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The Impact of Cocoa Flavanols on Cardiovascular
Health
Julia Vlachojannis,
1
Paul Erne,
2
Benno Zimmermann
3,4
and Sigrun Chrubasik-Hausmann
1
*
1
Institute of Forensic Medicine, University of Freiburg, Albertstr. 9, 79104 Freiburg, Germany
2
Labor Signal Transduction, Department of Biomedicine, University Hospital, Hebelstrasse 20, 4041 Basel, Switzerland
3
Department of Nutritional and Food Sciences, Chair of Molecular Food Technology, University of Bonn, Römerstr. 164, 53117 Bonn, Germany
4
Institut Prof. Dr. Georg Kurz GmbH, Stöckheimer Weg 1, 50829 Köln, Germany
The aim of the study was to review the effect of cocoa flavanols on cardiovascular health, with emphasis on the
doses ingested, and to analyze a range of cocoa products for content of these compounds. PubMed was searched
from 2010 to locate systematic reviews (SR) on clinical effects of chocolate consumption. Thirteen SRs were
identified and reviewed, and provided strong evidence that dark chocolate did not reduce blood pressure. The
evidence was however strong for an association with increased flow-mediated vasodilatation (FMD) and
moderate for an improvement in blood glucose and lipid metabolism. Our analysis showed that cocoa products
with around 100 mg epicatechin can reliably increase FMD, and that cocoa flavanol doses of around 900 mg or
above may decrease blood pressure in specific individuals and/or if consumed over longer periods. Out of 32 co-
coa product samples analyzed, the two food supplements delivered 900 mg of total flavanols and 100 mg epicat-
echin in doses of 7 g and 20 g and 3 and 8 g, respectively. To achieve these doses with chocolate, around 100 to
500 g (for 900 mg flavanols) and 50 to 200g (for 100mg epicatechin) would need to be consumed. Chocolate
products marketed for their purported health benefits should therefore declare the amounts of total flavanols
and epicatechin. Copyright © 2016 John Wiley & Sons, Ltd.
Keywords: cocoa; chocolate; flavanols; blood pressure; flow-mediated vasodilatation; blood glucose; blood lipids.
INTRODUCTION
The seed of Theobroma cacao L. contains a number of
phenolic compounds including monomeric flavanols
(mainly epicatechin and catechin), oligomeric flavanols
(procyanidins, mainly B2, B5, C1, tetramers to
heptamers and A-type dimers), flavonols (mainly quer-
cetin derivatives), hydroxycinnamic acid amides and
others (Wollgast, 2004). The total quantity of polyphe-
nols expressed as a percentage of the weight of the dry
bean can be up to 18% (Arranz et al., 2013), depending
upon the area of cultivation, bean maturity, climatic
conditions, the harvest season and the storage time after
harvest (Oracz et al., 2015). Processed dark chocolate
contains less than one tenth of this amount (1.7 to
8.4 mg/g polyphenols) and milk chocolate even less
(0.7 to 5 mg/g).
The ripe cocoa bean undergoes a fermentation proce-
dure before roasting, which has a great impact on
flavanol and total proanthocyanidin loss. A temperature
of 135 °C is associated with the highest total phenolic
index (TPI), whereas 145 °C produced the lowest TPI
values (Ioannone et al., 2015).
In the 15th century, the Aztecs used cacao for
religious ceremonies, as means of for payment and
as an aphrodisiac. The Spanish conquistadors re-
ferred to it as ‘brown treasure’and when introduced
to Europe it was very rapidly accepted and also used
medicinally (Verna, 2013). Brewed cocoa was given
to emaciated or weak patients to achieve weight gain
and provide stimulation of the central nervous system
(CNS). It was used to stimulate bowel function and
increase diuresis (Wollgast, 2004). The CNS effects
of cocoa can be attributed to the methylxanthines
theobromine and caffeine and biogenic amines. To-
day, brewed cocoa is no longer popular but chocolate
in all its forms is consumed in vast amounts, despite
the high caloric value (about 500 kcal per 100 g; Arts
et al., 1999).
The aims of this study were to evaluate any benefits of
cocoa to cardiovascular (CV) health and relate them to
the dose of flavanols required for CV effects. An analy-
sis of cocoa products for their content of total flavanols,
epicatechin, catechin and theobromine was then carried
out to assess the feasibility of ingesting these doses in
the different products.
METHODS
A review of the cardiovascular effects of cocoa products.
PubMed was searched from January 2010 to November
2015 using the term ‘cocoa review’to identify systematic
reviews on health effects of cocoa products. The reviews
were retrieved and authors JV, SC-H, PE evaluated the
data independently of each other. The studies and data
were sorted according to the total number of studies
and patients included, the outcome measures used, the
results obtained and the analytical methods of the cocoa
flavanols considered in the reviews. Only reviews
* Correspondence to: Prof. Dr. Sigrun Chrubasik-Hausmann, Institut für
Rechtsmedizin, Albertstr. 9, D 79104 Freiburg i.Br, Germany.
E-mail: sigrun.chrubasik@klinikum.uni-freiburg.de
PHYTOTHERAPY RESEARCH
Phytother. Res. 30: 1641–1657 (2016)
Published online 1 July 2016 in Wiley Online Library
(wileyonlinelibrary.com) DOI: 10.1002/ptr.5665
Copyright © 2016 John Wiley & Sons, Ltd.
Received 14 March 2016
Revised 16 May 2016
Accepted 17 May 2016
including 15 or more interventional studies were
extracted and further examined for their flavanol
content in the individual studies. These were compared
with those used in the meta-analyses of the reviews.
The individual studies were classified as ‘confirmatory’
(an adequately controlled and appropriately sized trial
where hypotheses were stated in advance) or ‘explo-
ratory’(all other studies) in order to evaluate the
evidence of effectiveness for the outcomes as previously
reported (Chrubasik-Hausmann et al., 2014a, 2014b;
Vlachojannis et al., 2009, 2010a, 2010b, 2013, 2015a,
2015b, 2016).
The outcomes were awarded a rating of ‘strong’if at
least two confirmatory studies demonstrated a clinically
relevant effect; as ‘moderate’for consistent findings
from one confirmatory study with a clinically relevant
effect and/or multiple exploratory studies of high inter-
nal validity (quality trial score of at least 10) or both,
or as ‘poor’if multiple exploratory studies were of low
internal validity or there was only one single study of
high quality.
Analyses of various cocoa products. Table 1 summarizes
the characteristics of the cocoa products analyzed. Details
of the analyses are published in Damm et al. (2016). In
short, samples were extracted by acetone/water (polyphe-
nols) and hot water (methylxanthines) using pressurized
liquid extraction. Extracts were analyzed by HPLC on
reversed phase (individual polyphenols and methylxan-
thines) and normal phase (proanthocyanidins according
to their degree of polymerization) columns. Flavanols
were quantified by UV at 280nm using epicatechin as an
external standard.
