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Coffee, consumed for its refreshing and stimulating effect, belongs to the tribe Coffea of the subfamily Cinchonoidea of Rubiaceae family. Coffee is a complex chemical mixture composed of several chemicals. It is responsible for a number of bioactivities and a number of compounds accounting for these effects. Few of the significant bioactivities documented are antioxidant activity, anticarcinogenic activity, antimutagenic activity etc. Various compounds responsible for the chemoprotective effects of coffee are mainly polyphenols including chlorogenic acids and their degradation products. Others include caffeine, kahweol, cafestol, and other phenolics. Coffee also shows protective or adverse effects on various systems like the skeletal (bone) system, the reproductive system, the nervous system, the cardiovascular system, the homocysteine levels, the cholesterol levels etc. Harmful effects of coffee are associated with people who are sensitive to stimulants. Overall, with the available information, it can be concluded that the moderate consumption, corresponding to 3 to 4 cups/day with average strength is safer to human health.
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A Perception on Health Benefits of Coffee
Sunitha Elizabeth George
a
; Kulathooran Ramalakshmi
a
; Lingamallu Jagan Mohan
Rao
a
a
Department of Plantation Products, Spices and Flavour Technology, Central Food
Technological Research Institute, Mysore, India
Online Publication Date: 01 May 2008
To cite this Article: George, Sunitha Elizabeth, Ramalakshmi, Kulathooran and
Mohan Rao, Lingamallu Jagan (2008) 'A Perception on Health Benefits of Coffee',
Critical Reviews in Food Science and Nutrition, 48:5, 464 — 486
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Critical Reviews in Food Science and Nutrition, 48:464–486 (2008)
Copyright
C
Taylor and Francis Group, LLC
ISSN: 1040-8398
DOI: 10.1080/10408390701522445
A Perception on Health Benefits
of Coffee
SUNITHA ELIZABETH GEORGE, KULATHOORAN RAMALAKSHMI,
and LINGAMALLU JAGAN MOHAN RAO
Department of Plantation Products, Spices and Flavour Technology, Central Food Technological Research Institute,
Mysore - 570020, India
Coffee, consumed for its refreshing and stimulating effect, belongs to the tribe Coffea of the subfamily Cinchonoidea of
Rubiaceae family. Coffee is a complex chemical mixture composed of several chemicals. It is responsible for a number of
bioactivities and a number of compounds accounting for these effects. Few of the significant bioactivities documented are
antioxidant activity, anticarcinogenic activity, antimutagenic activity etc. Various compounds responsible for the chemopro-
tective effects of coffee are mainly polyphenols including chlorogenic acids and their degradation products. Others include
caffeine, kahweol, cafestol, and other phenolics. Coffee also shows protective or adverse effects on various systems like the
skeletal (bone) system, the reproductive system, the nervous system, the cardiovascular system, the homocysteine levels, the
cholesterol levels etc. Harmful effects of coffee are associated with people who are sensitive to stimulants. Overall, with the
available information, it can be concluded that the moderate consumption, corresponding to 3 to 4 cups/day with average
strength is safer to human health.
Keywords coffee, biological activities, physiological effects, antioxidant, anticarcinogenic, cardiovascular
INTRODUCTION
Legend scripted that Kaldhi, an Arab goatherd living around
850 A.D., puzzled by his flock’s queer antics, tasted the berries
of the evergreen bush the goats were feeding on. Experiencing a
sense of exhilaration, he proclaimed his discovery to the world
(Sivetz and Foote, 1963).
At present, coffee—the dark, aromatic, non-alcoholic brew
loved the world over for its stimulating and refreshing taste is
a product of the coffee plant. It is the bean extracted from the
fruit of the coffee plant that is roasted, ground, and liquored to
produce the fascinating brew. Coffee is the most popular bever-
age consumed by about one-third of the world’s population in
an amount larger than any other beverage. Arabica accounts for
75% of the worlds coffee production
All coffee plants belong to the tribe Coffea of the subfamily
Cinchonoidea of Rubiaceae family. Coffee is one of the two
genera of the Coffea tribe, and it has three recognized subgenera.
Coffea contains about 85 species and only three of these namely
C. arabica, C. canephora (robusta) and C. liberica have been
successfully used in commercial cultivation.
Address correspondence to Lingamallu Jagan Mohan Rao, Department of
Plantation Products, Spices, and Flavour Technology, Central Food Techno-
logical Research Institute, Mysore - 570020, India. +91-821-2512352; Fax:
+91-821-2517233; E-mail: ljnatpro@yahoo.com
Chemical Composition
The chemical composition of green coffee depends mainly on
the variety of the coffee, although slight variations are possible
due to agroclimatic conditions, agricultural practices, process-
ing, and storage. The average approximate composition of coffee
is given in Table 1.
Processing
To obtain marketable coffee, termed as “Green coffee” the
processing techniques are dry method and wet method. The wet
method gives coffee a superior cup quality. It includes steps
like (i) harvesting, (ii) pulping, (iii) demucilaging, (iv) washing,
(v) drying and storage (Scheme 1). For the dry method simple
drying is carried out using solar energy or other driers (Scheme
2). Grading, roasting, and grinding comprise the industrial phase
of coffee processing (The Wealth of India, 2001).
Roasting and Grinding
Roasting is a process involving the passage of hot air at
200–260
C through the beans. The time required for roasting
is 5–10 min in a continuous roaster and more then 20 min in
464
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HEALTH BENEFITS OF COFFEE 465
Table 1 Composition of coffee
Component Composition (%)
Reducing sugar 1.0
Sucrose 7.0
Pectin 3.0
Starch 10.0
Pentosan 5.0
Hemi cellulose 15.0
Holocellulose (fiber) 18.0
Lignin 2.0
Oils 13.0
Protein 13.0
Ash 4.0
Chlorogenic acid 7.0
Other acids 1.0
Trigonelline 1.0
Caffeine 1.0
(Ramalakshmi and Raghavan, 1999).
a non-continuous roaster (Carvalho and Chalfoun, 1989). The
characteristic aroma is developed during roasting. Grinding is
essential to obtain maximum extraction of solubles including
aroma and flavor. Various types of grinders are available. The
chemical composition of green, roasted, and brewed solids is
presented in Fig. 1 (Barter, 2004). ISO specification for roasted
and ground coffee is presented in Table 2.
PHYSIOLOGICAL EFFECTS
Coffee is consumed because of its desirable bitter taste and
medicinal benefits. The effect of coffee on human physiology
varies from person to person and also on the quality and quantity
of coffee consumed. Coffee is a complex chemical mixture. It is
composed of over 1000 different chemicals. Theoretically, it can
be anticipated that according to the doses involved, some may
possess biological activities that could be considered potentially
SCHEME 1
SCHEME 2
adverse to health or, conversely, beneficial. Although coffee has
a long history of human food use for over 1000 years, until re-
cently most of the studies on its health effects have focused on
potential adverse and toxic effects. Despite a vast amount of re-
search, evidence to support a direct link of coffee with diseases
has been limited and inconsistent. However, although not yet
proven, recent scientific literature suggests the potential benefi-
cial health effects of coffee and several of its constituents. For ex-
ample, its positive effects on performance and protection against
some types of cancers, liver disease, and radiation–induced tis-
sue damage have been documented.
Several diseases have been alleged to be caused or exac-
erbated by coffee consumption (Leviton et al. 1994). Among
others, issues have concerned hypertension, cardiovascular dis-
ease, cancer, spontaneous abortion, delayed conception, low
birth weight, and osteoporosis. Coffee contains a substantial
amount of antioxidants and this may explain some of its po-
tential beneficial activities, although several other important ad-
vantageous active components have also been identified. The
major pharmacologically active compound in coffee is caffeine
(methylxanthine), which is known to have effects on a number
of functions including the stimulation of the central nervous sys-
tem (CNS), the stimulation of cardiac muscle, and the relaxation
of smooth muscle especially bronchial muscle and to act on the
kidney to produce diuresis. The caffeine is metabolically de-
graded and involves demethylation steps to yield theobromine,
theophylline, xanthine, and finally to urea (Fig. 2) (Waler and
Suzuki, 1989). Caffeine also produces a slight increase in the
basal metabolic rate and increases the capacity for muscular
work. Medicinally one of the important components of coffee
Table 2 ISO Specification for roasted and ground coffee
Characteristics Requirement (% by wt)
Moisture (Max.) 4.0
Total ash 3.0
Acid soluble ash (max) 1.0
Water soluble matter 26–35
Caffeine 1.0
Petroleum ether extract (min) 8.5
(Rao et al., Indian coffee, 1993)
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466 S. E. GEORGE ET AL.
FIGURE 1 Chemical composition of green, roasted, and brewed coffee solids.
is caffeine, but a cups caffeine content depends on how the
coffee is prepared. Dark roasted coffee contains less caffeine
than coffee made from light and medium roasted beans. The
caffeine content of different coffee products are presented in
Table 3 (Anon, 2004).
A number of other compounds, such as chlorogenic acid, are
also present and are also pharmacologically active. The biolog-
ical and health effects of coffee have been extensively inves-
tigated in various animal and in vitro model systems as well
as in humans. Coffee contains substantial amounts of antiox-
idants and this may explain some of its potentially beneficial
Table 3 Caffeine content of different coffee products
Coffee product Caffeine range (mg/100 ml)
Coffee
Brewed 27–50
Instant 25–35
Decaffeinated, brewed 0.8–1.7
Decaffeinated, instant 0.4–1.7
Espresso 100–165
Cappuccino and Latte 100–165
Moccachino, 1-oz. shot 115–185
activities. Whatever effects are attributed specifically to the con-
sumption of coffee, one must assume that these are associated
with compounds in coffee beverage. Immediately this focuses
attention upon caffeine, the chlorogenic acids, possibly the spar-
ingly water-soluble diterpenes kahweol and cafestol and miscel-
laneous products of roasting. The biological and health effects
of coffee have been extensively investigated in various animals
and in vitro model systems as well as in humans. Both poten-
tial adverse and beneficial effects of the bioactivities would be
discussed. This paper summarizes an overview of various bio-
logical activities such as anticarcinogenic, antioxidant, and the
antimicrobial activities of coffee.
Antioxidant Activity
The antioxidants may be of great benefit in improving the
quality of life by helping to prevent or postpone the onset of de-
generative diseases (Svilaas et al., 2004). Many countries have
recommended an increase in consumption of fruits and veg-
etables, as they are known to reduce the risk of such degener-
ative diseases. Further, recent research in Norway has shown
the role of coffee as a source of antioxidants in the diet. The
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HEALTH BENEFITS OF COFFEE 467
FIGURE 2 Metabolic degradation of caffeine.
total intake of antioxidants from various food groups is given in
Table 4.
