Effects of intraduodenal administration of lauric acid and L-tryptophan, alone and combined, on gut hormones, pyloric pressures, and energy intake in healthy men.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 31051504 · doi:10.1093/ajcn/nqz020
What was done
In a randomized, double-blind, crossover trial, 16 healthy lean men (age 24 ± 1.5 y) received 90-minute intraduodenal infusions of saline (control), lauric acid (C12, 0.3 kcal/min), L-tryptophan (Trp, 0.1 kcal/min), or combined C12 + Trp (0.4 kcal/min). Antropyloroduodenal pressures were measured continuously, and plasma CCK, GLP-1, and ghrelin concentrations, appetite perceptions, and gastrointestinal symptoms were assessed at 15-minute intervals. Ad libitum energy intake was quantified from a standardized buffet meal immediately post-infusion.
What was found
Combined C12 + Trp significantly reduced energy intake compared with control (1,056 ± 106 kcal vs 1,232 ± 72 kcal, P < 0.05), whereas C12 alone (1,180 ± 82 kcal) and Trp alone (1,269 ± 73 kcal) did not. C12 + Trp stimulated plasma CCK AUC0-90 min (229 ± 22 vs 21 ± 8 pmol/L*min for control, P < 0.05) and GLP-1 AUC0-90 min (545 ± 138 vs 102 ± 41 pmol/L*min, P < 0.05), and suppressed ghrelin AUC0-90 min (-18,188 ± 4,165 vs -3,433 ± 2,647 pg/mL*min, P < 0.05). C12 and Trp individually stimulated CCK to a lesser degree than C12 + Trp and did not suppress ghrelin; C12 alone stimulated GLP-1 and phasic pyloric pressures.
Why it matters
Combining low, individually non-suppressive doses of lauric acid and L-tryptophan synergistically reduces acute energy intake while stimulating satiety hormones CCK and GLP-1 and suppressing ghrelin.
Limits
The sample was small (n = 16) and restricted to young, lean, healthy men. Direct intraduodenal infusion bypasses normal cephalic, oral, and gastric digestive phases, and long-term effects on weight and oral feeding were not evaluated.
Cited by
- supports Lauric acid (C12) suppresses ghrelin in the gastrointestinal tract.