RESULTS
Review of the cardiovascular effects of cocoa products
We identified 196 references, of which one was a
‘systematic review of “systematic reviews”’; 111 were
reviews but were either not carried out in a systematic
way or were not related to clinical effectiveness.
Twenty-seven references were clinical trials or letters.
This left ten SRs for extraction. Hand searching identi-
fied three further SRs (Fig. 1).
The three SRs which included epidemiological studies
(Buitrago-Lopez et al., 2011; Zhang et al., 2013; Kwok
et al., 2015) showed that chocolate consumption reduced
the relative risks of coronary heart diseases (CHD),
stroke and CV mortality. The amount of chocolate
consumed by the participants was ‘self-reported’and
the products consumed were not characterized, so that
the daily amount of cocoa flavanols ingested could not
be surmised.
Four of the SRs included 15 or more studies (Table 2).
The number of overlapping trials in the Cochrane
review (Ried et al., 2012) and the review by Shrime
et al. (2011) was 17 and that by Hooper et al. (2012)
and Shrime et al. (2011) was 22 (Table 3). Ellinger
et al. (2012) used stricter in-/exclusion criteria than the
other reviews.
In all reviews, blood pressure (BP) decreased after
2 weeks of cocoa consumption, especially when com-
pared to a flavanol-free control group (Ried et al.,
2012). An association between BP decrease and mono-
meric flavanols consumed was, however, not seen in
the Cochrane review. In the review by Hooper et al.
(2012) doses of 50 mg of epicatechin per day and higher
resulted in greater effects on systolic and diastolic BP.
The Ellinger et al. (2012) used a nonlinear regression
model to identify any dose-dependent relationship
between epicatechin consumption and BP and calcu-
lated that a daily dose of only 25 mg of epicatechin
decreased systolic BP by 4 mmHg and diastolic by
2 mmHg (Ellinger et al., 2012).
Five of the clinical trials included in the SRs had a
confirmatory study design with regard to BP (van den
Bogaard et al., 2010; Desch et al., 2010a; Davison et al.,
2010; Muniyappa et al., 2008; Taubert et al., 2007)
(Table 3). One of these was excluded from the Cochrane
review because it compared groups with high or low levels
of chocolate consumption and had no control group
(Desch et al., 2010a). In three studies, the primary out-
come measure was based on 24-h BP measurements
(van den Bogaard et al., 2010; Desch et al., 2010a; Davison
et al., 2010). Desch et al., (2010a) found a BP decrease over
3 weeks but no difference between the effects of daily con-
sumptions of 6 g and 25 g dark chocolate, contrary to the
hypothesis that the effect is dose related, which means that
the study is exploratory in nature. The van den Bogaard
(2010) and Davison et al. (2010) studies did not find any ef-
fect on BP except in very high doses. Whereas Muniyappa
et al., (2008) did not find a significant effect on BP, Taubert
et al. (2007) found that systolic BP decreased by 3 mmHg
and diastolic by 2 mmHg after 18 weeks of dark chocolate
consumption. In both studies the primary outcome mea-
sure was based on only three BP assessments over the
study period, which is unreliable due to the great intra-
individual variability of BP (Warren et al., 2010). Based
on these findings, there is strong evidence that dark choc-
olate, in the doses and populations investigated, had no
BP-lowering effect, and this conclusion is supported by a
number of exploratory studies (see SRs).
Hooper et al. (2012) and Shrime et al. (2011) inves-
tigated other CV variables and demonstrated an in-
crease in flow-mediated vasodilatation (FMD) after
acute and chronic intake of dark chocolate, regardless
of the epicatechin dose consumed. A decrease in insulin
resistance and mild effects on blood lipids were also
observed. Hooper et al. included three confirmatory
studies which found that the FMD increase was main-
tained during the study period of up to 8 weeks. In the
individual studies 821 mg (with 22 mg epicatechin, Faridi
et al., 2008), 444 mg (with 107 mg epicatechin, Farouque
et al., 2006) and an unknown quantity (Flammer et al.,
2012) of flavanols were consumed. These confirmatory
studies reflect numerous exploratory studies and pro-
vide strong evidence that dark chocolate increases
FMD. The evidence for some other outcomes is mode-
rate, because there is only one confirmatory study for
blood glucose (Almoosawi et al., 2010) and one for
blood lipids (Mellor et al., 2010), both supported by
several exploratory studies.
Importantly, in both, the Cochrane and the Shrime
reviews, the cocoa flavanols were incorrectly calculated
by pooling values assessed using different methods
(photometric/HPLC) and using inaccurate values in
1642 J. VLACHOJANNIS ET AL.
Copyright © 2016 John Wiley & Sons, Ltd. Phytother. Res. 30: 1641–1657 (2016)
Table 1. Sample numbers (No), CP cocoa powder, FS food supplement, DC dark chocolates, MC milk chocolate, cocoa product, manufacturer, cocoa preparation (type), declared amount of cocoa in
percent, if fat was declared: non-fat cocoa solids (NFCS) in percent, cultivar and/or provenience, use best before and lot numbers of the cocoa products analyzed
No Product Manufacturer Type Cocoa (%)
a
NFCS (%)
b
Cultivar and/
or provenience Best before LOT
FS-1 CocoaVia
Unsweetened
Dark Chocolate
Mars Symbioscience
(Mars, Inc.) Germantown (USA)
cocoa powder +
cocoa extract powder
07.2016 510BAIDS02
FS-2 CocoaVia
Cocoa Extract
Supplement
Capsules
Mars Symbioscience
(Mars, Inc.) Germantown (USA)
Powder filled in
capsules (cocoa extract)
02.2017 505BAIDS01
CP-1 Poudre Cacao
Naturel (Nestle)
Cargill
(USA)
Cocoa powder 100 89.0
CP-2 Poudre Cacao
Naturel (Nestle)
Die Archer Daniels Midland
Company (ADM) (USA)
Cocoa powder 100 79.0
DC-1 Chocalat Tonic Bonnat Chocolatier-Confiseur
Voiron Cedex
(France)
Raspers 100 10.2015
DC-2 Chocolat Bonnat
Noir
Bonnat Chocolatier-Confiseur
Voiron Cedex
(France)
Bar 100 12.2015
DC-3 Labooko Dark Zotter Schokoladen
Manufaktur GmbH (Austria)
Bar 100 41.0 Peru 27.04.2016
DC-4 100% Cacao Andrea Stainer (Italy) Bar 100 39.6 30.04.2016 L6041
DC-5 Criolloro
Reiner Edelkakao
Aeschbach Chocolatier
(Switzerland)
Bar 99 30.04. 2016 19441
