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Cocoa as an antioxidant

Everybody should drink a cup of cocoa daily. Good quality cocoa requires only 20 grams to deliver your 5000 ORAC units, so a kilogram should last 50 days. However, as you will also eat other healthy foods, do not plan to get all your ORAC’s from cocoa. See the ORAC score sheet.

 

Cocoa is an antioxidant

Chocolate products have a higher total flavanol content on a per weight basis than many other plant-based foods and beverages, such as apples and red wine. Studies show that flavanols and other flavonoid components in chocolate are rapidly absorbed in humans in a dose-dependent manner. The potential health effects of flavanols in certain chocolates are seen in a variety of functions, including antioxidant properties, reductions in platelet activity (Rein et al, 2000), modulation of eicosanoid (hormone-like substances that play a role in inflammation processes and platelet activity) synthesis, and regulation of immune response.

The chemical structure of flavonoids reveals their antioxidant capacity (Steinberg et al, 2003). These flavonoids can scavenge free radicals, and chelate (combine with) redox active metal ions. Such bioactive compounds could contribute to the maintenance of an integrated network of cellular and plasma oxidant defense mechanisms, to vascular wall tone, and to a reduction in platelet reactivity with a subsequent reduction in the risk for clot formation.

The flavan-3-ols are the major antioxidant components of different cocoa ingredients and chocolate preparations. Oxygen radical absorbance capacity (ORAC) data show that chocolate, as a whole food, has a potent antioxidant capacity when compared with other phytochemical-rich foods such as garlic, blueberries, and strawberries. Chocolate products have higher ORAC values than most other flavanol-containing foods.

Cocoa is a potentially rich dietary source of flavonoids. High concentrations of flavonoids are present in certain cocoas, predominately as the flavanol monomers ()-epicatechin (epicatechin) and (+)-catechin (catechin), and as oligomers of these monomeric base units, which are known as the procyanidins (Kris-Ethertona, and Keenb, 2002)

Antioxidant Power http://www.immunesupport.com/library/print.cfm?ID=3464

Cocoa contains high concentrations of polyphenols — about 8 per cent by weight in the raw beans. Cocoa powder provides a higher concentration of polyphenols than milk or dark chocolate (Chocolate Manufacturers Asociation). The absorpion of polyphenols can depend factors such as what else you have been eating at the time. Blood plasma antioxidant capacity (measured by the total antioxidant potential (TRAP) assay) increased more than 2-fold within 3 hr and remained unchanged for 4 hr after the consumption of cocoa extract (Zhu et al, 2002). Blood levels of the polyphenol epicatechin rise after the consumption of chocolate, reflecting rapid absorption.

Important cocoa flavanols are epicatechin and catechin. Epicatechin and catechin have a relatively high water solubility. Dietary flavanols, such as those found in cocoa, display variable oral absorption, with reported values varying from less then 1 to greater than 50 percent of the ingested dose (Baba et al., 2000; Rein et al., 2000; Hollman et al., 2001). Some of this  difference is due to investigations that assess absorption based on urinary vs plasma measures (Richelle et al., 1999; Baba et al., 2000). In a study by Schramm (2003) average absorption was around five percent. Other published data showed similar plasma levels (Richelle et al., 1999; Wang et al., 2000). Schramm’s conclusion was that food can have a significant effect on polyphenolic absorption. The consumption of bread and sugar significantly increased flavanol absorption compared to when they consumed cocoa alone.

 

Origin of Cocoa

Cacao is the unprocessed cocoa bean from the plant Theobroma cacao and originated deep in the equatorial rain forests of the Americas. Chocolate was first discovered by the Mayas when they used the cocoa bean from the Cacao tree as an ingredient in their favorite drink “xocotlatl. Over the centuries, the use of cacao has evolved to what we now know as chocolate (processed bean in solid or liquid form containing varying percentages of cocoa liquor, cocoa butter, sugar, and milk), and commercial cultivation has extended globally to include equatorial regions of Africa and Asia.

The unprocessed cocoa bean has a seed coat, also termed bran, which accounts for 15% of the total bean weight. The bran is a good source of insoluble fiber (44%) and also has some soluble fiber (11%) that could contribute to lower serum lipids. Cocoa powder contains less than 2% bran (Steinberg et al, 2003).

