Joao Tomé-Carneiro

Resveratrol and Clinical Trials: The Crossroad from In Vitro Studies to Human Evidence

Resveratrol (3,5,4’-trihydroxy-trans-stilbene) is a non-flavonoid polyphenol that may be present in a limited number of food-stuffs such as grapes and red wine. Resveratrol has been reported to exert a plethora of health benefits through many different mechanisms of action. This versatility and presence in the human diet have drawn the worldwide attention of many research groups over the past twenty years, which has resulted in a huge output of in vitro and animal (preclinical) studies. In line with this expectation, many resveratrol-based nutraceuticals are consumed all over the world with questionable clinical/scientific support. In fact, the confirmation of these benefits in humans through randomized clinical trials is still very limited. The vast majority of preclinical studies have been performed using assay conditions with a questionable extrapolation to humans, i.e. too high concentrations with potential safety concerns (adverse effects and drug interactions), short-term exposures, in vitro tests carried out with non-physiological metabolites and/or concentrations, etc. Unfortunately, all these hypothesis-generating studies have contributed to increased the number of ‘potential’ benefits and mechanisms of resveratrol but confirmation in humans is very limited. Therefore, there are many issues that should be addressed to avoid an apparent endless loop in resveratrol research. The so-called ‘Resveratrol Paradox’, i.e., low bioavailability but high bioactivity, is a conundrum not yet solved in which the final responsible actor (if any) for the exerted effects has not yet been unequivocally identified. It is becoming evident that resveratrol exerts cardioprotective benefits through the improvement of inflammatory markers, atherogenic profile, glucose metabolism and endothelial function. However, safety concerns remain unsolved regarding chronic consumption of high RES doses, specially in medicated people. This review will focus on the currently available evidence regarding resveratrol’s effects on humans obtained from randomized clinical trials. In addition, we will provide a critical outlook for further research on this molecule that is evolving from a minor dietary compound to a possible multi-target therapeutic drug.

One-year supplementation with a grape extract containing resveratrol modulates inflammatory-related microRNAs and cytokines expression in peripheral blood mononuclear cells of type 2 diabetes and hypertensive patients with coronary artery disease

Numerous studies have shown that resveratrol (RES) exerts anti-inflammatory effects but human trials evidencing these effects in vivo are limited. Furthermore, the molecular mechanisms triggered in humans following the oral intake of RES are not yet understood. Therefore, the purpose of this study was to investigate the molecular changes in peripheral blood mononuclear cells (PBMCs) associated to the one-year daily intake of a RES enriched (8 mg) grape extract (GE-RES) in hypertensive male patients with type 2 diabetes mellitus (T2DM). We used microarrays and RT-PCR to analyze expression changes in genes and microRNAs (miRs) involved in the inflammatory response modulated by the consumption of GE-RES in comparison to a placebo and GE lacking RES. We also examined the changes in several serobiochemical variables, inflammatory and fibrinolytic markers. Our results showed that supplementation with GE or GE-RES did not affect body weight, blood pressure, glucose, HbA1c or lipids, beyond the values regulated by gold standard medication in these patients. We did not find either any significant change on serum inflammatory markers except for a significant reduction of ALP and IL-6 levels. The expression of the pro-inflammatory cytokines CCL3, IL-1β and TNF-α was significantly reduced and that of the transcriptional repressor LRRFIP-1 increased in PBMCs from patients taking the GE-RES extract. Also, a group of miRs involved in the regulation of the inflammatory response: miR-21, miR-181b, miR-663, miR-30c2, miR-155 and miR-34a were found to be highly correlated and altered in the group consuming the GE-RES for 12 months. Our results provide preliminary evidence that long-term supplementation with a grape extract containing RES downregulates the expression of key pro-inflammatory cytokines with the involvement of inflammation-related miRs in circulating immune cells of T2DM hypertensive medicated patients and support a beneficial immunomodulatory effect in these patients.

One-year consumption of a grape nutraceutical containing resveratrol improves the inflammatory and fibrinolytic status of patients in primary prevention of cardiovascular disease.

The search for complementary treatments in primary prevention of cardiovascular disease (CVD) is a high-priority challenge. Grape and wine polyphenol resveratrol confers CV benefits, in part by exerting anti-inflammatory effects. However, the evidence in human long-term clinical trials has yet to be established. We aimed to investigate the effects of a dietary resveratrol-rich grape supplement on the inflammatory and fibrinolytic status of subjects at high risk of CVD and treated according to current guidelines for primary prevention of CVD. Seventy-five patients undergoing primary prevention of CVD participated in this triple-blinded, randomized, parallel, dose-response, placebo-controlled, 1-year follow-up trial. Patients, allocated in 3 groups, consumed placebo (maltodextrin), a resveratrol-rich grape supplement (resveratrol 8 mg), or a conventional grape supplement lacking resveratrol, for the first 6 months and a double dose for the next 6 months. In contrast to placebo and conventional grape supplement, the resveratrol-rich grape supplement significantly decreased high-sensitivity C-reactive protein (-26%, p = 0.03), tumor necrosis factor-α (-19.8%, p = 0.01), plasminogen activator inhibitor type 1 (-16.8%, p = 0.03), and interleukin-6/interleukin-10 ratio (-24%, p = 0.04) and increased anti-inflammatory interleukin-10 (19.8%, p = 0.00). Adiponectin (6.5%, p = 0.07) and soluble intercellular adhesion molecule-1 (-5.7%, p = 0.06) tended to increase and decrease, respectively. No adverse effects were observed in any patient. In conclusion, 1-year consumption of a resveratrol-rich grape supplement improved the inflammatory and fibrinolytic status in patients who were on statins for primary prevention of CVD and at high CVD risk (i.e., with diabetes or hypercholesterolemia plus ≥1 other CV risk factor). Our results show for the first time that a dietary intervention with grape resveratrol could complement the gold standard therapy in the primary prevention of CVD.

