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Date palm is one of the oldest trees cultivated by man. In the folk-lore, date fruits have been ascribed to have many medicinal properties when consumed either alone or in combination with other herbs. Although, fruit of the date palm served as the staple food for millions of people around the world for several centuries, studies on the health benefits are inadequate and hardly recognized as a healthy food by the health professionals and the public. In recent years, an explosion of interest in the numerous health benefits of dates had led to many in vitro and animal studies as well as the identification and quantification of various classes of phytochemicals. On the basis of available documentation in the literature on the nutritional and phytochemical composition, it is apparent that the date fruits are highly nutritious and may have several potential health benefits. Although dates are sugar-packed, many date varieties are low GI diet and refutes the dogma that dates are similar to candies and regular consumption would develop chronic diseases. More investigations in these areas would validate its beneficial effects, mechanisms of actions, and fully appreciate as a potential medicinal food for humans all around the world. Therefore, in this review we summarize the phytochemical composition, nutritional significance, and potential health benefits of date fruit consumption and discuss its great potential as a medicinal food for a number of diseases inflicting human beings.
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Critical Reviews in Food Science and Nutrition, 52:249–271 (2012)
Copyright C
Taylor and Francis Group, LLC
ISSN: 1040-8398 / 1549-7852 online
DOI: 10.1080/10408398.2010.499824
Date Fruits (Phoenix dactylifera Linn):
An Emerging Medicinal Food
PRAVEEN K. VAYALIL
Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294
Date palm is one of the oldest trees cultivated by man. In the folk-lore, date fruits have been ascribed to have many medicinal
properties when consumed either alone or in combination with other herbs. Although, fruit of the date palm served as the
staple food for millions of people around the world for several centuries, studies on the health benefits are inadequate and
hardly recognized as a healthy food by the health professionals and the public. In recent years, an explosion of interest in the
numerous health benefits of dates had led to many in vitro and animal studies as well as the identification and quantification
of various classes of phytochemicals. On the basis of available documentation in the literature on the nutritional and
phytochemical composition, it is apparent that the date fruits are highly nutritious and may have several potential health
benefits. Although dates are sugar-packed, many date varieties are low GI diet and refutes the dogma that dates are similar
to candies and regular consumption would develop chronic diseases. More investigations in these areas would validate
its beneficial effects, mechanisms of actions, and fully appreciate as a potential medicinal food for humans all around the
world. Therefore, in this review we summarize the phytochemical composition, nutritional significance, and potential health
benefits of date fruit consumption and discuss its great potential as a medicinal food for a number of diseases inflicting
human beings.
Keywords Glycemic index, chemoprevention, ACE inhibitor, anti-diabetic, medicinal food, antioxidant
INTRODUCTION
From time immemorial, fruits constituted a major compo-
nent of the human diet. Besides being a part of the regular diet,
people also consumed fruits as a part of their religious prac-
tices as well as nutritional therapy in different human traditions
around the world. However, in modern industrialized nations,
like the United States (US), human food selections and dietary
patterns are not governed mainly by their nutritional significance
or health benefits. Instead, they have been determined by neces-
sity and economics and influenced by the promotion of foods
more on their merits of taste, cost, or convenience (Heber and
Bowerman, 2001). In the US, the public has recently realized
the health benefits of fruits and vegetables and recognized them
as one of the healthiest foods in existence. This is evident from
the results of USDA’s 1994–1996 Continuing Survey of Food
Intakes by Individuals released in 1998. The survey reported
that Americans eat only two to three servings of fruits and veg-
etables and a minority does not eat them at all (Beltsville Human
Address correspondence to Praveen K. Vayalil, Department of Pathology,
University of Alabama at Birmingham, BMR II Room 329, 901 19th Street
South, Birmingham, AL 35294-2172. Tel.: (205) 934-9568; Fax: (205) 934-
7447. E-mail: praveen@uab.edu
Nutrition Research Center, 1998). In the past two decades, sub-
stantial progress has been made concerning our knowledge of
bioactive components in plant foods and their direct links to
human health. The scientific perception on the health benefits
of fruits and vegetables led to the implementation of Five-a-Day
program in the US in the 1990s in order to increase the public
awareness of the health benefits fruits and vegetables and en-
courage daily consumption as a part of a regular diet (Assembly
of Life Sciences (US). Committee on Diet Nutrition and Cancer.
1982). In 1991, the National Cancer Institute also adopted the 5-
A-Day campaign as a national 10-year initiative (Heimendinger
et al., 1996). As a result of these initiatives, the progress in
recommended intake of fruits and vegetables among Americans
mounted from 19% to 23% during 1990 to 1996. Although this
achievement in six years is encouraging, additional efforts are
needed to accomplish the objectives of this program (Li et al.,
2000).
Health or medicinal foods have recently received immense
interest among the health professionals and public. Conse-
quently, the global health market has been swamped with
such products claiming to improve health as well as prevent
chronic diseases. Because of increased commercial exploitation
of medicinal foods, all varieties of fruits and vegetables were
re-evaluated for their phytochemical composition and health
249
250 P. K. VAYALIL
benefits under both laboratory conditions and clinical settings.
Although date fruit (DF) is admired for its nutritional and phar-
macological properties by the natives of Middle East and north-
ern Africa, it is still hardly recognized in the west due to the lack
of sufficient scientific documentation. Owing to its high nutri-
tive values and potential health promoting activities, DF may
be considered as an emerging and potential candidate for the
development of health-promoting foods. Therefore, this review
summarizes current knowledge on the phytochemical compo-
sition, nutritional significance, and potential health benefits of
DF.
THE DATE PALM AND DATE FRUIT
Date palm is an important and one of the oldest trees
(5500–3000 BC) cultivated by man (Barreveld 1993; Beech and
Shepherd, 2001; Anon., 2003; Beech, 2003; Tengberg, 2003).
For over 5000 years, date palm has provided food, ornament, and
material for shelter, fiber, and fuel in a harsh environment where
relatively few other plants are able to thrive. Thus, date palm
cultivation was always blended with the entire social, cultural,
religious, and economical development of the people inhabit-
ing the hot, arid regions of the world extending from Middle
East to Northern Africa (Barreveld, 1993; Beech and Shep-
herd, 2001; Anon., 2003; Beech, 2003; Tengberg, 2003). Until
now, date palm continues to be the principal crop cultivated in
this region and the Middle East nations are the major produc-
ers and exporters of DF (Barreveld, 1993; Anon. 2003). More
details on the cultivation, varieties, geographical distribution,
harvesting, etc., have been reviewed in detail elsewhere (Nixon
and Carpenter, 1978; Barreveld, 1993; Anon., 2003; Rieger,
2006).
In the US, commercial introduction of date palm and pro-
duction of DF was started in the early 19th century. There are
more than 600 date varieties, including cultivars, grown world-
wide, and in the US, major varieties of date palms cultivated
include Deglet Noor and Medjool whichwereimportedfrom
Algeria and Morocco, respectively. Date palm cultivation is still
an important component of desert agriculture in southern Cal-
ifornia, Arizona, and Texas. There are now about a quarter of
a million trees in California and Arizona and mostly grown on
7,000 acres in the Coachella Valley, California and 600 acres in
the BARD area near Yuma, Arizona. The annual DF production
in the US in 2003 was about 16,662 metric tons (Nixon and
Carpenter, 1978; Johnson et al., 2002; Karp, 2002; Johnson and
Hodel, 2007; Wright, 2007). However, large-scale commercial
exploitation of DF as a healthy food and medicine has not yet
commenced in the US. Therefore, this review is intended to
incite large-scale commercial exploitation and generate enthu-
siasm among researchers in various scientific fields in the US
as well as abroad to study DF as a health promoting food for in-
fants, youths and healthy adults, as well as patients with chronic
diseases.
The fruit of the date palm (edible flesh of the fruit) is es-
pecially delicious and highly nutritious (Vinson et al., 2005).
