Intraduodenal calcium enhances the effects of L-tryptophan to stimulate gut hormone secretion and suppress energy intake in healthy males: a randomized, cross-over, clinical trial
Abstract
BACKGROUND
In humans, intraduodenal infusion of L-tryptophan (Trp) increases plasma concentrations of gastrointestinal hormones and stimulates pyloric pressures, both key determinants of gastric emptying and associated with potent suppression of energy intake. The stimulation of gastrointestinal hormones by Trp has been shown, in preclinical studies, to be enhanced by extracellular calcium and mediated in part by the calcium-sensing receptor.
OBJECTIVE
To determine whether intraduodenal calcium can enhance the effects of Trp to stimulate gastrointestinal hormones and pyloric pressures, and if so, whether it is associated with greater suppression of energy intake, in healthy males.
METHODS
Fifteen males with normal weight (mean±SD; age: 26±7 years; body mass index: 22±2 kg/m2), received on three separate occasions, 150-min intraduodenal infusions of 0, 500 or 1000 mg calcium (Ca), each combined with Trp (load: 0.1 kcal/min, with submaximal energy intake-suppressant effects) from t=75-150 min, in a randomized, double-blind, cross-over study. Plasma concentrations of GI hormones (gastrin, cholecystokinin, glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), peptide tyrosine-tyrosine (PYY)), and Trp, and antropyloroduodenal pressures were measured throughout. Immediately post-infusions (t=150-180 min), energy intake at a standardized buffet-style meal was quantified.
RESULTS
In response to calcium alone, both 500-mg and 1000-mg doses stimulated…
How strong is the evidence?
Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design.
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