Beverages prepared from roasted coffee have several hun-
dreds of chemicals, which are both naturally occurring and
formed during the roasting process. The chemistry and biologi-
cal activity of all these substances have not yet been completely
revealed. The high worldwide consumption of coffee has stim-
ulated research to study other biological activities of green and
especially roasted coffee. Green coffee has shown to possess
Table 4 Antioxidants in various food groups (Svilaas et al., 2004)
Quantity of antioxidant intake
Source (mmol) %
Coffee 11.164
Fruit 1.811
Tea 1.48
Wine 0.85
Cereals 0.85
Vegetables 0.42
Other foods (fruit juices,
edible fat, and cakes)
0.85
in vitro antioxidant activity against lipid peroxidation (Kroyer
et al., 1989) and antineoplastic activity (Rosenberg, 1990). The
roasting process gives rise to changes which confer on coffee
its pleasant taste and aroma. It leads to profound changes in the
chemical composition and biological activities of coffee, accord-
ing to the transformation of naturally occurring substances in
green coffee as well as the compounds derived from the Millard
reaction, namely carbohydrate caramelization and the pyrolysis
of organic compounds (Belitz and Grosch, 1999).
The antioxidant activity of coffee brews using different meth-
ods of preparation was studied by Sanchez et al. 2005. They
observed that the antioxidant activity of coffee brews increased
significantly when the brews were kept hot (80
C). The cause
of this increase may be the formation of Maillard compounds
during the heat process.
The antioxidant capacity was evaluated by a chain-breaking
activity, which allows the evaluation of the quenching rate of
coffee compounds towards a reference radical (DPPH). Higher
antioxidant capacity was observed in Colombian conventional
roasted coffee blends due to the presence of more robusta coffee
beans that contain more chlorogenic acids (Galilea et al., 2006).
Yen et al. (2005) evaluated the antioxidant activity of roasted
coffee spent residues in different in vitro model systems. The
data obtained, clearly indicated that the coffee spent residues
have excellent potential for use as a natural antioxidant source
because the antioxidant compounds remained in roasted cof-
fee residues. They have reported that the antioxidant activ-
ity of spent coffee residue may be due to the presence of
phenoloic compounds such as chlorogenic acid and caffeic
acid.
Bio-Active Components Responsible for Antioxidant Activity
Phenolic compounds in coffee are known to have antioxidant
activity in which the prevalent one is hydroxy cinnamic acid and
the major component of this class is caffeic acid, which occurs in
food mainly as esters called chlorogenic acid (CGA) (Rice-evans
et al., 1996). Coffee is the major source of CGA in human diet,
daily intake by coffee drinkers being 0.5–1.0 g whereas cof-
fee abstainers typically ingest <100 mg/day (Clifford, 1999).
Roasting markedly affects the composition (mainly CGA) and
antioxidant properties are lost during roasting of coffee beans but
the overall antioxidant properties of coffee brews are maintained
or even enhanced, due to the formation of compounds possess-
ing antioxidant activity, including Maillard reaction products
(Nicoli et al., 1997). Some of the compounds produced during
roasting of coffee beans are represented in Fig. 3.
GCA (Green Coffee Antioxidants) is an all-natural green cof-
fee bean extract containing at least 65 percent total polyphenol
antioxidants. This extract is a potent antioxidant, also a highly
bio-available and cost–effective ingredient for adding increased
functionality to nutrition based products. It provides a neutral
taste profile, high solubility, and high activity level and so is an
ideal ingredient for functional foods and beverages as well as
bars, chews, and dietary supplements.
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468 S. E. GEORGE ET AL.
FIGURE 3 Phenolic compounds produced during roasting of coffee beans.
Coffee due to its antioxidant activity is known to show a
protective effect on cancer (Benoit et al., 2001) and other car-
diovascular diseases. It also protects Low Density Lipoprotein
from oxidation. This protective effect is the result of action of
several polyphenolic constituents. The physical and chemical
properties of individual phenolics, strongly affect their antiox-
idant activities. In addition, these molecules can have a syner-
gistic or antagonistic effect when present in complex mixtures.
Indeed, the polyphenol composition of the beverage varies in
species of coffee and tea (Richelle et al., 2001). In the case of
coffee, robusta exhibits a high antioxidant activity than arabica,
which could be due to the higher amount of chlorogenic acid.
Following light roasting, the antioxidant activities of both cof-
fees decreased markedly but further roasting produced the hete-
rocyclic compounds having the antioxidant activity, and as these
polyphenolic rich beverages are often consumed with milk, the
effect of milk on different beverages (coffee, cocoa, black tea)
were evaluated and coffee was found to have high antioxidant
activity.
An understanding of the protective role of dietary antioxi-
dants in vivo requires a better characterization of the polyphe-
nol composition of the antioxidant matrix as well as quanti-
tative data on their absorption, their tissue distribution, their
metabolism, and their biological actions (Scalbert, et al., 2000).
Indeed, after consumption, polyphenols have to cross the intesti-
nal wall but must also resist further catabolism. The metabolism
of polyphenols involves two important organs—the liver, where
biotransformation enzymes convert them or their metabolites
into conjugated forms such as glucuronides or sulphates, and
the colon where microorganisms degrade unabsorbed ones. At
present, only little information is available on the absorption
of the vast diversity of polyphenols present in these bever-
ages (Richelle et al., 2001). So the antioxidant activity of cof-
fee has to be considered while estimating the daily-ingested
dose of polyphenols. Thus, the beneficial effects of coffee may
be attributed in part to polyphenols and caffeine serving as
antioxidants.
In general the antioxidant ability of caffeine (1,3,7-trimethyl
xanthine) was similar to that of the established biological an-
tioxidant glutathione and significantly higher than ascorbic acid
(Devasagayam et al., 1996). The pro- and anti-oxidative ef-
fects of coffee are also reflected in its mutagenic and antimu-
tagenic activity in the Ames test. Coffee is directly mutagenic
on strains TA100 and TA102 due to H
2
O
2
formation. However,
coffee is also an antioxidant and antimutagen (Stadler et al.,
1994). This beverage exerts a strong protective effect against
the mutagenicity and cytototoxicity induced by the oxidant t-
butylhydroperoxide (t-BuOOH). Thus, coffee like many antiox-
idants, exhibits dual effects in vitro which are highly depen-
dent upon parameters such as dose, atmospheric O
2
, transition
metals, as well as the biological and the chemical end points
used for measurement. The mechanism of action of caffeine
to scavenge free radicals is shown by the following reaction
(Fig. 4).
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HEALTH BENEFITS OF COFFEE 469
FIGURE 4 Mechanism of scavenging of free radicals by caffeine.
All types of coffee, mainly instant, caffeine-containing, or
decaffeinated and various others have similar mutagenic effects
on Salmonella typhimurium TA100, TA104, as well as on Es-
cherichia coli WP2 uvrA/pKM101 and K12. Some strains of
Salmonella are insensitive to coffee which proves the specificity
of coffee action on the genome of certain bacteria (Aeschbacher,
1988).
The mutagenic effect of coffee has also been well established
in vivo studies. The effect is observed in cultured mammalian
cells, lung cells, and rat fibroblasts, mouse blastocytes, leukemia
cell lines, human lymphocytes, fibroblasts, melanoma and hep-
atoma cell lines, endothelial cells, and keratinocytes. However,
the mutagenic effect is dependant on the dose of coffee which is
administered to the cells during the study (Aeschbacher, 1988).
The antimutagenic effect of coffee is well documented (Kim
and Levin, 1988). The antimutagenic activity varies with the
intensity of the coffee exposed rather than the concentration
of antimutagenic agents. Caffeine is usually protective when
administered before the genotoxic agent in various in vivo tests.
However, the mouse bone marrow micronucleus test showed
that coffee administered twice orally, 2 and 20 h before DMBA,
benzo[a]pyrene or aflatoxin B 1 significantly inhibits their in
vivo genotoxicity (Abraham, 1989).
Caffeine has also been investigated for its potential an-
tioxidant activity against oxidative damage to rat liver mi-
crosomes. Such damage was induced by three reactive oxy-
gen species of cardinal importance in causing membrane dam-
age in vivo namely hydroxyl radical (OH
), Peroxyl radical
(ROO
), and singlet oxygen (1O
2
). The results showed that caf-
feine was an effective inhibitor of lipid peroxidation at mil-
limolar concentrations against all the three reactive species
(Devasagayam et al., 1996). The extent of inhibition was high
against O
2
and low against ROO.
Apart from phenolic compounds (chlorogenic acids and caf-
feoyl tryptophan) and organic bases (caffeine and its derived
products) that are naturally present in green coffee beans, the
melanoidins and phenylindanes are also responsible for the an-
tioxidant activity in coffee brews. Characterestic volatile het-
erocyclic compounds found in brewed coffee extracts namely
pyrroles, furans, thiophenes, and thiazoles, exhibited certain lev-
els of antioxidant activity (Fluckiger et al., 1976). More than 300
heterocyclic compounds including pyrroles, oxazoles, furans,
thiazoles, thiophenes, imidazoles, and pyrazines were identified
and quantified in brewed coffee (Kenichi et al., 2002).
Anticarcinogenic Activity
A number of epidemiological studies have investigated the
relationship between coffee consumption and cancer incidence
at various sites. Overall there is no conclusive evidence that cof-
fee drinking represents a significant risk for the development of
cancer in humans. Thorough reviews on coffee and cancer had
been published by the World Health Organization/International
Agency for Research on Cancer (IARC, 1991; Nehling and
Debry, 1996). In a large study conducted in Norway (per capita
coffee consumption is among the largest in the world) on 43,000
people, no association was reported between coffee drinking and
the overall risk of cancer (Stensvold and Jacobsen, 1994).
In contrast, many studies revealed an inverse (protective) as-
sociation between coffee consumption and the risk of certain
cancers (Giovannucci, 1998; Inoue et al., 1998). The epidemiol-
ogy of colorectal cancer provides the most supportive evidence
of a potential coffee–dependent protection. In a recent meta-
analysis comprising five cohort and 12 case–control studies, a
significant inverse association was found between coffee con-
sumption and colorectal cancer (Giovannucci, 1998).
In a number of animal studies, evidence supporting the poten-
tial chemoprotective effect of coffee was provided. In chronic
studies conducted in rodents, coffee administered at high lev-
els in the diet resulted in a decreased incidence of sponta-
neous tumors at different organ sites (Wurzner et al., 1977;
Stadler et al., 1990). Some other studies had shown that cof-
fee or coffee constituents protect against the action of well-
known carcinogens such as nitrosamines or 1,2 dimethyl hy-
drazine (Gershbein, 1994). Several other studies had shown
that green as well as roasted coffees inhibit the development
of 7,12– dimethylbenz(a)anthracene (DMBA)–induced carcino-
genesis at various tissue sites in different experimental animal
cancer models. (Wattenberg, 1983; Miller et al., 1988, 1993).
Cafestol and Kahweol (C+K)
Caffeine and polyphenols including chlorogenic acids and
their degradation products were considered potentially respon-
sible for the chemoprotectiveeffects of coffee (Schilter et al.,
2001). In addition, investigations performed in rats, mice, and
hamsters led to the identification of a specific lipid fraction as
potentially responsible for the chemo preventive effects of coffee
on DMBA–induced cancer (Lam et al., 1982; Miller et al., 1991).