Cocoa butter makes up 50% to 57% of the dry weight of cocoa beans and is responsible for the melting properties of chocolate. The predominant fatty acids in cocoa butter are saturated (stearic; 18:0, 35% and palmitic; 16:0, 25%) and monounsaturated (oleic; 18:1, 35%), with the remaining fat being primarily polyunsaturated linoleic (3%). Palmitic and stearic acid are chemically defined as saturated fatty acids (SFA).

Cocoa flavonoids

Flavonoids are found in a variety of foods and beverages, including cranberries, peanuts, apples, chocolate, tea and red wine. Flavonoids are a sub-group of the broader class of polyphenols; there are more than 4,000 flavonoid compounds. Flavanols are a more specific sub-class of flavonoids.

Although numerous polyphenolic compounds are present in the cocoa bean, cocoa powder is particularly rich in a subclass of polyphenolics known as flavonoids. Cocoa liquor has three time more ORAC generating antioxidants than dark chocolate (Steinberg et al, 2003). The primary flavonoids in cocoa and chocolate are the fiavan-3-ols (monomers) catechin and epicatechin (monomeric units) and proanthocyanidins (also termed procyanidins), which are polymeric compounds comprising catechin and epicatechin subunits (Zhu et al 2002). Procyanidin oligomers make up 12% to 48% of the dry weight of the cocoa bean.

Time, temperature and other manufacturing processes such as alkalization, can lower the flavonoid content in chocolate. With the proper processing and manufacturing controls in place, substantial amounts of these potentially beneficial compounds can be retained from the cocoa bean. With good production methods, cocoa powder can contain as much as 10% flavonoids on a dry-weight basis. Dark chocolate is formulated with a higher percentage of cocoa bean liquor than is milk chocolate, so it often contains larger amounts of flavonoids. This is an important distinction because not all chocolates are equal sources of flavonoids.

The nutrient density (fat content) of a given flavonoid-containing food should be considered when recommending appropriate sources of dietary phytochemicals.

Flavonoid bioavailability in humans ranges from 1% to 26% and has a large inter-individual variability (Steinberg et al, 2003). There is also a variability between differing compounds such as quercetin, epicatechin, and soy isoflavones. The flavonoid chemical structure largely determes the absorption, distribution, metabolism and excretion, and ultimately the biologic properties of these phenolic compounds. Flavonoids circulating in plasma, including those derived from cocoa, occur primarily as glucuronide, methyl and sulfate conjugates, or combinations thereof, formed through enzyme action in the small intestine and liver. Direct evidence of bioavailability is measured as plasma concentrations of the flavonoid or its metabolites. Indirect evidence can be obtained from biomarkers such as plasma antioxidant capacity, LDL oxidation susceptibility, platelet function, vascular tone, and immune responsiveness.

Flavonoid-rich chocolate contains epicatechin (a monomeric flavanol) that is rapidly absorbed in humans. In healthy human adults, plasma epicatechin concentrations can approach 1 [micro]mol/L within two hours after the consumption of flavonoid-rich chocolate. The rise in plasma epicatechin concentrations is dose-dependent and dictated by the flavonoid concentration in the chocolate eaten. Plasma epicatechin concentrations return within six to eight hours to baseline values. Dimeric procyanidins are also found in human plasma after the consumption of flavonoid-rich cocoa. The monomers and oligomers can have markedly differently biological or physiological effects, so research is continuing.

Health Benefits

Plant-derived polyphenols are historically a significant and natural constituent of the human diet. Diets rich in flavonoids (a class of polyphenols) have been associated with a reduced risk for cardiovascular disease (Zhu et al, 2002). Generally, the consumption of cocoa powder (22g daily in trials) or dark chocolate (16g daily in trials) leads to improved cholesterol ratios, with a higher ratio of high density lipoproteins (HDL) to LDL. A higher ratio of HDL to LDL is associated with a lower risk for heart disease.

