scientific paper anastasia dark chocolate and mci

7/31/2019 Scientific Paper Anastasia Dark Chocolate and MCI

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Dark Chocolate AndCardioprotective Effect

Scientific Paper

Name : Anastasia

NIM : 07120070071

Faculty of Medicine

Universitas Pelita Harapan

2007

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Table Of Content

Chapter 1 : Cardiovascular.......................................................................................3

1.1. Cardiovascular disease.........................................................................................3

1.2. Acute Myocardial Infraction(AMI).....................................................................41.2.1. What causes a heart attack?............................................................................................5

1.3. CVD Marker..........................................................................................................6

1.4. CVD risk factors ...................................................................................................7

Chapter 2 : Chocolate................................................................................................8

2.1. Chocolate in modern life.......................................................................................8

2.2. The content of chocolate.......................................................................................82.2.1. Lipids..............................................................................................................................8

2.2.2. Stearic acid in chocolate...............................................................................................10

2.2.3. Sterols............................................................................................................................12

2.2.4. Fiber..............................................................................................................................13

2.2.5. Minerals........................................................................................................................13

2.2.6. Flavonoids.....................................................................................................................15

2.2.7. Flavonoids in chocolate................................................................................................16

Chapter 3 : Chocolate in relationship with cardiovascular effect.......................21

3.1. Effects of cocoa flavonoids on cardiovascular health.......................................213.1.1. Antioxidant effects........................................................................................................22

3.1.2. Effects on platelet activation.........................................................................................23

3.1.3. Effects on modulation of immune response..................................................................25

3.2. Nitric Oxide and chocolate.................................................................................26

3.3. Dose of chocolate.................................................................................................26

3.4. Chocolate and long term effect for cardiovascular...........................................27

3.5. Aspirin and Cocoa...............................................................................................27

Chapter 4 : Observational Study.............................................................................28

4.1. Stearic Acid Observational Studies....................................................................28

4.2. Flavonoid Observational Studies.......................................................................29

References.................................................................................................................32

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Chapter 1 : Cardiovascular

1.1. Cardiovascular diseaseCardiovascular Disease (CVD) includes dysfunctional conditions of

the heart, arteries, and veins that supply oxygen to vital life-

sustaining areas of the body like the brain, the heart itself, and

other vital organs. If oxygen doesn't arrive the tissue or organ will

die.

Ischemic Heart Disease is the technical term for obstruction ofblood flow to the heart. In general this results because excess fat

or plaque deposits are narrowing the veins that supply oxygenated

blood to the heart. Excess buildup of fat or plaque are respectively

termed arteriosclerosis and atherosclerosis. Equally significant

would be inadequate oxygen flow to the brain, which causes a

stroke.

High Blood Pressure (hypertension) often results from this excess

fat or plaque buildup because of the extra effort it takes to

circulate blood. Even though the heart works harder, blockages

still shortchange the needed blood supply to all areas of the body.

The body's amazing survival systems will mask the subtle damage

that is occurring from this extra wear and tear, but not forever.

High blood pressure is called "The Silent Killer" because the first

warning sign is an angina attack or a deadly heart attack or a

stroke.

Kidney disorders (which leave extra fluids, sodium, and toxins in

the body), obesity, diabetes, birth control pills, pregnancy,

smoking, excess alcohol, stress, and thyroid and adrenal gland

problems can also cause and exacerbate a high blood pressure

condition.

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Damage to the heart tissues from CVD or from heart surgery will

disrupt the natural electrical impulses of the heart and result in

cardiac arrhythmia (an abnormally high or abnormally low heart

rate). Individuals often don't realize the aftermath and side effects

that invasive surgical procedures leave. Sudden fluctuations in

heart rate can cause noticeable palpitations, with an associated

faintness, or dizziness, and if severely abnormal could interfere

with blood flow and even initiate a heart attack.

Proper ranges of cholesterol are also important in the prevention

of heart attack or stroke. Total blood cholesterol above 200 mg/dl,

LDL cholesterol above 130 mg/dl, HDL cholesterol below 35 mg/dl;

and lipoprotein(a) level greater than 30 mg/dl are indicators of

problematic cholesterol. Cholesterol is not actually a damage

mechanism but is more an indicator of compromised liver function,

and increased risk of heart attack.

Infection of the heart, carditis and endocarditis, is an additionalcomplication that can occur as a result of a weak immune system,

liver problems, heart surgery, or from an autoimmune disorder like

rheumatic fever. Endocarditis is quite common in persons with

compromised immune systems from HIV or AIDS. If not

appropriately handled, permanent heart muscle damage can occur

from the infection. Many scientific studies validate the effect diet

and supplements can have for the body to heal damages to the

cardiovascular system. Lifestyle changes can also make a big

difference(1).

1.2. Acute Myocardial Infraction(AMI)

A heart attack (also known as a myocardial infarction) is the death

of heart muscle from the sudden blockage of a coronary artery by

a blood clot. Coronary arteries are blood vessels that supply the

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heart muscle with blood and oxygen. Blockage of a coronary

artery deprives the heart muscle of blood and oxygen,causing

injury to the heart muscle. Injury to the heart muscle causes chest

pain and chest pressure sensation. If blood flow is not restored to

the heart muscle within 20 to 40 minutes, irreversible death of the

heart muscle will begin to occur. Muscle continues to die for six to

eight hours at which time the heart attack usually is "complete."