Besides its nutritive value and in contrast to other major fruits
commonly consumed by humans, DF is unique and character-
ized by certain distinct properties (Barreveld, 1993). One of the
major characteristics that render DF exceptional is that it is the
only fruit consumed as a dietary staple in the world and has
remained as a major diet for millions of people for thousands
of years. Another property is that dates may be consumed at
any of the three major stages of maturity such as khalal (fresh,
hard ripe, color stage), rutab (crisp to succulent or ripe stage),
or tamr (soft pliable, full ripe stage). Although newly ripened
dates are preferred in many date producing countries, dehy-
drated dates are the common form available commercially and
enjoyed globally. More importantly, DF is nature’s semi-dried
fruit. Unlike other fruits, fully tree ripened dates are a natu-
rally preserved food that can be transported or stored for several
months without further processing (Barreveld, 1993; Rieger,
2006). Although dates are generally considered as a dried fruit,
it is not comparable to the traditional dried fruits. This is be-
cause a fully ripened date is a semi-dried fruit and is akin to
any other fresh fruit. In contrast, the dried fruits are produced
by artificially dehydrating raw fruits to increase the shelf life
or for other specific purposes. For that reason, fresh dates are
nutritionally superior and exceptionally delicious compared to
dried fruits (Vinson et al., 2005; Al-Farsi et al., 2005b). Finally,
production and cultivation of date palm is possible in severe
climatic conditions, where growth of other crops or plants is
virtually impossible and economically difficult. Therefore, in
addition to fruit production, mature date palms are highly de-
sirable landscape plants in these regions and regarded as highly
ornamental (Johnson et al., 2002; Johnson and Hodel 2007).
PHYTOCHEMICAL COMPOSITION OF DATE FRUIT
The protective effects of fruits against chronic diseases are at-
tributed to bioactive non-nutrients called phytochemicals. Phy-
tochemicals are secondary plant metabolites or integral cel-
lular components. Phytochemicals have gained increased in-
terest among several investigators including clinicians due to
their antioxidant activity, cholesterol-lowering properties, and
other potential health benefits such as chemoprevention of can-
cer, prevention of diabetes, and cardiovascular diseases. DF is
renowned for the presence of many classes of bioactive com-
ponents such as carotenoids, polyphenols especially phenolic
acids isoflavons, lignans, and flavonoids, tannins, and sterols
(Maier and Metzler, 1965; Maier et al., 1964; Kikuchi and Miki,
1978; Regnault-Roger et al., 1987; Duke, 2001; Al-Farsi and
Lee, 2008; Duke and Beckstrom-Sternberg, Accessed 2007).
Several studies have also been published related to the chem-
ical composition of different varieties of dates grown in dif-
ferent parts of the world (Maier and Metzler, 1965; Maier
et al., 1964; Salem and Hegazi, 1971; Mustafa, 1986; Mustafa
et al., 1986; Alshowiman, 1990; Fayadh and Alshowiman, 1990;
DATE FRUITS: AN EMERGING MEDICINAL FOOD 251
Figure 1 Carotenoids identified in date fruits.
Alshowiman and Baosman, 1992; Ahmed et al., 1995; Krajew-
ski et al., 1995; Al-Hooti et al., 1995; 1997; Myhara et al.,
1999; Al-Shahib and Marshall, 2002; 2003a; 2003b; Ishurd
et al., 2001; 2002; 2004; Omar Ishurd, 2004; Al-Farsi et al.,
2005b; 2007; Ahmed and Ramaswamy, 2006; Ismail et al., 2006;
Thompson et al., 2006; Bendahou et al., 2007; Liolios et al.,
2008). However, studies pertaining to the detailed identification,
characterization, and quantification of phytochemicals in differ-
ent DF varieties at different stages of fruit ripening are still in-
sufficient (Kikuchi and Miki, 1978; Gross et al., 1983; Regnault-
Roger et al., 1987; Krajewski et al., 1995; Ben-Amotz and
Fishier, 1998; Gu et al., 2003; Al-Farsi et al., 2005a; Mansouri
et al., 2005; Hong et al., 2006; Thompson et al., 2006; Boudries
et al., 2007; Biglari et al., 2008; Liolios et al., 2008). Detailed
studies in these directions are expected in the near future.
The quantity and composition of the phytochemicals present
in DF vary widely depending on the date variety, stage of matu-
ration, storage, postharvest processing, extent of hydration, ex-
perimental conditions used for the analysis, and the geographical
origin of the dates (Al-Laith 2009; Amoros et al., 2009; Al-Turki
et al., 2010). It was reported that DF upon sun drying signif-
icantly loses total carotenoids (up to 30%) and anthocyanins
(93%) and increases total phenolics (22–153%) and phenolic
acids (64–107%) (Al-Farsi et al., 2005a). In our experience,
initially we could only detect very low free radical scavenging
activity in aqueous extracts prepared from dried fruits. Freshly
prepared extracts from fresh, ripened DF showed significant
free radical scavenging activity and was used throughout our
studies (Vayalil, 2002). Extracts prepared from fresh fruits are
highly unstable and lose their free radical scavenging activity
significantly within a few hours at room temperature. Therefore,
these factors are critical and need serious consideration during
the assessment of their biological activity. Appropriate steps
should also be taken to minimize the changes in the phytochem-
ical composition and quantity during extraction and analysis;
otherwise, the results will be misleading. For example, in one
study the extraction solvent contained sodium fluoride to in-
hibit polyphenoloxidases to prevent phenolic degradation in DF
(Hong et al., 2006).
Carotenoids
The major class of phytochemicals found in the lipid frac-
tions of DF is carotenoids (Fig. 1). Carotenoids are a diverse
group of over 600 structurally related isoprenoids biosynthe-
sized by plants, fungi and bacteria (Krinsky, 1993; Castenmiller
and West, 1998) and have been shown to be important in human
health and prevention of chronic diseases (Krinsky and John-
son, 2005). Analysis of total carotenoid pigments in dates have
revealed that DF is rich in carotenoids. The total carotenoids
have been shown to decrease rapidly as the fruit ripens (Gross
et al., 1983). The major carotenoids found in DF are β-carotene
and lutein (Boudries et al., 2007). Even though not quantified,
Duke’s ethnopharmacological database reports the presence of
lycopene, violaxanthin, flavoxanthin, and leukoxanthin in DF
(Duke 2001; Duke and Beckstrom-Sternberg, Accessed 2007).
The total carotenoid content ranging from 0.22 mg to 3.0 mg per
100 g of date depending on maturity and DF variety has been
already reported (Gross et al., 1983; Ben-Amotz and Fishier,
1998; Al-Farsi et al., 2005a; Boudries et al., 2007). According
to USDA National Nutrient Database for Standard Reference,
Release 19 (2007) the total carotenoids in Deglet Noor and
Medjool are 81 (6.0 µgofβ-carotene and 25.0 µg of leutin plus
zeaxanthin) and 112 µg/ 100 g (89.0 µgofβ-carotene and 23.0
µg of leutin together with zeaxanthin), respectively. A detailed
252 P. K. VAYALIL
analysis of total carotenoids in few varieties of Algerian dates
has shown that lutein (89–94%) and β-carotene (3–10%) are the
major forms of carotenoids present in DF and another 2–8% con-
sists of unidentified minor carotenoids (Boudries et al., 2007).
Ben-Amotz and Fishier (1998) analyzed different carotenoids in
Israeli DF. They estimated 2.2 µg/g of total carotenoids and the
major carotenoids identified were cis-violaxanthin (0.1 µg/g),
Zeaxanthine (1.1 µg/g), β-zeacarotene (0.3 µg/g), α-carotene
(0.1 µg/g), and β-carotene (0.6 µg/g). However, details of the
DF used for the analysis are unavailable.
The provitamin A value of Algerian dates have been calcu-
lated (Boudries et al., 2007). The provitamin A activity (repre-
sented as retinol equivalents) of DF was directly related to the
amount of β-carotene present at each stage of ripening of the
fruit, where 1 µg of retinol equivalents (RE) corresponds to 6 µg
of β-carotene. They showed that depending on the type of fruit
and edible maturation stages of the fruit, provitamin A activity
reduced from khalal to tamr stage (Boudries et al., 2007) and it
ranged from 0.4 to 12 RE. USDA National Nutrient Database
for Standard Reference, Release 19 (2007) expresses vitamin A
content in µg of retinol activity equivalents (RAEs). One µg
RAE is equivalent to 1 µg of all-trans-retinol, 12 µg of all-
trans-β-carotene, or 24 µg of other provitamin A carotenoids.