In a study where people consumed chocolate with bread and water on two separate occasions: first consuming 40 g of chocolate, and one week later, consuming 80 g of chocolate. The total polyphenol intake from chocolate was 892mg, and 1783mg respectively. Blood samples were drawn before chocolate consumption and at intervals of one, two, three and four hours after consumption. Blood analysis found levels of the polyphenol epicatechin rose after consumption of each chocolate sample, reflecting rapid absorption. Another study showed that feeding 35 g of cocoa powder to 12 male subjects demonstrated a significant increase in LDL cholesterol’s resistance to oxidation within two hours of cocoa consumption (CMA, 2003). In another trial, the inhibitory effect of the cocoa extract was stronger than ascorbic acid.  Vitamin C (ascorbic acid) has been shown to act as an antioxidant (Zhu et al, 2002).

Studies show that cocoa powder, dark chocolate and milk chocolate have higher Oxygen Radical Absorption Capacity (ORAC) values than many common foods, such as prunes and blueberries. (ORAC values measure how powerful an antioxidant a substance is.) An antioxidant is a substance that inhibits oxidation or reactions promoted by oxygen and peroxides, and that include many held to protect the living body from the deleterious effects of free radicals. Examples include beta-carotene, vitamin C, and alpha-tocopherol.

Dark chocolate has more than 13,000 ORAC units and milk chocolate has about 6,700, according to the Chocolate Manufacturers Association. Unsweetened powdered cocoa starts out with almost twice as much antioxidants as dark chocolate, but when it's diluted with water or milk and sugar to make hot chocolate, the flavonoid total per serving plummets to about half that in milk chocolate.

In different terms, a 40-gram serving of milk chocolate contains about 400 milligrams of antioxidants.

A study of a tribe of indians (Kuna Indians living on islands off Panama, Central America ) who consume an average of five cups of cocoa a day has shown that chocolate may prevent high blood pressure. Researchers are investigating a link between consumption of flavanol-rich cocoa and nitric oxide synthesis. There is also a link between antioxidants in chocolate and a reduction in platelet aggregation in blood, and an increase in "good cholesterol" levels. Nitric oxide plays such an important role in the maintenance of healthy blood pressure and, in turn, cardiovascular health (Prof Norman Hollenberg of Brigham and Women's Hospital and Harvard Medical School, 2002).

Flavanols found in cocoa seem to play a role in helping the body use nitric oxide. Flavanols are one class of a group of naturally occurring substances called flavonoids, which are found in foods such as cocoa, dark chocolate, purple grape juice, and tea. Previous studies have also indicated that eating foods high in flavonoids can have positive effects on the heart. Two clinical studies conducted by Heiss et al (2003) in Germany, suggest that the flavanols found in cocoa and chocolate products may have positive effects on vascular health. They studied the idea that the consumption of a flavanol-rich cocoa products improve endothelial function, and that this improvement is related to an increase in circulating nitric oxide concentrations.

Forms of Cocoa

It is worth noting that chocolate and the cocoa bean have saturated fat but the saturated fat does not elevate your cholesterol. Stearic acid found in cocoa, is a unique fatty acid in that it does not elevate blood cholesterol levels as other saturated fats do. Studies have found that diets containing cocoa and chocolate have a neutral effect on blood cholesterol levels in humans.

Cocoa powder

Cocoa powder is either alkalized or nonalkalized. Alkalized cocoa powder contains potassium carbonate, sodium carbonate, sodium hydroxide, or magnesium, all of which neutralize the naturally occurring acids and make the powder easier to dissolve in liquids. Cocoa powder may also contain added starch (e.g., corn starch) to keep it from caking during storage. Unsweetened cocoa powder is used primarily in baking. Sweetened cocoa powder is often mixed with hot milk or water to produce “hot chocolate” or “hot cocoa.”

Unsweetened chocolate

Unsweetened chocolate contains up to 75 percent cocoa solids, and no added sugar or milk products. It is used primarily for baking, because although it has a chocolate flavor, it is too bitter to eat on its own.

Dark chocolate

Dark chocolate is also known as “bittersweet” or “semisweet” chocolate. It contains a high percentage (up to 75%) of cocoa solids, and little (or no) added sugar. Semisweet chocolate has a rich, intense flavor, and is found in candies and the chocolate morsels (chips) used in baking.

