Zarling E J, Ruchim M A
J Lab Clin Med. 1987 May;109(5):566-70.
Normal human stool contains five commonly recognized volatile fatty acids, of which three (acetate, propionate, and butyrate) are the product of carbohydrate degradation. We investigated whether the remaining two volatile fatty acids, isobutyrate and isovalerate, are produced by degradation of amino acids. Stools from six healthy subjects were incubated with albumin, valine, leucine, tryptophan, phenylalanine, glucose, or sucrose under atmospheres containing oxygen in the range of 0% to 5%. Isobutyrate was produced only from albumin and valine, and isovalerate was produced only from albumin and leucine. Glucose- and sucrose-containing incubates produced only acetate, propionate, and butyrate. The rate of production for each of the volatile fatty acids was constant over the various oxygen concentrations tested. We conclude that isobutyrate and isovalerate in stool are formed from valine and leucine degradation respectively. Quantitation of individual fecal volatile fatty acid excretions may reflect intracolonic degradation of protein and carbohydrate.
正常人类粪便含有五种常见的挥发性脂肪酸，其中三种（乙酸盐、丙酸盐和丁酸盐）是碳水化合物降解的产物。我们研究了其余两种挥发性脂肪酸，异丁酸盐和异戊酸盐，是否由氨基酸降解产生。在含氧量为0%至5%的环境下，将六名健康受试者的粪便与白蛋白、缬氨酸、亮氨酸、色氨酸、苯丙氨酸、葡萄糖或蔗糖一起孵育。异丁酸盐仅由白蛋白和缬氨酸产生，而异戊酸盐仅由白蛋白和亮氨酸产生。含葡萄糖和蔗糖的孵育物仅产生乙酸盐、丙酸盐和丁酸盐。在测试的各种氧浓度下，每种挥发性脂肪酸的产生速率是恒定的。我们得出结论，粪便中的异丁酸盐和异戊酸盐分别由缬氨酸和亮氨酸降解形成。对个体粪便挥发性脂肪酸排泄量的定量分析可能反映结肠内蛋白质和碳水化合物的降解情况。
