Hemilä H
Department of Public Health, University of Helsinki, Finland.
Br J Nutr. 1997 Jan;77(1):59-72. doi: 10.1017/s0007114500002889.
Although the role of vitamin C in common cold incidence had been studied extensively, the level of vitamin C intake has not been unequivocally shown to affect the incidence of colds. In the present study the six largest vitamin C supplementation (> or = 1 g/d) studies, including over 5000 episodes in all, have been analysed, and it is shown that common cold incidence is not reduced in the vitamin C-supplemented groups compared with the placebo groups (pooled rate ratio (RR) 0.99; 95% CI 0.93, 1.04). Consequently these six major studies give no evidence that high-dose vitamin C supplementation decreases common cold incidence in ordinary people. Nevertheless, the analysis was continued with the hypothesis that vitamin C intake may affect common cold susceptibility in specific groups of people. It was assumed that the potential effect of supplementation might be most conspicuous in subjects with low dietary vitamin C intake. The average vitamin C intake has been rather low in the UK and plasma vitamin C concentrations are in general lower in males than in females. In four studies with British females vitamin C supplementation had no marked effect on common cold incidence (pooled RR 0.95; 95% CI 0.86, 1.04). However, in four studies with British male schoolchildren and students a statistically highly significant reduction in common cold incidence was found in groups supplemented with vitamin C (pooled RR 0.70; 95% CI 0.60, 0.81). Thus, these studies with British males indicate that vitamin C intake has physiological effects on susceptibility to common cold infections, although the effect seems quantitatively meaningful only in limited groups of people and is not very large.
尽管维生素C在普通感冒发病率中的作用已得到广泛研究，但维生素C的摄入量水平尚未明确显示会影响感冒发病率。在本研究中，分析了六项规模最大的维生素C补充剂研究（≥1克/天），总共涉及超过5000例病例，结果表明，与安慰剂组相比，补充维生素C的组中普通感冒发病率并未降低（合并率比（RR）为0.99；95%置信区间为0.93，1.04）。因此，这六项主要研究没有提供证据表明高剂量补充维生素C会降低普通人的普通感冒发病率。然而，研究继续基于这样的假设，即维生素C的摄入量可能会影响特定人群对普通感冒的易感性。据推测，补充剂的潜在效果在饮食中维生素C摄入量低的受试者中可能最为明显。英国的平均维生素C摄入量一直较低，男性的血浆维生素C浓度总体上低于女性。在四项针对英国女性的研究中，补充维生素C对普通感冒发病率没有显著影响（合并RR为0.95；95%置信区间为0.86，1.04）。然而，在四项针对英国男学生和男大学生的研究中，发现补充维生素C的组中普通感冒发病率在统计学上有高度显著的降低（合并RR为0.70；95%置信区间为0.60，0.81）。因此，这些针对英国男性的研究表明，维生素C的摄入量对普通感冒感染的易感性有生理影响，尽管这种影响似乎仅在有限的人群中在数量上有意义，而且影响不大。
