Volume 4 Number 1

 

Review Articles
1

ROLE OF DIETARY POLYPHENOLS IN THE PLATELET AGGREGATION NETWORK - A REVIEW OF THE IN VITRO STUDIES
Fausta Natella, Mirella Nardini, Fabio Virgili and Cristina Scaccini[ABSTRACT]

23

EFFECTS AND SAFETY OF ANTIOXIDANT SUPPLEMENTATION
Helmut Schroeder, Estanis Navarro[ABSTRACT]

33

BIOAVAILABILITY OF DIETARY FLAVONOIDS AND CAROTENOIDS
CY Lee, HM Cheng and SM Sim

53

CAROTENOIDS AND OCULAR HEALTH
Da You Zhao, Prakash Bhosale, and Paul S. Bernstein

Research Articles
69

SERUM AND MACULAR RESPONSES TO ANTIOXIDANT SUPPLEMENTATION VERSUS A CAROTENOID-RICH DIETARY INTERVENTION IN THE ELDERLY
Jessica L. Franciose, E. Wayne Askew, John C. Lang, and Paul S. Bernstein[ABSTRACT]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Current Topics in Nutraceutical Research, Volume 4, Number 1, pp. 1-22 (2006)

ROLE OF DIETARY POLYPHENOLS IN THE PLATELET AGGREGATION NETWORK - A REVIEW OF THE IN VITRO STUDIES
Fausta Natella, Mirella Nardini, Fabio Virgili and Cristina Scaccini

ABSTRACT: Several epidemiological studies reported the intake of dietary polyphenols to be inversely associated with risk for cardiovascular disease. The bases of this association are very complex and at least in part can be due to an effect on haemostasis. In fact, polyphenols have been reported to inhibit platelet aggregation both in vitro and in vivo. In this review, the available literature on the in vitro effect of polyphenols on platelet aggregation by different agonists is critically revised, taking into consideration all experimental conditions employed. All polyphenols show some anti-aggregating activity, however the anti-aggregative effect greatly differs between and within the different phenolic classes. Polyphenols have been shown to have an effect on platelet function through a multitude of mechanisms, significantly affecting different steps of the transductional pathway of platelet activation. The analysis of the results indicates a promising role for food polyphenols in preventing thrombosis and cardiovascular diseases, but, at the same time, suggests caution when transferring in vivo the in vitro findings.

 

 

 

Current Topics in Nutraceutical Research, Volume 4, Number 1, pp. 23-32 (2006)

EFFECTS AND SAFETY OF ANTIOXIDANT SUPPLEMENTATION
Helmut Schroeder, Estanis Navarro

ABSTRACT: The use of dietary supplements is widespread in the general population. About half the US population reported a frequent consumption of dietary supplements. Sports men and women mainly take supplements in the belief that they increase their performance, although the bulk of scientific evidence indicates that antioxidant supplements have no effect on physical performance. However, their potential to scavenge strong reactive oxygen species (ROS) protects the organism from oxidative damage, which is associated with several adverse health outcomes. Physical exercise increases oxygen consumption that in turn leads to an increase in the production of ROS. If this production overwhelms the antioxidant capacity of the organism oxidative the result is stress. However, the data that demonstrate prevention in the rise of exercise induced oxidative stress markers is limited. In addition, more studies are needed to evaluate the effects of antioxidant supplementation on immunological function. The consumption of vitamins E and C, in amounts below the tolerable upper limits (UL) established by the Food and Nutrition Board of the Institute of Medicine, seems to be safe over long-term period (more than 1 year). However, recent data on the adverse effects of vitamin E supplementation should make us think more about this issue. In the absence of data, as well as established UL thresholds of other antioxidant supplements, such as flavonoids and ubiquinone, and because of the lack of studies addressing the side effects of such supplementations, no serious recommendations can be given. The absence of such data should be a strong reason, therefore, to think twice before promoting antioxidant consumption in amounts that can be impossible to reach by only following a healthy diet.

