Hiratsuka Chiaki, Sano Mitsue, Fukuwatari Tsutomu, Shibata Katsumi
Department of Nutrition, School of Human Culture, The University of Shiga Prefecture.
J Nutr Sci Vitaminol (Tokyo). 2014;60(4):255-60. doi: 10.3177/jnsv.60.255.
We have previously reported that dietary supplementation with up to 5.0 g/d of L-tryptophan (L-Trp) for 21 d has no adverse effects, judging from the levels of general blood variables, in healthy women. We performed a randomized, double-blind, placebo-controlled, crossover intervention study in 17 apparently healthy Japanese women. The subjects were randomly assigned to receive a placebo (0 g/d) or 1.0, 2.0, 3.0, 4.0, or 5.0 g/d of L-Trp for 21 d each with a 5-wk washout period between trials. We examined the 24-h urine profiles on days -1 (1 d before starting L-Trp), 7, 14, and 21 to determine whether administration of L-Trp at doses of up to 5.0 g/d affects time-dependent urinary excretion of L-Trp or its metabolites in healthy women. The urinary excretion of L-Trp, kynurenic acid, 3-hydroxykynurenine, xanthurenic acid, 3-hydroxyanthranilic acid, quinolinic acid, N(1)-methylnicotinamide, N(1)-methyl-2-pyridone-5-carboxamide, and N(1)-methyl-4-pyridone-3-carboxamide increased in an L-Trp dose-dependent manner on day 7. The amount of urinary excretion of these compounds was unchanged on days 14 and 21. The urinary excretion of serotonin, 5-hydroxyindole-3-acetic acid, 2-oxoadipic acid, and nicotinamide was unaffected by L-Trp at any of the doses tested. L-Trp doses had weak effects on the urinary excretion of kynurenine and anthranilic acid. Based on these findings, we conclude that there are no time-dependent effects of L-Trp administration in urinary excretion of L-Trp metabolites. Additionally, L-Trp and its metabolites do not accumulate in the body.
我们之前报道过，从一般血液指标水平判断，健康女性连续21天每日补充高达5.0克的L-色氨酸（L-Trp）没有不良影响。我们对17名看似健康的日本女性进行了一项随机、双盲、安慰剂对照的交叉干预研究。受试者被随机分配接受安慰剂（0克/天）或1.0、2.0、3.0、4.0或5.0克/天的L-Trp，各为期21天，试验之间有5周的洗脱期。我们在第-1天（开始服用L-Trp前1天）、第7天、第14天和第21天检测了24小时尿液谱，以确定每日服用高达5.0克剂量的L-Trp是否会影响健康女性中L-Trp及其代谢产物的时间依赖性尿排泄。在第7天，L-Trp、犬尿酸、3-羟基犬尿氨酸、黄尿酸、3-羟基邻氨基苯甲酸、喹啉酸、N(1)-甲基烟酰胺、N(1)-甲基-2-吡啶酮-5-甲酰胺和N(1)-甲基-4-吡啶酮-3-甲酰胺的尿排泄量以L-Trp剂量依赖性方式增加。在第14天和第21天，这些化合物的尿排泄量没有变化。在任何测试剂量下，L-Trp对血清素、5-羟基吲哚-3-乙酸、2-氧代己二酸和烟酰胺的尿排泄均无影响。L-Trp剂量对犬尿氨酸和邻氨基苯甲酸的尿排泄有微弱影响。基于这些发现，我们得出结论，L-Trp给药对L-Trp代谢产物的尿排泄没有时间依赖性影响。此外，L-Trp及其代谢产物不会在体内蓄积。