The dead heart muscle is eventually replaced by scar tissue.

Approximately one million Americans suffer a heart attack each

year. Four hundred thousand of them die as a result of their heartattack.

1.2.1. What causes a heart attack?

Atherosclerosis is a gradual process by which plaques (collections)

of cholesterol are deposited in the walls of arteries. Cholesterol

plaques cause hardening of the arterial walls and narrowing of the

inner channel (lumen) of the artery. Arteries that are narrowed byatherosclerosis cannot deliver enough blood to maintain normal

function of the parts of the body they supply. For example,

atherosclerosis of the arteries in the legs causes reduced blood

flow to the legs. Reduced blood flow to the legs can lead to pain in

the legs while walking or exercising, leg ulcers, or a delay in the

healing of wounds to the legs. Atherosclerosis of the arteries that

furnish blood to the brain can lead to vascular dementia (mentaldeterioration due to gradual death of brain tissue over many

years) or stroke (sudden death of brain tissue).

In many people, atherosclerosis can remain silent (causing no

symptoms or health problems) for years or decades.

Atherosclerosis can begin as early as the teenage years, but

symptoms or health problems usually do not arise until later in

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adulthood when the arterial narrowing becomes severe. Smoking

cigarettes, high blood pressure, elevated cholesterol, and diabetes

mellitus can accelerate atherosclerosis and lead to the earlier

onset of symptoms and complications, particularly in those people

who have a family history of early atherosclerosis.

Coronary atherosclerosis (or coronary artery disease) refers to the

atherosclerosis that causes hardening and narrowing of the

coronary arteries. Diseases caused by the reduced blood supply to

the heart muscle from coronary atherosclerosis are called

coronary heart diseases (CHD). Coronary heart diseases includeheart attacks, sudden unexpected death, chest pain (angina),

abnormal heart rhythms, and heart failure due to weakening of the

heart muscle(2).

1.3. CVD Marker

The current study suggests that C-reactive protein, a marker of

systemic inflammation, is a stronger predictor of future

cardiovascular events than LDL cholesterol. In this study, C-

reactive protein was superior to LDL cholesterol in predicting the

risk of all study end points; this advantage persisted in

multivariable analyses in which we adjusted for all traditional

cardiovascularrisk factors and was clear among users as well as

nonusers ofhormone-replacement therapy at base line. However,

C-reactive protein and LDL cholesterol levels were minimally

correlated. Thus, the combined evaluation of both C-reactive

protein andLDL cholesterol proved to be superior as a method of

risk detection to measurement of either biologic marker alone.

Finally, atall levels of estimated 10-year risk for events according

tothe Framingham risk score and at all levels of LDL cholesterol,C-

reactive protein remained a strong predictor of future

cardiovascularrisk(3).

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1.4. CVD risk factors1. Major

Cigarette smoking

Elevated blood pressure

Elevated serum total (and LDL) cholesterol

Low serum HDL cholesterol

Diabetes mellitus

Advancing age

2. Others

Predispositional risk factor

Obesity

Abdominal obesity

Physical inactivity

Family history of premature coronary heart disease

Ethnic characteristics

Psychosocial factors

Conditional risk factors

Elevated serum triglycerides

Small LDL particles

Elevated serum homocysteine

Elevated serum lipoprotein(a)

Prothrombotic factors (eg, fibrinogen)

Inflammatory markers (eg, C-reactive protein) (4)

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Chapter 2 : Chocolate

2.1. Chocolate in modern life

Beneficial effects of eating chocolate:

release of endorphins in the brain, which act as pain-relievers,

boost one's appetite, but does not cause weight gain,

the sugar in chocolate may reduce stress and have a calming

and pain relieving effect

does not give someone acne or other skin eruptions,

does not trigger migraine headaches,

moderate amounts of chocolate makes ones live almost a year

longer,

reduces the risk of heart disease and cancer.

Negative effects of eating chocolate:

People with the highest intake of chocolate either end up with

elevated

VLDL triglycerides (from all that sugar) or with excessive copper

levels. On average, most chocoholic patients test high in both,

and they sooner or later start to exhibit any number of health

problems that area associated with those aspects(5).

2.2. The content of chocolate2.2.1. LipidsCocoa butter accounts for 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

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saturated fatty acids (SFA). In general, SFA consumption is

correlated with an increased risk of coronary heart disease

because of their propensity to elevate plasma lipids and

lipoproteins and to increase thrombosis. Conversely, unsaturated

fatty acids have been reported to decrease atherogenic factors. As

a consequence of the high SFA content of chocolate and cocoa, it

is often viewed as a negative food with respect to the vascular

system. However, stearic acid is an unusual SFA, in that it does

not elevate blood cholesterol levels to the same extent as other

saturated fatty acid. Possible explanations for this disparity may

include chain length, inefficient absorption, metabolism kinetics,

and hepatic desaturation of stearic into oleic acid.