According to the National Nutrient database, the Medjool va-
riety contains 7.0 µg of RAE. Therefore, it may be presumed
that for thousands of years DF might have served as one of the
major sources of vitamin A for the people who lived in the hot
and arid regions of the world.
Phytosterols
Another major group of lipid soluble phytochemicals present
in DF are the phytosterols (Fig. 2). These phytochemicals are
exclusively found in plants and structurally resemble choles-
terol. About 200 phytosterols exist naturally and many of them
are present in fruits and vegetables (Bradford and Awad, 2007).
DF contains many phytosterols in the edible portion of the fruit.
Seeds of date palm (date pits) and the pollen grains are the major
reservoirs of phytosterols (Duke 2001; Duke and Beckstrom-
Sternberg, Accessed 2007) and have been used since ancient
times for the treatment of various hormone related health con-
ditions. Kikuchi and Miki (1978) first isolated crystalline plant
sterol mixture from the edible flesh of the date and identified
them as campesterol, stigmasterol, β-sitosterol, and isofucos-
terol (Fig. 2). However, the difference in phytosterol composi-
tion among DF cultivars and stages of fruit ripening is still ob-
scure and is an important avenue for further research. In addition
to the sterols mentioned above, date pits also contain brassicas-
terol, ergasterol, estrogen, and esterone (Duke, 2001; Duke and
Beckstrom-Sternberg, Accessed 2007). In a most recent study,
in another species of date palm (P. theophrasti)manyphytos-
terols have been identified in the edible part of the fruit. They
include Campesterol, stigmasta-5,22-dien-3β-ol, β-sitosterol,
γ-sitosterol, lupenone, lupeol, 24-methylenecy-cloartanol, (E)-
24-propylidenecholesterol, stigmastan-3, 5-diene, cholest-4-en-
3-one, 4-methyl-cholest-4-en-3-one, spinasterone, stigmast-4-
en-3-one, and cholesta-3,5-diene (Liolios et al., 2008).
Polyphenols
DF is a good source of polyphenols. They are rich in simple
phenolic acids and flavonoids like procynidines. According to
Duke’s Phytochemical and Ethnobotanical Databases, DF con-
tains 30,000 ppm (3.0 g/100 g) of polyphenols (Duke 2001;
Duke and Beckstrom-Sternberg Accessed 2007).
Figure 2 Phytosterols identified in date fruits.
DATE FRUITS: AN EMERGING MEDICINAL FOOD 253
Tab le 1 Free and total phenolics quantified in fresh and dried date fruits cultivated in different parts of the world
Free Phenolics Total Phenolics
Date Variety Fresh Dried Fresh Dried Ref
California 257 mg CAE/100g 400 mg Catechin/100g 2,546 mg Catechin/100 g 12,730 mg Catechin/100 g Vinson et al., 2005
NA NA NA 5.72–6.61 mg GAE/g Wu et al., 2004
Algerian NA NA 2.49–8.36 mg GAE/100 g NA Mansouri et al., 2005
Omani 2.6 mg/100g 14.8 mg/100g 134 mg FAE/100 g 343 mg FAE/100 g Al-Farsi et al., 2005a,; 2007
Iranian NA NA 1.62–4.82 mg GAE/100 g 141 mg GAE/100 g Biglari et al., 2008
Bahraini NA NA 67 – 376 mg GAE/100 g NA Abdul Ameer, 2008
Egypt NA NA NA 1461 mg of GAE/100 g Mohammed and Al-Okbi, 2005
NA-Data Not available; GAE-Galic acid equivalents; FAE-Ferulic acid equivalents.
Total Phenolics in Date Fruit
Studies have been conducted to analyze the total phenolics
present in different varieties of DF at different stages of ripening
(Table 1). Analysis were also performed to determine the level
of total phenolics in processed dates (Al-Farsi et al., 2005a;
Mohamed and Al-Okbi, 2005; Vinson et al., 2005; Abdul Ameer,
2008). It was observed that drying increased the amount of total
phenols in DF which was statistically significant in Omani dates
(Al-Farsi et al., 2005a) and Iranian dates (Biglari et al., 2008)
and not significant in California dates (Vinson et al., 2005).
Vinson et al. (2005) compared the amount and quality of phe-
nolic antioxidants among dried and fresh fruits. Among seven
fruits studied (apricots, cranberries, dates (Deglet Noor and Za-
hidi), figs, green grapes, and plums), it was observed that DF
contains the highest concentration of polyphenols among the
dried fruits. It was also demonstrated that the total phenolic
content in fresh DF was six times higher than the dried ones
(Vinson et al., 2005). Moreover, some of the varieties of DF
have much higher total phenolic content than many fruits and
vegetables consumed in the US (Vinson et al., 1998; Wu et al.,
2004). Extremely high levels of phenolics in dates are consid-
ered to be due to greater exposure to extreme temperatures and
sunlight compared to other fruits (Vinson et al., 2005).
Phenolic Acids in Date Fruit
In DF, the phenolic acids occur largely as benzoic or cinnamic
acid derivatives (Fig. 3). Phenolic acids like other phenolics are
thought to help in plant defense against variety of pests and
pathogens. Based on the available data (Al-Farsi et al., 2005a),
DF may be considered a phenolic acid rich fruit (Table 2) when
compared with other fruits and berries (Mattila et al., 2006).
Experimental studies on the presence of phenolic compounds
as browning substrates in DF dates back to the early 1960s.
During the studies on enzymic browning substrates in DF,
Maier et al. (1964) isolated a new crystalline compound, which
they named dactyliferic acid and elucidated its structure as 3-
o-Caffeoylshikimic acid (Maier and Metzler 1963). Detailed
phenolic profile in DF was first published in the late 80s by
Regnault-Roger et al. (1987). They identified several phenolic
acids by reversed phase high performance liquid chromatogra-
phy and were further confirmed by thin-layer chromatography.
They identified gallic acid, protocatechuic, p-hydroxybenzoic,
syringic, vanillic, caffeic, p-coumaric, and ferulic acids as ma-
jor phenolic acids in DF. In addition to these phenolic acids,
recent studies demonstrated the presence of sinapic acid, 5-
o-caffeoylshikimic acid and its three isomers, xantoxylin, hy-
drocaffeic acid, and coumaroylquinic acid in seven varieties of
ripe Algerian DF (Mansouri, et al., 2005). According to Duke’s
ethnopharmacological database, DF also contain chlorogenic
and isochlorogenic acid (Duke 2001; Duke and Beckstrom-
Sternberg, Accessed 2007).
In another recent study, the amount of individual phenolic
acids present in the free and bound fractions of fresh and sun-
dried Omani dates was quantified by HPLC (Al-Farsi et al.,
Figure 3 Phenolic acids identified in date fruits.
254 P. K. VAYALIL
Tab le 2 Composition of phenolic acids in free and bound phenolic fractions
in fresh and sundried date fruits in certain varieties of date fruits cultivated in
Oman
Bound Free
Phenolic acid (mg/100g) Fresh Dried Fresh Dried
Gallic nd - 0.5 nd - 3.1
Protocatechuic nd - 4.5 nd - 8.3 nd nd - 2.0
p-hydroxybenzoic nd - 0.5 nd
Vanillic nd nd - 2.3 1.5 - 2.1 2.18 - 4.1
Caffeic nd - 10.1 nd - 7.6
Syringic nd - 1.7 nd - 3.2 nd - 5.5 nd - 6.0
p-coumaric 0.49 - 6.3 1.4 - 14.19
Ferulic 2.1 - 12.3 6.1 - 13.28 1.2 - 4.7 1.8 - 5.1
o-coumaric nd - 1.46 nd - 6.71
Total 6.84 - 30.25 14.18 - 49.67 2.61 - 12.3 6.1 - 14.8
nd =not detectable. The values are given as a range from minimum to maximum
quantified in different date fruits. Modified from (Al-Farsi et al., 2005a)
2005a). Depending on the fruit variety and extent of hydration,
the quantity of individual phenolic acids present in the DF varied
(Table 2). They showed that phenolic acids increase upon drying
probably due to degradation of complex, high molecular weight
polymers such as tannins (Al-Farsi et al., 2005a; Al-Farsi and
Lee, 2008).