The major constituents of this fraction were found to be the
diterpenes cafestol and kahweol (Fig. 5). Recently attention has
been focused on the biological effects of these diterpenes. These
FIGURE 5 Structures of cafestol and kahweol
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470 S. E. GEORGE ET AL.
components, which appear to be relatively specific to coffee, are
found in both Arabica and Robusta varieties and comprise up to
about 10–15% of the lipid fraction of roasted coffee beans (Rat-
nayake et al., 1993; Lercker et al., 1995). These specific coffee
constituents are very difficult to isolate independently and kah-
weol is highly unstable when purified. Therefore, the biological
properties of these compounds have been studied traditionally
using a mixture of both (Cavin et al., 2002).
Chemoprotective Mechanisms
Early studies indicated that cafestol and kahweol induced glu-
tathione S-transferase (GST) activity in mouse liver and small
intestine (Lam et al., 1982). Since GST is known to detoxify
electrophilic compounds through conjugation with glutathione,
these data led to the hypothesis that cafestol and kahweol may
possess the properties of blocking agents. It is known that the
initiation of tumor formation, which generally consists of a
permanent modification of DNA with electrophilic or oxidant
metabolites derived from procarcinogen biotransformation, is a
target for several dietary anticarcinogenic compounds or block-
ing agents (Wattenberg, 1985). These act through an inhibition
of the formation and or the stimulation of the detoxification of
the electrophiles or oxidant intermediates, resulting in decreased
DNA damage and in the blocking of initiation. Chemoprotective
agents may intervene at one or several steps of the carcinogenic
process namely during the initiation, promotion, or progression
stages (De Flora and Ramel, 1988; Harris, 1991). Recent reports
further confirm that cafestol and kahweol preventive effects may
be mediated by both an inhibition of bioactivation and a stim-
ulation of detoxification. Further, it was reported that patients
who consumed caffeine-containing beverages such as coffee at
the time of their radiotherapy against cervical cancer had signifi-
cantly decreased incidence of severe late radiation injury (Stelzer
et al., 1994).
a) Induction of Detoxifying Enzymes
Following up on the early observations showing an in-
duction of GST activity in mouse liver and small bowel
(Lam et al., 1982), the effects of cafestol and kahweol on
the expression of various GST subunits were studied in the
rat (Schilter et al., 1996; Cavin et al., 1998). Rats were ad-
ministered C + K in the diet (0, 92, 460, 2300, 6200 ppm)
up to 90 days. The most striking effects reported were a
strong dose dependent induction of the GST inorganic phos-
phates subunit Yp and the alpha subunit Yc2 (rGSTA5) in
the liver following 28 or 90 days of treatment. The effects
were found at the mRNA and protein levels and these were
significant (P <0.05) at C + K dietary concentrations of 460
ppm and higher. With respect to GST inorganic phosphates,
time course experiments indicated that the C + K mediated
induction occurred within a few days. In addition, it was
shown that the increased expression was dependent on the
continuous presence of C + K in the diet and was reversible
following removal of C + K (Schilter et al., 1996). Consid-
erable organ–specific differences were observed regarding
the effects of C + K on overall GST activity using CDNB
as substrate. In rats fed 0.2% C+ K, increases the activity
in the liver and kidneys (two to threefold as compared to
controls) were paralleled by a moderate enhancement in the
lung, a marginal one in the colon, and no changes in several
other organs such as the pancreas, the salivary gland, and the
testes (Schilter et al., 1996; Huber et al., 1997; 2000a). The
liver and other well-perfused organs may thus contribute to
Chemoprotective effects that occur in distant organs as well.
b) Molecular Mechanism of Induction
The cis-acting responsive element (ARE) sequence has
been identified on the promoter of several genes involved
in detoxification processes (Hayes et al., 1999). It has been
suggested that altering the expression of these genes through
ARE—mediated transcriptional activation is likely to be a
key molecular mechanism explaining how many blocking
agents may prevent mutagenesis. bZip Nrf proteins had been
found to activate gene induction through this specific en-
hancer (Venugopal and Jaiswal, 1996). The role of NrF2 tran-
scription factor in the C + K mediated activation of intestinal
detoxifying enzymes has been addressed using a mouse line
bearing a targeted disruption of the gene encoding factor
(McMahon et al., 2001). The results show the key role of this
transcription factor in the chemopreventive activity of C +
K in the small intestine.
c) Inhibition of Activating Enzyme Expression
Reduction of carcinogen activation was shown to play an
important role in the C + K mediated prevention of car-
cinogen DNA binding besides stimulation of detoxification
processes. It was observed that in rats fed diets containing C
+ K over 28 days, the hepatic expression of the cytochrome
P450 (P450) CrP3A2 was significantly decreased at both the
mRNA and the protein levels (Cavin et al., 1998). Significant
differences as compared to controls were found at dietary C
+ K concentrations of 2300 ppm and above. The two major
P 450s, CYP 2C11, and CYP3A2, responsible for the bioac-
tivation of AFB into AFBD in the rat, was hypothesized that
a reduction in the expression of these genes may contribute
to the C + K mediated prevention of AFB
1
–DNA adduct
(Forrester et al., 1990). In a DNA binding assay, the use of
microsomes from the liver of C + K treated rats as an acti-
vating system resulted in a significant reduction in AFB
1
-
DNA adducts formation (Cavin et al., 1998). This effect was
dose dependent and maximal at 6200 ppm in the diet (40%
reduction). These data support a role for the decrease in phase
I enzyme expression in the Chemoprotective effects of C+K
against AFB
1
genotoxicity.
d) Inhibition of Enzymatic Activity
A direct inhibition of P450 enzymatic activity without any
effects on protein expression is an additional phase I medi-
ated mechanism through which the coffee diterpenes may act.
For example C + K has been shown to produce on inhibition
of P 4501A1 activity in liver cells which resulted in a reduc-
tion of B[a]P activation and DNA binding. Similar inhibitory
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HEALTH BENEFITS OF COFFEE 471
effects were found with human P 450 CYP 2B6, a human
P450 responsible for AFB
1
bioactivation (Cavin et al. 2001).
In addition, it is suggested that the reduction of PhIP–DNA
adducts found in C + K treated rats involves an inhibition of
the PhIP–activating enzymes P 4501A2 and N-acetyl trans-
ferase (NA) (Huber et al., 1998, 2000) C + K was also found
to reduce the N-hydroxylation of 4-amino biphenyl in vitro
(Hammons et al., 1999).
Cancer with Relevance to Human Data
Coffee consumption has been linked to cancers (Benoit et al.,
2001) in many organs but currently there appears to be little, or
no supportive evidence for these contentions. For many years,
the attention of the epidemiologists studying coffee was focused
on the possible association between coffee drinking and devel-
opment the of cancer at different sets. Evidence showed less
or more links between coffee consumption and cancer. In the
following subtitles the association between coffee and different
cancers will be discussed.
Cancers of the Gastrointestinal Tract.
a) Cancer of the Pancreas
A number of studies have been carried out to examine the
potential link between coffee consumption and risks of pan-
creatic cancer. Farrow and Davis (1990) examined the risk of
pancreatic cancer in relation to medical history and the use of
tobacco, alcohol, and coffee. Here the association of coffee
with risk of pancreatic cancer was confirmed to be insignifi-
cant. The risk of pancreatic cancer was increased in case of
use of tobacco and alcohol. A study (La vecchia et al., 1989)
conducted on 214 patients in Milan, Italy showed no evi-
dence for pancreatic cancer due to coffee consumption. Most
of the studies do not support any association; some have
raised the possibility of a weak increase in pancreatic can-
cer of heavy coffee drinkers (WHO/IARC, 1991). The IARC
Working Group (1991) found that “there is inadequate evi-
dence in humans that coffee drinking is carcinogenic in the
pancreas. Further studies and more recent analysis of the
etiological factors for pancreatic cancer have revealed that
the weak effects of coffee, if any, are likely to be related to
confounding factors such as smoking and therefore coffee
consumption is not considered to represent a significant risk
factor for cancer of the pancreas (Nehling and Debry 1996;
Silverman et al., 1998; Weiderpass et al., 1998). However, a
U-shaped dose response effect was observed through a meta-
analysis involving 14 studies published between 1981 and
1993. In another case control study a U-shaped relationship
was found between the level of coffee consumption and the
rise of pancreatic cancer. The lowest relative risk of pan-
creatic cancer was found at low consumption levels ranging
from one to four cups a day.
b) Oesophageal and Gastric Cancers
Several studies were reported on the relationship between
coffee consumption and cancers of the mouth, the pharynx,
oesophagus, and the stomach and was concluded that coffee
consumption was not causing these cancers (IARC, 1991;
Nehling and Debry, 1996). However, protective effects had
been suggested (Inoue et al., 1998).
c) Colorectal Cancer
The relationship between coffee consumption and col-
orectal cancer was inconsistent as per numerous studies con-
ducted in different geographical areas (WHO/IARC, 1991;
Nehling and Debry, 1996). Many case control studies have
revealed an inverse (protective) association between coffee
drinking and the risk of colorectal cancer. Meta analysis of
several studies on coffee consumption and colorectal can-
cer from 1960–1999 revealed the risk of colorectal cancer to
be 24% lower among those who drink four or more cups of
coffee per day than the non-coffee drinkers (Anon, 2004a).
Rosenberg (1990) reviewed the epidemiological investigations
of the relationship of methyl xanthine ingestion to the risk of
large bowel cancer and on the basis of the available data it was
concluded that there was little reason for concern that coffee con-
sumption increases the risk. The same conclusion was reached
at the meeting of the IARC Working Group (1991).
A meta analysis of coffee consumption and risk of colorec-
tal cancer was published (Giovannucci, 1998) which strongly
suggests that the risk of colorectal cancer associated with a sub-
stantial consumption of coffee ( >4 cups a day) is less.
Cancer of the Sexual Organs.
a) Ovarian Cancer
A weak positive association is seen between coffee con-
sumption and ovarian cancer in case control studies. Leviton
(1990) reviewed the epidemiological studies of the associa-
tion of coffee consumption and the risk of ovarian malignancy
and concluded that coffee and tea consumption did not in-
crease the risk of ovarian cancer and in most of the studies, the
effect was not significant (Nehling and Debry, 1996; IARC,
1991). In its review IARC concluded that the evidence for an
association between coffee drinking and ovarian cancer is in-
adequate although the data indicate a marginal but significant
increase in relative risk (IARC, 1991).
b) Prostate Cancer
Studies have shown that there is no association between
coffee consumption and prostate cancer (Jain et al., 1998;
Hsieh et al., 1999).
c) Breast Cancer
In a prospective study on Norwegian women with a follow
up period of 12 years (the age of the women at the time of en-
quiry was between 35–51 years) 152 incident cases of breast
cancer were observed. The coffee consumption (cups per
day) was established from the food frequency questionnaire.
There was an overall weak negative association between daily
coffee intakes and risk of breast cancer. The review of seven
case studies by IARC (IARC, 1991) did not reveal any as-
sociation between breast cancer risk and the consumption of
coffee. Other studies further support that coffee intake is not
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472 S. E. GEORGE ET AL.
related to breast cancer (Folsom et al., 1993; Smith et al.,
1994; Tavani et al., 1998) in both pre and post–menopausal
women.