That cocoa butter could have a neutral effect on blood cholesterol

in humans was first reported by Grande and colleagues in 1970.

More recently, Kris-Etherton and colleagues studied subjects who

consumed 10 ounces of chocolate per day incorporated into foods,

supplying 80% of the approximately 37% of total caloriescontributed by fat in a controlled diet. Despite the fact that the

chocolate-enriched diet was high in saturated fat (approximately

20% of calories), subjects experienced a neutral cholesterolemic

response compared with their usual diet that did not include

chocolate and which contained about 14% of calories from

saturated fatty acids. A subsequent study demonstrated that the

daily substitution of a 1.6-ounce milk chocolate bar (a typical

candy bar weighs 1.4 ounces), in place of a high carbohydrate

snack in a National Cholesterol Education Program/American Heart

Association Step One Diet, did not adversely affect LDL-cholesterol

level.

These studies suggest that strategies to reduce dietary fat should

emphasize reduction of the cholesterolemic SFA that are regularly

consumed in relatively larger quantities rather than stearic acid.

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Chocolate consumption in the United States, based on the 1987-

1988 USDA Nationwide Food Consumption Survey, averaged 30 to

90 g/day/person and contributed approximately 1% to 3% of the

total intake of energy and saturated fat intake. A recent analysis

of food sources of dietary SFA and cardiovascular risk in the

Nurse's Health study indicated that chocolate was not a main

contributor to total SFA or stearic acid intake in this large cohort.

Thus, the inclusion of a moderate amount of chocolate containing

stearic acid into the diet is not predicted to have adverse effects

on the lipid and lipoprotein profile of individuals, as long as the

total fat and caloric intake is held constant. Consumption of large

amounts of chocolate, which provides excess fat and calories to

the diet beyond estimated maintenance needs, could contribute to

obesity and negatively impact CVD incidence.

The effects of stearic acid on thrombosis and hemostasis are less

clear and seem to vary among in vitro and in vivo studies. In vitro,

stearic acid is effective in promoting platelet aggregation andfactor VII coagulant activity, whereas, in vivo, preliminary studies

show mixed results. The clinical studies reported on stearic acid to

date are contradictory in that some report neutral effects on

platelet activity and procoagulant factors, whereas others report

negative effects. The long-term effects of stearic acid consumption

on thrombogenic factors are not well elucidated and require

further research.

2.2.2. Stearic acid in chocolateSaturated fat has long been thought to contribute to

atherosclerosis, and thus, adverse for CVD risk. However, stearic

acid has been suggested to be a non-atherogenic type of dietary

saturated fat. Stearic acid is a long-chain 18:0 saturated fatty acid

found commonly in meats and dairy products. Cocoa butter, a fat

derived from cocoa plants and predominantly found in dark

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chocolate, contains an average of 33% oleic acid (cis-18:1

monounsaturated), 25% palmitic acid (16:0 saturated), and 33% of

stearic acid. Thought it is generally considered that saturated fats

overall adversely increase the total cholesterol and LDL levels,

early studies have also suggested stearic acid may be non-

cholesterolemic. This has been confirmed in a series of studies and

a meta-analysis of 60 controlled feeding trials which concludes

stearic acid neither lowers HDL, nor increases LDL or total

cholesterol. The meta-analysis also estimates, that per 1% energy

isocaloric replacement of stearic acid for carbohydrates, stearic

acid intake is predicted to beneficially lower serum triglycerides by

-17.0 nmol/L (p < 0.001). The most recent trial also shows the

effects of stearic acid on lipids is even similar to oleic and linoleic

acids.

Emerging studies have begun to explain how stearic acid in

chocolate may be cholesterol-neutral. One suggested mechanism

is stearic acid's lower absorption, which has been found in severalanimal and human studies though only minimally in others. These

discrepancies may be attributed to the relative position of stearate

on the triglyceride molecule which may affect its relative

absorption rate. This might also explain the suggestion that stearic

acid from plants sources, such as cocoa, may be different from

animal derived sources of stearic acid. Furthermore, some feeding

trials found lower absorption of cocoa buttered compared to corn

oil, though not in others However, heterogeneity may be due to

the dual-presence of calcium in chocolate, in which other trials

found cocoa butter absorption further decreased 13% when

supplemented with calcium (1% by weight), as is done in

chocolate manufacturing. Finally, another strongly supported

protective mechanism relate to the relatively high percent

desaturation of stearic acid to monosaturated oleic acid, a fat

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considered hypocholesterolemic and protective against coronary

heart disease.

Two other pathways suggested for potential benefit are stearicacid's potential anti-platelet and blood pressure reductions

actions(6). Feeding trials have shown that stearic acid reduces

mean platelet volume, an index of platelet activation. However,

mixed findings have been observed regarding the relationship

between stearic acids and factor VIIc coagulation factor, a

predictor of fatal CHD. Though an early study suggested that

stearic acid may increase factor VIIc. no effect on levels of factorVIIc by stearic acid was observed in two other trials. Moreover,

additional trials have refuted the earlier small study and, in fact,

shown that stearic acid lowered the levels of factor VIIc

coagulation factor compared to palmitic and other saturated fatty

acids . As for the relationship between stearic acid and blood

pressure, two feeding trials found stearic acid did not adversely

affect systolic blood pressure. Furthermore, cross-sectionalanalysis within the Multiple Risk Factor Intervention Trial even

found stearic acid levels may be inversely associated with diastolic

blood pressure.

