Showing papers by "Mauro Serafini published in 2011"

The Biological Relevance of Direct Antioxidant Effects of Polyphenols for Cardiovascular Health in Humans Is Not Established

Abstract: Human studies provide evidence for beneficial effects of polyphenol-rich foods on cardiovascular health The antioxidant activity of polyphenols potentially explains these effects, but is the antioxidant activity a reliable predictor for these effects? An International Life Sciences Institute Europe working group addressed this question and explored the potential of antioxidant claims for polyphenols in relation to cardiovascular health by using the so-called Process for the Assessment of Scientific Support for Claims on Foods project criteria In this process, analytical aspects of polyphenols, their occurrence in foods, dietary intake, and bioavailability were reviewed Human studies on polyphenols and cardiovascular health were reviewed together with methods for biomarkers of oxidative damage and total antioxidant capacity (TAC) In retrospective studies, F2-isoprostanes and oxidized LDL, the most reliable biomarkers of lipid peroxidation, and measures for TAC showed the expected differences between cardiovascular disease patients and healthy controls, but prospective studies are lacking, and a causal relationship between these biomarkers and cardiovascular health could not be established Therefore, the physiological relevance of a potential change in these biomarkers is unclear We found limited evidence that some types of polyphenol-rich products modify these biomarkers in humans A direct antioxidant effect of polyphenols in vivo is questionable, however, because concentrations in blood are low compared with other antioxidants and extensive metabolism following ingestion lowers their antioxidant activity Therefore, the biological relevance of direct antioxidant effects of polyphenols for cardiovascular health could not be established Overall, although some polyphenol-rich foods exert beneficial effects on some biomarkers of cardiovascular health, there is no evidence that this is caused by improvements in antioxidant function biomarkers (oxidative damage or antioxidant capacity)

Health Benefits of Tea

Abstract: The health benefits ascribed to the consumption of teas may be related to the high content of bioactive ingredients such as polyphenols. Polyphenols have been reported to possess antioxidant, antiviral, and anti-inflammatory activities; modulate detoxification enzymes; stimulate immune function and decrease platelet aggregation (Lampe 2003; Frankel and Finley 2008). Among all tea polyphenols, epigallocatechin gallate (EGCG) has been found to be responsible for much of the health-promoting ability of GT (Khan et al. 2006). In general, GT has been found to be superior to black tea (BT) in terms of health effects, owing to the higher content of EGCG, although the role of thearubigins and theaflavins contained in BT have not been properly investigated. In vitro and animal studies provide strong evidence that polyphenols derived from tea possess bioactivity to delay the onset of risk factors associated with disease development (Cabrera, Artacho, and Gimenez 2006; Wolfram 2007; Yang et al. 2007; Yang et al. 2009; Yang, Lambert and Sang 2009). Studies conducted on cell cultures and animal models indicate a potentially modulating effect of tea on gene transcription, cell proliferation, and other molecular functions (McKay and Blumberg 2002). Over the last few years, clinical studies have revealed several physiological responses to tea that may be relevant to the promotion of health and the prevention or treatment of some chronic diseases (Crespy and Williamson 2004; Cabrera, Artacho, and Gimenez 2006). This chapter covers recent findings on the medicinal properties and health benefits of tea with special reference to antioxidant and anti-inflammatory actions as key mechanisms for cancer and CVD prevention.

Modulation of Plasma Non Enzimatic Antioxidant Capacity (NEAC) by Plant Foods: the Role of Polyphenol

Abstract: A large body of evidence has described the antioxidant properties of phytochemicals such as PolyPhenols (PP) in different in vitro and ex vivo models. PP have been shown to scavenge oxygen and nitrogen derived free radicals, modulating antioxidant enzymes and cellular redox transcription factors. Dietary intervention studies have shown that consumption of plant foods modulate plasma Non Enzymatic Antioxidant Capacity (NEAC), biomarker of endogenous antioxidant network, in human subjects. However the identification of the molecules responsible for this effect is far to be obtained and evidences of an antioxidant in vivo action of PP are contrasting. There is a clear discrepancy between PP concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the in vivo antioxidant network. The available evidence from human intervention studies on the role of plant foods as modulators of plasma/serum NEAC and the involvement of PP will be presented and critically discussed.

Compliance, tolerability and safety of two antioxidant-rich diets: a randomised controlled trial in male smokers.

Abstract: It has been suggested that antioxidants attenuate oxidative stress and prevent oxidative stress-related diseases. Paradoxically, randomised controlled trials (RCT) using pharmacological doses of antioxidant supplements have demonstrated harmful effects in smokers. The aim of the present study was to test the compliance, tolerability and safety of two food-based antioxidant-rich diets in smokers. One of the diets provided antioxidants at levels similar to that used in RCT using supplements which previously have generated harmful effects. The present study followed a randomised, parallel-arm dietary intervention for 8 weeks (n 102) in male smokers (age ≥ 45 years). Participants were randomised to either antioxidant-rich diet, kiwi fruit or control groups. The antioxidant-rich foods provided about 300 mmol antioxidants/week from a wide range of plant-based food items. The kiwi fruit group consumed three kiwi fruits/d. Compliance to both diets was good. Only mild, undesirable events were reported by a minority of the participants. The safety of both diets was demonstrated as no potentially harmful or pro-oxidative effects were observed. In the antioxidant-rich diet group, the mean intake of antioxidants increased from 30 mmol/d at baseline to 62 mmol/d during the intervention. In conclusion, we have demonstrated that male smokers can comply with two food-based antioxidant-rich diets. Furthermore, the present study is the first to demonstrate the tolerability and safety of dietary antioxidants at levels similar to dosages provided in RCT using supplements. Such diets may be useful in future studies investigating whether dietary antioxidants may reduce oxidative stress and related diseases.