Bed rest is necessary for many medical conditions but also used as a ground-based model for space flight (along with head-down tilt to simulate fluid shifts in microgravity). The purpose of this review is to examine nutritional interventions during bed rest and spaceflight for prevention of muscle and strength loss, glucose intolerance, bone resorption, and cardiovascular problems. Increased dietary protein intake and supplementation with amino acids, β-hydroxy-β-methylbutyrate, or cofactors with antioxidant properties are effective for ameliorating bed rest-induced loss of muscle mass and strength. Previous literature involving bed rest with dietary protein/amino acid supplementation had mixed findings, likely due to differences in dosage. Although high protein intake in some studies prevents bed rest-induced muscle loss, it also increases bone resorption. High calcium intake and vitamin D supplementation are not beneficial for preventing bone degradation during bed rest or spaceflight. Very few studies investigated countermeasures to prevent glucose intolerance and cardiovascular risks during bed rest/spaceflight. Low-glycemic index diets might be beneficial for the prevention of bed rest-induced glucose intolerance and cardiovascular problems. The present evidence warrants additional studies on the exact threshold of protein/amino acid intake to prevent the loss of muscle mass and strength during bed rest/spaceflight specifically to maintain the beneficial effects of proteins on muscle mass and function without increasing bone resorption. Furthermore, it is suggested to study the effects of vitamin K supplementation on bone health during bed rest/spaceflight and determine the role of long-term low-glycemic index diets on glucose regulation and cardiovascular health during extended bed rest.

中文翻译：

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卧床休息和太空飞行期间的营养干预：预防肌肉质量和力量损失、骨吸收、葡萄糖耐受不良和心血管问题

许多医疗条件都需要卧床休息，但也用作太空飞行的地面模型（以及低头倾斜以模拟微重力中的流体移动）。本综述的目的是检查卧床休息和太空飞行期间的营养干预，以预防肌肉和力量损失、葡萄糖耐受不良、骨吸收和心血管问题。增加膳食蛋白质摄入量和补充氨基酸、β-羟基-β-甲基丁酸盐或具有抗氧化特性的辅助因子，可有效改善卧床休息引起的肌肉质量和力量损失。先前涉及卧床休息并补充膳食蛋白质/氨基酸的文献有不同的发现，可能是由于剂量不同。虽然在一些研究中高蛋白质摄入可以防止卧床引起的肌肉流失，它还增加骨吸收。高钙摄入量和维生素 D 补充剂不利于防止卧床休息或太空飞行期间的骨骼退化。很少有研究调查在卧床休息/太空飞行期间预防葡萄糖耐受不良和心血管风险的对策。低血糖指数饮食可能有助于预防卧床休息引起的葡萄糖耐受不良和心血管问题。目前的证据需要进一步研究蛋白质/氨基酸摄入的确切阈值，以防止在卧床休息/太空飞行期间肌肉质量和力量的损失，特别是在不增加骨吸收的情况下保持蛋白质对肌肉质量和功能的有益影响。此外，