trans-Resveratrol in Nutraceuticals: Issues in Retail Quality and Effectiveness

Abstract

Fourteen brands of resveratrol-containing nutraceuticals were evaluated in order to verify their actual resveratrol content and to control if their health-promoting properties are related to manufacturing quality. Products included pure resveratrol capsules or multi-ingredient formulations with standardized amounts of resveratrol and other phytochemicals. Samples were analyzed for total trans-resveratrol, flavonoids, procyanidin, polyphenol content and the results were compared with the content declared on-label. Only five out of 14 brands had near label values, compliant with Good Manufacturing Practices (GMP) requirements (95–105% content of active constituent), four products were slightly out of this range (83–111%) and three were in the 8–64% range. Two samples were below the limit of detection. The greater the difference between actual and labeled resveratrol content, the lower was the antioxidant and antiproliferative activity strength. Dietary supplements containing pure trans-resveratrol exhibited a greater induction of differentiation towards human leukemic K562 cells when compared to multicomponent products. Great differences currently exist among resveratrol food supplements commercially available and GMP-grade quality should not be taken for granted. On the other side, dosages suggested by most “pure”, “high-dosage” supplements may allow a supplementation level adequate to obtain some of the purported health benefits.

(Poly)phenolic characterization of three food supplements containing 36 different fruits, vegetables and berries

“…values, compliant with Good Manufacturing Practices requirements, and two samples were below the limit of detection [53]. The second reason deals with the bioavailability, metabolism, tissue distribution, dose/response and toxicity of these bioactive compounds in form of nutraceuticals, which have not been well established.…”

Parenchymal and Stromal Cells Contribute to Pro-Inflammatory Myocardial Environment at Early Stages of Diabetes: Protective Role of Resveratrol

“…Although reaching an intake of 85 mg of RSV through dietary sources is almost impossible, food supplements usually contain relatively high amounts of the compound, ranging from 55 mg to more than 500 mg per capsule [52], making the 85 mg target relatively easy, even considering the bioavailability factor.…”

A Synergetic Screening Approach with Companion Effector for Combination Therapy: Application to Retinoblastoma

“…For these reasons, we sought an alternative approach, whose rationale is rooted in the observation that many cancer patients consume supplements as a mean to improve their condition [9], [10]. Nutraceuticals very often consist of natural products, which have historically been the main source of new drugs [11], [12].…”

“…As a proof of concept of our approach, we sought to screen chemical libraries for approved drugs that synergize with the antioxidant trans-resveratrol (referred to as resveratrol in this manuscript) widely consumed as a supplement [9], to prevent the growth of retinoblastoma cells. Retinoblastoma is a rare cancer of the eye affecting young children for which more effective chemotherapeutic approaches are needed [13].…”