In summary, given the vast majority of studies showing stearic

acid has beneficial or neutral effects on blood pressures and

clotting parameters, it appears unlikely stearic acid intake would

adversely affect CVD risk through these risk factors. Data indicates

stearic acid does not adversely affect established traditional lipid

risk factors, with even favorable lowering of serum triglycerides if

isocalorically replaced for carbohydrates(7)

2.2.3. SterolsPlant sterols and stanols can contribute to improved blood lipid

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profiles by competitive inhibition of dietary cholesterol absorption

in the gut. Very small amounts of plant sterols including sitosterol

and stigmasterol are present in cocoa butter. It is likely that the

minor levels of sterols in finished chocolate have limited impact on

cholesterol absorption; however, this has not been investigated.

2.2.4. FiberThe 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. A novel useof this in a high fiber (25 g total dietary fiber/day) cocoa-bran

cereal was found to increase fecal bulk and resulted in a modest

improvement in serum lipid ratios. In comparison, cocoa powder

contains less than 2% bran, and finished chocolate products have

very little fiber (USDA Nutrient Database, Release 14 July, 2001).

Thus, chocolate consumption does not contribute significantly to

dietary fiber intake.

2.2.5. MineralsThe cocoa bean contains several minerals, some of which are

found in high amounts in processed chocolate.The amount

retained from the cocoa bean depends on the amount of cocoa

bean solids in chocolate; therefore, dark chocolate typically has a

higher amount of minerals than milk chocolate. Although the

cocoa bean itself has a high phytate content, the fermentation and

heat treatments during processing cause hydrolysis of the

phytates; therefore, mineral availability from chocolate and

chocolate products is reasonably good. Chocolate milk has even

been advocated as a potential vehicle for iron fortification. Many

minerals are needed for vascular function, but adequate amounts

of dietary magnesium, copper, potassium, and calcium merit

special attention for their roles in preventing high blood pressure

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and contributing to cardiovascular disease risk reduction.

Magnesium is involved in catalyzing a multitude of biologic

reactions, including protein synthesis, transmission of nerve

impulses, muscle relaxation, energy production, and bone and

teeth adsorption. Although controversial, numerous investigators

have argued that low dietary magnesium intake (


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other biochemical pathways related to cardiovascular health.

Large epidemiologic studies have indicated an inverse association

between potassium intake, blood pressure, and stroke-related

mortality. This association has been reinforced based on results of

clinical trials. The potassium content in a serving of dark and milk

chocolate is very similar (161 and 169 mg, respectively) and is

comparable with the level found in an apple (159 mg; USDA

Nutrient Database, Release 14 July, 2001).

Calcium has also been inversely associated with blood pressure

based on epidemiologic and intervention studies, although lessstrongly than potassium. The calcium content of a serving of milk

chocolate (84 mg) is substantially greater than the level in dark

chocolate (14 mg), and can provide 8% of the USRDA for an adult

woman (USDA Nutrient Database, Release 14 July, 2001). Although

this level is not significant compared with other calcium-rich food

sources, it can make a contribution to the overall ratio of minerals

in the diet. It is becoming clear that consumption of foods in whichminerals exist in combination with other essential nutrients and

phytochemicals in a prudent diet pattern that incorporates a

variety of fruits, vegetables, and whole grains yields the greatest

dietary effects on cardiovascular health.

2.2.6. Flavonoids

The primary flavonoids in cocoa and chocolate are the flavan-3-ols

catechin and epicatechin (monomeric units) and

proanthocyanidins (also termed procyanidins), which are

polymeric compounds comprising catechin and epicatechin

subunits. Procyanidin oligomers make up 12% to 48% of the dry

weight of the cocoa bean. Procyanidins consisting of as many as

10 subunits have been identified in chocolate, and, whereas

apples and chocolate have a similar procyanidin profile, tea and

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wine consist mainly of the monomeric flavonoids. Chocolate

products have a higher total flavan-3-ol concentration on a per

weight basis than is found in most plant-based foods and

beverages that contain flavan-3-ols, yet apples are a very rich

source when expressed on a per kilocalorie basis. Analogous to

many vitamins, time and temperature, in addition to other

manufacturing processes such as alkalization, can be detrimental

to the flavonoid content in chocolate. However, with the proper

processing and manufacturing controls in place, substantial

amounts of these potentially beneficial compounds can be

retained from the cocoa bean. Depending on the methods used in

production, 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, and,

therefore, it often contains greater amounts of flavonoids. This is

an important distinction because not all chocolates are equal

sources of flavonoids. Furthermore, nutrient density of a given

flavonoid-containing food should be considered, along with

enjoyment of the food, when recommending appropriate sources

of dietary phytochemicals. The physiologic effects of flavonoids

present in cocoa and chocolate are described in following sections

of this paper, and the findings are compared briefly with literature

reports of structurally similar flavonoids found in other foods and

beverages(8).