DC-6 Lindt Excellence
Noir Absolu
Lindt & Sprüngli (Switzerland) Bar 99 50.0 02.2016 L253430
DC-7 Labooko Dark Zotter Schokoladen
Manufaktur GmbH (Austria)
Bar 90 38.0 Bolivia 30.03.2016
DC-8 Lindt Excellence
Noir Prodigieux
Lindt & Sprüngli
(Switzerland)
Bar 90 35.0 04.2016 L5975 17
DC-9 Lindt Excellence
Noir Puissant
Lindt & Sprüngli (Switzerland) Bar 85 39.0 01.2016 L2564 34
DC-10 Moser Roth Edel
Bitter Schokolade
Moser Roth GmbH;
Berlin, (Germany)
Bar 85 34.8 01.12. 2015 F58C
DC-11 Qualite´& Pix Noir
Extra dunkle Schokolade
Chocalat Halba (Switzerland) Bar 85 33.0 09.05. 2016 L14513
DC-12 Labooko Dark Zotter Schokoladen
Manufaktur GmbH (Austria)
Bar 82 31.0 Criollo/Peru 30.03. 2016
DC-13 Labooko Dark Zotter Schokoladen
Manufaktur GmbH (Austria)
Bar 82 33.0 Belize (Toledo) 20.01. 2016
(Continues)
1643COCOA FLAVANOLS AND CARDIOVASCULAR HEALTH
Copyright © 2016 John Wiley & Sons, Ltd. Phytother. Res. 30: 1641–1657 (2016)
Table . (Continued)
No Product Manufacturer Type Cocoa (%)
a
NFCS (%)
b
Cultivar and/
or provenience Best before LOT
DC-14 Criolloro
Dunkle Edelschokolade
Aeschbach Chocolatier
(Switzerland)
Bar 80 Criollo 15.01. 2016 19292
DC-15 Supreme
Noir Authentique
CHOCOLAT FREY AG;
Buchs/Aargau, (Switzerland)
Bar 78 31.0 01.2016 KGM5
DC-16 Chocolat de cru Reichmuth von Reding
(Switzerland)
Bar 75 Greneda Criollo
Trinitarion
11.2015
DC-17 Chocolat de cru Reichmuth von Reding
(Switzerland)
Bar 74 Criollo,Dominican Republic,
(HaciendaElvesia)
11.2015
DC-18 Chocolat de cru Reichmuth von Reding
(Switzerland)
Bar 72 Arriba/Ecuador 12.2015
DC-19 Qualite´& Pix Noir
Extra dunkle Schokolade
Chocolat Halba
(Switzerland)
Bar 72 27.0 24.03. 2016 L 14446
DC-20 Cioccolato Puro
al 70%
CioKarrua Sicilia (Italy) Bar 70 32.2 27.07. 2015 sza70-14/002
DC-21 Lindt Excellence
Noir intense
Lindt & Sprüngli
(Switzerland)
Bar 70 29.0 30.01. 2016 L4574 11
DC-22 Chocolat de cru Reichmuth von Reding
(Switzerland)
Bar 68 Criollo/Venezuela 11.2015
DC-23 Criolloro
Dunkle Edelschokolade
Aeschbach Chocolatier
(Switzerland)
Bar 66 Criollo 30.05. 2016 19473
DC-24 Cailler
Cuisine Zartbitterschokolade
Nestle (Switzerland) Bar 64 25.5 03.2015 32460011
DC-25 CHD-Q65ACTICOA Barry Callebaut
Wieze (Belgium)
Drops 63.5 29.9 Criollo/Venezuela 04.11.15
DC-26 Cioccolato senza
Zuccheri Aggiunti
CIOKARRUA
Sicilia (Italy)
Bar 60 26.0 Criollo 05.06. 2015 SNZ13/013
DC-27 Cailler Crémant Nestle (Switzerland) Bar 46 14.7 05.2016 431600114
MC-1 Labooko Milk Zotter Schokoladen
Manufaktur GmbH (Austria)
Bar 35 28.10. 2015 28.10.15
a
As declared.
b
NFCS = non-fat cocoa solids as calculated by declared percentage of cocoa and fat.
Table 1. (Continued)
1644 J. VLACHOJANNIS ET AL.
Copyright © 2016 John Wiley & Sons, Ltd. Phytother. Res. 30: 1641–1657 (2016)
some calculations. The correct values are listed in
Table 3. Hooper et al. (2012) and Ellinger et al. (2012)
however related the clinical effects to the marker com-
pound epicatechin.
Analyses of cocoa products
Table 4 summarizes the content of total flavanols,
monomers (epicatechin + catechin) and epicatechin (all
mg/gram), and theobromine (mg per 10 g) of chocolate,
and the amounts of chocolate containing 900 and 200 mg
of total flavanols and 100 mg epicatechin. The correla-
tions between the cocoa percentages and the nonfat co-
coa solids (NFCS) and the polyphenols are presented in
Fig. 2a–d and the correlations between total flavanols
and epicatechin and NFCS and theobromine in Figs.
2e and 2f, respectively.
DISCUSSION
Epidemiological studies
The protective CV effects of cocoa flavanols has been
the subject of many epidemiological and interventional
trials. Data obtained from the most recent epidemiolo-
gical studies confirm an association between high intake
of flavanol-rich cocoa products and decreased incidence
of CV events, especially stroke and myocardial infarc-
tion (Corti et al., 2009, Table 2). However, the CV risk
reduction is not solely related to the cocoa flavanols,
and compounds other than flavan-3-ols are also in-
versely associated with a reduced CV risk. These include
anthocyanidins, flavones, flavanones and flavanols, and
sensitivity and subgroup analyses further support this
association (Wang et al., 2014). There are several reasons
to question data obtained by questionnaires or phone
calls on habitual chocolate consumption, including:
(i) The outcomes attributed to cocoa flavanols may
have been affected by the daily intake of other nat-
ural antioxidants obtained from selected fruits and
vegetables, such as guaraná, coffee, collard greens,
apples, beets, beans, oranges and onions (Ferrari
et al., 2016);
(ii) The quantities which people remember or admit to
eating, or those assumed from product weight, may
be incorrect. Even in prospective studies, the choco-
late product weight rather than the amount of cocoa
flavanols has been sometimes considered (e.g.
Kwok et al., 2015). Table 4 shows that the amount
of cocoa flavanols varies greatly even in dark choco-
late, and in the epidemiological studies, milk choco-
late products (which contain only low quantities of
cocoa flavanols) were included as a determinant.
(iii) Vogiatzoglou and coworkers (2014a) assessed the
average habitual intake of flavan-3-ols in the Euro-
pean Union. The quantities consumed were consid-
erably below the amounts used in most dietary
intervention studies. The mean habitual intake of
flavan-3-ol monomers, theaflavins and
proanthocyanidins ranged from 181 mg/d (Czech
Republic) to 793 mg/d (Ireland). The daily intake
of proanthocyanidins was highest in Spain
(175 mg/d) and lowest in The Netherlands (96 mg/d).
The major contributor of the total flavanols in all
subjects was pome fruits (27%) followed by black
tea (25%) (Vogiatzoglou et al., 2014). The ob-
served decreases of cardiovascular disease and
mortality in epidemiological studies cannot there-
fore convincingly be attributed to self-reported co-
coa product consumption, although cocoa products
rich in polyphenols may indeed lower the risk of
CV diseases and mortality. The Kuna Indians in
Panama and Columbia, who consume daily 600 to
900 mg of flavanols (as well as other polyphenols),
have a very low risk of cardiovascular disease.
