Ghrelin is an orexigenic
hormone that may affect substrate utilization in humans.
Ghrelin is influenced by macronutrients, but the effects of insoluble
dietary fiber and
polyphenols are unknown. We investigated the effects of a
polyphenol-rich insoluble
dietary fiber preparation from
carob pulp (
carob fiber) on postprandial
ghrelin responses and substrate utilization. Dose-dependent effects of the consumption of
carob fiber were investigated in a randomized, single-blind, crossover study in 20 healthy subjects, aged 22-62 y. Plasma total and acylated
ghrelin,
triglycerides, and serum
insulin and
nonesterified fatty acids (
NEFA) levels were repeatedly assessed before and after ingestion of an isocaloric standardized liquid meal with 0, 5, 10, or 20 g of
carob fiber over a 300-min period. The respiratory quotient (RQ) was determined after consumption of 0 or 20 g of
carob fiber.
Carob fiber intake lowered acylated
ghrelin to 49.1%,
triglycerides to 97.2%, and
NEFA to 67.2% compared with the control meal (P < 0.001). Total
ghrelin and
insulin concentrations were not affected by consumption of a
carob fiber-enriched liquid meal. Postprandial energy expenditure was increased by 42.3% and RQ was reduced by 99.9% after a liquid meal with
carob fiber compared with a control meal (P < 0.001). We showed that the consumption of a
carob pulp preparation, an insoluble
dietary fiber rich in
polyphenols, decreases postprandial responses of acylated
ghrelin,
triglycerides, and
NEFA and alters RQ, suggesting a change toward increased
fatty acid oxidation. These results indicate that
carob fiber might exert beneficial effects in energy intake and
body weight.