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Cocoa Polyphenols

Cocoa Polyphenols. Pennington Biomedical Research Center Division of Education

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Cocoa Polyphenols

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  1. Cocoa Polyphenols Pennington Biomedical Research Center Division of Education Heli Roy, PhD Shanna Lundy, BS Phillip Brantley, PhD- Chief PBRC 2005

  2. Overview… • An increasing body of epidemiologic evidence supports the concept that diets rich in fruits and vegetables promote health and attenuate, or delay, the onset of various diseases, including cardiovascular disease, cancer, and certain neurodegenerative disorders • Epidemiologic data has linked these health benefits, at least in part, to the presence of certain flavonoids in fruits and vegetables PBRC 2005

  3. Flavonoids… • Flavonoids are a group of polyphenolic compounds that occur widely in fruits, vegetables, tea, red wine, and chocolate • Cocoa and chocolate products have the highest concentration of flavonoids among commonly consumed foods • Over 10 percent of the weight of cocoa powder is flavonoids PBRC 2005

  4. Cocoa and chocolate products have been delicacies for hundredsof years • Cocoa and chocolate have only recently have they been recognized as significant sources of phytochemicals, with healthful effects • Cocoa and chocolate are among the most concentrated sources of the procyanidin flavonoids,catechin and epicatechin PBRC 2005

  5. Chocolate Candy Consumption • Americans eat a lot of chocolate in the form of candy (about 4.6 kg/year per person or 10 pounds), but not as much as people in some northern European countries • In Switzerland, the country with the highest chocolate consumption, it is estimated at 9.9 kg/year (22 pounds) for each person • Each candy bar contains about 210 calories, 13 g fat (7 of which is saturated), 23 g of carbohydrate, and 3 g of protein PBRC 2005

  6. Flavonoids in Chocolate • Chocolate and cocoa are unique in the type of flavonoids present • The flavonoids in cocoa/chocolate, principally catechinand epicatechin, exist in long polymers • They containtwo, three, or up to ten of the catechin or epicatechin unitslinked, which is fairly distinctive, since most flavonoid-richfoods tend to have more catechins and epicatechins in dimersor trimers, not pentamers, hexamers, etc PBRC 2005

  7. Flavonoids in Chocolate • Also intriguing isthe chemistry of flavonoids in cocoa which are really R-oligomers • These structural characteristics of catechin and epicatechin represent the molecular basis for both their hydrogen-donating (radical-scavenging) properties and their metal-chelating antioxidant properties PBRC 2005

  8. Flavonoid Content:Is Variable • As with most plants, genetic and agronomic factors can markedly influence the contents of phytochemicalsavailable at the time of harvest • Postharvest handling also playsa critical role, because most cocoas undergosome fermentation steps, which subject flavonoids in the cocoato heat and acidic conditions • Subsequent processing steps,such as roasting and alkali treatment, can also reduce the flavonoidcontents PBRC 2005

  9. Flavonoid ContentIs Variable • The actual recipe for the finished food or beverage product determines the amount of a given cocoa (and flavonoid)added. • Depending on harvesting and processing procedures, asmuch as 90% of the flavonoids can be lost during processing PBRC 2005

  10. Flavonoid Content • Different types of chocolate contain varying antioxidant content • In finished products, the amount of cocoa ranges from 7% to 35% in milk chocolate and 30% to 80% in dark chocolate • Consequently, the polyphenol content varies and is generally twice as high in dark than in milk chocolate • Also interesting is the fact that white chocolate does not contain polyphenols PBRC 2005

  11. Recent Studies • Recently, Joe Vinson at the University of Scranton (PA), who has been studying total polyphenols in foods and beverages in the American diet, has found even higher levels of antioxidants in chocolate • His studies have shown that on a weight basis, “the concentration of polyphenols in milk chocolate is higher than in red wines and black or green teas. It is 20 times higher than in tomatoes, 2 times higher than in garlic, and over 3 times higher than in grapes.” PBRC 2005

  12. Foods High in Antioxidants • Beverages: Tea (green and black), red wine, grape, tomato, orange, and apple juice • Top 10 vegetables: Garlic, kale, spinach, Brussels sprouts, alfalfa sprouts, broccoli flowers, beets, red bell peppers, onions, and corn • Top 10 fruits: Strawberry, plum, orange, red grapes, kiwi fruit, pink grapefruit, white grapes, banana, apple, tomato In addition to chocolate, the following foods and beverages are high in antioxidants: PBRC 2005

  13. Numerous dietary intervention studies in humans and animals indicate that flavanol-rich foods and beverages might exert cardioprotective effects with respect to vascular function and platelet reactivity. PBRC 2005

  14. Antioxidant Capacity PBRC 2005

  15. Atherogenesis… • Phenolic antioxidants have been shown to inhibit the oxidation of low-density lipoprotein (LDL) cholesterol, and mounting evidence suggests that it is the oxidized form of LDL that leads to the buildup of fatty plaques in arteries PBRC 2005

  16. Atherogenesis… • Extracts of cocoa powder have also significantly inhibited LDL oxidation in vitro • Kondo et. Al. reported that cocoa prolongs the lag time of LDL oxidation in a concentration-dependent manner • Cocoa phenols has shown to inhibit LDL oxidation by 75%, whereas red wines only inhibit LDL oxidation by 37-65% PBRC 2005