The effect of cocoa on CV risk factors
Pooling of the data from interventional studies in SRs
shows that the consumption of cocoa flavanols over a
short period may have beneficial consequences when
considering cardiovascular risk factors (Table 2). Long-
term studies have not yet been carried out.
Effect on BP
Table 3 illustrates that the three reviews which included
15 trials or more were largely based on the same studies
and explains why their findings were similar. Ellinger
et al. (2012) concluded that even a daily dose as low as
25 mg of epicatechin derive d from a cocoa product was
associated with a remarkable BP decrease which might
be consistent with a decreased CV risk. Di Renzo and
coworkers observed a BP decrease in pregnant women
consuming daily 30 g of dark chocolate with 13 mg of
monomeric flavanols (Di Renzo et al., 2012). These
overall conclusions must, however, be examined very
carefully.
Flavanol doses administered. Two studies with a confir-
matory study design investigated dark chocolate with
low doses (25 mg or less) of epicatechin (van den
Bogaard et al., 2010; Desch et al., 2010a) and found ei-
ther no effect on BP (van den Bogaard et al., 2010) or
an effect which could not be related to the dose admin-
istered (Desch et al., 2010a, 2010b). A dose of 100 mg of
pure epicatechin per day was not associated with a BP
decrease in healthy adults (Dower et al., 2015a), al-
though no data are available to compare ingestion of
Figure 1. Flow chart of the PubMed search.
1645COCOA FLAVANOLS AND CARDIOVASCULAR HEALTH
Copyright © 2016 John Wiley & Sons, Ltd. Phytother. Res. 30: 1641–1657 (2016)
Table 2. Data extracted from the systematic reviews. N number of included studies, n number of included patients, CHD coronary heart disease
Year First author N=n= Outcome measures Results Co-active principle
2015 Kwok 1 20.951 CHD, stroke Cohort study:
CHD 9.7% vs. 13.8% and
stroke 3.1% vs. 5.4%
for chocolate consumption
of 16–99 g/day vs. Zero/day
Self-reported quantities
9 157.809 CHD, stroke Reduced relative risks for
CHD, stroke, mortality with
chocolate consumption
2015 Peluso 13 278 Platelet aggregation (PA) Single doses decreased PA,
no increase with higher
doses/longer treatment
durations
Marker epicatechin
2015 Mellor 6
a
242 Weight, glycemic
control in diabetics
type 2
Inconsistencies in reporting,
limited information
Listed
b
2013 Scholey 8 306 Cognitive function, mood No consistent results on
cerebral functions
Not assessed in all
2012 Ried 20 856 Systolic (sBP) and
diastolic (dBP) BP
sBP and dBP decrease
by 2.8 and 2.2 mmHg
in short-term studies with
30–1080 mg flavanols
(mean 546 mg), effect
greater when control
received zero flavanols.
Effect was seen in studies
lasting 2 weeks
Pooling of different
compounds assessed
with different methods
2012 Hooper 42 1297 Insulin resistance
(HOMA-IR), fasting
insulin (FI) and glucose
(FG), flow-mediated
vasodilatation (FMD),BP,
serum cholesterol
(LDL-, HDL-Chol)
FMD increased
(chronic by 1.3%,
acute by 3.2%), HDL-Chol
by 0.03 mmol/L, BP
decreased with higher EC
doses, dBP by 1.6 mmHg,
mean BP by 1.6 mmHg,
HOMA-IR by 0.7, LDL-Chol
by 0.07 mmol/L, in
short-term studies
(up to 18 weeks).
Marker epicatechin
2011 Shrime 24 1106 Blood pressure, pulse,
total Chol, HDL-Chol,
LDL-Chol, triglycerides
sBP decreased by 1.6 mm Hg,
LDL-Chol by 0.08 mmol/L,
HOMA-IR by 0.94; total
Pooling of different
compounds assessed
with different methods
(Continues)
1646 J. VLACHOJANNIS ET AL.
Copyright © 2016 John Wiley & Sons, Ltd. Phytother. Res. 30: 1641–1657 (2016)
Table . (Continued)
Year First author N=n= Outcome measures Results Co-active principle
(TG), body mass index
(BMI), C-reactive protein
(CRP), FMD,FG, FI, serum
isoprostane, HOMA-IR
cholesterol, TG, CRP remained
the same. HDL-Chol increased
by 0.05 mmol/L, FMD by 1.5%
(max effect with 500 mg
flavanols/day in studies
up to 18 weeks.
2011 Buitrago-Lopez 7 114.009 CHD, stroke, diabetes,
metabolic syndrome
From one cross-sectional and 6
cohort astudies: Highest levels
of chocolate consumption were
associated with a 37% reduction
in CHD (relative risk (RR) 0.63)
and a 29% reduction in stroke
compared with the lowest levels
in 5 studies.
Self-reported quantities
2011 Tokede 10 320 Lipid profile LDL-Chol 5.9 mg/dL, total
Chol 6.2 mg/dL. No statistically
significant effects for HDL-Chol
and TG (study duration up
to 12 weeks).
Pooling of different
compounds assessed with
different methods
2010b Desch 10 297 BP in normotensives or
prehypertensives (stage 1)
Mean BP 4.5 mm Hg, sBP 5.9
to 3.2, dBP 2.5 to 1.2 mm
Hg in up to 18 weeks
Marker epicatechin
2013 Zhang 10 135335 Cardiovascular disease Overall relative risk reduction 25% Self-reported quantities
2012 Ellinger 16 401 Systolic and diastolic BP 25-mg epicatechin lowered
systolic BP by 4 mmHg, diastolic
BP by 2 mmHg
Marker epicatechin
2010 Jia 8 215 Total Chol, LDL-Chol,
HDL-Chol
Short-term cocoa consumption
significantly reduced blood Chol.
No effect in high quality studies,
no dose-effect relation was
observed. More data on long-term
studies are needed.
Pooling of different
compounds assessed
with different methods.
a
The studies offering cocoa polyphenols plus isovlavones were excluded.
b
Details of the flavanol assessments not stated in some studies.
