The Effects of 5-Hydroxytryptophan in Combination with Different Fatty Acids on Gastrointestinal Functions: A Pilot Experiment

Abstract

Background. Fat affects gastric emptying (GE). 5-Hydroxythryptophan (5-HTP) is involved in central and peripheral satiety mechanisms. Influence of 5-HTP in addition to saturated or monounsaturated fatty acids (FA) on GE and hormone release was investigated. Subjects/Methods. 24 healthy individuals (12f : 12m, 22–29 years, BMI 19–25.7 kg/m²) were tested on 4 days with either 5-HTP + short-chain saturated FA (butter), placebo + butter, 5-HTP + monounsaturated FA (olive oil), or placebo + olive oil in double-blinded randomized order. Two hours after FA/5-HTP or placebo intake, a 13C octanoid acid test was conducted. Cortisol, serotonin, cholecystokinin (CCK), and ghrelin were measured, as were mood and GE. Results. GE was delayed with butter and was normal with olive (P < 0.05) but not affected by 5-HTP. 5-HTP supplementation did not affect serotonin levels. Food intake increased plasma CCK (F = 6.136; P < 0.05) irrespective of the FA. Ghrelin levels significantly decreased with oil/5-HTP (F = 9.166; P < 0.001). The diurnal cortisol profile was unaffected by FA or 5-HTP, as were ratings of mood, hunger, and stool urgency. Conclusion. Diverse FAs have different effects on GE and secretion of orexigenic and anorexigenic hormones. Supplementation of 5-HTP had no effect on plasma serotonin and central functions. Further studies are needed to explain the complex interplay.

Visceral hypersensitivity in irritable bowel syndrome: evidence for involvement of serotonin metabolism – a preliminary study

“…We recently documented comparable alterations following 5‐HTP in duodenal mucosa . These observations are in line with previous findings in healthy controls using oral 5‐HTP showing that while plasma 5‐HIAA levels increased significantly, no changes in 5‐HT levels occurred . This can be explained by the action of the SERT on platelet membranes, aimed to maintain steady state concentrations of 5‐HT.…”

“…10 These observations are in line with previous findings in healthy controls using oral 5-HTP showing that while plasma 5-HIAA levels increased significantly, no changes in 5-HT levels occurred. 17,18 This can be explained by the action of the SERT on platelet membranes, aimed to maintain steady state concentrations of 5-HT. Furthermore, plasma 5-HTP levels have been shown previously to parallel 5-HIAA concentrations but the increase in 5-HIAA levels was greater than that of the 5-HTP levels, 19 an observation that supports our study.…”

Short communication: Supplementation of colostrum and milk with 5-hydroxy-l-tryptophan affects immune factors but not growth performance in newborn calves

“…5-Hydroxy-l-tryptophan has been used to increase blood 5-HT concentrations in humans (Gendle et al, 2013;Sauer et al, 2014), mice (Yamada et al, 2006;Laporta et al, 2013), and cows (Weaver et al, 2016;Hernández-Castellano et al, 2017a,b). In contrast to the native amino acid tryptophan, 5-HTP is used exclusively for 5-HT synthesis because it cannot be used in any other metabolic pathway.…”