Cancers of the Urinary Tract.
a) Kidney, Urinary Tract
The etiology of renal cancer is still largely undefined
(Nehling and Debry, 1996; Tavani and La Vecchia, 1997).
Available information indicates that renal cancer is unlikely
to be associated with coffee consumption (IARC, 1991,
Nehling and Debry, 1996; Tavani and La Veechia, 1997).
A similar conclusion can be drawn for cancer of the urinary
tract (IARC, 1991; Nehling and Debry, 1996).
b) Bladder Cancer
The IARC Working Group (1991) on the “Evaluation of
Carcinogenic Risks to Humans from Coffee” concluded that
there is limited evidence in humans that coffee drinking is
carcinogenic in the urinary bladder. Many studies had sug-
gested the possibility that coffee consumption and occurrence
of bladder cancer is often a weak association and many others
found no correlation (IARC, 1991; Nehling and Debry 1996;
Donoto et al., 1997; Probert et al.; 1998). From the differ-
ent studies carried out it appears that coffee consumption is
unlikely to be an important risk factor for bladder cancer in
humans.
Altogether, the data on the biological effects of C + K provide
a plausible hypothesis to explain some anticarcinogenic effects
of coffee observed in human epidemiological studies and in an-
imal experiments.
Mutagenic and Antimutagenic Effects
Numerous studies were carried out to check the mutagenic
effects of coffee, using various biological test systems like bac-
teria, yeast, fungi, mammalian cells, and whole animal (IARC,
1991). Results of these studies showed that high concentrations
of coffee had a slightly mutagenic effect on the biological test
systems. In bacterial assays coffee is particularly mutagenic to
strain sensitive to oxidative mutagens (electrophiles).
Roasted coffee has been found to possess mutagenic activity,
probably due to the formation of hydrogen peroxide, as a result
of polyphenolic thermal degradation products of chlorogenic
and caffeic acid, and was catalyzed by transition metals. At low
doses coffee suppresses in vitro mutagenicity of oxidants such
as tertiary butyl hydroperoxide and could inhibit lipid peroxida-
tion and malondialdehyde formation (Turesky et al., 1993). The
same group also reported that roasted coffee can act as a po-
tent antioxidant and inhibit lipid proxidation in a model system
(Stadler et al., 1994).
Spectra of new compounds, having pharmacological poten-
tial were produced by the coffee beans on roasting. Some of them
were called mutagens (Aeschbacher, 1984; Blair and Shibamoto,
1984; de Kruijif et al., 1987; Starvic et al., 1983). Among the
complex system of chemical constituents of coffee, compounds
like chlorogenic acid, kahweol palmitate, and cafestol palmitate,
and nicotinic acid are known to be beneficial to human health
also. Others apparently possess antimutagenic effects.
The role of coffee in modulating the in vivo genotoxicity of
some genotoxic chemicals (mitomycin C, cyclophosphamide,
procarbazine, and adriamycin) in mice was evaluated and found
that coffee (regular, instant, decaffeinated, freeze dried) reduced
the in vivo genotoxicity of the first three chemicals, provided it
coffee was given 2 hours before the genotoxin (Abraham, 1989).
Coffee and selected ingredients from coffee like chlorogenic
acids, and premelanoidins inhibit nitrosourea–induced DNA
damage in mice when mice were orally closed with NaNO
2
plus
N-methyl urea simultaneously received coffee, the formation of
nitrosourea in the stomach of mice was prevented (Aeschbacher
and Jaccaud, 1990).
A study using instant coffee revealed a dismutagenic effect,
when the mixtures of N-methyl-N-nitro-N-nitroguanidine (mu-
tagen) and instant coffee extract was assayed using the Ames
test assay with Salmonella typhimurium TA 1535. The antimu-
tagenic effect though not strong was observed (Obana and Naka-
mura, 1989). On the other hand it was found that roasting of cof-
fee beans to high temperature generated several mutagenic com-
pounds (Kikugawa et al., 1989). A sample of coffee roasted at
high temperature (400
C) contained about ten times more muta-
gens than an unroasted sample (Kato et al., 1989). The structures
are still unknown but they appear to be amino-imidazo-azarenes
(AIA), which are generally produced by heat treatment in foods.
Such compounds were found to be carcinogenic in mice and rats
(Sugimura and Wakabayashi, 1990).
Most of the mutagenicity of coffee is abolished by the addi-
tion of exogenous detoxification systems such as liver extracts,
catalase, or peroxidases, implying that hydrogen peroxide plays
a key role in mediating coffee genotoxicity (Nagao et al., 1986).
All organisms possess efficient oxidant detoxifying mechanism
as well as repair systems. In contrast to the results of the in vitro
studies in various biological test systems, in vitro experiments
in rodents had not shown any evidence of mutagenicity (Nehling
and Debry, 1994).
Instant coffee and its polyphenolics which catalyze H
2
O
2
formation and mutagenicity, also exhibit potent antioxidant and
antimutagenic activity as evidenced by the protective effect of
coffee against t-butylhydroperoxide–challenged cells (Stadler
et al., 1994). Other in vitro studies had documented that cof-
fee or polyphenolic rich coffee fractions protect against the
mutagenicity of several carcinogenic compounds such as het-
erocyclic amines (Obana et al., 1986) or nitrosating agents
(Stich et al., 1982) as well as counteracting the effects of UV-
radiation. Studies conducted in in-vivo test systems confirm the
antimutagenic effects of coffee. Like, in case of instant and
roasted ground coffee, it was reported to protect mice against the
genotoxic actions of various carcinogenic chemicals (Abraham,
1991). On an overall review of the studies of mutagenicity in vivo
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HEALTH BENEFITS OF COFFEE 473
and in vitro, the risk of any genetic damage can be ruled out when
considering the usual amount of coffee consumed by humans
(Nehling and Debry, 1994a; Nehling and Debry, 1996). Thus
the possibility of protective, antimutagenic effects has gained
experimental support.
Effects on Central Nervous System (CNS)
Coffee is an enjoyable beverage containing the alkaloid caf-
feine with psychotropic effects. A usual cup of coffee contains
about 100 mg of caffeine. Caffeine is a strong stimulating agent
of the brain cortex, and the respiratory and circulatory centers.
Higher doses of caffeine (Single dose of 1000–1500 mg) may
lead to symptoms such as trembling, anxiety, loss of mental con-
centration, tachycardia, and sleep disorder. Few studies so far
have been concerned on the relationship between coffee con-
sumption and the central nervous system. In a study conducted
on healthy male subjects a shift in EEG (Electron Encephalo-
graph) power towards the fast side (high frequency, low ampli-
tude) of the total spectrum was observed, and this effect was very
similar to that produced by active behavioral attention (Gibbs
and Maltby, 1943). Another similar observation was made when
250 mg of caffeine was administered and showed further that
the effect was similar to that obtained with other stimulant drugs
(Goldstein et al., 1963).
Caffeine at low doses was found to have direct effects on sin-
gle neuron activity in the reticular formation (Forde and Hirsh,
1976) and using a similar technique, (Chou et al., 1980) it was re-
ported that the arousing effect of caffeine might in part be related
to the suppressive effect of the drug on the medical thalamic nu-
clei system. It was found that caffeine increases the turnover rate
of the catecholamines, noradrenalin, and dopamine in the brain
(Watanabe et al., 1978). Thus in summary, these experiments
present good evidence that caffeine enhances cortical arousal
and that this effect is mediated by the ascending activating sys-
tems of the brain (Battig, 1985).
Coffee was known to increase alertness as seen with the cen-
tral nervous system (CNS) and improve performance on vig-
ilance tasks and reduce fatigue (Smith, 1998). Also, it was
known to provide a potential preventive influence of caffeine
on suicide and depression (Klatsky et al., 1993). A dose de-
pendent study showed that people consuming more than six
cups of coffee/day showed a 5 fold lower risk of suicide than
non-consumers.
Caffeine–Mechanism of Pharmacological Action
Earlier it was believed that the action of caffeine was re-
lated to the inhibition of phosphodiesterase, leading to in-
creased concentrations of cyclic AMP. However, for the in-
hibition much higher doses of caffeine is required (Mandel,
2002). A more likely mechanism following the intake of low
doses of caffeine, involves antagonism of adenosine recep-
tors, which are present in the brain, the blood vessels, the kid-
neys, the heart, the GI tract, and the respiratory system (Chou
and Benowitz, 1994). Other investigators concluded that the
stimulatory effect of caffeine was largely due to a blockade
of AZA receptors that stimulate GABAergic neurons of in-
hibitory pathways to the dopaminergic reward system of the
striatum. However, this blockade of A1 receptors was con-
sidered to also play a role. High affinity A1 receptors inhibit
adenylate cycles, whereas low affinity A2 stimulates the activ-
ity of that enzyme (Daly, 1993). The functions of adenosine
receptors and the role of caffeine have been recently reviewed
(Svenningsson et al., 1999).
The behavioral stimulant potencies of caffeine and several
metabolites, such as paraxanthine and theophylline, correlate
with their affinity for occupation of adenosine receptors (Ka-
plan et al., 1997). These effects includes mental stimulation,
systemic catecholamine release, and sympathetic neural stimu-
lation, leading to an increase in blood pressure and lipolysis with
an increase in plasma free fatty acid concentrations (Benowitz
et al., 1995; Kalpan et al., 1997).
Parkinson’s Disease
In the past 30 years, different studies had shown that regular
coffee consumption might reduce the risk of Parkinson’s disease
(Popoli et al., 1991; Fall et al., 1999; Benedetti et al., 2000).
Sufferers develop tremors and have difficulty in moving their
arms and legs. One of the characteristics of these patients is a
reduced amount of dopamine in certain areas of the brain. Mice,
whose brain dopamine content has been depleted, exhibit some
symptoms of Parkinson’s disease. In a study, caffeine given to
these mice prevented the development of Parkinson’s symptoms
(Popoli et al., 1991).
Six retrospective studies found that people who drank cof-
fee on a regular basis were 50–80% less likely to develop
Parkinson’s disease than those who did not consume coffee (Hel-
lenbrand et al., 1996). Three of the studies showed a dose re-
sponse relationship–strong support that the more one consumes
coffee, the less likely are the chances to develop Parkinson’s
disease (Hellenbrand et al., 1996, Fall et al., 1999; Benedetti
et al., 2000). Further, in a prospective study covering 30 years,
the more coffee consumption lowers the risk of Parkinson’s dis-
ease when examined at the end (Ross et al., 2000). Consumption
of decaffeinated coffee did not lower the risk. In a laboratory
study, mice were given a chemical that depletes dopamine in
important areas of the brain. Levels of caffeine intake compara-
ble to human consumption successfully reduced the amount of
dopamine depleted in the brain as well as the physical symptoms
typical of Parkinson’s disease in humans (Chen et al., 2001). In
this study it was revealed that caffeine’s neuroprotective effect
in slowing down the progression of Parkinson’s disease is due
to its ability to block the adenosine A2A receptor.