Consumption of a grape extract supplement containing resveratrol decreases oxidized LDL and ApoB in patients undergoing primary prevention of cardiovascular disease: A triple-blind, 6-month follow-up, placebo-controlled, randomized trial

SCOPE The cardioprotective role of resveratrol as part of the human diet is not yet clear. Our aim was to investigate the effect of a grape supplement containing 8 mg resveratrol in oxidized LDL (LDLox), apolipoprotein-B (ApoB), and serum lipids on statin-treated patients in primary cardiovascular disease prevention (PCP). METHODS AND RESULTS A triple-blind, randomized, placebo-controlled trial was conducted. Seventy-five patients (three parallel arms) consumed one capsule (350 mg) daily for 6 months containing resveratrol-enriched grape extract (GE-RES, Stilvid®), grape extract (GE, similar polyphenolic content but no resveratrol), or placebo (maltodextrin). After 6 months, no changes were observed in the placebo group and only LDL cholesterol (LDLc) decreased by 2.9% (p = 0.013) in the GE group. In contrast, LDLc (-4.5%, p = 0.04), ApoB (-9.8%, p = 0.014), LDLox (-20%, p = 0.001), and LDLox/ApoB (-12.5%, p = 0.000) decreased in the Stilvid® group, whereas the ratio non-HDLc (total atherogenic cholesterol load)/ApoB increased (8.5%, p = 0.046). No changes were observed in hepatic, thyroid, and renal function. No adverse effects were observed in any of the patients. CONCLUSION This GE-RES reduced atherogenic markers and might exert additional cardioprotection beyond the gold-standard medication in patients from PCP. The presence of resveratrol in the GE was necessary to achieve these effects.

Resveratrol in primary and secondary prevention of cardiovascular disease: a dietary and clinical perspective

Primary prevention of cardiovascular disease (CVD) aims to avoid a first event in subjects that are at risk but have not yet been diagnosed with heart disease. Secondary prevention of CVD aims to avoid new events in patients with established heart disease. Both approaches involve clinical intervention and implementation of healthy lifestyles. The grape and wine polyphenol resveratrol (3,5,4′‐trihydroxy‐trans‐stilbene) has shown cardioprotective benefits in humans. Most of these approaches deal with rather high doses and short follow‐ups, and do not address the issue of long‐term resveratrol consumption safety, especially in medicated individuals. Here, we review the trials conducted with resveratrol in patients at risk for or with established CVD, focusing on the two longest human clinical trials reported so far (1‐year follow‐up). We also discuss the expectations for resveratrol from a dietary and clinical perspective in relation to CVD. However, statistically significant changes in CVD‐risk markers do not necessarily equal clinical significance in the daily care of patients.

Comprehensive characterization of the effects of ellagic acid and urolithins on colorectal cancer and key-associated molecular hallmarks: MicroRNA cell specific induction of CDKN1A (p21) as a common mechanism involved

SCOPE Ellagitannins, ellagic acid, and the colonic metabolites urolithins (Uros) exhibit anticancer effects against colon cells, but a comprehensive molecular analysis has not been done. Herein, we used a panel of cell lines to first time evaluate the antiproliferative properties and accompanying molecular responses of two ellagitannin metabolites mixtures mimicking the situation in vivo and of each individual metabolite. METHODS AND RESULTS We examined cell growth, cell cycle, apoptosis, and the expression of related genes and microRNAs (miRs) in a panel of nonmalignant and malignant colon cell lines. Regardless of the composition, the mixed metabolites similarly inhibited proliferation, induced cycle arrest, and apoptosis. All the metabolites contributed to these effects, but Uro-A, isourolithin A, Uro-C, and Uro-D were more potent than Uro-B and ellagic acid. Despite molecular differences between the cell lines, we discerned relevant changes in key cancer markers and corroborated the induction of CDKN1A (cyclin-dependent kinase inhibitor 1A gene (p21, Cip1); encoding p21) as a common step underlying the anticancer properties of Uros. Interestingly, cell-unique downregulation of miR-224 or upregulation of miR-215 was found associated with CDKN1A induction. CONCLUSION Physiologically relevant mixtures of Uros exert anticancer effects against colon cancer cells via a common CDKN1A upregulatory mechanism. Other associated molecular responses are however heterogeneous and mostly cell-specific.

Pharma-Nutritional Properties of Olive Oil Phenols. Transfer of New Findings to Human Nutrition

The Mediterranean diet has been long associated with improved cardiovascular prognosis, chemoprevention, and lower incidence of neurodegeneration. Of the multiple components of this diet, olive oil stands out because its use has historically been limited to the Mediterranean basin. The health benefits of olive oil and some of its components are being rapidly decoded. In this paper we review the most recent pharma-nutritional investigations on olive oil biophenols and their health effects, chiefly focusing on recent findings that elucidate their molecular mechanisms of action.