Tab le 2 . (Continued)
1647COCOA FLAVANOLS AND CARDIOVASCULAR HEALTH
Copyright © 2016 John Wiley & Sons, Ltd. Phytother. Res. 30: 1641–1657 (2016)
Table 3. Studies considered in the four systematic reviews including 15 and more trials in their meta-analysis. Individual total f lavanol dose studied (Folin or HPLC assessment) and and individual
flavanols if declared (EC epicatechin, C catechin, P procyanidine assessed by HPLC), c confirmatory, & did not investigate cocoa active principle, $ excluded from analysis
Study
Design
Ellinger et al.,
2012
Hooper et al.,
2012
Shrime et al.,
2011
Ried et al.,
2012
Total flavanols
mg
Sum monomeric
(EC + C) mg
EC
mg
C
mg
Total P
mg
%E/
total F E/C
Theobromine
mg
Exploratory Al-Faris, 2008 Folin 500 8 4 4 Not stated 1 Not stated
Allen et al.,
2008
&
Exploratory Allgrove et al.,
2011
Not stated 55 39 16 Not stated 2.4-fold 267
c (for fasting
blood glucose)
$ Almoosawi
et al., 2010
Folin 500,
1000
18–99, 37–98 Not stated Not stated Not stated Not stated
Exploratory Baba et al.,
2007a
Baba et al.,
2007a
Not stated Up to 163 65–129 17–34 Not stated Total flavanols
and Total
P: Not stated
Exploratory Baba et al.,
2007b
Not stated 128 98 35 Not stated 3.8-fold 570
Exploratory $ Balzer et al.,
2008
Balzer et al., 2008 Balzer et al., 2008 HPLC 963 254 203 51 709 21% 4-fold 586
HPLC 377 99 79 20 272 576
Exploratory Berry et al.,
2010
HPLC 701 178 139 39 523 20% 3.6-fold 268
c for blood
pressure
van den Bogaard
et al., 2010
van den Bogaard
et al., 2010
van den Bogaard
et al., 2010
van den Bogaard
et al., 2010
Folin 500
HPLC 305
38 25 13 267 13% 1.9-fold 106
Exploratory $ Crews et al.,
2008
Crews et al.,
2008
Crews et al.,
2008
Crews et al.,
2008
HPLC 755 Not stated Not stated Not stated Not stated Not stated
Exploratory Davison et al.,
2008
Davison et al.,
2008
Davison et al.,
2008
Davison et al.,
2008
HPLC 902 Not stated Not stated Not stated Not stated 337
Exploratory Davison et al.,
2008
HPLC 36 Not stated Not stated Not stated Not stated 327
c for blood
pressure
Davison et al.,
2010
Davison et al.,
2010
Davison et al.,
2010
33, 372,
712, 1052
97–266 69–208 28–58 275–785 About
20%
3.6-fold 402–461
c for blood
pressure
$Desch et al,
2010a
Desch et al,
2010a
Desch et al,
2010a
Not stated 7, 28 5, 21 2, 7 Not stated 26, 105
Exploratory $Engler et al.,
2004
Engler et al.,
2004
Engler et al.,
2004
Engler et al.,
2004
HPLC 213 Not stated 46 Not stated Not stated About
15%
Not stated
c for FMD Faridi et al.,
2008
HPLC 821 32 22 10 821 3% 2.2-fold 525
HPLC 805 69 48 21 736 436
c for FMD Farouque et al.,
2006
Farouque et al.,
2006
HPLC 444 Not stated 107 Not stated Not stated 24% About 500
(Continues)
1648 J. VLACHOJANNIS ET AL.
Copyright © 2016 John Wiley & Sons, Ltd. Phytother. Res. 30: 1641–1657 (2016)
Table . (Continued)
Study
Design
Ellinger et al.,
2012
Hooper et al.,
2012
Shrime et al.,
2011
Ried et al.,
2012
Total flavanols
mg
Sum monomeric
(EC + C) mg
EC
mg
C
mg
Total P
mg
%E/
total F E/C
Theobromine
mg
Exploratory $Fisher et al.,
2003
HPLC 451 112 84 28 339 25% 3-fold Not stated
c for FMD Flammer et al.,
2011
Folin 624 Not stated Not stated Not stated Not stated Not stated
Exploratory Fraga et al.,
2005
Fraga et al.,
2005
Fraga et al.,
2005
Fraga et al.,
2005
HPLC 168 39 Not stated Not stated 126 179
Exploratory $Grassi et al.,
2005a
Grassi et al.,
2005a
Grassi et al.,
2005a
Grassi et al.,
2005a
Not stated 88 66 22 Not stated 3-fold 560
Exploratory Grassi et al.,
2005b
Grassi et al.,
2005b
Grassi et al.,
2005b
Grassi et al.,
2005b
Folin 500 Not stated (88) 66 22 Not stated 3-fold 560
Exploratory Grassi et al.,
2008
Grassi et al.,
2008
Grassi et al.,
2008
Grassi et al.,
2008
Folin 1008
or 1080 (unclear)
147 111 36 Not stated 3.1-fold 170
Exploratory Heiss et al.,
2003
HPLC 176 70 Not stated Not stated 106 Not stated
Exploratory Heiss et al.,
2005
HPLC about 90,
180, 360
36, 77, 144 11, 22, 44 25,50,100 54, 108, 224 12% 65, 130, 260
Exploratory $Heiss et al.,
2007
Heiss et al.,
2007
HPLC 918 222 177 45 696 19% 4-fold 684
Exploratory Heiss et al.,
2010
Heiss et al.,
2010
Heiss et al.,
2010
Heiss et al.,
2010
HPLC 750 142 130 12 608 17% 10.8-fold 186
Exploratory Hermann et al.,
2006
Not stated Not stated Not stated Not stated Not stated Not stated
Exploratory Kurlandsky
and Stote, 2006
HPLC 213 Not stated 46 Not stated Not stated Not stated
c for HDL-Chol Mellor et al.,
2010
Mellor et al.,
2010
Mellor et al.,
2010
Not stated Not stated 17 Not stated Not stated Not stated
Exploratory Monagas
et al., 2009
Monagas et al.,
2009
Monagas
et al., 2009
Monagas et al.,
2009
HPLC 495 56 46 10 426 4.6-fold 176
c for blood pressure Muniyappa
et al., 2008
Muniyappa
et al., 2008
Muniyappa
et al., 2008
Muniyappa
et al., 2008
HPLC 912 236 174 62 676 19% 2.8-fold 674
Exploratory $Murphy et al.,
2003
Murphy et al.,
2003
Murphy
et al., 2003
Murphy et al.,
2003
HPLC 234 Not stated Not stated Not stated Not stated Not stated
Exploratory Nijke et al.,
2011
Nijke et al.,
2011
Nijke et al.,
2011
HPLC 805 69 48 21 736 6% 2.3-fold 436
Polagruto
et al., 2006
&
Exploratory $Ried et al.,
2009
Ried et al.,
2009
Ried et al.,
2009
Ried et al.,
2009
Folin 750 Not stated Not stated Not stated Not stated Not stated
(Continues)
Table 3. (Continued)
1649COCOA FLAVANOLS AND CARDIOVASCULAR HEALTH
Copyright © 2016 John Wiley & Sons, Ltd. Phytother. Res. 30: 1641–1657 (2016)
Table . (Continued)
Study
Design
Ellinger et al.,
2012
Hooper et al.,
2012
Shrime et al.,
2011
Ried et al.,
2012
Total flavanols
mg
Sum monomeric
(EC + C) mg
EC
mg
C
mg
Total P
mg
%E/
total F E/C
Theobromine
mg
c for chronic
fatigue
Sathyapalan
et al., 2010
Folin 783 73 55 18 Not stated 3.2-fold Not stated
Exploratory Schnorr et al.,
2008
HPLC 985 244 183 61 741 3-fold 585
Exploratory Schroeter et al.,
2006
HPLC 917 Not stated About 210 Not stated Not stated Not stated
Exploratory $Shiina et al.,
2009
Shiina et al.,
2009
Shiina et al.,
2009
Shiina et al.,
2009
HPLC 550 Not stated Not stated Not stated Not stated Not stated
Exploratory Sorond et al.,
2008
Not stated 902 Not stated Not stated Not stated 673
Exploratory Taubert et al.,
2003
Taubert et al.,
2003
Taubert et al.,
2003
Taubert et al.,
2003
Folin 500 Not stated (88) 66 22 Not stated 3-fold 560
c for blood pressure Taubert et al.,
2007
Taubert et al.,
2007
Taubert et al.,
2007
Taubert et al.,
2007
Not stated 7 5 2 Not stated 2.5-fold 26
Exploratory Tzounis et al.,
2011
Tzounis et al.,
2011
HPLC 494 110 89 21 384 18% 4.2-fold 185
Exploratory Vlachopoulos
et al., 2005
Not stated Not stated Not stated Not stated Not stated Not stated
Exploratory Wan et al., 2001 Wan et al., 2001 HPLC 466 111 Not stated Not stated 355 614