 

 

Current Topics in Nutraceutical Research, Volume 4, Number 1, pp. 33-52 (2006)

BIOAVAILABILITY OF DIETARY FLAVONOIDS AND CAROTENOIDS
CY Lee, HM Cheng and SM Sim

ABSTRACT: Dietary antioxidants may help to supplement the body antioxidant defenses in handling free radicals. Studies on different food sources to discover their antioxidant property have received considerable attention since 1960s. However, the majority of these studies were from epidemiological studies and in vitro experiments. There are much fewer in vivo studies on the bioavailability of consumed antioxidants. Bioavailability of antioxidants is important, as the in vitro data cannot be simply extrapolated to the physiological situation. Hence, it is not convinced that dietary antioxidants can act as supplemental free radical scavengers to the body. Carotenoids and flavonoids are among the most extensively studied phytochemicals and were first reported to have antioxidant effects in the late 1970s and mid-1980s, respectively. The present review summarizes the existing bibliography over the last few decades on bioavailability studies of carotenoids and flavonoids, both in human and in rodents. Those findings well implied that it is extremely necessary to increase the bioavailability study of antioxidants so as to demonstrate direct absorption of antioxidants in vivo and, thus enable a more definite conclusion to be drawn on the beneficial effects that dietary antioxidants may have on the body.

 

 

 

Current Topics in Nutraceutical Research, Volume 4, Number 1, pp. 53-68 (2006)

CAROTENOIDS AND OCULAR HEALTH
Da You Zhao, Prakash Bhosale, and Paul S. Bernstein

ABSTRACT: Lutein and zeaxanthin are isomeric xanthophyll carotenoids found abundantly in dark-green leafy vegetables, orange and yellow fruits and vegetables, and in egg yolks. They and other dietary carotenoids such as lycopene and α- and Β-carotene are distributed throughout human tissues, but they are the predominant carotenoids in the human retina and lens. Research studies conducted in different parts of world indicate an inverse relationship between lutein and zeaxanthin intake and/or their serum and tissue levels and both age-related macular degeneration (AMD) and cataract, indicating that that these xanthophyll carotenoids might play a protective role. The ability to raise the levels of macular carotenoid pigments in some members of a healthy population and in AMD patients encourages further study into whether the rises would benefit elderly individuals at risk for visual loss from AMD. So far, no serious side effects have been reported in xanthophyll supplementation studies or in clinical practice.

 

 

 

 

Current Topics in Nutraceutical Research, Volume 4, Number 1, pp. 69-78 (2006)

SERUM AND MACULAR RESPONSES TO ANTIOXIDANT SUPPLEMENTATION VERSUS A CAROTENOID-RICH DIETARY INTERVENTION IN THE ELDERLY

Jessica L. Franciose, E. Wayne Askew, John C. Lang, and Paul S. Bernstein

ABSTRACT: The aim of this study was to observe responses of serum antioxidants, oxidative stress biomarkers, and macular carotenoid pigments to antioxidant supplements or dietary intervention in a single-masked, randomized, pilot clinical study of elderly subjects receiving antioxidant supplements or a dietary intervention. Methods: From a pool of ninety-eight community volunteers, forty-eight male and female subjects (age 65-85) with the lowest baseline serum lutein + zeaxanthin levels were selected and randomly assigned to receive for 12 weeks one of two different antioxidant supplements or a diet rich in fruits and vegetables containing approximately matched levels of four classes of carotenoids: carotenes, the xanthophylls lutein and zeaxanthin, and lycopene. Forty-six completed the study. Both supplements and diet also were rich in vitamins C and E. Outcome measures were changes from baseline: 1) in serum levels of antioxidant micronutrients (vitamins C and E, lutein, zeaxanthin, and Β-carotene); 2) in levels of indicators of oxidative stress: serum lipid peroxides (LPO) and urinary 8-hydroxydeoxyguanosine (8-OHdG); and 3) macular pigment, measured by heterochromatic flicker photometry. Results: Interventions to promote eye health by either diet or supplementation showed consistent serum responses, with substantial improvements within twelve weeks. Serum lutein and vitamin C increased for all groups (p< 0.05), and lipid peroxides decreased for all subjects (p< 0.05); nonetheless, mean macular pigment did not increase significantly during the designated timeframe. Conclusion: Supplementation of elderly individuals potentially at risk for AMD with two different types of antioxidant formulations exhibited positive serum responses similar to a dietary intervention containing approximately comparable levels of carotenoids. This pilot study indicates that the ocular supplements tested in this study elicited responses in serum parameters similar to daily consumption of four servings of carotenoid-rich fruits and vegetables. The study also provides useful criteria for the design of larger-scale and longer-term studies of antioxidant supplementation in an elderly population potentially at risk for AMD.