Flavonoids in Date Fruit
Flavonoids present in DF have been revealed recently
(Fig. 4). It include proanthocynidines especially procynidines,
flavanoid glycosides (Tom´
as Lorente and Ferreres, 1988; Gu
et al., 2003; Mansouri et al., 2005; Hong et al., 2006) and an-
thocyanins (Al-Farsi et al., 2005a). Gu et al. demonstrated that
Deglet Noor contain proanthocynidines of type B consisting ex-
clusively of (epi) catechin while in Medjool proanthocynidines
were not detected. Mansouri et al. (2005) indicated the presence
of flavonoid glycosides in many Algerian dates. A detailed
characterization of flavanoid composition in DF (Deglet Noor
at Khalal stage) was performed by Mitchell’s group using liquid
chromatography-Electrospray ionization-tandem mass spec-
trometry (LC-ESI-MS/MS) (Hong et al., 2006). They identified
that procynidines in dates are homogeneous B type oligomers
and these oligomers were identified through decamers. Higher
molecular weight polymers were also documented and were
composed mainly of undecamers through heptadecamers.
Moreover, in this study, nineteen flavonoid glycosides of
luteolin, quercetin, and apigenin were also identified together
with their isomeric forms. Luteolin, quercetin, and apigenin
glycosides also exist as methylated and sulfated forms in DF.
The presence of sulfated forms of flavanol glycosides in dates
is exceptional and is not detected in other fruits and vegetables
(Hong et al., 2006). The presence of sulfated and non-sulfated
forms of luteolin, quercetin, chrysoeriol, and isorhamnetin
glycosides in dates were also indicated in an earlier study
(Tom´
as Lorente and Ferreres, 1988).
Anthocyanins
Another flavonoid that is found in DF in low amounts is the
anthocyanins. Anthocyanins were extensively studied in many
fruits and vegetables due to their antioxidant properties and
potential as natural colors. It was reported that anthocyanins
were undetectable in dried dates (Al-Farsi et al., 2005a). How-
ever, in fresh dates, depending on the variety, it ranged from
0.24–1.52 mg/cyanidin 3-glucoside equivalents/ 100 g (Al-Farsi
Figure 4 Flavonoids identified in date fruits.
DATE FRUITS: AN EMERGING MEDICINAL FOOD 255
et al., 2005a). Therefore, DF may not be a good source of an-
thocyanins compared with other fruits and vegetables.
Phytoestrogens
Phytoestrogens are a group of biologically active plant com-
pounds with a chemical structure similar to that of estradiol.
These compounds have the ability to bind to estrogen receptors
and exert various estrogenic or antiestrogenic effects. There are
three major classes of phytoestrogens—isoflavones, coumes-
tans, and lignans that occur in plants, their fruits, or seeds.
Although DF were well known for their high phenolic content,
only recently it was revealed (Thompson et al., 2006) to contain
phytoesterogens (Fig. 5). Some of the phytoestrogens quantified
in dried dates are given in Table 3. It is very interesting to note
that among the several fruits tested, DF rank the highest in con-
taining phytoestrogens (Thompson et al., 2006). Although very
complex, detailed quantitative analysis on the different classes
of phytoestrogens present in different forms and varieties of DF
at different stages of ripening remains unexplored.
NUTRITIONAL SIGNIFICANCE OF DATE FRUIT
The Second AICR and WCRF Expert Committee report
recommended that individuals should meet nutritional needs
through diet alone and not through dietary supplements for can-
cer prevention (Anonymous 2007). This recommendation may
be also applicable to the prevention of other chronic diseases as
well. Being a staple food, DF has provided nutrition to millions
of people around the world for thousands of years. Therefore,
it is worthwhile to analyze its nutritional significance as a food
Figure 5 Phytoestrogens identified in date fruits. 1 =Matairesinol; 2 =Lariciresinol; 3 =Pinoresinol; 4 =Secoisolariciresinol; 5 =Coumesterol.
256 P. K. VAYALIL
Tab le 3 Phytoesterogens identified and quantified in Date fruits
Fruits
Phytoestrogen
(µg/100 g) Apple Dried Dates Oranges Blue Berries Cranberry
Formononetin 0.2 0.4 1.1 0.9 0.3
Daidzein 0.2 1.2 0.8 0.4 0.6
Genistein 1.6 3.4 0.5 0.7 6.1
Glycitein 0.1 0.2 0.0 0.2 0.1
Matairesinol 0.4 0.3 1.8 0.7 0.3
Lariciresinol 1.4 116.9 9.2 2.0 0.9
Pinoresinol 0.8 100.2 3.1 4.1 0.9
Secoisolariciresinol 0.3 106.2 2.5 8.4 25.6
Coumestrol 0.0 0.8 0.2 0.2 0.0
Total Isoflavones 2.1 5.1 2.4 2.1 7.2
Total Lignans 2.9 323.6 16.5 15.2 27.7
Tot al
Phytoestrogens
4.9 329.5 19.0 17.5 34.9
The numbers represented in bold are the highest value among the group.
Modified from (Thompson et al., 2006)
for regular consumption and a good source of nutritional com-
ponents for maintaining health and to prevent various diseases.
DF is remarkable for its high nutritive value and ranks very
high among fruits commonly consumed by humans. One can
in fact comprehend the nutritional value and significance of DF
by comparing with the nutritional composition of fruits com-
monly consumed and considered highly nutritious and healthy,
such as apples, grapes, and oranges, cranberries or blue berries
(Tables 4, 6, 7). These tables are modified from USDA National
Nutrient Database for Standard Reference, Release 20 (2007).
The nutritional composition of different varieties of dates culti-
vated in different parts of the world has been reviewed elsewhere
(Al-Shahib and Marshall 2003a; Al-Farsi and Lee, 2008). It is
evident from the tables that the DF contains many of the nutri-
ents 3–10 times more than the others do and may be considered
as one of the highly nutritious fruits available on earth for hu-
man consumption. Vinson et al. (2005) have indicated that fresh
dates have the best nutrient score among the fresh apricots,
cranberries, figs, green grapes, and plums.
Date Fruit: A Low Glycemic Index (GI) Diet
Carbohydrate foods when consumed in isoglucidic or isoen-
ergetic amounts have different glycemic potential and insuline-
mic response. Therefore, carbohydrates or carbohydrate foods
are classified based on their glycemic responses and is referred
to as the glycemic index (GI) and is a widely accepted measure
of the effect of carbohydrate foods on human health (Jenk-
ins et al., 1981; 2002). An extension of the GI concept is the
glycemic load (GL). The GL value incorporates the amount of
digestible carbohydrates in a serving in order to better gauge
the impact of a diet on postprandial glucose response (Wolever
et al., 1991). Based on GI, the diets are classified as low GI
(55 or less), medium GI (56–69), and high GI (70 or more) and
based on GL the diets are categorized into low GL (10 or less)
medium GL (11–19), and high GL (20 or more). Several studies
have demonstrated that high GI diet may have adverse health
consequences by increasing the risk of chronic diseases such as
cardiovascular disease (CVD), Type 2 diabetes, and obesity. A
high GI diet may increase the risk of chronic diseases through
the induction of hyperglycemia and hyperinsulinemia. Several
health benefits have been suggested for reducing the rate of car-
bohydrate absorption by means of a low GI diet. These include
reduced insulin demand, improved blood glucose control, and
reduced blood lipid levels and these factors are considered to
play major roles in the prevention or management of several
chronic diseases and probably certain cancers as well (Jenk-
ins et al., 1981; Wolever et al., 1991; Augustin et al., 2002;
Foster-Powell et al., 2002; Jenkins et al., 2002; Ludwig 2002;
Brand-Miller, 2003).
DF constitutes a very high-energy diet due to its high sugar
content (as high as 65–75% of the fruit weight). The predom-
inant sugars found in DF are simple reducing sugars like glu-
cose, fructose, (approximately equal amounts) and negligible
amounts of non-reducing sugar sucrose depending on the stage
of the fruit development and the date palm variety (Table 4).