2.2.7. Flavonoids in chocolateA 100 g bar of milk chocolate contains 170 mg of flavonoid

antioxidants, procyanidins and flavanols. It is estimated that

chocolate is a leading source of procyanidin intake in Western

nations (1820%) .Flavonoids belong to a class of antioxidants

called polyphenols from plants. The basic structure of flavonoids is

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a C6-C3-C6 backbone with two armomatic rings and varying

degrees of hydroxylation differentiating one flavonoid type from

another . Flavonoids can be divided into various subclasses,

important of which are flavones, flavonols, flavanones, catechins,

anthocyanidins and isoflavones. Cocoa, is particularly rich in the

flavonoids, epicatechin, catechin, and procyanidins (polymers of

catechins and epicatechins)

Various studies have compared the content of the flavanoids in

cocoa with other food stuffs quantitatively. Cocoa has been shown

to have the highest content of polyphenols (611 mg/serving) and

flavanoids (564 mg/serving of epicatechin), greater than even tea

and wine. Per serving, dark chocolate contains substantially higher

amounts of flavonoids than milk chocolate (951 mg of catechins

per 40 g serving compared to 394 mg in white chocolate) , and

levels of epicatechin in dark chocolate is comparable to red wine

and tea. Also of note, dark chocolate contains significantly greater

amounts of total phenols as well as catechins than milk chocolate

per serving (126+-7.4 mol/g vs. 52.2+-20.2 mol/g). In addition

to dark chocolate having higher flavonoid content, the biologic

effects of flavonoids may also be greater in dark chocolate

because milk in milk chocolate may inhibit the intestinal

absorption of flavanoids. Finally, chocolate is also abundant in

procyanidin flavonoids, comparable with levels in procyanidin-rich

apples . Thus, chocolate is a rich source of flavonoids, particularly

catechins, epicatechins and procyanidins. The earliest

international ecologic study suggested flavonoid intake may be

associated with lower rates of CHD mortality (9).

Mechanisms

Chocolate flavonoids have shown good dose-response

bioavailability in humans. There exists several mechanisms of how

flavonoids may be protective against CVD; these include:

antioxidant, anti-platelet, anti-inflammatory effects, as well as

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possibly increasing HDL, lowering blood pressure, and improving

endothelial function. The body of trials involving chocolate

flavonoid(10).

Central to the pathogenesis of atherosclerosis is the oxidation of

low-density lipoprotein (LDL). The chemical structure of flavonoids

gives the compound free radical scavenging ability, which means

flavonoids may have antioxidant effects.Various studies have

confirmed the role of flavanoids as antioxidants in biological

systems. Flavanoids in chocolate have been shown to exert potent

antioxidant effects in vitro assays under artificial oxidative stressas well increase antioxidant capacity as part of various chocolate

feeding trials. Additionally, because lipid soluble flavonoids may

intercalate into the membranes of lipoprotein particles, studies

have shown flavonoids to decrease lipid peroxidation of biological

membranes . Furthermore, a randomized trial also demonstrated

that flavonoid-rich foods can protect human lymphocytes from

oxidative damage in vivo.

Additionally, aggregation of platelets at the site of plaque rupture

and endothelial dysfunction has been implicated in the

pathogenesis of atherosclerosis. Current research has shown that

a number of components of chocolate, particularly catechin and

epicatechin, have significant antiplatelet effects, quantitatively

similar to that of aspirin. Randomized trials studying platelet

activation markers, microparticle formation and primary platelet

aggregation as end points have found that daily intake of cocoa

beverages produces a significant reduction in all these endpoints

among healthy volunteers. There were also significant correlations

between the reduction in these end points and the plasma

concentrations of catechin and epicatechin. Another study found a

significant reduction in platelet activation in groups consuming

100 g of dark chocolate when compared to those consuming

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similar amounts of white chocolate and milk chocolate. In addition,

randomized trials have also shown that consumption of high-

flavanoid dark chocolate is associated with a significant

improvement of endothelial function, marked by increase in

brachial artery flow mediated dilation, likely mediated by

chocolate flavonoids increasing local production of nitric oxide.

Chocolate may also influence levels of leukotrienes and

prostacyclins. Leukotrienes are potent vasocontrictors,

proinflammatory agents and stimulate platelet aggregation,

whereas prostacyclin is a vasodilator and inhibits plateletaggregation. Consumption of chocolate with high procyanidin

content (147 mg) was shown in a feeding trial to significantly

lower the levels of leukotrienes (29%) and increase the levels of

prostacyclin (32%) when compared to a group consuming a low

procyanidin (3.3 mg) chocolate. In vitro studies have indeed

demonstrated chocolate components to inhibit lipoxygenase

pathways, which gives rise to proinflammatory leukotrienes.Inflammation is now recognized as another independent

mechanism in the pathogenesis of atherosclerosis, with various

inflammatory markers having been shown to predict risk of future

CVD events. In addition to anti-inflammatory effects on the

lipoxygenase pathway, cocoa polyphenols have also been shown

to decrease inflammation via several mechanisms, namely:

inhibition of mitogen induced activation of T cells, polyclonal

activation of B cells, reduced expression of interleukin-2 (IL-2)

messenger RNA, and reduced secretion of IL-2 by T cells Other

have also found chocolate procyanidins can modulate of a variety

of other cytokines (e.g. IL-5, TNF-, TGF-), reducing their

inflammatory effects.

