外推至富含这些维生素的个别食物组时需要谨慎。结果表明，仅将血浆生物标志物用作膳食摄入量的替代指标的做法是无效的，并强调血浆生物标志物不仅反映膳食摄入量，还反映许多生理过程。然而，营养流行病学研究中的生物标志物对于测量组织水平的营养状况是有用的。