Deglet Noor is an exception, where sucrose constitutes 38% of
the total carbohydrates present in the fruit, which is most likely
due to low invertase activity compared to other varieties. Duke’s
Ethnobotanical Database also indicates the presence of sorbitol
Tab le 4 A comparison of macro nutrient composition between date fruits and other fruits and berries consumed in United States
Components Units/100g Apple Dates, Deglet Noor Dates, Medjool Navel Oranges Blue Berries Cranberry
Energy kcal 52.00 282.00 277.00 49.00 57.00 46.00
Protein g 0.26 2.45 1.81 0.91 0.74 0.39
Total lipid (fat) g 0.17 0.39 0.15 0.15 0.33 0.13
Fiber, total dietary g 2.40 8.00 6.70 2.20 2.40 4.60
Sugars, total g 10.39 63.35 66.47 8.50 9.96 4.04
Sucrose g 2.07 23.84 0.53 4.28 0.11 0.13
Glucose (dextrose) g 2.43 19.87 33.68 1.97 4.88 3.28
Fructose g 5.90 19.56 31.95 2.25 4.97 0.63
Maltose g 0.00 0.12 0.30 0.00 0.00 0.00
Modified from USDA national Nutrient Database for Standard Reference, Release 21 accessed in September 2008. The numbers represented in bold are the highest
value among the group.
DATE FRUITS: AN EMERGING MEDICINAL FOOD 257
Tab le 5 A comparison between Glycemic Index and Glycemic load of Date fruits and commonly consumed fruits in United States
Fruits GI (glucose =100) Mean Available Carbohydrate (g) Serving Size (g/serving) GL
Apple (Raw) (6 Varieties) 28–44 38 13–16 120 4–6 (6)
Apricot (Raw) 57 57 9.0 120 5
Banana (Raw) (10 Varieties) 30–70 52 21–25 120 6–16 (12)
Dates, Khalas, sun-dried, vacuum-packed 36 41.1 55 14.8
Dates, Khalas, traditional dried, dark brown color 45 41.3 55 18.6
Dates, dried (Australia) 103 40.3 60 41.5
Grapes (Raw) (2 Varieties) 43–49 46 17–19 120 7–9 (8)
Orange (Raw) (6 Varieties) 31–51 42 10–11 120 3–6 (5)
Peaches (Raw) (2 Varieties) 28–56 42 8–13 120 4–5 (5)
Pear (raw) (4 Varieties) 33–42 38 8–13 120 3–4 (4)
Modified from GI Database, and Denyer and Dickinson, 2005; Foster-Powell et al., 2002; Krinsky, 1993.
in DF (Duke 2001; Duke and Beckstrom-Sternberg, Accessed
2007).
Few studies were conducted to test the GI of DF. However,
the calculated GI values are inconsistent and sometimes are
contradictory (Table 5). Perhaps the first study to estimate the
GI values of DF was carried out by Lock et al. (1988). In their
report, the GI of DF was shown to be 61.1 in pregnancy-related
diabetic patients. However, in this study, the DF variety, stage of
maturity of the fruit, type of date preparation, and the percentage
available carbohydrate in these dates are not certain. Moreover,
the methodology adopted in this study to determine the GI was
also questioned (Miller et al., 2002; 2003). International table
of GI/GL and GI/GL database reported that the GI of Australian
dried dates to be 103 (Krinsky, 1993; Foster-Powell et al., 2002;
Denyer and Dickinson, 2005). Miller et al. (2002) determined
the GI of three different varieties of DF in normal healthy
subjects. In this study they adopted the standard methodology
to estimate GI which was developed by Wolever et al. (1991)
and tested the GI of commercial dehydrated date forms of
khalas,barhi, and bo ma’an equivalent to 50 g of available
carbohydrate ( =67 g of date). They demonstrated that the GI
value ranged from 31–50 in normal subjects depending on the
variety. In another study, the same group has also shown that
different forms of Khalas date preparations consumed either
alone or as mixed meals in yogurt had low GI’s (ranging from
29–47) (Miller et al., 2003; Denyer and Dickinson, 2005). This
suggests that certain DF varieties are low GI food like apples
(GI ranges from 28–44), grapes (GI ranges from 25–49), and
oranges (GI ranges from 31–51) (Foster-Powell et al., 2002) and
is not affected by mixed meals. In contrast to these reports, ear-
lier studies on glycemic response of Khalas dates were reported
to have higher GI of 58 (Ahmed et al., 1991). However, in this
study, GI was estimated based on the isocaloric equivalence to
75 g of glucose, which is equal to 110 g of dates. Similarly, in
another study by Famuyiwa et al. (1992) oral glucose tolerance
test with 75 g dextrose and an oral DF tolerance test using
isocaloric amounts of semi-dried Sukkari dates were performed
in non-insulin-dependent diabetic patients (NIDDM) as well
as healthy volunteers. They documented GI value of 56 and
67 in healthy individuals and NIDDM patients, respectively.
More recently, GI of different varieties of dates from Oman
was reported to range from 47.6 to 57.7 (Ali et al., 2009).
Several factors influence the GI value of DF. It depends on
the type of component sugars (e.g., glucose, fructose, sucrose,
or sorbitol), the physical form of the carbohydrate (e.g., particle
size), the nature of the food item (fat, protein, and fiber content),
and the modification of the food (e.g., food processing, extend of
hydration) (Wolever et al., 1991; Augustin et al., 2002; Jenkins
et al., 2002). In addition, the above factors are dependent upon
the stage of fruit ripening. Consequently, to appreciate DF as a
low GI diet and use as a part of the regular diet for healthy people
and patients with chronic diseases, detailed and well-controlled
Tab le 6 A comparison of mineral content between date fruits and other fruits and berries consumed in the US
Minerals Units/100 g Apple Dates, Deglet Noor Dates, Medjool Navel Oranges Blue Berries Cranberry
Calcium, Ca mg 6.00 39.00 64.00 43.00 6.00 8.00
Iron, Fe mg 0.12 1.02 0.90 0.13 0.28 0.25
Magnesium, Mg mg 5.00 43.00 54.00 11.00 6.00 6.00
Phosphorus, P mg 11.00 62.00 62.00 23.00 12.00 13.00
Potassium, K mg 107.00 656.00 696.00 166.00 77.00 85.00
Sodium, Na mg 1.00 2.00 1.00 1.00 1.00 2.00
Zinc, Zn mg 0.04 0.29 0.44 0.08 0.16 0.10
Copper, Cu mg 0.03 0.21 0.36 0.04 0.06 0.06
Manganese, Mn mg 0.04 0.26 0.30 0.03 0.34 0.36
Fluoride, F µg3.30 0.00 0.00 0.00 0.00 0.00
Selenium, Se µg0.00 3.00 0.00 0.00 0.10 0.10
Modified from USDA National Nutrient Database for Standard Reference Release 21 accessed in 2008. The numbers represented in bold are the highest value
among the group.
258 P. K. VAYALIL
Tab le 7 A comparison of vitamin content in date fruits and fruits regularly consumed in the US
Vitamins Units/100 g Apple Dates, Deglet Noor Dates, Medjool Navel Oranges Blue Berries Cranberry
Vitamin C mg 4.60 0.40 0.00 59.10 9.70 13.30
Thiamin (B-1) mg 0.02 0.05 0.05 0.07 0.04 0.01
Riboflavin (B-2) mg 0.03 0.07 0.06 0.05 0.04 0.02
Niacin (B-3) mg 0.09 1.27 1.61 0.43 0.42 0.10
Pantothenic acid (B-5) mg 0.06 0.59 0.81 0.26 0.12 0.30
Pyridoxine (B-6) mg 0.04 0.17 0.25 0.08 0.05 0.06
Folate, total (B-9) µg3.00 19.00 15.00 34.00 6.00 1.00
Choline, total mg 3.40 6.30 9.90 8.40 6.00 5.50
Betaine mg 0.10 0.40 0.40 0.10 0.20 0.20
Vitamin A, IU IU 54.00 10.00 149.00 247.00 54.00 60.00
Vitamin K (phylloquinone) µg2.20 2.70 2.70 0.00 19.30 5.10
Modified from USDA National Nutrient Database for Standard Reference Release 21 accessed 2008. IU =International Unit. The numbers represented in bold
are the highest value among the group.
clinical studies must be conducted in both healthy volunteers
and patients after systematically considering all the influential
factors in such trials. Such studies would help to classify DF
that is more appropriate from those unsuitable for consumption.