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474 S. E. GEORGE ET AL.
Effects on Human Behavior
Even a single dose of consumption of caffeine affected acute
changes in human behavior and less is known about the effects
of regular consumption. In addition to studying the effects
of caffeine consumption, the research also considered possi-
ble changes in behavior as a function of caffeine withdrawal
(Warburton, 1995).
Effects of Caffeine on Mood
Consumption of caffeine leads to increased alertness or re-
duced fatigue (Warburton, 1995). It is unclear whether the
change in behavioral effects is due to caffeine alone or in com-
bination with other compounds in coffee. The beneficial effects
of caffeine on alertness are mostly demonstrated when circadian
alertness is low, and the mood is measured in the context of do-
ing demanding performance tasks (Liberman, 1992). The other
effects are that over doses of caffeine could lead to increased
anxiety in some individuals. Caffeine withdrawal increases the
negative effect but this may reflect expectancy effects (Smith,
2002).
Caffeine and Performance Efficiency
A number of different central nervous system mechanisms
were identified by which caffeine could change performance.
Earlier reviews suggested variable or slight effects. There ap-
peared to be no direct effects of caffeine on sensory functions.
A number of studies showed that caffeine improved simple and
choice retention time. Sustained attention had also been shown to
be improved by caffeine. Effects of caffeine on memory had not
been demonstrated. Simulations of real-life tasks (driving) had
shown beneficial effects of caffeine. Caffeine has been shown to
remove impairments produced by decreases in arousal. Complex
interactions between caffeine, personality, and the time of day
had been reported. Some studies had shown that caffeine im-
pairs fine motor control. A cost-benefit analysis suggested that
doses of caffeine similar to those consumed by the majority of
the population increase alertness and the ability to sustain atten-
tion. Adverse effects occur when excessive doses are consumed
or when caffeine is given to certain individuals (Smith, 2002).
Effects of Caffeine on Sleep
It is quite clear that high doses of caffeine in the late evening
will increase the time taken for some individuals to go to sleep.
The effects of smaller doses vary from individual to individual
and even when sleep is affected there is no clear evidence that the
effects are of a sufficient magnitude to influence health and well
being. Indeed, people are usually very good at controlling their
caffeineintake, which means that there is not any strong evidence
relating level of caffeine consumption to sleep problems.
Reproductive and Developmental Potentials
Several reports attempted to determine whether women who
consume caffeine-containing beverages had any adverse effect
in their reproductive system or during the developmental stage
of the foetus. The results of the studies were conflicting. Since
caffeine was shown to be teratogenic in animal models, safety
concerns were raised regarding coffee drinking during preg-
nancy (Cook et al., 1996). It is well documented that caffeine
metabolism is slower in pregnant women, resulting in longer
and possibly higher exposures. Consequently a number of stud-
ies were carried out to study the potential effects of caffeine on
various reproductive and developmental outcome.
Effect on Fertility
The effect of caffeine on fertility is dose dependent as per the
limited numbers of reports available. i.e., the time to become
pregnant increased in rodents suggesting a possible effect of
coffee (Benoit et al., 2001). The reports on humans gave incon-
sistent and controversial results. A study on women in Denmark
reported that a delayed time of conception was found in smokers
consuming high doses (>8cups) of coffee (Olsen et al., 1991).
High levels of caffeine (>300 mg/day) consumption resulted
in delayed conception even in non-smokers (Staton and Gray,
1995).
Based on the data reports caffeine could be considered as
a weak risk factor that probably reduces fecundity by a cer-
tain fraction, but without being a sufficient cause of infertility.
Delayed conception is relatively common and many factors, in-
cluding exercise, stress, nutrition, lifestyle, and social influences
may be involved. The question of the mechanism involved in
the potential effects of coffee or caffeine is not answered. In
conclusion there is no solid evidence linking moderate coffee
consumption and adverse effects on fertility parameters.
Spontaneous Abortion
Here again the results of the studies are conflicting. It is docu-
mented that nausea is associated with a decrease in spontaneous
abortion (Stein and Susser, 1991) Therefore it was postulated
that a pregnancy with a higher probability of a viable outcome
might increase nausea and in consequence decrease caffeine
ingestion. Another survey found a modest increased risk of clin-
ically recognized spontaneous abortion when caffeine intake
exceeds 300 mg/day (Dlugosz et al., 1996). Also the associa-
tion between material serum paraxanthine, the primary caffeine
metabolite and the risk of spontaneous abortion was associated
with 6 cups/day. The intake of caffeinated or decaffeinated cof-
fee showed no effect on spontaneous abortion (Fenster et al.,
1997).
Low Birth Weight, Growth Retardation, and Pre-maturity
Low birth weight ( <2500 g) of infants may be the re-
sult of a shortened gestational period (prematurity) or the
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HEALTH BENEFITS OF COFFEE 475
consequence of intrauterine growth retardation. Many medi-
cal, social, and lifestyle factors are known to influence birth
weight, some of them are correlated with coffee consumption.
A significant trend towards lower birth weight was found with
increasing consumption of coffee and teas, however, these ef-
fects became non-significant after correlating with smoking
(Brooke et al., 1989)
The use of treatment of idiopathic aponea in premature in-
fants using caffeine or theophylline showed that the two drugs
were equally effective (Fuglsang et al., 1989). The authors re-
ported preference to use caffeine because of the wider therapeu-
tic range and the ease of administration. Thereby no evidence
was reported on potential long-term adverse consequences re-
sulting from coffee-or caffeine-induced low birth weight.
A beneficial use of caffeine in pre-term infants was reported
(Walther et al., 1990). The cardiovascular effects of caffeine
were evaluated in 20 clinically stable pre-term infants. Com-
pared with controls, caffeine significantly increased left ventric-
ular output and stroke volume. Although theophylline is more
frequently used to treat breathing problems, caffeine, which is
less toxic, is generally used.
NeuroDevelopment Effects
Caffeine is a stimulant because of its neuropharmacological
properties. The potential effect of caffeine on neurodevelopment
had been widely investigated both in humans and animal mod-
els. Limited information is available regarding the potential in-
fluence of caffeine intake by pregnant women on the function of
the newborn nervous system. Studies showed that prenatal caf-
feine exposure did not influence neurobehavioural outcomes and
the suckling reflex in the first 2 days of life (Barr and Streissguth,
1991) and no effects on cognitive and motor development could
be observed at 8 months of age (Streissguth et al., 1980, Barr
et al., 1984). In addition, no effects on intelligence quotient at
4–7 years or on motor ability at 4 years and on vigilance at 7
years were found (Barr and Streissguth, 1991).
Congenital Malformations
Borlee et al. (1978) suggested that drinking more than eight
cups of coffee a day during pregnancy was weakly associated
with an increased frequency of congential malformations.
In a later report, three cases of extrodactyly in children
born from mothers consuming high amounts of coffee (8–25
cups/day) (Jacobson et al., 1981) unless an increased incidence
of such a malformation is observed and confirmed in other con-
trolled, large-scale epidemiological studies, this report may not
be appropriately interpreted.
The rate of different types of congenital malformation in-
cluding chromosomal abnormalities was found to be about twice
as high in the coffee drinkers than in non-drinkers (Furuhashi
et al., 1985) suggesting that coffee may have teratogenic and
mutagenic effects. This outcome is surprising since most of the
well-documented teratogens are known to produce a specific
pattern of teratogenicity and not a wide variety of different mal-
formations.
Several epidemiological surveys examined the association
between caffeine ingestion and congenital malformations. Most
of the reports do not support any link between caffeine intake and
teratogenicity (Nehling and Debry, 1994 b, Brent, 1998). Overall
there is no evidence to implicate moderate coffee/caffeine con-
sumption in the etiology of human congenital malformations.
Effect on Homocysteine
Consumption of unfiltered or filtered coffee raises total ho-
mocysteine concentration in healthy volunteers. The respon-
sible compound, however, is unknown (Verhoef et al., 2002).
A high plasma total homocysteine concentration is associated
with increased risk of cardiovascular disease. Elevated serum
concentrations of total homocysteine have been correlated with
an increased risk of atherosclerotic cardiovascular disease. The
mechanism involved is still unclear. Experimental evidence
has indicated that homocysteine may promote vascular damage
through oxidative stress (Meleady and Graham, 1999), suggest-
ing a potential link between heavy coffee consumption and total
plasma homocysteine (Nygard et al., 1998; Oshaug et al., 1998;
Stolzenberg–Soloman et al., 1999) and reported a direct and dose
dependent association between coffee consumption and blood
homocysteine. The subjects generally had nine or more cups of
coffee a day. No effect was found with decaffeinated coffee. In
contrast, no association was found between coffee consumption
or caffeine intake and the total blood homocysteine in a sam-
ple of the atherosclerotic risk in community study (Nieto and
Comstock, 1997). In another study it was observed that the con-
sumption of1Lofstrong unfiltered boiled coffee everyday for
2 weeks was associated with a 10% increase in mean plasma
total homocysteine concentration (Grubben et al., 2000). How-
ever, this extreme coffee intake may affect diet composition
and other factors, which may influence plasma homocysteine
(Vollset et al., 2000).
Elevated plasma homocysteine levels were correlated with
coffee intake mainly in people with low to intermediate homo-
cysteinemia (Nygard et al., 1997). Therefore the link between the
coffee–dependent increase in homocysteine and overall cardio-
vascular risk within the general population may not be straight-
forward to establish.
Daily intake of one liter of unfiltered French press coffee
for two weeks increased homocysteine levels by 10% after a
washout period of 8 weeks. The researchers claim that the 10%
rise seen in plasma homocysteine by drinking 6 cups of unfiltered
coffee a day could increase cardiovascular risk by 10% if homo-
cysteine is an independent casual factor (Vollset et al., 2000).
There is clear evidence that high homocysteine levels are
linked to poor nutrition, in particular, deficient levels of folate
and vitamins B6 and B12 (Selhub, 1997; Lindenbaum, 1994). An
adverse effect on homocysteine levels from coffee consumption
was observed and the lead scientist stated, “The largest variation
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476 S. E. GEORGE ET AL.
in plasma total homocysteine was observed in subjects with low
intakes of dietary folate, mostly determined by fruit and veg-
etable intake” (Grubben et al., 2000). Another work in 1999
demonstrated that people with sound diets showed no effect on
their plasma homocysteine levels from all forms of coffee con-
sumption. (Stolzenberg -Solomon et al., 1999).
Verhoef et al. (2002) reported that caffeine treatment had
a much weaker acute effect on homocysteine concentration,
wherein 48 subjects aged 16–65 years underwent 3 treatments
(6 capsules providing 870 mg of caffeine/day) each lasting 2
weeks. The effects of caffeine were stronger in women than in
men, but the effects of coffee did not differ significantly between
men and women. It is concluded that caffeine is partly responsi-
ble for the homocysteine-raising. Coffee but not caffeine, affects
homocysteine metabolism within hours of intake, although the
effect is still substantial after an overnight fast. In summary, a
slight increase in blood homocysteine in heavy coffee drinkers
had been shown in several studies. The direct implication of cof-
fee and the health significance of such an effect, have still to be
demonstrated (Benoit et al., 2001).