Milk chocolate

Milk chocolate contains powdered or condensed milk; it is a sweet, mild-flavored type of chocolate. It contains approximately 20 percent cocoa solids. Many candy bars are made with milk chocolate.

Baking chocolate

Both semisweet and unsweetened baking chocolates are available. Baking chocolate is sold in one-ounce (28-gram) squares, which are convenient for use in recipes.

Couverture

Couverture is a high-quality chocolate used in making specialty candies and truffles. It contains a high percentage of cocoa solids, which gives it a high gloss.

White chocolate

White chocolate is not really chocolate, since it is not made from cocoa beans. However, it is made from cocoa butter to which milk, sugar, and vanilla extract have been added, and it is similar to chocolate in texture. White chocolate is very sweet.

Conclusions

The incorporation of dark chocolate and cocoa powder in a diet that is rich in other food sources of antioxidants- such as fruit, vegetables and rooibos tea, results in a high antioxidant intake and may consequently reduce the risk of cardiovascular disease.

Consumption of flavonoid-rich cocoa and chocolate can result in increased plasma antioxidant activity in healthy human adults (Zhu, et al, 2002).

 

Notes

  • Vinson and his colleagues found that the flavonoids in chocolate are more powerful than vitamins such as ascorbic acid in protecting circulating lipids from oxidation.
  • Atherosclerosis studies suggest that oxidation of lipoproteins is part of the process that creates the plaque that clogs artery walls. "Chocolate just stands out," Vinson said. "It's much higher than anything else."
  • Researchers from the Harvard School of Public Health found that those who eat chocolate and sweets up to three times each month live almost a year longer than those who eat too much or those who steer clear of junk altogether.
  • http://my.webmd.com/content/article/17/1671_52817
  • Cocoa is a potentially rich dietary source of flavonoids. High concentrations of flavonoids are present in certain cocoas, predominately as the flavanol monomers ()-epicatechin (epicatechin) and (+)-catechin (catechin), and as oligomers of these monomeric base units, which are known as the procyanidins (Kris-Ethertona, and Keenb, 2002).
  • Schewe, T., and Sies, H. Flavonoids as protectants against prooxidant enzymes. Biol. Med. 34, 243–253, February 3, 2003 http://www.uni-duesseldorf.de/WWW/MedFak/PhysiolChem/_pdf/Research_monographs.pdf
  • "Nitric oxide plays such an important role in the maintenance of healthy blood pressure and, in turn, cardiovascular health," said study author Norman Hollenberg, MD, PhD, professor of medicine at Brigham and Women's Hospital and Harvard Medical School, in a release. It is produced in the lining of blood vessels and promotes heart health by opening up the arteries and maintaining good blood flow.
  • Researchers say the flavanols found in cocoa seem to play a role in helping the body use nitric oxide. Flavonoids are one class of a group of naturally occurring substances called flavonoids, which are found in foods such as cocoa, dark chocolate, purple grape juice, and tea. Previous studies have also indicated that eating foods high in flavonoids can have positive effects on the heart.
  • Hollenberg's study on cocoa was prompted by an observation that the indigenous people of the island of Kuna in Central America rarely develop high blood pressure and drink an average of 5 cups of cocoa a day and include it in many of their recipes. But once they leave their native island and move to the mainland, their risk of high blood pressure increases, and it's not related to sodium intake or obesity.
  • In the study, researchers fed Boston volunteers cocoa that either had a high or low amount of flavanols. Those who drank the high-flavanol version showed more nitric oxide activity. "If our research results continue to support a link between consumption of flavanol-rich cocoa and nitric oxide synthesis, there could be significant implications for public health," said Hollenberg, in a release.
  • Another presentation at the conference showed that flavanol-rich cocoa and chocolate may work much like aspirin to promote healthy blood flow. Researchers at the University of California at Davis compared the effects of low-dose aspirin and a flavanol-rich cocoa beverage. They found both had similar effects on preventing blood platelets from sticking together, which can harm blood flow. The study authors say those platelet effects may be related to the nitric oxide benefits found by Hollenberg's study.

 

 

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