Furthermore, multiple cocoa feeding trials have also found

chocolate to increase HDL cholesterol, and decrease blood

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pressure. Finally, there are also suggestive findings in a few trials

that indicate high-flavonoid chocolate may also lower LDL

cholesterol, and improve insulin sensitivity.

Thus, the large body of evidence from laboratory findings and

randomized trials suggest that high-flavonoid chocolate may

protect against LDL oxidation, inhibit platelet aggregation,

improve endothelial function, increase HDL, lower blood pressure,

and reduce inflammation thereby protective against risk of

CVD(7).

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Chapter 3 : Chocolate inrelationship with cardiovascular

effect

3.1. Effects of cocoa flavonoids oncardiovascular health

The inverse association of high fruit and vegetable intakes with

risk of CVD mortality in numerous epidemiologic studies has led to

many hypotheses regarding the physiologic role of flavonoids.

Cocoa, tea, and wine are increasingly viewed as sources of dietary

components with potentially beneficial functional activities. It

should be noted, however, that there are no epidemiologic studies

specifically evaluating the relationship of chocolate intake and

CVD risk. The chemical structure of flavonoids suggests that they

have antioxidant capacity, with the ability to scavenge free

radicals, and chelate redox active metal ions. It has been

postulated that these bioactive compounds can contribute to the

maintenance of the 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 key to determining the physiologic

significance of dietary flavonoids will be developing anunderstanding of their metabolism and mechanisms of action(11).

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3.1.1. Antioxidant effectsThe flavan-3-ols have been identified as 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. Furthermore, chocolate

products have higher ORAC values than most other flavanol-containing foods. Purified epicatechin oligomers obtained from

cocoa have been shown to protect LDL and liposomes from

oxidation in several in vitro studies and have also been shown to

protect against peroxynitrite-dependent oxidation reactio. This

suggests that procyanidins can protect against reactive nitrogen

species as well as reactive oxygen species. Commercial chocolate

products were found to decrease lipid oxidation when added toLDL preparations in vitro. That the amount of epicatechin

absorbed from a dose of chocolate can be physiologically

important is suggested by the observation that significant

increases in plasma antioxidant capacity and decreases in plasma

lipid oxidation products correlate with the changes in plasma

epicatechin concentrations. Consistent with the above, ingestion

of flavonoid-rich cocoa products resulted in increased resistance of

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LDL to ex vivo oxidation in three different studies.

For comparison, examination of the literature regarding CVD risk

reduction and plasma antioxidant effects of catechins from dietarysources other than chocolate reveals mixed results, but, overall, a

trend toward beneficial health effects is apparent. A recent

metaanalysis of epidemiologic studies on tea consumption

concluded that 3 cups a day may reduce the population incidence

rate of myocardial infarction. Comparison of individual clinical

trials must take into account variations in design, methods, and

outcome measures of the studies. For example, two studiesreported that consumption of six cups of green or black tea, or a

green tea infusion containing about 400 mg of catechin, resulted

in a significant increase in the total plasma antioxidant capacity in

humans. In contrast to this, consumption of green or black tea was

not shown to increase the resistance of LDL to ex vivo oxidation,

despite observations that tea catechins significantly increased LDL

resistance when added to the assay in vitro. Yet another studyreported a borderline significant increase in the oxidation

resistance of lipoproteins in whole serum in the acute period (90

minutes) following ingestion of tea. Consumption of red wine or

red wine polyphenols was shown to enhance the plasma

antioxidant capacity, and increase the resistance of LDL to ex vivo

oxidation, in five studies, whereas no effect was seen in two

studies, including a recent one(12).

3.1.2. Effects on platelet activationIn addition to the antioxidant effects observed, cocoa flavonoids

may influence cardiovascular health through other mechanisms.

Platelets function to maintain vascular integrity. However,

increased platelet reactivity and aggregation in the presence of

endothelial dysfunction can lead to the development of arterial

thrombosis and the progression of atherosclerosis.

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Rein and colleagues evaluated whether the consumption of a

cocoa beverage modulates human platelet function. Platelet

activation markers, platelet microparticle formation, and primary

aggregation were measured at baseline and at two and six hours

after ingestion of a flavonoid-rich cocoa beverage, a caffeine-

containing control beverage, or water. Diminished expression of

platelet activation markers was present at both two- and six-hour

time points, and decreased platelet aggregation was observed in

response to the cocoa beverage, at six hours. The outcome with

cocoa flavonoids is supported by similar results in a study

demonstrating the ability of flavonoid-rich purple grape juice to

decrease platelet aggregation following its consumption by

healthy subjects. It is important to note that all flavonoid-rich

foods are not equal with regard to their ability to alter platelet

reactivity. Indeed, several types of flavonoids may have only

minimal effects on platelets.