Effects on Bone System
The effect of coffee on bone health and calcium metabolism
was studied (Sakamoto et al., 2001). The potential role
of caffeine, mainly through coffee consumption as a con-
tributing factor of bone loss in humans has received a
lot of attention. In recent years numerous studies have
reported on caffeine consumption as a possible risk for
osteoporosis.
Osteoporosis is a chronic degenerative bone disease that af-
fects mainly, but not exclusively, post menopausal women, and
the demineralization of bones leads to fractures. It has a common
etiology that includes genetic, physiological, and environmental
contributors. Among the factors, estrogen deficiency, smoking,
heavy alcohol consumption, lack of exercise, obesity, and in-
adequate nutrition are believed to play significant roles in the
development of this disease (Benoit et al., 2001).
Calcium Metabolism
Debry (1994) showed that caffeine increases calcium ex-
cretion in experimental animals. The urinary loss of calcium
has been advocated as a significant factor affecting osteoporo-
sis (Nordlin and Morris, 1989). The effect of caffeine on cal-
cium intake economy in premenopausal women was reported
by Heaney and Recker (1982). Other reports indicated that caf-
feine induces a significant acute calcium diuersis (Massey and
Wise, 1984; Debry 1994; Heaney, 1998). However, subsequent
investigation suggested that the increase in calcium excretion
was followed by reduction in excretion, resulting in a net neg-
ative effect on calcium balance lower than previously thought
(Kynast–Gales and Massey, 1994).
The effect of caffeine on calcium metabolism was addressed
in a double blind, randomized placebo-controlled, cross-over
metabolic study. The administration of 400 mg of caffeine over
19 days did not produce any effect on a total 24 hours calcium
loss (Heaney and Recker, 1982; Barger–Lux and Heaney, 1995).
However, a small negative balance effect was detected due to a
slight difference in the calcium absorption efficiency. Massey
et al. (1994) confirmed that caffeine only produced observable
effects on calcium. Overall, the magnitude of the caffeine effect
on calcium balance is low and it has been estimated that it could
offset simply by the addition of one or two tablespoons of milk
to a cup of coffee (Barger-Lux and Heaney, 1995). It is currently
thought that at standard recommended calcium intake, caffeine
is unlikely to have harmful effects on calcium bone economy. In
the most recent United States Recommended Daily Allowances
(USRDA), it was stated that the available evidence does not
warrant a specific calcium intake recommendation for people
with different caffeine intake.
Osteoporosis
Contradictory results have been obtained on the potential
link between caffeine consumption and the risk of osteoporosis
(Debry, 1994; Heaney, 1998). Caffeine, which increases urinary
calcium excretion, is a risk factor for osteoporosis. Since a fre-
quent result of osteoporosis is hip fracture, experiments were
carried out to examine the effect of coffee drinking on the inci-
dence of hip fractures (Kiel et al., 1990). A study conducted on
3170 individuals showed that hip fractures occurred in 135 sub-
jects during 12 years of follow up. These relative risks were not
elevated for 1.5–2 cups of coffee or 3–4 cups of tea per day. Con-
sumption of more than 2.5 cups of coffee per day significantly
increased the risk of fracture. However, other than coffee con-
sumption, other factors may also be responsible like smoking,
consuming high calorie foods, etc.
Some epidemiological studies have also suggested that caf-
feine may slightly increase the risk of fracture or may decrease
bone density, but the majority of reports available failed to find
any effects of caffeine (Debry, 1994; Heaney, 1998). A review
of 23 observational studies indicated that 5 showed a negative
effect of caffeine on bone health and 16 showed no effect, also
two showed a partial effect (Heaney, 1998). A negative effect
was proposed for women whose dietary intake of calcium is be-
low the recommendations (Barrett-Connor et al., 1994; Harris
and Dawson-Hughs, 1994).
The potential link between caffeine and bone health was eval-
uated on women who are still in the period of bone gain. Caffeine
did not affect the rate of gain in spinal bones in women of 30
years age or less (Packard and Recker, 1996). Lloyd et al. (1998)
revealed that caffeine at levels presently consumed by American
teenage women was not correlated with total mineral bone gain
or hipbone density at age 18.
Cardiovascular System
Numerous reports are available to describe the effect of cof-
fee on the cardiovascular system. The circulatory effect of sub-
stances like theophylline, caffeine is complex and mediated in
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HEALTH BENEFITS OF COFFEE 477
part through antagonistic actions. The main actions appear to be
the direct effects on the heart and the vascular tissues and the
indirect effects through increased release of catecholamines and
possibly the rennin angiotensin system (Robertson et al., 1978;
Burghardt et al., 1982).
Studies had focused on the potential link between coffee con-
sumption and cardiovascular studies in humans and have recog-
nized end points of it such as myocardial infarction and arrhyth-
mias. Other reports being investigated on the possible effects of
coffee on known cardiovascular risk factors are hypertension,
elevated blood cholesterol, and more recently, increased homo-
cysteine levels.
Conflicting results were obtained from epidemiological stud-
ies on coffee and coronary heart disease and suggested that this
conflict could be due to other factors including bio-chemical con-
stituents other than caffeine (Rosmarin, 1989). It was reported
that coffee might induce cardiac arrhythmias, including poten-
tially lethal ventricular ectopy in certain individuals. However,
the chronic ingestion of coffee does not induce hypertension, but
only a small, short-lived increase in blood pressure as reported.
He suggested that coffee is a safe beverage in moderate amounts
in healthy persons (Stavric, 1992).
Stensvold et al., (1989) reported the relative risk of coro-
nary deaths with coffee consumption. The results showed that
in men the difference between the daily consumption of 9 or
more and from 1 to 4 cups of filter coffee corresponded to
a relative risk of 0.94. This was based on a cross–sectional
study of more than 29,000 participants in which coffee drink-
ing was correlated with serum cholesterol levels and blood
pressure.
The association between the number of cups of coffee con-
sumed per day and deaths from heart disease was examined while
taking other major coronary risk factors into account (Tverdal
et al., 1990). The duration of the study was 6.4 years. Total
serum cholesterol, high-density lipoprotein cholesterol, blood
pressure, height, and weight were measured. Self-reported in-
formation of smoking, physical activity and coffee drinking was
recorded. But the method of brewing coffee was not recorded.
A total of 168 men and 16 women died of coronary heart dis-
ease. Mean cholesterol concentration increased in the coffee
consumption group. The relation, risk for men who consumed
less than one cup to those who consumed nine or more cups
of coffee per day was estimated to be 2.2. For women the cor-
responding data was 5.1. This study suggests that high coffee
consumption is related to death from coronary heart disease,
over and above its effect of raising cholesterol concentration
(Stavric, 1992).
The effect of coffee or caffeine intake on other risk factors for
cardiovascular diseases, such as oxidizability of LDL particles,
vascular proliferation, or thrombosis is little known. However,
prospective cohert studies from the United States and Western
Europe mostly failed to find a link between coffee intake and
cardiovascular disease (Myers et al., 1992; Greenland, 1993;
Kawachi et al., 1994).
Effects on the Heart
Caffeine increases both the force and the rate of contraction
in isolated mammalian preparations (de Gubareff and Sleator,
1965). It has been reported that for caffeine the duration of the
action potentials increased isolated atria at low frequencies of
stimulation, resembling catecholamine action, whereas at high
frequencies of stimulation the rise in the action potentials was
faster and the duration shorter, resembling the action of calcium
(Gualtierotti, 1955a, 1955b, Shibata and Hollander, 1967). High
consumption of boiled coffee (decanted without filtering), a brew
particular to Scandinavian countries, is related to coronary heart
disease (Tverdal et al., 1990). In Scandinavia, a substantial per-
centage of the decline in serum cholesterol over the years has
been attributed to the switch from boiled to filtered coffee, lead-
ing to a reduction in cardiovascular disease (Tverdal et al., 1990;
Johansson et al., 1996).
Several mechanisms may explain the stimulant effects of caf-
feine and other xanthines on the heart muscle tissue. An increase
in plasma adrenaline and noradrenaline by about 100 and 50%
respectively was observed, when caffeine (250 mg) was sup-
plemented (Robertson et al., 1978). Another hypothesis sug-
gests that the xanthines inhibit phosphodiesterase, leading to
increased levels of cyclic AMP, which in turn is followed by
increased glycogenolysis and a rise in glucose–6–phosphate
levels (Ellis, 1956; 1959; Belford and Feinleib, 1962). But, caf-
feine was found to be less potent than other xanthines and that
even maximal doses of caffeine were found to inhibit phosphodi-
esterase by only a few percent (Beavo et al., 1970). The potency
of caffeine to release calcium from the cistern of the sarcoplas-
mic reticulum suggests another mechanism of action. The effect
had been demonstrated for caffeine with low therapeutic doses
in skeletal muscle preparations (Katz et al., 1977), and simi-
lar effects in skeletal and cardiac muscle tissue have also been
shown (Blinks et al., 1972).
Effects on Blood Vessels
Therapeutic doses of caffeine produced a decline in periph-
eral resistance, which is generally found modest, independent
of arterial blood pressure, and temporary (Ogilvie et al., 1977).
Because of its modest effect it is less used in the treatment of
peripheral vascular disease. Certain studies had shown that the
xanthines have particularly been observed to increase coronary
blood flow. This increase, however, hardly contributes to an in-
crease in the oxygen supply to the cardiac muscle or may be
an indirect consequence of the simultaneous increases in heart
work. In contrast to the debating action of xanthines, including
that of caffeine on peripheral blood vessels, these substances
are known to increase cerebrovascular resistances (Moyer et al.,
1952). This effect is believed to be the clinically observed relief
for migraine and other types of headaches caused by cerebrovas-
cular distinction.
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478 S. E. GEORGE ET AL.
Effects on Medullary Centers
Caffeine is considered to be more active in stimulating the
medullary respiratory vasomotor and vagal centers than theo-
phylline and theobromine, which is more potent in its effects
like cardiac functions, coronary dilation, smooth muscle relax-
ation, and diuresis. These effects were also found to be modest
and the stimulation of the respiratory functions may become ap-
parent only in cases where these centers are depressed by drugs
like barbiturates, opioids etc. Electrophysiological studies had
shown increases in firing rates of neurones in the brain stem
reticular formation of the rat after administration of 1–2 mg/kg
caffeine (Foote et al., 1978).
Myocardial Infarction
In a meta–analysis involving a total of 1,43,030 people, it was
concluded that there is no association between coffee consump-
tion and coronary heart diseases (Myers, 1992). The relationship
between coffee consumption and myocardial infarction has been
assessed in many prospective surveys. Most of the studies did
not show any correlation between moderate coffee drinking and
myocardial infarction, while the absence of any link to heavy
coffee consumption is less clear (Debry, 1994). In another study
a higher risk of myocardial infarction was seen in women who
consumed more than five cups of coffee a day (Palmer et al.,
1995). In a recent case control study neither caffeinated nor de-
caffeinated coffee was associated with the risk of myocardial
infarction, even for those drinking more than four cups a day
(Sesso et al., 1999).
