Koutsari Christina, Sidossis Labros S
Laboratory of Nutrition and Clinical Diabetes, Harokopio University, Athens, Greece.
Br J Nutr. 2003 Aug;90(2):413-8. doi: 10.1079/bjn2003894.
The effect of diet composition on post-absorptive (15 h fast) fatty acid and glucose metabolism was investigated in five healthy men after 2 weeks on a low-carbohydrate (Low-CHO) diet (30 % energy intake from carbohydrates, 55 % from fat, 15 % from protein) and after 2 weeks on a high-carbohydrate (High-CHO) diet (energy intake 75, 10 and 15 % from carbohydrates, fat and protein respectively). The diets were isoenergetic and comprised real foods. Stable-isotope tracer methodology and indirect calorimetry were employed to measure glucose and fatty acid kinetics and oxidation. The relative contribution of carbohydrate to the total energy expenditure was significantly higher after the High-CHO diet. After the High-CHO diet, total and plasma fatty oxidation (2.4 (SE 0.7) and 2.1 (SE 0.4) micromol/kg per min respectively) were significantly lower than after the Low-CHO diet (4.8 (SE 0.5) and 4.6 (SE 0.8) micromol/kg per min for total and plasma fatty oxidation respectively). The rate of appearance (Ra) of non-esterified fatty acids (NEFA) in plasma and the arterial NEFA concentration were both significantly lower following the High-CHO than the Low-CHO diet. However, even after the High-CHO diet, NEFA Ra was threefold higher than plasma fatty acid oxidation. Thus, the decrease in fatty acid oxidation after consumption of a high-carbohydrate diet for 2 weeks in healthy men is unlikely to result from decreased fatty acid delivery to the tissues. Glucose Ra and arterial plasma glucose concentration were similar after the two diets. After the High-CHO diet, arterial lactate concentration was higher and total carbohydrate oxidation rate well exceeded glucose Ra in plasma. Therefore, alterations in intracellular mechanisms may limit fatty acid oxidation after high-carbohydrate diets.
研究了饮食组成对五名健康男性吸收后（禁食15小时）脂肪酸和葡萄糖代谢的影响。这些男性先进行了两周的低碳水化合物（Low-CHO）饮食（碳水化合物提供30%的能量摄入，脂肪提供55%，蛋白质提供15%），之后又进行了两周的高碳水化合物（High-CHO）饮食（能量摄入分别来自碳水化合物、脂肪和蛋白质的比例为75%、10%和15%）。两种饮食的能量相同且均由天然食物组成。采用稳定同位素示踪法和间接量热法来测量葡萄糖和脂肪酸的动力学及氧化情况。高碳水化合物饮食后，碳水化合物对总能量消耗的相对贡献显著更高。高碳水化合物饮食后，总脂肪酸氧化和血浆脂肪酸氧化（分别为2.4（标准误0.7）和2.1（标准误0.4）微摩尔/千克每分钟）显著低于低碳水化合物饮食后（总脂肪酸氧化和血浆脂肪酸氧化分别为4.8（标准误0.5）和4.6（标准误0.8）微摩尔/千克每分钟）。高碳水化合物饮食后，血浆中非酯化脂肪酸（NEFA）的出现率（Ra）和动脉血NEFA浓度均显著低于低碳水化合物饮食。然而，即使在高碳水化合物饮食后，NEFA的Ra仍比血浆脂肪酸氧化高三倍。因此，健康男性食用高碳水化合物饮食两周后脂肪酸氧化的降低不太可能是由于脂肪酸向组织的输送减少所致。两种饮食后葡萄糖的Ra和动脉血浆葡萄糖浓度相似。高碳水化合物饮食后，动脉血乳酸浓度更高，且总碳水化合物氧化率远超过血浆中葡萄糖的Ra。因此，细胞内机制的改变可能会限制高碳水化合物饮食后的脂肪酸氧化。
