Clinical trial NCT03741218: Grape Polyphenols and Second-meal Effect
Official title: Potential Modulatory Effect of Whole Grape on Second-meal Tolerance in Obese Subjects: Role of Polyphenols
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Obesity
Keywords: Polyphenols
Obesity
Grape
Postprandial
Insulin resistance
Second meal effect
Lead sponsor: National Research Council, Spain
Sponsor class: OTHER_GOV
Collaborators: name: California Table Grape Commission
First posted: 2018-11-14
Enrollment: 25
Sex: ALL
Minimum age (years): 18
Maximum age (years): 70
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Intervention model description: GRAP: dried and milled grape pomaces. PLA: control period. All the subjects will pass the two periods: one half will receive the acute PLA supplementation followed by the acute GRAP supplementation, and the other half will do it inversely. The assignment to each order will be done randomly. Both period will be separated by a two weeks washing period.
Primary purpose: BASIC_SCIENCE

Brief summary: The aim of this is study is to evaluate the effects of a single intake of grapes (a polyphenol-rich food) in postprandial metabolism in subjects with obesity, including a first intake (high-fat breakfast) after overnight fasting a second one (medium-fat lunch). Studies on the effects of polyphenols on postprandial (glucidic and lipidic) metabolism have commonly been performed in animal models and have used grape extracts, ignoring the whole pool of polyphenols present in grapes (extractable and non-extractable polyphenols). Besides, the contribution of polyphenols to the so-called second-meal effect has not been explored. It should be highlighted that this study aims to explore the potential beneficial role of fresh grapes, consumed as fruit; in order to ensure the stability of the product, they will be provided as freeze-dried milled material, but the amount received by the subjects could be incorporated into a common diet, being equivalent to 300 g of fresh grapes.

Detailed description: Twenty-five subjects with obesity will be were recruited. Detailed inclusion and exclusion criteria are provided below.

The subjects will receive, after overnight fasting, either a monodose of freeze-dried grapes (equivalent to 300 g of fresh grapes) or isocaloric placebo solved in water, together with a high-fat breakfast. Blood samples will be collected before the intake, up to 5 h after breakfast, then a medium-fat lunch will be provided and blood samples will be collected for three additional hours. Both interventions will be separated by two weeks. The following determinations will be performed in blood samples collected at different periods: glucose, insulin, triglycerides, uric acid, viscosity, antioxidant capacity. Additionally, a satiety test will be provided. It is expected that grape supplementation, as compared with an isocaloric placebo, causes significant modifications in all the parameters indicated. Nevertheless, the primary outcome of this study is the area under the curve for glucose after the second meal (300-420 min from basal time).

Eligibility criteria: Inclusion Criteria:

* Obesity (BMI = 30-40 kg/m2).

Exclusion Criteria:

* Subjects with a pharmaceutical treatment set to modify blood pressure, lipid profile or glucose.
* Subjects with diagnoses of type 2 diabetes, cardiovascular diseases or thyroid diseases.
* Values above the following ones: glucose, \> 115 mg/dL; triglycerides, \> 350 mg/dL; total cholesterol, \> 280 mg/dL; systolic blood pressure, \> 150 mmHg; diastolic blood pressure, \> 100 mmHg
* Previous bariatric surgery.
* Volunteers participating in other studies (currently or during last year) or weight loss plans.
* Pregnant or breastfeeding women.
* Adherence to vegetarian diets or usual consumption of dietary supplements.

Primary outcomes:
measure: Postprandial glucose (300-420 min)
timeFrame: Up to two months
Secondary outcomes:
Other outcomes:
measure: Postprandial glucose and insulin
timeFrame: Up to four months
measure: Plasma triglycerides
timeFrame: Up to four months
measure: Plasma uric acid
timeFrame: Up to four months
measure: Plasma antioxidant capacity
timeFrame: Up to five months
measure: Plasma viscosity
timeFrame: Up to six months
measure: Satiety
timeFrame: Up to three months
Locations:
city: Madrid
country: Spain
facility: Institute of Food Science, Technology and Nutrition, National Research Council (ICTAN-CSIC)
Study officials:
affiliation: Institute of Food Science, Technology and Nutrition (ICTAN-CSIC)
name: Jara Pérez-Jiménez, PhD
role: PRINCIPAL_INVESTIGATOR
References:
citation: Garcia-Diez E, Cuesta-Hervas M, Veses-Alcobendas AM, Alonso-Gordo O, Garcia-Maldonado E, Martinez-Suarez M, Herranz B, Vaquero MP, Alvarez MD, Perez-Jimenez J. Acute supplementation with grapes in obese subjects did not affect postprandial metabolism: a randomized, double-blind, crossover clinical trial. Eur J Nutr. 2021 Aug;60(5):2671-2681. doi: 10.1007/s00394-020-02451-6. Epub 2021 Jan 2.