There is no clear cut evidence showing any correlation be-
tween coffee consumption and myocardial infarction for moder-
ate coffee drinkers, but the risk at the same time cannot be ruled
out for high coffee consumers.
Arrhythmias
Experimental, epidemiological, and clinical reports explain
the defects of coffee on the heart rate. Caffeine has been the focus
of many reports, being a pharmacologically active compound,
on arrhythmias. The results suggest that moderate amounts of
coffee or caffeine do not affect cardiac rhythm.
In a review on arrhythmias it was judged that caffeine in-
gestion at levels equivalent to five or six cups of coffee a day
does not affect the severity or frequency of cardiac arrhyth-
mias in healthy subjects or patients with coronary heart dis-
ease or persons with known ventricular ectopy (Myers, 1991).
A similar result was also found in an epidemiological report on
more than 125,000 people, which did not find any influence of
coffee consumption on death attributed to cardiac arrhythmias
(Klatsky et al., 1993).
The information on the relationship between arrhythmias and
coffee consumption was further confirmed saying that moderate
caffeine is unlikely to affect the heart rate in both normal people
and patients with heart disease (Newby et al., 1996; Arciero et
al., 1998; Daniels et al., 1998, Myers, 1998).
Blood Pressure
Surveys on animal models and humans show that caffeine
can interfere with purinergic receptors and can therefore antag-
onize the vasodilating effect of adenosine. The pharmacological
effect increases peripheral vascular resistance and may there-
fore induce hypertension. A caffeine dependent stimulation of
the sympathetic nervous system activity resulting in neither in-
creased plasma nor epinephrine had also been proposed as a
possible trigger for high blood pressure (Debry, 1994). Several
studies have been carried out, involving acute caffeine dosing in
the presence or absence of stress, or chronic exposure to caffeine.
The potential link between coffee consumption and blood
pressure in the general population has been addressed in several
epidemiological studies. The results are variable and inconsis-
tent (Green et al., 1996; Myers, 1988, 1998) and these suffer
from methodological limitations. Few reports had shown no as-
sociation, a positive association, and inverse relationships with
systolic and diastolic blood pressure (Green et al., 1996). One
study found a curvilinear association with abstainers and high
users (more than nine cups) showing no difference in blood pres-
sure, but with those taking one to four cups per day showing a
slight rise (Stensvold et al., 1989).
a) Acute Dosing
Effects of acute dosing are either a small or a transient
rise within the first few hours following the dosing. Increase
in blood pressure was seen in people where caffeine was re-
stricted for variable periods of time before dosing. Abstinence
from caffeine, for periods as short as 24 hours, may lead to
a partial loss of tolerance to caffeine (Benoit, 2001). Phys-
ical and mental stress is known to increase blood pressure.
In a review, it was concluded that, overall, stress plus acute
dosing of caffeine cause small increases in blood pressure in
caffeine na¨ıve individuals (Green et al., 1996).
b) Chronic Exposure
The studies on repeated/chronic exposure to caffeine are
in agreement with that of acute dosing (Green et al., 1996;
Myers, 1988, 1998). Many of them did not find any effects on
blood pressure while some reported a small increase. When
increase was found the magnitude of the effect was very lit-
tle than that found in acute dosing (Myers, 1998). In a recent
meta–analysis of 11 controlled clinical trials in which the
effects of long-term coffee drinking on blood pressure was
assessed, a small increase of 2.4 and 1.2 mm Hg were found
respectively, for systolic and diastolic pressure (Jee et al.,
1999). Compared to other factors known to affect blood pres-
sure on a daily basis, the clinical significance of the increases,
if any, resulting from caffeine ingestion was considered to be
minimal (Green et al., 1996; Myers; 1998).
c) Potential Effects on Hypertensive People
Studies show that there is no effect of caffeine on am-
bulatory blood pressure. For example two weeks of caffeine
use versus placebo were compared in hypertensive patients
who were treated. No effect on blood pressure was observed.
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HEALTH BENEFITS OF COFFEE 479
Similarly in untreated patients with borderline hypertension,
caffeine use over two weeks had no effect on ambulatory
blood pressure (Mac Donald et al., 1991).
Effects on Cholesterol, Triglycerides, and Lipoprotein
It is increasingly acknowledged that foods contain non-
nutritional constituents, which may possess biological activities
compatible with beneficial health effects. The full assessment of
such food components requires a thorough investigation of both
efficacy and safety. The coffee specific diterpenes Cafestol and
Kahweol (C+K) can be considered as interesting examples of
such biologically active food components.
Cholesterol
It is well documented that cafestol potently raises choles-
terol in humans (Weusten et al., 1994; Ugert et al., 1997). In a
meta–analysis of 11 experiments with cafestol rich preparations
each 10 mg of cafestol consumed per day (equivalent to 2–3
cups of coffee brewed without the use of a paper filter) raises
serum cholesterol by 0.15 mmol/L (Urgert and Katan, 1997).
Coffee beans of commercial blends will inevitably contain the
cholesterol raising compound cafestol. Filtered coffee does not
contain kahweol or cafestol, as the diterpenes are retained by
paper filters (Van et al., 1991). Diterpene levels are low in in-
stant coffee also (Urgert et al., 1995b); an experiment explained
that “boiled” coffee indeed raised cholesterol, whereas in a par-
allel group, filtered coffee had no effect (Aro et al., 1987). The
brewing method thus made the crucial difference (Table 5).
High consumption of boiled coffee (decanted without fil-
tering), a brew particular to Scandinavian countries, had been
clearly associated with elevated levels of serum cholesterol (Urg-
ert and Katan, 1997). In Scandinavia, a substantial percentage
of the decline in serum cholesterol over the years has been at-
tributed to the switch from boiled to filtered coffee (Tuomile-
hto and Pietinen, 1991). Subsequent epidemiological and con-
trolled clinical studies have further confirmed that the hyperc-
holesterolemic effect of coffee was dependent on the method of
preparation of the coffee brew.
The coffee brews with moderate amount of diterpenes in it
like Mocha and Espresso coffee appear harmless with consump-
tion of few cups per day. The ones which are rich in diterpenes,
a recommendation to limit their use in favor of filtered or instant
coffee seems justified in patients with a high cholesterol level or
an increased coronary risk (Urgert and Katan, 1997).
Cholesterol Raising Factor. Several reports attempted to find
the factor in boiled coffee that raised the cholesterol level. Inges-
tion of 1.3 g of boiled coffee per day by 10 volunteers increased
the serum cholesterol by 23% (Zock et al., 1990). Experiments
found that boiled coffee had 1–2g of lipid/liter, whereas fil-
tered coffee hardly had any (Van et al., 1991). This showed that
the cholesterol-raising factor was a lipid. Another experiment
showed that ingestion of 148 mg of purified diterpene alco-
hol per day raised cholesterol by 32% and similar raises were
observed with purified diterpene esters. (Heckers et al., 1994;
Weusten et al. 1994; Urgert et al., 1997). Cafestol alone and the
mixture of cafestol and kahweol (63 mg) was given to 10 volun-
teers and cholesterol levels were monitored. Cafestol raised the
cholesterol by 17% whereas the mixtures of 60 mg of cafestol
plus 51 mg of kahweol per day increased the cholesterol by a
further 2% only (Urgert et al., 1997). Thus the content of cafestol
was the main factor contributing to the rise in cholesterol than
kahweol.
In a trial of eleven humans given supplements of known diter-
pene content, the serum total cholesterol was found to be raised
by 0.13 mmol / liter (5.0 mg / dl) with each 10 mg of cafestol and
by 0.02 m mol / liter (0.9 mg / dl) with each 10 mg of kahweol
consumed per day for four weeks. This indicates that cafestol
raises the cholesterol level more than kahweol. The effect was
linear up to 100 mg of cafestol/day (the amount present in 15–
30 cups of boiled coffee). About 80% of the increase in total
cholesterol was accounted for by LDL cholesterol and the rest
was due to rise in very low-density lipoproteins. HDL (High
density lipoproteins) may fall slightly when cafestol and kah-
weol are ingested (Urgert et al 1997; Weusten et al., 1994; Zock
et al., 1990).
The mechanism by which coffee diterpenes affect lipid
metabolism is by far unknown. But a study shows the involve-
ment of the LDL receptor, which is synthesized / generated on
all membranes and is responsible for the removal of LDL choles-
terol from the blood stream. Cafestol decreased uptakes of LDL
cholesterol into human fibroblasts (Halvorsen et al., 1994) and
hepatoma cells (Halverson, 1996) but raised it in an intestinal
cell line (Ranheim et al., 1995). More studies are required to
clarify this discrepancy.
Triglycerides
A marked increase in serum triglyceride was found when vol-
unteers were supplemented with boiled coffee. Again cafestol
was the major factor responsible for the increase. Cafestol alone
raised triglycerides by 86% while kahweol increased the re-
sponse by only 7% (Urgert et al., 1997). However most of the
rise in triglycerides may subside with chronic intake of coffee
diterpenes.
Lipoprotein
Lipoprotein, which consists of an LDL particle attached to
apolipoprotein is a risk of cardiovascular diseases (Dahlen,
1994). Most of the rises in total LDL cholesterol caused by
coffee diterpenes persist with chronic intake, whereas most of
the rise in triglycerides subside coffee diterpenes which re-
duces the serum lipoprotein in the first months of intake only
(Urgert et al., 1997).
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480 S. E. GEORGE ET AL.
Table 5 Effect of coffee diterpenes
on serum cholesterol
Serum cholesterol
Coffee type C or k
@
C
#
K
#
C
$
K
$
C (Mean) K (Mean) (mmol/liter)
Paper filtered 0.1 0.1 0.1 <0.1 <0.1 0.1 0.1 <0.01
Instant 0.1 0.2 0.2 0.2 0.2 0.2 0.2 0.2
Percolator 0.3 0.3 0.3 0.3 0.02
Mocha 1.1 1.4 2.3 2.3 1.7 1.9 0.13
Espresso 3.6 1.5 1.8 1.0 1.0 2.0 2.1 0.15
Cafeteria 1.6 3.5 4.4 2.6 3.0 0.20
Turkish 3.4 3.9 3.9 5.3 5.4 4.2 4.2 0.32
Boiled 8.4 3.0 3.9 7.2 7.2 6.2 6.5 0.47
+
Qunatity - mg/cup; Intake - five cups per day.
@
Ratnayake et al., 1993;
#
Urgert et al. 1995;
$
Gross et al., 1997.
Other Effects
Risk of Liver Disease
The intake of coffee diterpenes (Van Rooji, 1995; Weusten
1994) or unfiltered coffee (Urgert, 1996; Wensten, 1994) raised
the serum activity of alanine amino transferase in volunteers.