Hitherto, based on the available evidence, it is apparent that
some of the DF varieties belong to low GI diet and may be
included as a part of daily diet for the general population and
possibly to patients with chronic diseases.
Date Fruit: Rich in Low GI Sugar Fructose
Fructose is a monosaccharide sweetener abundant in nature
especially in sources like fruits, vegetables, and berries. Fruc-
tose is a valuable traditional source of energy. Fructose has been
considered beneficial and promoted over the years for the dietary
or nutritional management of diabetes mellitus and insulin resis-
tant conditions (Watford, 2002). Consumption of fructose low-
ers the postprandial glucose compared with glucose, or glucose
containing carbohydrates (Shiota et al., 2002). Fructose may be
beneficial in diets for weight control because of its effects on ap-
petite, food choices, and non-insulin dependent/thermogenesis
(Tappy and Jequier 1993). Fructose preloads also may have ben-
efit on increasing performance during strenuous endurance ex-
Tab le 8 A comparison of antioxidant capacity of Date fruits and fruits
regularly consumed in the US
L-ORACFL H-ORACFL TAC
Fruit (µmol of TE/g) (µmol of TE/g) (µmol of TE/g)
Apples 0.05 0.41 22.1–42.322.1–42.7
Blackberry (n=4) 1.03 52.45 53.48
Blueberry 0.360.51 61.892.162.292.6
Cranberry (n=3) 2.00 92.56 94.56
Grapes 11.212.611.212.6
Orange, navel (n=8) 0.29 17.85 18.14
Deglet Noor (n=7) 0.32 38.63 38.95
Medjool (n=2) 0.27 23.60 23.87
Modified from (Wu et al., 2004). H-/L-OARCFL Hydrophylic -/Lipophilic-
oxygen radical absorbance capacity assay with fluorescein as the fluorescent
probe; TAC =Total antioxidant capacity; TE =Trolox equivalents.
ercise (Craig, 1993). On the contrary, fructose has been shown
to have adverse effects on the health (Le and Tappy, 2006).
However, most of these investigations, both in vivo and in vitro,
have been carried out in animal models using unphysiological
concentrations of purified fructose and in addition most stud-
ies conducted to date have not demonstrated adverse effects on
consuming moderate amounts of fructose (Watford, 2002).
More relevant to humans is the increase in plasma fructose
levels and its physiological effects after ingestion of fruit or a
mixed meal of whole foods, which have not been investigated
in detail. However, it is presumed that the increase in plasma
fructose after consumption of fruits would be negligible because
the fructose would be absorbed relatively slowly (Gaby, 2005).
The gradual release of fructose thus allows intestinal brush bor-
der and hepatic enzymes to metabolize and assimilate fructose
completely or almost completely. Therefore, fructose in fruits,
vegetables, and whole foods are considered to be of less con-
cern (Uusitupa, 1994; Gaby, 2005; Bantle, 2006) compared to
the consumption of purified fructose, sucrose, or other added
fructose in foods.
Fully ripened DF contains more than twice the amount of
fructose compared to any other commonly consumed fruits (Ta-
ble 4). Occurrence of high amounts of fructose in dates may
provide several beneficial effects on human health and delay
or prevent the development of chronic diseases. Studies have
shown that infusion of catalytic amounts of fructose into the por-
tal vein increases hepatic uptake of glucose by the induction of
hepatic glucokinase (Shiota et al., 2002; Watford, 2002). Small
quantities of fructose also increase carbon flux through glycogen
synthetase and stimulate glycogen synthesis (Van Schaftingen
and Davies, 1991; Shiota et al., 2002; Watford, 2002). Conse-
quently, it is likely that fructose present in dates, which may be
released in small to moderate amounts into the blood stream,
could behave catalytically to attenuate postprandial glycemia
considerably in both hyperglycemic patients and healthy indi-
viduals. Thus, the low GI value of DF may be attributed partly
to the high concentrations of fructose and it has been reported
that there exists an inverse correlation between fructose and
the GI Values of DFs (Ali et al., 2009). Moreover, it has been
clearly demonstrated that DF consumption had a blunted insulin
DATE FRUITS: AN EMERGING MEDICINAL FOOD 259
response in healthy volunteers compared to dextrose (Famuyiwa
et al., 1992) indicating a potential benefit in preventing the de-
velopment of chronic diseases.
Date Fruit: Richest Source of Dietary Minerals
Living organisms require several chemical elements other
than carbon, hydrogen, nitrogen, and oxygen, which are ubiq-
uitously present in common organic molecules. These essential
chemical elements are called dietary minerals. They are required
to maintain skeletal structure, perform many biochemical reac-
tions, and to support the cellular functions. Therefore, adequate
intake of these dietary elements is required for optimal growth
and maintenance of the human body. Based on the available
data, DF may be considered as the richest source of dietary min-
erals than any other fruit currently consumed by humans. The
mineral composition of a variety of DF have been published in
detail elsewhere (Ahmed et al., 1995; AlHooti et al., 1995; Al-
Warthan and AlSwaidan, 1995; Mohamed, 2000; Al-Farsi et al.,
2005b; Ismail et al., 2006; Sahari et al., 2007). Table 6 is a list of
minerals quantified in DF and other fruits regularly consumed
in the US. Several studies report variations in mineral content
across different varieties of DF’s (Ahmed et al., 1995; AlHooti
et al., 1995; Mohamed, 2000; Al-Shahib and Marshall, 2003a;
Al-Farsi et al., 2005b; Ismail et al., 2006; Sahari et al., 2007).
These variations may be due to the differences in geographical
location, mineral content in the soil, fertilizer composition, etc.
It was also reported that the amount of many of the minerals in
dates changes (20–50%) depending on the maturity of the dates
(Sawaya et al., 1982; 1983; AlHooti et al., 1995).
DF may be considered as the richest source of macrominerals
such as Ca, P, Mg, and K and microminerals such as Fe, Zn, Cu,
Mn, and Se compared to any other commonly consumed fruits
(Ahmed et al., 1995; AlHooti et al., 1995; Mohamed, 2000;
Al-Shahib and Marshall, 2003a; Al-Farsi et al., 2005b; Ismail
et al., 2006; Sahari et al., 2007). Table 6 clearly demonstrates
that dates cultivated in US contain 2 to 11-fold higher con-
centrations of certain minerals than other fruits or berries and
suggests the potential use of dates in many mineral deficiency
diseases.
Dates are recognized as a fruit with extremely high levels
of potassium and very low amounts of sodium. Five Deglet
Noor dates provide about 272 mg of potassium. According
to USDA National Nutrient Database for Standard Reference,
Release 20, dates rank the highest in potassium content among
the fruits or vegetables commonly consumed in the US. DF has
also been described as a major source of Fe among fruits and
berries (Ahmed et al., 1995; AlHooti et al., 1995; Mohamed,
2000; Al-Shahib and Marshall, 2003a; Al-Farsi et al., 2005b;
Ismail et al., 2006; Sahari et al., 2007). Based on the published
reports, some varieties of dates have been reported to contain Fe
ranging from 4–60% of RDA (Ahmed et al., 1995; Al-Shahib
and Marshall, 2003a). Duke’s ethnobotanical database reports
that dates contain 10–151 ppm (1.0–15 mg/ 100 g) of Fe
(Duke, 2001; Duke and Beckstrom-Sternberg, Accessed 2007).
Another important microelement present in high concentration
in dates is Zn. In the Medjool variety the amount of Zn is about
2–11 times higher than the fruits that are regularly consumed
in the US. A more remarkable nutritional significance of
dates is the presence of high levels of selenium, which is
deficient in many of the fruits consumed by Americans.
According to USDA, Deglet Noor contains 3.0 µg/ 100 g of
dates (1.2 µg in 5 dates). However, in certain date varieties,
it has been documented to contain 100–300 µg of Se in 100
g of dates (Al-Shahib and Marshall 2003a; Al-Farsi et al.,
2005b).