Exploratory $Wang-Polagruto
et al., 2006
Wang-Polagruto
et al., 2006
Wang-Polagruto
et al., 2006
446 Folin?
HPLC?
Not stated Not stated Not stated Not stated Not stated
Table 3. (Continued)
1650 J. VLACHOJANNIS ET AL.
Copyright © 2016 John Wiley & Sons, Ltd. Phytother. Res. 30: 1641–1657 (2016)
the pure marker substance with characterized dark
chocolate. These results are unsurprising as Davison
et al. (2010) found that only the highest dose (1052 mg
total flavanols/208 mg epicatechin) reduced BP signifi-
cantly, but not lower doses (712/138mg and 372/69mg
flavanols/epicatechin). The observation that the Kuna
Indians have a low average BP and do not experience
age-related increases supports the assumption that regu-
lar doses of around 900 mg of flavanols have a beneficial
effect on BP (Schroeter et al., 2006).
Measuring changes in BP. Five of the studies were of a
confirmatory design (Table 3), and only three of them
used 24-h ambulatory BP measurements (the gold stan-
dard) to assess outcomes (van den Bogaard et al., 2010;
Desch et al., 2010a; Davison et al., 2010). Establishing
changes in BP requires an understanding of the wide
range of normal values and high intra-individual vari-
ability. In the studies by Taubert et al. (2007) and West
et al. (2014), and in other exploratory studies, the ob-
served BP decreases were within this range. The mean
of three or fewer BP measurements is not considered re-
liable enough to assess a clinically relevant effect over
time (Warren et al., 2010), as shown by Heiss et al.
(2015) who assessed BP by means of the gold standard
from two days before and after cocoa flavanol consump-
tion: although BP decreased (mean of three assess-
ments), the actual values obtained fluctuated
considerably when compared with the 24-h ambulatory
BP measurement.
Patient response. The studies involving higher flavanol
doses indicate that future studies should focus on cocoa
flavanol responders and non-responders. In the study by
Muniyappa et al. (2008), a dose of 912-mg flavanols, pro-
viding 178-mg epicatechin per day, consumed over
2 weeks did not decrease BP (average of three measure-
ments) in patients suffering from essential hypertonus.
In contrast, when a 900 mg flavanol dose containing
128 mg of epicatechin was consumed over 4 weeks by
low risk, healthy, middle-aged individuals without signs
and symptoms of cardiovascular disease, a BP decrease
(average of three BP measurements) was observed
(Sansone et al., 2015). When the same product was con-
sumed over 2 weeks by young and elderly healthy par-
ticipants, a significant decrease in mean 24-h BP was
Table 4. Amounts of co-active ingredients in chocolate and grams of chocolate with 900 and 200 mg of total flavanols and 100 mg of
epicatechin. FS food supplement, CP1 to DC-7 (100% or 99% cocoa), DC-7 to DC-11 (90 or 85% cocoa), DC-12 to DC-15 (82% to
78% cocoa), DC-16 to DC-26 (75% to 60% cocoa) and DC-27, M C-1 (46%, 35% cocoa)
Total flavanols Monomers Epicatechin Theobromine ------- Grams of chocolate with ------- mg E
No (TF) mg/g mg/g (E) mg/g mg per 10 g 900 mg TF 200 mg TF 100 mg E per 200 mg TF
FS-1 43.8 14.58 12.40 197 21 4.7 8 58
FS-2 125.61 39.58 36.91 107 7 1.6 3 59
CP-1 3.77 1.02 0.83 242 239 53 120 44
CP-2 7.83 2.33 2.00 349 115 26 50 52
DC-1 3.72 1.14 1.03 97 242 54 97 57
DC-2 5.27 1.80 1.62 118 171 38 62 62
DC-3 6.47 2.22 1.98 112 139 31 51 61
DC-4 5.07 2.08 1.55 106 178 40 65 62
DC-5 5.42 2.08 1.60 102 166 37 63 57
DC-6 1.7 0.56 0.41 122 529 118 242 48
DC-7 3.44 1.12 0.92 101 262 58 109 53
DC-8 1.9 0.78 0.44 88 474 105 227 46
DC-9 3.26 1.09 0.88 101 276 61 114 54
DC-10 2.85 1.21 0.82 100 316 70 122 57
DC-11 2.25 0.76 0.59 73 400 89 169 53
DC-12 3.91 1.38 1.22 71 230 51 82 62
DC-13 2.34 0.65 0.58 81 385 86 172 50
DC-14 3.76 1.51 1.18 73 239 53 85 63
DC-15 3.2 1.26 0.98 69 281 62 102 61
DC-16 2.42 0.89 0.73 66 372 83 137 61
DC-17 2.99 1.10 0.95 76 301 67 105 64
DC-18 2.62 0.99 0.82 69 344 76 122 62
DC-19 1.9 0.72 0.56 64 474 105 179 59
DC-20 1.91 0.58 0.50 76 471 105 200 53
DC-21 1.84 0.66 0.50 80 489 109 200 55
DC-22 2.31 0.96 0.75 62 390 87 133 65
DC-23 3.6 1.48 1.18 65 257 57 85 67
DC-24 3.9 1.58 1.22 76 231 51 82 62
DC-25 5.17 2.04 1.71 82 174 39 58 67
DC-26 2.24 0.65 0.49 67 402 89 204 44
DC-27 1.66 0.64 0.53 45 542 120 189 64
MC-1 0.08 0.03 0.018 5 11.3 kg 2.5 kg 5.6 kg 45
1651COCOA FLAVANOLS AND CARDIOVASCULAR HEALTH
Copyright © 2016 John Wiley & Sons, Ltd. Phytother. Res. 30: 1641–1657 (2016)
found only in the elderly group (Heiss et al., 2015). In
pre-hypertensive patients a dose of 1064 mg flavanols
consumed over 6 weeks tended to lower systolic BP
and improved vascular function compared to chocolate
with 88 mg flavanols but the effect was not statistically
significant (Rull et al., 2015). In overweight and obese
participants, Davison et al. (2010) observed a BP de-
crease after a single dose of dark chocolate with
1052 mg total flavanols but in contrast, Balzer et al.