  17. Interestingly, cocoa powder and cocoa extractshave been shown to exhibit greater antioxidant capacity thanmany other flavanol-rich foods and food extracts, such as greenand black tea, red wine, blueberry, garlic, and strawberry in vitro • However, no long-term studies have evaluated the effects of cocoa polyphenol compounds on the oxidative modification of LDL in humans PBRC 2005

  18. Short-term human studies… • Researchers set out to test whether or not these effects shown from in vitro studies could be seen in humans • The levels of epicatechin and catechin were measured in humans at zero, one, two, and six hours following consumption of a single meal of chocolate • The concentration in plasma levels peaked at about one hour; however, by six hours the concentrations had almost disappeared from the plasma PBRC 2005

  19. Same Effects in Humans? Short-term human studies… • Indicated that cocoa flavonoids are absorbed and cleared from circulation relatively quickly • Support the recommendations to consume several servings of fruit and vegetables per day as seen in a number of clinical trials with chocolate and other flavonoid-rich foods, • Spacing intake of flavonoid-rich foods throughout the day could help to provide a continuous supply PBRC 2005

  20. More studies… • Because there is six to seven times more epicatechin than catechin in cocoa/chocolate, most attention has focused on epicatechin in studies • Consistent with in vitro studies, human studies indicate that small doses of epicatechin are effective • There is a statistically significant increase in plasma antioxidant capacity and reduction in lipid peroxides following cocoa/chocolate consumption PBRC 2005

  21. Benefits… • Epicatechin and other flavonoids not only have a direct antioxidant effect, but they may also have a sparing effect on other antioxidants such as Vitamins C and E PBRC 2005

  22. Other Mechanisms… Although flavanol-rich cocoa and chocolate have the potential to augment an individual’s antioxidant defense system, there are other cellular mechanisms through which these flavanol-rich foods can affect cardiovascular health: InflammationPlatelet aggregationNitric oxide (NO)-mediated endothelial changes PBRC 2005

  23. Inflammation PBRC 2005

  24. Atherosclerosis and heart failure, as well as risk factors suchas hypertension and hypercholesterolemia, can activate severalproinflammatory enzyme systems, such as xanthine oxidase, NADH/NADPH oxidase, and myeloperoxidase • Once activated, these enzymesproduce reactive oxygen species and other radicals that, asindicated above, can modify NO availability and LDL and contributeto endothelial dysfunction PBRC 2005

  25. Flavanol-rich cocoa liquorhas been shown to stimulate NO production and to significantlyreduce the activities of xanthine oxidase and myeloperoxidaseafter ethanol-induced oxidative stress • In addition, cocoaflavanols and procyanidins may modulate other mediators of inflammation PBRC 2005

  26. Platelets PBRC 2005

  27. In addition to its influence on oxidative defense mechanisms, polyphenols seem to benefit cardiovascular health in other ways- through regulation of platelet reactivity • Given the prominent role of platelets in the development and manifestation of acute myocardial infarction, stroke, and venous thromboembolism, antiplatelet strategies are an important consideration • A modest decrease in platelet reactivity can be of value because it reduces the probability of clotting PBRC 2005

  28. In one study to determine whether cocoa inhibits platelet activation and function, subjects were given either water or 300 ml of cocoa that provided a very high amount of polyphenols • During the six hour time period following intake of cocoa, there was a reduction in P-selectin, suggestive of less reactive platelets • This is the same response that would be seen following intake of antiplatelet agents such as aspirin PBRC 2005

  29. Endothelium PBRC 2005

  30. Shear stress, ischemia and reperfusion, inflammation, and diseasestates, such as atherosclerosis, diabetes mellitus, and hypertension,can disrupt endothelial function • This is associated with alterationsin endothelium-derived regulatory mediators, an inability toregulate vascular tone, and an overall shift toward the prothromboticstate • Possible that flavanols, by functioning as antioxidants,in addition to modulating prostacylin and leukotriene concentrations, can improve endothelial function through the preventionand possible reduction of oxidative damage PBRC 2005

  31. Conclusions… • Although in vitro studies provide strong support for the hypothesis that flavanol-rich food consumption is associated with the reduced risk for vascular diseases, at this time the majority of studies that have been reported are in the form of short-term clinical trials • The health benefits of these nutrients will best be determined from long-term, randomized, clinical trials PBRC 2005

  32. References • Keen C, et al. Dietary polyphenols and health: Proceedings of the 1st international conference on polyphenols and health. Amer J Clin Nutr. 2005. 81:1 298S-303S. Available at: http://www.ajcn.org/cgi/content/full/81/1/298S • Keen C. Chocolate: Food as medicine/medicine as food. J Amer Coll of Nutr. 2001. 20:90005 436S-439S. Available at: http://www.jacn.org/cgi/content/full/20/suppl_5/436S • Wan Y, et al. Effects of cocoa powder and dark chocolate on LDL oxidative susceptibility and prostaglandin concentrations in humans. Amer J Clin Nutr. 2001. 74:5 596-602. Available at: http://www.ajcn.org/cgi/content/full/74/5/596

  33. References • http://pubs.acs.org/hotartcl/tcaw/99/jul/chocolate.html • http://sciweb.nybg.org/science2/pdfs/mb/chocolate.pdf#search='alternative%20therapies%20sept/oct%20chocolate‘ PBRC 2005

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