In addition to the minerals listed in Table 6, it has been re-
ported that certain varieties of dates cultivated in the Middle
East contain fluorine (0.1–0.2 mg/ 100 g), cobalt (0.8–1.0 mg.
100 g), boron (3.3–5.6 mg/ 100 g) (Alwarthan et al., 1993;
Al-Shahib and Marshall, 2003a), and chromium (0.01 mg/ 100
g) (Al-Farsi et al., 2005b). Moreover, Duke’s ethnobotanical
database reports that DF contains 0.06 ppm (6.0 µg/ 100 g) of
iodine (Duke 2001; Duke and Beckstrom-Sternberg, Accessed
2007). Meanwhile, in the literature, analysis of iodine in dif-
ferent date varieties at different edible maturities has not been
reported. If the iodine levels are found similar to be higher
than Duke’s estimates, then, DF may be considered as one of
the richest sources of iodine among fruits. Therefore, a fur-
ther detailed analysis is required to elucidate the concentration
of iodine in different varieties of dates at different levels of
maturity.
Date Fruit: A Good Source of Vitamins
Vitamins are essential for the normal growth and develop-
ment of an organism. Although required only in tiny amounts,
vitamins have diverse biochemical functions. They function as
hormones, antioxidants, cell signaling mediators, and regula-
tors of cell growth and differentiation. Many vitamins, espe-
cially B complex vitamins, functions as coenzymes of variety
of enzyme reactions. Table 7 is a list of vitamins present in DF
(Deglet Noor,Medjool) and other common fruits published by
the USDA National Nutrient Database for Standard Reference,
Release 21. The concentration of vitamins presents in other date
varieties grown in other parts of the world have been reviewed
elsewhere (Al-Shahib and Marshall, 2003a; Ahmed et al., 2008).
Many vitamins are found in higher concentration in DF than the
fruits consumed in the US. They include B complex vitamins
such as thiamine (B1), riboflavin (B2), niacin (B3), pantothenic
acid (B5), B6, and folate B9and vitamin K. According to the
USDA nutrient database, Vitamin C content is found to be very
low in Medjool and Deglet Noor dates. However, in certain va-
rieties of DF, vitamin C concentration ranges from 1.0 mg to 16
mg/100 g of DF (Sawaya et al., 1982; Yousif et al., 1982).
Choline and its metabolite betaine are grouped under vi-
tamin B is also found in higher amounts in DF. Choline is
needed for structural integrity of cell membranes, cholinergic
260 P. K. VAYALIL
neurotransmission (acetylcholine synthesis), and as a major
source for methyl groups. Betaine is utilized as an osmolyte
and source of methyl groups and thereby helps to maintain
liver, heart, and kidney health. Therefore, DF may be consid-
ered as a good source of many vitamins compared to fruits that
are regularly consumed by Americans.
Date Fruit: A fiber Rich Diet
Dietary fiber is defined as the indigestible dietary compo-
nents of the plant materials such as polysaccharide components
of the cell wall. These components are divided into water-soluble
(pectin and hydrocolloids) and -insoluble (cellulose, hemicellu-
lose, and lignin) dietary fiber. Dietary fiber plays an important
role in human health as low intake of dietary fiber has been
linked to several diseases in the industrialized nations. Table 4
shows the amount of total fiber present in DF and fruits com-
monly consumed in the US. It is apparent that DF contains
more than twice the amount of dietary fiber than any other
fruits.
Analysis of fiber content in different varieties of dates has
been published (Lund et al., 1983; Elzoghbi, 1994; AlHooti
et al., 1995; Al-Shahib and Marshall, 2002; Al-Farsi et al.,
2005b; Elleuch et al., 2008) and reviewed elsewhere (Al-Shahib
and Marshall, 2003a; Al-Farsi and Lee 2008). Based on the
published reports, the total fiber content varied from 1.7–11.4%
(w/w) depending on the fruit variety and method of analysis
(Al-Shahib and Marshall, 2003a). However, in a recent study
(Elleuch et al., 2008) Deglet Noor and Allig cultivars were ana-
lyzed and the total dietary fiber content was reported as 14.4%
and 18.4% of the dry matter respectively. The insoluble dietary
fiber in Deglet Noor and Allig cultivars constituted 9.19% and
11.7% of dry matter and soluble dietary fiber constituted 5.16%
and 6.68% of dry matter respectively. In the same study, it was
also demonstrated that dietary fiber concentrates have a high
water- and oil-holding capacity. Al-Farsi et al. (2005b) reported
that certain DF’s grown in Oman had a total fiber content ranging
from 6.26–8.44 g/100 g. The insoluble dietary fiber constituted
the major fraction and was about 5.9–7.4 g/100 g and soluble
form was about 0.37–1.3 g/ 100 g.
HEALTH BENEFITS OF DATE FRUIT
In Indian traditional medicine, Ayurveda, and Middle Eastern
folk-lore, DF is considered to have several medicinal properties.
Dates have been considered to be a general tonic in Ayurveda
(Puri, 2003). DF is a demulcent, expectorant, nutrient, emetic,
laxative, aphrodisiac and prescribed for tuberculosis, gastroen-
teritis, coughs, respiratory diseases, asthma, etc. (Puri, 2003).
A recent ethnopharmacological survey reports that in certain
regions of Morocco DF is widely used in folk-lore to treat dia-
betes and hypertension (Tahraoui et al., 2007). As dates are rich
in sugars, the major concern among the health professionals and
public is whether DF consumption increases the risk of chronic
diseases in normal population. However, a growing number of
reports and nutritional facts on DF imply that such concerns are
unwarranted, at least for certain varieties, and may be used as
a part of the regular diet for healthy people and presumably for
the patients with chronic diseases as well.
Date Fruit has Strong Antioxidant Activity
Fruits are very popular as a source of antioxidants. Although,
several fruits have been studied extensively for their in vitro and
in vivo antioxidant activity, only recently has the scientific com-
munity admired the antioxidant property of DF. We first reported
in late 2001 that aqueous extract of DF flesh has potent free rad-
ical scavenging activity (Vayalil 2002). We demonstrated that
water extract of fresh DF is a strong scavenger of reactive oxy-
gen species like superoxide (O) and hydroxyl (OH) radicals.
The same extract also showed a strong inhibitory effect on in
vitro macromolecular damages such as lipid peroxidation and
protein oxidation. Since then, several studies have demonstrated
potential antioxidant activity in different varieties of DF culti-
vated in different parts of the world including those cultivated in
the US. Some investigators have also demonstrated high antiox-
idant capacity of DF using specific fractions isolated from DF.
Vinson et al. (2005) have demonstrated that the concentration of
extracts required to prevent LDL +VLDL oxidation with cupric
ions (1/IC50)bydriedDeglet Noor and Zahidi dates was about
2.17, which is five times higher than the antioxidant vitamins
such as Vitamin C and E.
The free radical scavenging capacity of different solvent
extracts of Deglet Noor and Alig were tested recently using
1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging as-
say (Chaira et al., 2007). They have demonstrated that 100 µg
of ethyl acetate extract of Deglet Noor inhibited 54% DPPH
radical formation, which is thought to be due to high levels of
flavonoids and tannins present in ethyl acetate extract. However,
extracts from the Alig variety did not scavenge DPPH radicals
at the same concentration. In another study, it has been shown
that for certain varieties of Algerian ripe DF, the efficient con-
centration to scavenge free radicals ranged from 4.5 to 12.7 µg
by DPPH method (Mansouri et al., 2005). In this study, Deglet
Noor as well as Tantbouchte varities were shown to have the
highest antioxidant activity and it correlated well with the phe-
nolic content in the fruits. In a more recent study, Ranilla et al.
(2008) have shown that date fruit sugar has the highest antiox-
idant activity among several carbohydrate sweeteners using the
DPPH method which was directly related to the phenolic con-
tent in the sugars. Medjool and Hallawi DF were also tested for
DPPH radical scavenging activity. Both forms of DF’s inhibited
DPPH radical by 44% and 39% at a concentration of 10 µg/mL
(Rock et al., 2009).
The antioxidant capacity of DF has been evaluated in vitro
by different methods.