(2008) who investigated a cocoa product with 963 mg
flavanols over 30 days in diabetics found no effect on
BP (assessment method not specified). These discrepan-
cies indicate that the cocoa action may be patient-
dependent.
Pooled data and analytical methods. To relate this pur-
ported decrease in BP to pooled ‘mean’flavanol doses
in the SRs is not yet possible due to missing data and dif-
ferent assessment methods. Cochrane reviews do not
usually differentiate between types of herbal medicinal
products and do not distinguish between confirmatory
and exploratory studies (Davidson et al., 2013). The ob-
served effect of a cocoa product is the result of its com-
plex composition. The total flavanol content is
comprised of the sum of monomeric and oligomeric
flavanols. Unsaturated fatty acids (Torres-Moreno
et al., 2015), flavonoids (Wollgast, 2004) and theobro-
mine (Franco et al., 2013) may also contribute to benefi-
cial cocoa CV effects. When considering the flavanol
content, then the HPLC and photometric analyses are
not numerically comparable and photometric assess-
ments can overestimate the true content of co-active
compounds (Chrubasik-Hausmann et al., 2014a, 2014b;
Davidson et al., 2014; Vlachojannis et al., 2015a,
2015b). Our analysis of the cocoa active components re-
vealed that many compounds need to be considered
(Damm et al., 2016) to understand the relationship be-
tween cocoa and health.
Based on these arguments, the modest decrease of
systolic and diastolic BP calculated in the meta-analyses
of the SRs may be unreliable, mainly due to insufficient
BP measurements. At present there is no evidence that
the doses of cocoa flavanols and epicatechins used in the
studies included reliably decrease BP.
More research is required to elucidate the optimal
flavanol/epicatechin dose that might reliably decrease
BP. Research is also required to refine our understand-
ing of the hypotensive effect of the pure compounds as
well as their synergistic dynamic. For instance, the mini-
mum adult therapeutic dose for theobromine to decrease
the BP exceeds that typically delivered with chocolate by
one magnitude (van den Bogaard et al., 2010). However
lower theobromine doses may interact with other co-
active compounds. This needs to be clarified (Berends
et al., 2015). Table 4 shows that in the dark chocolate
samples we analyzed the theobromine content varied be-
tween 62 and 349 mg per 10 g.
Effect on FMD
Based on three confirmatory studies (Table 3), dark
chocolate is capable of increasing FMD, in a dose-
dependent manner (Grassi et al., 2015; Heiss et al.,
2007; Monahan et al., 2011). Whereas the dose-
dependent effect was seen with products containing
doses of epicatechin between 17 and 177 mg, higher
doses were not necessarily associated with increased
benefit: 349 mg epicatechin was not more effective than
Figure 2. (a –f) Various correlations between percent cocoa and
percent nonfat cocoa solids (NFCS) and coactive compounds of
the cocoa active principle (R
2
coefficients of determination).
1652 J. VLACHOJANNIS ET AL.
Copyright © 2016 John Wiley & Sons, Ltd. Phytother. Res. 30: 1641–1657 (2016)
98 mg epicatechin (contained in dark chocolate) when
consumed by overweight men (Esser et al., 2014).
Studies investigating the effect of 900 mg flavanols
(128 mg epicatechin) found improved FMD in both
young and elderly healthy participants (Heiss et al.,
2015). The effect plateaued after 2 weeks in healthy,
middle-aged individuals (Sansone et al., 2015). A study
in Portugal (with no details about the product) gave a
similar result (Pereira et al., 2014). These results suggest
that a dose of epicatechin of around 100 mg in a daily
chocolate portion may increase FMD, although the ther-
apeutic dose and apparent ceiling effect need to be fur-
ther elucidated.
These reported beneficial effects are supported by
several pre-clinical and mechanistic studies.
Endothelium-derived nitric oxide may be involved in
the mechanism, either by enhancement of nitric oxide
synthesis or decrease in nitric oxide breakdown (Sudano
et al., 2012; Grassi et al., 2013). Microparticles (MPs) are
circulating membrane particles shed from endothelial
and blood cells, which carry a functional endothelial ni-
tric oxide synthase enzyme (Horn et al., 2012). Endothe-
lial dysfunction is associated with increasing levels of
MPs, and after administering cocoa with 375 mg total
flavanols (124 mg epicatechin/catechin) for 30 days to
patients suffering from coronary artery disease, MP
levels were found to have decreased. Higher endothelial
function was also reported in these patients, lending cre-
dence to the concept that flavanols may improve endo-
thelial integrity (Horn et al., 2014).
Endothelial resistance and dysfunction characterize
insulin-resistant subjects. Five studies in the Hooper
et al. (2012) noted a decrease in insulin resistance after
dark chocolate consumption (one study showed no ef-
fect) so it may be that this contributes to the improve-
ment of FMD. In nine of 11 studies blood glucose was
found to decrease and the confirmatory study by
Almoosawi et al. (2010), not included in that review, also
showed a blood glucose decrease. The evidence that co-
coa products have a beneficial effect on glucose metab-
olism can therefore be categorized as ‘moderate’.
Other effects
Sarriá et al. (2015) recently suggested that the insoluble-
dietary-fiber and theobromine content of cocoa products
may contribute to the hypoglycemic effects observed,
and also that the flavanol content may increase high den-
sity lipoprotein-cholesterol (HDL-Chol). An increase in
HDL-Chol was seen with a cocoa product delivering as
little as 45 mg flavanols daily (Martínez-López et al.,
2014) and in the confirmatory study by Mellor et al.
(2010) a chocolate bar containing 17 mg of epicatechin
produced a significant increase in HDL-Chol together
with an improved Chol to HDL-Chol ratio. The evi-
dence supporting the positive effects of dark chocolate
on blood lipids might now be categorized as ‘moderate’,
although some meta-analyses in SRs have come to differ-
ent conclusions (Table 2).
High doses of theobromine (>500 mg) may increase
HDL-Chol, but it remains to be established whether
lower theobromine doses synergistically interact with
the flavanols to induce the HDL-Chol-raising effect
(Berends et al., 2015, Table 4). It seems also likely that
theobromine accounts for the platelet-inhibiting effect
(Rull et al., 2015) observed after single or repeated
doses of cocoa products in healthy and ill subjects. More
data are needed to clarify the mechanism of action of
the cocoa active constituents and long-term studies are
warranted (Berends et al., 2015). Cocoa phytochemicals
also interact with specific molecular targets linked to the
pathogenesis of other human chronic diseases (e.g. Kim
et al., 2014) but are outside the scope of this study.
