PBRC 2005

Cocoa PolyphenolsPennington Biomedical Research Center

Division of Education

Heli Roy, PhD Shanna Lundy, BS

Phillip Brantley, PhD- Chief

PBRC 2005

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

• 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

Flavonoids…

PBRC 2005

• Cocoa and chocolate products have been delicacies for hundreds of 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

• 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

Chocolate Candy Consumption

PBRC 2005

• Chocolate and cocoa are unique in the type of flavonoids present

• The flavonoids in cocoa/chocolate, principally catechin and epicatechin, exist in long polymers

• They contain two, three, or up to ten of the catechin or epicatechin units linked, which is fairly distinctive, since most flavonoid-rich foods tend to have more catechins and epicatechins in dimers

or trimers, not pentamers, hexamers, etc

Flavonoids in Chocolate

PBRC 2005

• Also intriguing is the 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

Flavonoids in Chocolate

PBRC 2005

• As with most plants, genetic and agronomic factors can markedly influence the contents of phytochemicals

available at the time of harvest

• Postharvest handling also plays a critical role, because most cocoas undergo some fermentation steps, which subject flavonoids in the cocoa to heat and acidic conditions

• Subsequent processing steps, such as roasting and alkali treatment, can also reduce the flavonoid contents

Flavonoid Content:Is Variable

PBRC 2005

• 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, as much as 90% of the flavonoids can be lost during processing

Flavonoid ContentIs Variable

PBRC 2005

• 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

Flavonoid Content

PBRC 2005

• 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.”

Recent Studies

PBRC 2005

• 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

Foods High in AntioxidantsIn addition to chocolate, the following foods and beverages are high in antioxidants:

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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

Antioxidant Capacity

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• 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

Atherogenesis…

PBRC 2005

• 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%

Atherogenesis…

PBRC 2005

• Interestingly, cocoa powder and cocoa extracts have been shown to exhibit greater antioxidant capacity than many other flavanol-rich foods and food extracts, such as green and 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

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

Same Effects in Humans?• 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

Short-term human studies…

PBRC 2005

• 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

More studies…

PBRC 2005

• 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

Benefits…

PBRC 2005

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 aggregation

Nitric oxide (NO)-mediated endothelial changes

Other Mechanisms…

PBRC 2005

Inflammation

PBRC 2005

• Atherosclerosis and heart failure, as well as risk factors such as hypertension and hypercholesterolemia, can activate several proinflammatory enzyme systems, such as xanthine oxidase, NADH/NADPH oxidase, and myeloperoxidase

• Once activated, these enzymes produce reactive oxygen species and other radicals that, as indicated above, can modify NO availability and LDL and contribute to endothelial dysfunction

PBRC 2005

• Flavanol-rich cocoa liquor has been shown to stimulate NO production and to significantly reduce the activities of xanthine oxidase and myeloperoxidase after ethanol-induced oxidative stress

• In addition, cocoa flavanols and procyanidins may modulate other mediators of inflammation

PBRC 2005

Platelets

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• 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

• 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

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Endothelium

PBRC 2005

• Shear stress, ischemia and reperfusion, inflammation, and disease states, such as atherosclerosis, diabetes mellitus, and hypertension, can disrupt endothelial function

• This is associated with alterations in endothelium-derived regulatory mediators, an inability to regulate vascular tone, and an overall shift toward the prothrombotic state

• Possible that flavanols, by functioning as antioxidants, in addition to modulating prostacylin and leukotriene concentrations, can improve endothelial function through the prevention and possible reduction of oxidative damage

PBRC 2005

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

• 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

References

PBRC 2005

• 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‘

References