A rise of liver enzyme activity in serum may indicate injury
to hepatocytes. This is not due to cholestasis, as coffee diter-
penes reduce rather than raise the serum activity of γ - gutamyl
transferase and alkaline phosphatase (Urgert et al., 1995a). It is
unlikely that a perturbation of liver cell function explains the ef-
fects of coffee diterpenes on blood lipids, because both cafestol
and kahweol raise amino transferases, but kahweol had little
effect on blood lipids (Urgert, 1997).
Clinically relevant damage to liver cells in healthy subjects
drinking unfiltered coffee appears unlikely and the risk of liver
disease cannot be ruled out as patients with elevated alanine
aminotransferase levels would be preferred to reduce their coffee
consumption to not more than a few cups of boiled Turkish or
cafetiere coffee (containing high diterpene content) per day.
Risk of Asthma
Coffee prevented the clinical manifestation of bronchial
asthma. When a double-blind study was done on 10 asthmatic
patients who were given 7 mg/Kg body weight of caffeine be-
fore 2 hrs of exercise, it prevented exercise induced broncho
constriction (Kivity et al., 1990). After a dose of 3.5 mg caffeine
/Kg. there was a trend towards improvement.
Effect on Immune System
Studies showed that consumption of coffee modified the im-
mune system. The findings suggest that taking 5 cups/day of
instant coffee for 5 weeks brought up this effect (Melamed et al.,
1990). The abstinence from coffee, suppressed the lymphocyte
response to mitogen stimulation, but increased the proportion of
suppressor T-cells and natural killer cells.
Ergogenic Effect
In addition to steroid and hormones, caffeine has also be-
come a compound of interest because some athletes who have
used caffeine as an ergogenic aid and reported that it apparently
enhanced performance in endurance sports (Jurisic and Randic,
1990). Few studies also showed that subjects exercised signif-
icantly longer, performed more physical work, or experienced
longer neuromuscular reflex response time when they consumed
caffeine (Jacobson and Edwards, 1990)
Thermogenic Effect
In humans, caffeine was known to stimulate thermogenesis
by an unknown mechanism and its effect on body weight has
not been studied. A study found that a cup of coffee (4 mg
caffeine/kg body weight) consumed with a meal produced a
significantly greater thermic response than that with a cup of
decaffeinated coffee, and this difference can be almost totally
accounted for by the thermogenic effect of the caffeine (Acheson
et al., 1980). It appears that only a few different doses of caffeine
have been studied and other constituents of coffee, other than
caffeine, may influence lipid metabolism.
Hepatoprotective Effect
Coffee was found to antagonize the promoting effects of hep-
atitis B and C infection on cirrhosis development, suggesting a
protective effect of coffee on non-alcoholic cirrhosis (Benoit
et al., 2001). Also, coffee consumption has repeatedly found
in clinical and epidemiological studies to reduce the levels of
serum γ -glutamyl-1-transferase a marker of hepatobiliary dis-
eases (Tanaka et al., 1998), hence a protective effect on liver.
Antimicrobial Esffect
Antimicrobial effect may be due to the mutagenic effect of
coffee on the microbes (Alan and Jane, 1994). Roasted coffee
was shown to possess antibacterial activity against both gram-
positive and gram-negative bacteria including Streptococcus mu-
tans, which is considered to be a causative agent for dental caries
in humans.
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HEALTH BENEFITS OF COFFEE 481
Diabetes Mellitus (Type 2)
Coffee is a rich source of caffeine, which acutely reduces
insulin sensitivity but also possesses as potentially beneficial
effects. The association between coffee consumption and the
risk of clinical Type 2 diabetes was investigated in a population-
based cohort of men and women aged 30–60 years. Individuals
who drank more than 7 cups of coffee/day were 0.50 times (95%
confidence interval 0.35–0.72) as likely to develop type 2 dia-
betes. It is concluded that high coffee consumption is associated
with a substantial reduction of risk of type 2 diabetes (Dam
et al., 2002).
SUMMARY
Coffee has been enjoyed as a drink by millions of people
worldwide for over at least one thousand years. Coffee con-
tains a complex mixture of chemical compounds. Substances
that dissolved in water to form the beverage during brewing are
classified as nonvolatile components (viz., caffeine, trigonelline,
chlorogenic acid, phenolic acids, amino acids, carbohydrates,
and minerals). Volatile aroma components include organic acids,
aldehydes, ketones, esters, amines, and mercaptans. Some com-
ponents, particularly those related to the aroma, are produced
during roasting of the green beans.
Although coffee contains a wide variety of substances, it
is generally accepted that caffeine is responsible for many of
its physiological effects. Caffeine influences the central ner-
vous system in a number of ways, mainly it enhances alert-
ness, concentration, and mental and physical performance. A
cup (150 ml) of instant coffee contains about 60 mg caffeine,
filter coffee contains about 85 mg, and a decaffeinated beverage
contains only 3 mg of caffeine.
Coffee develops stimulating effects on the central nervous
the system, the heart, and blood circulation, which are mainly
caused by caffeine. Extensive epidemiological studies conclude
that there is no correlation between coffee consumption and cer-
tain risk factors such as hypertension, heart infarction, diabetes,
gout, or cancer diseases. Furthermore, there was no evidence that
coffee or its caffeine content is able to induce genetic alterations
or even malformations.
Coffee beans are one of the richest dietary sources of chloro-
genic acid for many consumers. It has been reported that a
cup (150 ml) of arabica coffee contains between 50–150 mg
of chlorogenic acid whereas a cup of robusta coffee contains
between 50–270 mg. The amount of chlorogenic acid or caf-
feic acid available to act as an antioxidant in vivo will depend
on absorption from the gut. It has recently been demonstrated
that humans absorb about 33% of ingested chlorogenic acid and
about 95% of ingested caffeic acid, when chlorogenic and caf-
feic acids were ingested at 2.8 mmol and 2.8 mmol caffeic acid
respectively on separate days (Olthof et al., 2001).
High consumption of boiled coffee (decanted without filter-
ing), a brew particular to Scandinavian countries, may cause
mild elevation of plasma cholesterol concentration in some peo-
ple due to the presence of cafestol and kaweol. But instant and
filter coffee have no such effects. The coffee brews with moder-
ate amount of diterpenes like Mocha and Espresso coffee which
appear to be harmless with consumption of 3–4 cups per day.
There is no evidence that coffee increases the risk of heart dis-
ease. Moderate consumption of coffee does not increase cardiac
arrhythmias. In some sensitive individuals, ingestion of coffee
after a period of abstinence may cause a temporary rise in blood
pressure but there is no persistent hypertensive effect in the long
term. There is no proof that coffee increases the risk of cancer of
the female breast, ovary, pancreas, or kidney. It is now accepted
that cigarette smoking primarily causes the small increased risk
of bladder cancer sometimes associated with coffee drinking.
The reports indicate that coffee protects against colon cancer,
male breast cancer, and gallstone disease.
Reports suggest that coffee does not promote indigestion in
the majority of people, although it is known to increase heartburn
and this effect is not large enough to justify advising people
with gastro-oesophageal reflux disease to abstain from drinking
coffee. There is no evidence that coffee increases the risk of
developing peptic ulcer disease. Research studies advocate that
modest consumption of coffee has no effects on pregnancy as
well as on infants.
Coffee has been linked to an increasing number of poten-
tial health benefits, including protection from Parkinson’s dis-
ease. Furthermore, few studies suggest that it might also pro-
tect against liver cancer and type 2 diabetes. The relationship
between coffee consumption and diabetes is an area of active
investigation but no clear picture has emerged so far. Available
evidence suggests that coffee might also protect against liver
cirrhosis.
Harmful effects of coffee are associated with people who
are sensitive to stimulants. Beyond this there is no evidence that
coffee intake is connected with adverse health effects. Therefore
the moderate consumption of 3–4 cups of instant or roasted
coffee per day, assuming an average caffeine concentration of
60-85mg per cup, is good for human health (Benoit et al., 2001).
ACKNOWLEDGEMENTS
The authors are thankful to the Director; the Head of
Plantation Products, Spices, and flavor Technology Depart-
ment and the Head of Human Resource Development, Central
Food Technological Research Institute, Mysore for their
support.
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... Coffee has been valued for years for its stimulating effect on the central nervous system, associated primarily with caffeine [23][24][25]. Nevertheless, studies show that consumption of two to three coffee cups a day brings many other potential health benefits, including prevention of cancer, type 2 diabetes, cardiovascular and liver diseases, and Alzheimer's and Parkinson's diseases [24][25][26][27][28][29][30][31][32][33][34]. In addition to caffeine, the most important bioactive compounds responsible for these effects are mainly polyphenols [21,[35][36][37], of which esters of caffeic and quinic acids, known as chlorogenic acid isomers, are the most abundant [23,24]. ...
... Nevertheless, studies show that consumption of two to three coffee cups a day brings many other potential health benefits, including prevention of cancer, type 2 diabetes, cardiovascular and liver diseases, and Alzheimer's and Parkinson's diseases [24][25][26][27][28][29][30][31][32][33][34]. In addition to caffeine, the most important bioactive compounds responsible for these effects are mainly polyphenols [21,[35][36][37], of which esters of caffeic and quinic acids, known as chlorogenic acid isomers, are the most abundant [23,24]. While caffeic acid has anticancer effects [38], chlorogenic acids (CGA, Figure 1), including the isomers of caffeoylquinic (CafQA), dicaffeoylquinic (diCafQA), feruloylquinic (FQA), and p-coumaroylquinic (pCoQA) acids, exhibit antibacterial, antifungal, antiviral, antioxidant, and chemoprotective properties [34,39,40]. ...
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Coffee is a very popular beverage worldwide. However, its composition and characteristics are affected by a number of factors, such as geographical and botanical origin, harvesting and roasting conditions, and brewing method used. As coffee consumption rises, the demands on its high quality and authenticity naturally grows as well. Unfortunately, at the same time, various tricks of coffee adulteration occur more frequently, with the intention of quick economic profit. Many analytical methods have already been developed to verify the coffee authenticity, in which the high-performance liquid chromatography (HPLC) plays a crucial role, especially thanks to its high selectivity and sensitivity. Thus, this review summarizes the results of targeted and non-targeted HPLC analysis of coffee-based products over the last 10 years as an effective tool for determining coffee composition, which can help to reveal potential forgeries and non-compliance with good manufacturing practice, and subsequently protects consumers from buying overpriced low-quality product. The advantages and drawbacks of the targeted analysis are specified and contrasted with those of the non-targeted HPLC fingerprints, which simply consider the chemical profile of the sample, regardless of the determination of individual compounds present.
... Previous studies have shown that caffeine and papaverine could influence antioxidant activities. In recent decades, many scientific studies and reviews have documented the interest in caffeine and other coffee bean constituents for their health-promoting properties [54,55]. Many authors have claimed that caffeine is a good antioxidant [56][57][58]. ...
... Stimulant laxatives, antimicrobials, anaesthetic drugs, and dye Previous studies have shown that caffeine and papaverine could influence antioxidant activities. In recent decades, many scientific studies and reviews have documented the interest in caffeine and other coffee bean constituents for their health-promoting properties [54,55]. Many authors have claimed that caffeine is a good antioxidant [56][57][58]. ...