Kretsch M J, Fong A K, Green M W, Johnson H L
The US Department of Agriculture, Agricultural Research Service, Western Human Nutrition Research Center, Presidio of San Francisco, California 94129, USA.
Eur J Clin Nutr. 1998 Jul;52(7):512-8. doi: 10.1038/sj.ejcn.1600598.
To determine the relationships between cognitive function and iron status in dieting obese women.
Longitudinal weight loss study (repeated measures within-subject design) with 3 weeks of baseline, 15 weeks of 50% caloric restriction, and 3 weeks of weight stabilization. Dietary iron was fed at twice the US Recommended Dietary Allowance with half of the iron from food sources and half from an oral supplement.
This was a free-living study with the exception that subjects came to the research center for one meal per day and were provided all other meals and snacks to take home.
Healthy, premenopausal, obese women (mean BMI=31.5) were recruited through local newspaper, poster and radio advertising. Twenty-four women volunteers were recruited and 14 completed the study.
Cognitive function, iron and hematological status, height, body weights and body composition were measured at baseline; at weeks 5, 10, and 15 of the energy restriction period; and at the end of weight stabilization. Computerized cognitive tests included: Bakan vigilance task, two finger tapping, simple reaction time, immediate word recall, and a focused attention task. Iron status and hematological measures included: serum iron, total iron binding capacity (TIBC), transferrin saturation, serum ferritin, hemoglobin (Hb), hematocrit, red cell count, MCV, MCH, MCHC, and RDW.
A significant reduction in Hb, hematocrit, and red blood cell count occurred across the study. Hb at the end of the study was positively correlated (r=0.72, P < 0.01) with mean performance on a measure of sustained attention. Transferrin saturation also correlated positively to sustained attention task performance for those subjects whose Hb declined across the study (r=0.86, P < 0.01).
These findings suggest that dieting diminishes iron status in obese women, even when sufficient dietary iron is available, and that the inability to sustain attention may be an early sign of developing iron deficiency in dieting women.
确定节食肥胖女性认知功能与铁状态之间的关系。
纵向体重减轻研究（受试者内重复测量设计），包括3周基线期、15周50%热量限制期和3周体重稳定期。膳食铁的摄入量为美国推荐膳食摄入量的两倍，其中一半来自食物来源，一半来自口服补充剂。
这是一项自由生活研究，受试者每天到研究中心吃一顿饭，其他餐食和零食则带回家中。
通过当地报纸、海报和广播广告招募健康的绝经前肥胖女性（平均BMI = 31.5）。招募了24名女性志愿者，14名完成了研究。
在基线期、能量限制期的第5、10和15周以及体重稳定期结束时测量认知功能、铁和血液学状态、身高、体重和身体成分。计算机化认知测试包括： Bakan警觉任务、双指敲击、简单反应时间、即时单词回忆和集中注意力任务。铁状态和血液学指标包括：血清铁、总铁结合力（TIBC）、转铁蛋白饱和度、血清铁蛋白、血红蛋白（Hb）、血细胞比容、红细胞计数、平均红细胞体积（MCV）、平均红细胞血红蛋白含量（MCH）、平均红细胞血红蛋白浓度（MCHC）和红细胞分布宽度（RDW）。
在整个研究过程中，血红蛋白（Hb）、血细胞比容和红细胞计数显著降低。研究结束时的Hb与持续注意力测量的平均表现呈正相关（r = 0.72，P < 0.01）。对于那些在研究过程中Hb下降的受试者，转铁蛋白饱和度也与持续注意力任务表现呈正相关（r = 0.86，P < 0.01）。
这些发现表明，即使有足够的膳食铁，节食也会降低肥胖女性的铁状态，而且无法持续保持注意力可能是节食女性缺铁的早期迹象。
