Consumption of a sourdough-leavened croissant enriched with a blend of fibers influences fasting blood glucose in a randomized controlled trial in healthy subjects.

BACKGROUND: An incorrect lifestyle, including diet, is responsible for the worldwide dramatic increase in obesity and type 2-diabetes. Increasing dietary fiber consumption may lead to health benefits and reformulation of bakery products may be a strategy to globally improve the diet. OBJECTIVE: This study aimed to assess the impact of a two-week breakfast consumption with a sourdough-leavened croissant containing a blend of dietary fiber from 10 sources (4.8g/100g, FIBCRO), compared to a control croissant (dietary fibers 1.3g/100g, CONCRO) on daily energy intake, appetite, metabolic variables, and the gut microbiome. METHODS: Thirty-two healthy participants were randomly allocated in two groups consuming FIBCRO or CONCRO. Participants self-recorded their diet and appetite through 7-day weighted food diaries and visual analogue scales every day over the two weeks. At baseline and after the intervention, fasting blood and urine samples, and fecal samples were collected beside blood pressure, anthropometry, and body composition. Serum glucose, lipids, C-reactive protein, and insulin according to the official methods and serum dipeptidyl peptidase-4 (DPPIV) activity by photometric method were measured. Polyphenols and urolithins in urines were analyzed by LC/MS/MS whereas gut microbiome in feces by shotgun metagenomics. RESULTS: FIBCRO consumption improved fasting blood glucose compared to CONCRO (mean changes from baseline -2.0 mg/dL in FIBCRO vs +3.1 mg/dL in CONCRO, p=0.022), also reducing serum DPPIV activity by 1.7 IU/L (p=0.01) and increasing urinary excretion of urolithin A-sulfate by 6.9 ng/mg creatinine (p=0.04) compared to baseline. No further changes in any of monitored variables or in the gut microbiome were detected. CONCLUSIONS: Results suggested that a two-week consumption of a sourdough croissant claimed as "source of dietary fiber" improved fasting glycemia compared to a conventional sourdough croissant in healthy subjects. The reduced serum DPPIV activity and increased bioavailability of urolithin likely contributed to determine that effect independently from gut microbiome changes. CLINICAL TRIAL REGISTRY NUMBER AND WEBSITE WHERE IT WAS OBTAINED: NCT04999280 (https://clinicaltrials.gov/).

Postprandial Gastrointestinal Function Differs after Acute Administration of Sourdough Compared with Brewer's Yeast Bakery Products in Healthy Adults.

Background: Europeans consume large quantities of bakery products, although these are known as one of the food categories that potentially leads to postprandial symptoms (such as fullness and bloating). Objective: The aim of this study was to evaluate the effects of sourdough baked goods on gastric emptying and gastrointestinal fermentation and symptoms in healthy people. Methods: In a double-blind, randomized crossover study, 2 sourdough croissants (SCs) or 2 brewer's yeast croissants (BCs) were served as single meals to 17 healthy adults [9 women; age range: 18-40 y; body mass index range (in kg/m2): 18-24]. Gastric volume (GV) was evaluated by magnetic resonance to calculate gastric-emptying rate in the 3-h interval after croissant ingestion. A hydrogen breath test was performed to measure hydrogen production after SC and BC ingestion. Palatability and postprandial gastrointestinal symptoms (discomfort, nausea, fullness, and bloating) over a 4-h period after the meal were evaluated. The area under the curve (AUC) was used to evaluate the overall effects on all variables tested. Results: The total GV AUC was reduced by 11% during the 3 h after the consumption of SCs compared with BCs (P = 0.02). Hydrogen production during the 4-h interval after ingestion of SCs was 30% lower than after BCs (P = 0.03). SCs were rated as being >2 times as palatable as BCs (P < 0.001). The overall severity of postprandial symptoms was 36% lower during the 4 h after intake of SCs compared with BCs (P = 0.05). Conclusion: Sourdough bakery products could promote better postprandial gastrointestinal function in healthy adults and be more acceptable than those prepared with brewer's yeast. This trial was registered at www.clinicaltrials.gov as NCT03207516.