Grape Pomace Polyphenols and Cardiometabolic Risk (GRAPOM)

The aim of this is study is to evaluate the long-term effects of grape polyphenols in the modulation of markers of metabolic syndrome. Most of the previous works about polyphenols have only considered a fraction of polyphenols, i.e., extractable polyphenols. As a consequence, an important amount of dietary polyphenols, the so-called non-extractable polyphenols are ignored. In contrast, the effect of both extractable and non-extractable polyphenols will be considered in this study. Also, studies on the long-term effect of grape polyphenol on markers of metabolic syndrome have been mostly conducted in animals, so clinical trials on this topic are needed.

Fifty supposedly healthy volunteers with at least two cardiometabolic risk factors were recruited. The cardiometabolic risk factors used to select the subjects are described below. The whole intervention will be divided in 2 periods, control (CTR) and dried and milled grape pomace (GRAPOM). The two periods will have a duration of 6 weeks. During the CTR period, subjects will follow their normal dietary habits and samples will be collected at the beginning and at the end. No proper placebo could be found for the product, so this CTR period was chosen. During the GRAPOM period, the subjects will daily consume 8 g of the product solved in water and samples will be collected at the beginning and at the end.

Polyphenols, Metabolic syndrome, Cardiometabolic risk, Grape pomace, Postprandial glucose, Insulin resistance, Obesity

GRAPOM: dried and milled grape pomaces. CTR: control period. All the subjects will pass the two periods: one half will do the CTRL period followed by the GRAPOM period, and the other half will do it inversely. The assignment to each order will be done randomly. Both period will be separated by a four weeks washing period.

Daily consumption for 6 weeks of 10 g of dried and milled grape pomaces solved in water. Samples will be collected at the beginning and the end of this period

Follow-up for 6 weeks without intervention. Samples will be collected at the beginning and the end of this period

The whole intervention will be divided in 2 periods, control (CTR) and dried and milled grape pomace (GRAPOM). The two periods will have a duration of 6 weeks. During the CTR period, subjects will follow their normal dietary habits and samples will be collected at the beginning and at the end. No proper placebo could be found for the product, so this CTR period was chosen. During the GRAPOM period, the subjects will daily consume 8 g of the product solved in water and samples will be collected at the beginning and at the end.

Changes of blood insulin fasting levels as result of long-term supplementation with grape pomace (GRAPOM).

Changes of blood glucose fasting levels as result of long-term supplementation with grape pomace (GRAPOM).

Changes of blood glucose response after an oral glucose load as result of long-term supplementation with grape pomace (GRAPOM).

Changes of blood insulin response after an oral glucose load as result of long-term supplementation with grape pomace (GRAPOM).

Changes of blood cholesterol (total, HDL, LDL) as result of long-term supplementation with grape pomace (GRAPOM).

Changes of blood C reactive protein as result of long-term supplementation with grape pomace (GRAPOM).

Changes of blood markers of iron metabolism as result of long-term supplementation with grape pomace (GRAPOM).

Changes of body weight (measured at a body-impedance equipment) as result of long-term supplementation with grape pomace (GRAPOM).

Changes of blood expression of selected miRNA as result of long-term supplementation with grape pomace (GRAPOM).

Inclusion Criteria: At least two of the following requirements: BMI ≥ 25 kg/m2. Fasting glucose values ≥ 100 mg/dL. Triglycerides ≥ 150 mg/dL. HDL-cholesterol: ≤ 50 mg/dL women, ≤ 40 mg/dL men. Blood pressure: systolic ≥ 130 mm Hg or diastolic ≥ 85 mm Hg. Exclusion Criteria: Subjects with a pharmaceutical treatment set to modify blood pressure, lipid profile or glucose. Volunteers participating in other studies or weight loss plans. Pregnant or breastfeeding women.