A study by Schramm and colleagues provides evidence that someof the effects of chocolate on platelet activity may be secondary to

changes in eicosanoid metabolism. Eicosanoids are bioactive

metabolites of arachidonic acid that mediate inflammatory

processes. A beneficial change in the ratio of two eicosanoids (a

decrease in leukotriene and an increase in prostacyclin) was

observed after consumption of a flavonoid-rich dark chocolate

compared with a flavonoid-poor dark chocolate (providing 147 mg

and 3.3 mg procyanidins/bar, respectively) in healthy volunteers.

Prostacyclin has been shown to inhibit platelet aggregation and is

also a potent vasodilator, whereas leukotriene stimulates platelet

aggregation, is a vasoconstrictor, and is proinflammatory. The

ratio of these two eicosanoids provides a measure of

proinflammatory vs antiinflammatory balance and thus suggests

that chocolate procyanidins may affect the inflammatory response

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via eicosanoid modulation. Cocoa procyanidins and other

flavanoids are capable of directly inhibiting mammalian 15-

lipoxygenase at low micromolar concentrations. This suggests a

mechanism by which they may modulate eicosanoid metabolism

and thereby contribute to cardiovascular protection.

3.1.3. Effects on modulation of immune responseCacao liquor polyphenols were first described to decrease the

expression of interleukin 2 messenger RNA (mRNA) in human

lymphocytes in 1997. Subsequently, Mao and colleagues have

published several in vitro studies reporting the ability of individualcocoa procyanidin fractions to modulate expression of a variety of

cytokines involved in immune responses. The effects of

procyanidins on cytokines were observed to be at the

transcriptional level and were reflected in the protein level as well.

Findings with cocoa procyanidins are consistent with results from

other cell culture studies of polyphenolics such as quercetin and

transreservatrol, indicating the ability of selected flavonoids to

modulate cytokines involved in acute inflammatory responses.

That cocoa flavonoids may have antiinflammatory properties in

vivo is suggested by the work of Osakabe and colleagues,

reporting that cocoa polyphenols can reduce the severity of

ethanol-induced gastric lesions.

The evidence reviewed in this paper demonstrates that flavonoids

have a multitude of actions in vitro and in vivo. Central to this are

the observations that biologic effects occur at physiologic plasma

concentrations of epicatechin that occur following consumption of

flavonoid-rich chocolates. The exact mechanisms for the actions of

the monomeric flavan-3-ols, oligomeric procyanidins, and their

metabolites in vivo remain to be elucidated. Free radical

scavenging activities and participation in the body's overall

antioxidant defense system could account for some, but not all, of

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the observed effects, and it is likely that the flavonoids also

interact with intracellular signaling mechanisms to elicit a variety

of biologic effects in the vascular and immune systems. Although

recent studies suggest that flavonoid-rich chocolate consumption

may contribute positively to maintaining cardiovascular health by

affecting multiple factors, further clinical investigations are clearly

needed to confirm these promising initial observations. To date,

these studies have all been acute and have provided preliminary

data. Larger chronic studies using appropriate biomarkers are

needed to accurately assess the role of many dietary flavonoids,

including cocoa and chocolate, in maintaining cardiovascular

health(8).

3.2. Nitric Oxide and chocolate

In the first study, researchers gave Boston volunteers cocoa with

either a high or low amount of flavonols. Those who drank cocoawith more flavonols showed more nitric oxide activity.

Nitric oxide plays such an important role in the maintenance of

healthy blood pressure and, in turn, cardiovascular health. Also

one study found that a substance in cocoa helps the body process

nitric oxide (NO), a compound critical for healthy blood flow and

blood pressure(13).

3.3. Dose of chocolateThe best effect is obtained by consuming an average amount of

6.7 grams of chocolate per day, corresponding to a small square of

chocolate twice or three times a week. Beyond these amounts the

beneficial effect tends to disappear. For comparison, a standard-

sized Hershey's Kiss is about 4.5 grams (though the classic Kiss is

not made of dark chocolate) and one Hershey's dark chocolate bar

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is about 41 grams (so a recommendation might be one of those

weekly).

The milk in milk chocolate interferes with polyphenols(13)

3.4. Chocolate and long term effect forcardiovascular

Limited evidence also supports the hypothesis that chocolate

might have long-term protective effects on cardiovascular events.

Population-based studies have found that chocolate or cocoa

consumption is associated with lower cardiovascular mortality

both amongst elderly men free of known coronary heart diseaseand postmenopausal women. The long-term effects of chocolate

consumption amongst patients with established coronary heart

disease is largely unknown and to the best of our knowledge the

prospective association between chocolate consumption and

prognosis in survivors of AMI has not been explored (15).

