Nelson M, Black A E, Morris J A, Cole T J
Department of Food and Nutritional Sciences, King's College London, UK.
Am J Clin Nutr. 1989 Jul;50(1):155-67. doi: 10.1093/ajcn/50.1.155.
In prospective studies of diet it is often necessary to know for how many days subjects should record food consumption in order to be able to rank subjects correctly according to their nutrient intakes. Data from six studies--of toddlers, families, schoolchildren, dietitians, pregnant women, and elderly subjects--were analyzed to estimate the number of recording days necessary for energy, 28 nutrients, and the ratio of polyunsaturated to saturated fatty acids (P:S). The most striking finding is that 7 d of diet record do not rank subjects with the degree of accuracy commonly assumed. For some nutrients, such as iron, zinc, nicotinic acid, and pyridoxine, it may be desirable to record diet over a number of short, separate periods to achieve the number of days required. For others, such as copper, retinol, carotene, vitamin B-12, polyunsaturated fatty acids, P:S, and alcohol, alternative methods of assessment based on dietary histories or questionnaires may be more appropriate.
在饮食的前瞻性研究中，常常需要知道受试者应记录食物摄入量多少天，以便能够根据其营养素摄入量正确地对受试者进行排名。分析了六项研究的数据，这些研究涉及幼儿、家庭、学童、营养师、孕妇和老年人，以估计记录能量、28种营养素以及多不饱和脂肪酸与饱和脂肪酸之比（P:S）所需的天数。最显著的发现是，7天的饮食记录并不能以通常假定的准确度对受试者进行排名。对于某些营养素，如铁、锌、烟酸和吡哆醇，可能需要在多个短的、分开的时间段记录饮食，以达到所需的天数。对于其他营养素，如铜、视黄醇、胡萝卜素、维生素B-12、多不饱和脂肪酸、P:S和酒精，基于饮食史或问卷的替代评估方法可能更合适。
