Heacox Hayley N, Gillman Patricia L, Zwart Sara R, Smith Scott M
Department of Chemistry, University of Central Arkansas, Conway, AR.
JES Tech, Houston, TX.
J Nutr. 2017 Jun;147(6):1113-1120. doi: 10.3945/jn.117.247437. Epub 2017 May 10.
Zinc and copper have many physiologic functions and little or no functional storage capability, so persistent losses of either element present health concerns, especially during extended-duration space missions. We evaluated the effects of short-term bed rest (BR), a spaceflight analog, on copper and zinc metabolism to better understand the role of these nutrients in human adaptation to (simulated) spaceflight. We also investigated the effect of artificial gravity on copper and zinc homeostasis. Zinc and copper balances were studied in 15 men [mean ± SD age: 29 ± 3 y; body mass index (in kg/m): 26.4 ± 2.2] before, during, and after 21 d of head-down tilt BR, during which 8 of the participants were subjected to artificial gravity (AG) by centrifugation for 1 h/d. Control subjects were transferred onto the centrifuge but were not exposed to centrifugation. The study was conducted in a metabolic ward; all urine and feces were collected. Data were analyzed by 2-factor repeated-measures ANOVA. Urinary zinc excretion values for control and AG groups were 33% and 14%, respectively, higher during BR than before BR, and fecal zinc excretion values for control and AG groups were 36% and 19%, respectively, higher during BR, resulting in 67% and 82% lower net zinc balances for controls and AG, respectively (both < 0.01), despite lower nutrient intake during BR. Fecal copper values for control and AG groups were 40% and 33%, respectively, higher during BR than before BR ( 0.01 for both). Urinary copper did not change during BR, but a 19% increase was observed after compared with before BR in the AG group ( 0.05). The increased fecal excretion of copper and zinc by men during BR suggests that their absorption of these minerals from the diet was reduced, secondary to the release of minerals from bone and muscle. These findings highlight the importance of determining dietary requirements for astronauts on space missions and ensuring provision and intake of all nutrients.
锌和铜具有多种生理功能，且几乎没有或完全没有功能性储存能力，因此任何一种元素的持续流失都会引发健康问题，尤其是在长期太空任务期间。我们评估了短期卧床休息（BR）这一太空飞行模拟条件对铜和锌代谢的影响，以更好地了解这些营养素在人类适应（模拟）太空飞行中的作用。我们还研究了人工重力对铜和锌体内平衡的影响。对15名男性[平均±标准差年龄：29±3岁；体重指数（kg/m²）：26.4±2.2]在头低位倾斜卧床休息21天之前、期间和之后的锌和铜平衡情况进行了研究，在此期间，8名参与者每天通过离心接受1小时的人工重力（AG）作用。对照组受试者被转移到离心机上，但未接受离心处理。研究在代谢病房进行；收集了所有尿液和粪便。数据通过双因素重复测量方差分析进行分析。对照组和人工重力组在卧床休息期间的尿锌排泄值分别比卧床休息前高33%和14%，对照组和人工重力组在卧床休息期间的粪锌排泄值分别比卧床休息前高36%和19%，尽管卧床休息期间营养摄入量较低，但对照组和人工重力组的净锌平衡分别降低了67%和82%（均P<0.01）。对照组和人工重力组在卧床休息期间的粪铜值分别比卧床休息前高40%和33%（均P<0.01）。卧床休息期间尿铜未发生变化，但人工重力组在卧床休息后与卧床休息前相比尿铜增加了19%（P<0.05）。男性在卧床休息期间粪便中铜和锌排泄增加表明，由于骨骼和肌肉中矿物质的释放，他们从饮食中对这些矿物质的吸收减少。这些发现凸显了确定太空任务中宇航员饮食需求以及确保所有营养素供应和摄入的重要性。