The role of epicatechin
In the reviews by Hooper et al. (2012) and Ellinger et al.
(2012) only epicatechin doses were considered and re-
lated to the clinical effects. There is evidence that the
()stereoisomer is at least in part responsible for the
vascular effects observed for dark chocolate (Ottaviani
et al., 2011; Ottaviani et al., 2012). Schroeter et al.
(2006) determined that the ingestion of flavanol-rich co-
coa was associated with elevated levels of circulating
NO species, an enhanced FMD response, and an
improved microcirculation in healthy male adults.
Concentrations of circulating flavanol metabolites were
determined, and identified ()-epicatechin and its me-
tabolite epicatechin-7-O-glucuronide as independent
predictors of vascular effects. Oral administration of
pure ()-epicatechin to humans (1 and 2 mg per kg)
closely emulated acute vascular effects of flavanol-rich
cocoa, supporting the conclusion that 100 mg epicate-
chin per day may be a reliable dose to increase FMD
(Dower et al., 2015a). FMD increased by 1.1% and insu-
lin resistance decreased (Dower et al., 2015a). The same
group also found that 100 mg of pure epicatechin im-
proved biomarkers of endothelial dysfunction in (pre)
hypertensive adults (Dower et al., 2015b).
Chronic intake of high-flavanol diets is associated
with prolonged enhanced NO synthesis, as evidenced
by the increase in urinary excretion of NO metabolites.
The study of the Kuna Indians, who have a high daily
consumption of flavanols, found that the excretion of
epicatechin equivalents was about 6 times higher than
in comparable populations (Schroeter et al., 2006). A
long-term effect of cocoa can thus be maintained, and
epicatechin plays a major role in it. Future research
should investigate the range of profiles of the active
compounds in cocoa products, and whether pure epicat-
echin –which is widely found in medicinal plants –is as
effective as a cocoa extract.
Health claim related to the flavanol dose
In a recent pilot study, 400 mg flavanols per day (64 mg
monomeric) had no impact on FMD or BP in pregnant
women (Mogollon et al., 2013), and chocolate with
45 mg epicatechin had no effect on FMD in patients with
peripheral artery disease (Hammer et al., 2015). Up to a
dose of 500 mg flavanols with 105 mg epicatechin, FMD
increased continuously without a further increase when
giving a cocoa dose containing 800 mg flavanols with
168 mg epicatechin (Grassi et al., 2015). This strengthens
the case for a dose of 100 mg of epicatechin in a cocoa
product, rather than 200 mg flavanols (with 46 mg epi-
catechin) as recently approved by the European Food
and Safety Authority (EFSA), to contribute to healthy
blood flow (EFSA, 2012). As the sugar present in
1653COCOA FLAVANOLS AND CARDIOVASCULAR HEALTH
Copyright © 2016 John Wiley & Sons, Ltd. Phytother. Res. 30: 1641–1657 (2016)
chocolate (Njike et al., 2011; Grassi et al., 2012), and nu-
merous other factors except age (Rodriguez-Mateos
et al., 2015) affect the absorption, metabolism and excre-
tion of the flavanols (Cifuentes-Gomez et al., 2015), the
generally recommended daily consumption of 200 mg of
flavanols (with 46 mg epicatechin) should be revised.
Labeling of cocoa products
Most chocolate products are labeled with a ‘% cocoa
solids’value which indicates the total ingredients by
weight from the cacao bean (Langer et al., 2011). Many
also declare the percentage of fat, so that the non-fat co-
coa solids (NFCS) can be calculated. In our samples, the
fat content varied between 11% and 60.4%, the Spear-
man correlation coefficient between NFCS and total
flavanols was 0.25 and between cocoa percentage and
total flavanols, 0.36 (Fig. 2a–d). In agreement with
Langer et al. (2011) we found a moderate correlation be-
tween theobromine and NFCS (Fig. 2f, r = 0.66) and a
good correlation with total flavanols and epicatechin
(Fig. 2e, r = 0.99). In the individual products, the per-
centage of epicatechin to total flavanols was 22–34%,
and 28–29% in the food supplements, and varied be-
tween 3 and 25% in the study medications investigated
(Table 3).
The epicatechin and catechin content decreasing or-
der of cocoa products were, as previously reported
(Miller et al., 2006): natural cocoa powder >baking
chocolate >dark chocolate/baking chips >milk
chocolate >chocolate syrup. There was a greater than
five-fold variation in epicatechin to catechin ratios. In
the Cochrane and Shrime reviews, the ratio ranged from
1:1 to a 10.8-fold difference (Table 3), whereas in our
samples, it varied 2- to 4.4-fold and was about six- and
nine-fold in the two food supplements (Table 4). In
none of the SRs was the heterogeneity of the study med-
ications considered in detail.
‘100% cocoa’chocolate bars have the highest total
polyphenol content and antioxidant capacity, measured
using the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and
ferric reducing antioxidant of potency (FRAP) tests
(Vertuani et al., 2014). We therefore support the sugges-
tion by Langer et al. (2011) that the total flavanol and
epicatechin content should be declared on chocolate
product labels, rather than simply the percentages of co-
coa solids and fat. The content of theobromine should
be recorded, although we do not yet know its contribu-
tion to the beneficial health effects of chocolate.
Chocolate product intake
Regarding our samples, the consumption of 900 mg of
flavanols delivered a mean of 256 mg of epicatechin
(‘food supplements’were excluded; range, 194 to
303 mg, see Table 4). To consume the 900 mg flavanol
required a mean intake of 300 g chocolate, and the con-
sumption of 100 mg of epicatechin required a mean in-
take of 125 g chocolate. It is not realistic that people
would consume such high amounts of dark chocolate ev-
ery day (Ried et al., 2009), but in contrast, some food
supplements are an exception and a valuable source
for cocoa flavanols including epicatechin. However,
milk chocolate products are not an appropriate source
of flavanols and white chocolate does not contain phe-
nolic compounds at all (Langer et al., 2011; Meng et al.,
2009).
The methylxanthine content of cocoa beans also
varies with the varietal type, and is influenced by the fer-
mentation process (Shively and Tarka, 1984; Brillo and
Di Renzo, 2015). In our 90%–100% cocoa product sam-
ples, the mean theobromine content per 100 g was
1064 mg and the 85% cocoa chocolate contained
731 mg to 1000 mg. Milk chocolate contained the least
amount of theo bromine, i.e. 49 mg per 100 g bar. Details
of the other co-active ingredients in the different cocoa
products are published elsewhere (Damm et al., 2016).
These examples illustrate the complexity of evaluating
the active constituents of cocoa as far as cardiovascular
health is concerned, and the issues involved in standard-
ization and understanding the possible interactions that
contribute to the observed clinical effects.
Acknowledgements
The authors sincerely thank R. Milnes/Bruchhausen-Vilsen for revis-
ing the English.
Conflict of Interest
None of the authors has any conflict of interest.
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