The present invention provides products having resveratrol with high water solubility and nutraceutical and/or phytotherapic compositions having said substances. The processes for obtaining them include the solubility increase of the polyphenol corresponding to a resveratrol compound, preferably trans-resveratrol in water, by its complexation with cyclodextrin under specific conditions that favor thermodynamic equilibrium. The products of the invention present high solubility and purity in aqueous medium, being, therefore, useful to prepare nutraceutical compositions (pharmaceutical and/or alimentary) with antioxidant, anti-inflammatory, antiviral, antidiabetics, cardioprotective, neuroprotective, chemoprotective activities; besides protecting against infections and ischemia, reducing obesity, and preventing aging. Phytotherapic compositions useful to the same therapeutical activities, prepared from the complex of resveratrol and cyclodextrin compound, preferably beta-cyclodextrin/trans-resveratrol, are also provided.