3.5. Aspirin and CocoaThe other study compared how blood platelets responded to aflavonol-rich cocoa drink with 25 grams of semi-sweet chocolate

pieces and a blood-thinning, 81-milligram aspirin dose. The

research found similar reactions to the two from a group of 20- to

40-year-olds: both the drink and the aspirin prevented platelets

from sticking together or clotting, which can impede blood flow. In

other words, flavonol-rich cocoa and chocolate act similarly to low-

dose aspirin in promoting healthy blood flow. Reducing the blood's

ability to clot also reduces the risk of stroke and heart attacks but

the effects you see in aspirin are longer-lasting than the effects

you see in flavonols(16)

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Chapter 4 : Observational

Study

4.1. Stearic Acid Observational StudiesHowever, the observational studies of stearic acid's association

with CVD are inconclusive. Among retrospective studies, a

Japanese case-control study of serum levels reported no

association for stenosis, a Norwegian study found lower odds of MI

, while a Costa Rican study of dietary intake found higher risk of MI

with higher intake of stearic acid. However, the results from the

Costa Rican study should not be given much weight since

retrospective self-report of dietary intakes are notoriously

inaccurate and susceptible to reporting bias. Nevertheless, higher

rates of CHD and CAD progression was found in several

prospective studies, while stroke was not increased in another

study.

On the other hand, several limitations exist for observational

studies of stearic acid. First, researchers have cautioned that

analyses of dietary stearic acid are very difficult due to high

correlations of stearic acid intake with other fatty acids (often r =

0.7 to 0.9), thus impeding optimal study of associations.

Additionally, the larger prospective study that found higher risk ofCHD also noted chocolate was a very small contributor (5%) of

total stearic acid intake, with red meats as primary sources of

stearic acid. Finally, since there exists high interconversion of

stearic acid to unsaturated fatty acids studies involving serum

levels of stearic acid do not answer the relevant causal question of

dietary intake of stearic acid and risk of disease. The associations

of long-term serum stearic acid levels represent the effects of

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post-conversion stearic acid levels after a large proportion of the

original dietary stearic acid has already been converted away to

monounsaturated fat, which is well-established to exert protective

effects against CVD.

Thus, relatively little information can be inferred from

observational studies of the association of stearic acid and CHD,

and no epidemiologic study has, thus far, appropriately and

optimally answered the causal question of the association of

dietary stearic acid intake and risk of CVD. However, a sufficient

body of strong evidence from short term randomized trialssuggests stearic acid components in chocolate may be beneficial

for cardiovascular health. However, further research in this area is

warranted.

4.2. Flavonoid Observational StudiesMechanistic studies involving stearic acid and flavonoids have only

assessed effects on intermediate cardiovascular endpoints.

However, one cannot always assume effects from short term trials

effects will necessarily translate into long term effects on CVD

outcomes. Therefore, one needs to examine observational studies

followed to CVD events. While one small study found moderate

consumption of candy and chocolate was associated with lower

all-cause mortality, this analysis neither isolates chocolate nor

CVD events. Thus, in absence of specific studies of chocolate

flavonoids and risk of CVD, studies of all flavonoids are the best

available evidence to infer risk.

The prospective studies of flavonoids and risk of CVD are

summarized. The earliest international ecologic study suggested

flavonoid intake may be associated with lower rates of CHD

mortality. While some studies report flavonoid intake is not

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associated with CHD incidence, two other prospective studies

suggested flavonoids may lower risk of MI. For stroke, the

evidence is fairly consistent. Other than one small early study

which found a significantly lower risk of stroke with higher total

flavonoid intake, most studies indicated no association for risk of

stroke. However, most of these studies had insufficient power to

adequately study stroke, nor enough power to stratify on various

subtypes of stroke with different etiologies.

However, the most extensively consistent finding is the

association between flavonoid intake and CHD mortality. A total ofeight cohort studies found risk of lower CHD mortality with total or

specific flavonoid intake, with one study finding marginally

protective association among men with prior CVD conditions. Only

one study reported absolutely no association between flavonoid

intake and CHD mortality. However, as noted by the authors of

one of the studies, a high background consumption of milk with

tea intake may have led to the null finding, since milk intake hasbeen shown to prevent the intestinal absorption of flavonoids.

A meta-analysis of the 7 prospective studies prior to September

2001 found that, overall, flavonoids may be protective against

CHD mortality. However, this meta-analysis did not include a large

subsequent cohort study of 38,445 women, which found a non-

significant inverse association between flavonoid intake and CHD

mortality. However, results from our updated meta-analysis still

indicate a significant protective association exists between

flavonoid intake and risk of CHD mortality, RR = 0.81 (95% CI:

0.710.92), comparing highest vs. lowest tertiles.

However, a limitation of inference exists in that flavonoids consists

of a wide variety of polyphenol compounds, the variety of which

may differ between studies due to varying sources of dietary

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flavonoids. Nonetheless, dark chocolate does contain substantially

more flavanols than tea, apple, onions, and red wine. Additionally,

chocolate has all the flavonoids of tea, has 4 times the catechins

of tea, has many flavonoids not found in tea, and substantially

contributes to the total flavonoid intake in the diet of many

countries. However, inference from observational studies on the

protective effect of flavonoids in chocolate on CVD risk is

somewhat indirect and may need to be examined by further

studies.

Overall, these epidemiologic findings, combined with the largebody of evidence from short term randomized chocolate feeding

trials, suggests flavonoid intake from chocolate is likely protective

against CVD, particularly CHD mortality. Additionally, given that

dark chocolate has substantially higher levels of flavonoids than

milk chocolate, and that milk may inhibit absorption of flavonoids

it would be more prudent to consume high flavonoid dark

chocolate rather than milk chocolate(7).

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