DATE FRUITS: AN EMERGING MEDICINAL FOOD 261
Trolox Equivalent Antioxidant capacity (TEAC): Reaction
between ABTS (2, 24-azonobis (3-ethylbenzothiazoline-6-
sulphonic acid) metmyoglobin and H2O2.
Cook et al. (1998) used Trolox assay (TEAC) to estimate the
antioxidant content of edible wild plants in Niger including DF.
However, dates were categorized as a fruit with the least antiox-
idant content. This may be due to the loss of active components
during their prolonged extraction process as well as the type
of fruit (e.g., post-harvest processing) which is not mentioned
in their study. The antioxidant content of some Iranian DF was
also measured by the TEAC method. They estimated it to range
from 22.83–41.17, 47.6–54.61, and 500.33 µmol Trolox equiv-
alents/100 g dry weights for soft dates, semi-dry dates, and dry
dates, respectively (Biglari et al., 2008).
Oxygen Radical Absorbance Capacity (ORAC): Radicals
generated by thermal decomposition of AAPH (2, 2’-azobis
(2-amidino-propane) dihydrochloride) were monitored using
phycoerythrin by fluorometry.
Wu et al. (2004) studied the lipophilic and hydrophilic antioxi-
dant capacities of a variety of food items commonly consumed
in the US including two varieties of dried DFs using the ORAC
method. In this study they have shown that the total antioxi-
dant capacity of dried Deglet Noor was about 38.95 and that of
Medjool was 23.87 µmol of Trolox equivalent/g. The antiox-
idant capacity of fresh and dried date varieties of Oman was
compared using the OARC method. Fresh date varieties, such
as Far d,Khasab, and Khalas were found to be a good source of
antioxidants (11687–20604 µmol of Trolox equiv/g). Similarly,
DF lost significant amounts of antioxidant activity on drying
which ranged from 8212 to 12543 µmol of Trolox equiv/g (Al-
Farsi et al., 2005a).
Ferric-Reducing Ability of Plasma (FRAP): Ferric to fer-
rous ion reduction at low pH causes a colored ferrous-
tripyridyltriazine complex to form.
A systematic assessment of antioxidant capacity of plant
foods has been published using FRAP. According to this study
DF from the US has an antioxidant capacity of 1.06 mmol/100
g (Halvorsen et al., 2002). In another study, the antioxidant ca-
pacities of peel, pulp, and seed fractions of 28 fruits consumed
in China including DF were determined by FRAP assay. The
total FRAP values of DF pulp and peal were shown to be 23.69
mmol/100 g wet weight (Guo et al., 2003). The antioxidant ca-
pacity by FRAP was also assessed for Medjool and Hallawi and
has shown that Hallawi has 24% higher activity than Medjool
(Rock et al., 2009).
Fruits of sixteen date varieties commonly grown in Bahrain
were evaluated for their antioxidant capacity using FRAP assay.
The highest total antioxidant activity was found at biser (un-
ripe) stage (5.71 ±4.31 mmol/ 100 g fresh weight), followed
by rutab (1.2 mmol per 100 g) and tamer (0.94 ±0.21 mmol per
100 g). Total antioxidant activities of locally collected and im-
ported tamer were found to be similar (Abdul Ameer, 2008).
Free radical quenching activity of DF extract has also been
demonstrated in cell culture system. Aqueous extract of DF in-
hibited H2O2-induced cell damage and apoptosis in a concentra-
tion dependent manner in HEPG-2, A172, U937, and PC12 cell
lines suggesting a potent activity against free radical induced
cell death (Asadi-Shekaari et al., 2008).
Although many studies have been published on the antioxi-
dant activity of DF in vitro, only recently was the antioxidant
activity of different DF extracts demonstrated in vivo. It has been
demonstrated that methanolic and water extract of DF flesh sig-
nificantly enhanced the serum antioxidant status by increasing
vitamin C, E, β-carotene, and retinol as well as reduced serum
malondialdehyde levels in rat Freund’s adjuvant arthritis model
(Mohamed and Al-Okbi, 2004). As DF was an an efficient an-
tioxidant in vitro and in animal studies, it may be expected that
DF consumption would have a potent antioxidant activity in
humans as well (Rock et al., 2009).
The antioxidant activity has been correlated with the
polyphenolic content of DF in a couple of studies. It has been
shown that the date sugar had the highest amount of polyphe-
nolics and highest antioxidant activity than other carbohydrate
sweeteners used in the US (Ranilla et al., 2008). Significant
correlation between the antioxidant activity and total phenolic
content at biser (unripe) stage has been reported and phenolics
were suggested to be the major contributor to the antioxidant
activity of dates (Abdul Ameer, 2008). Similarly, correlation
between efficient free radical inhibitory concentrations, antirad-
ical efficiencies, and total phenolic contents of different Algeria
DF’s has been studied (Mansouri et al., 2005). They obtained
a strong correlation between phenolic content and antioxidant
activity in all the seven DFs studied.
Date Fruit: A Potential Medical Nutritional Therapy for the
Prevention and Control of Diabetes Mellitus
As DF is rich in sugar, its consumption is a great concern
among the diabetic patients and health providers in regions
where it is the dietary staple. However, in traditional medicine
practiced in the Middle East and northern Africa, dates have
been used for the treatment of diabetes (Tahraoui et al., 2007).
Currently, we have some evidence to support this ancient wis-
dom. The first evidence has been already discussed elsewhere in
this review that some of the date varieties are low or medium GI
diet like any other fruits. In the studies with NIDDM and preg-
nancy related diabetic patients, dates are found to be medium
GI diet (Lock et al., 1988; Famuyiwa et al., 1992) even though
the experiment was conducted at higher carbohydrate intake
(75 g).
Few studies have been conducted to test the glucose
tolerance with dates in healthy subjects. Ahmed et al. (1991)
demonstrated that incremental area under the curve (IAUC)
after DF meal (khalas) was significantly lower than glucose
262 P. K. VAYALIL
as well as Saudi combo meal (DF meal and Saudi breakfast).
Moreover, insulin and C-peptide levels were also lower after the
date meal compared to glucose or combo meal (Ahmed, 1998).
Simultaneously, another study was published in which they
determined the acute glycemic and insulin response to dates
in diabetic and non-diabetic subjects (Famuyiwa et al., 1992).
They demonstrated that consumption of isocaloric amounts
of sukkari dates (Tama r stage) by well-controlled NIDDM
patients induced significantly lower glucose levels. The IAUC
for glucose following date consumption was significantly
lower than that for dextrose. IAUC for insulin in patients after
dextrose and DF consumption did not change significantly.
More interestingly, in healthy volunteers, the stimulation of
insulin secretion after DF consumption was 2.7 times less than
dextrose. These preliminary studies indicate that DF does not
adversely affect the glucose tolerance in healthy people and at
the same time it is too early to suggest that DF ingestion would
benefit or adversely affect the control of diabetes in patients.
Ranilla et al. (2008) have demonstrated that date sugars
are phenol rich, potent antioxidant, and strong inhibitor of α-
glycosidase, and α-amylase. Among the several sugars tested,
date sugar has been shown to have the highest activity and is
directly related to the total phenolics present and inhibitory ac-
tivity against DPPH radical formation. α-Glucosidase inhibitors
are widely used for the control of blood glucose level in type
II of diabetes. α-Amylase is also considered a potent drug tar-
get for the development of anti-diabetic drugs. α-Glucosidase
inhibitors block the membrane-bound intestinal α-glucosidases
that hydrolyze oligosaccharides, trisaccharides, and disaccha-
rides to glucose in the small intestine. Salivary and pancreatic
α-amylase inhibitors block hydrolysis of complex starches to
oligosaccharides. Inhibition of these enzyme systems reduces
the rate of digestion of carbohydrates and as a result, less glu-
cose is absorbed into the circulation.
In most varieties of DF, the major sugars present are glucose
and fructose which do not require enzyme systems to digest and
can be readily absorbed into the circulation. However, in Deglet
Noor, in addition to glucose (31%) and fructose (31%), about
38% of the total sugar is sucrose. As DF exerts significant in-
hibitory activity on carbohydrate digestive enzymes, it may be
speculated that much of the sucrose present in Deglet Noor ex-
its the digestive tract without being digested and absorbed into
the circulation. Deglet Noor might be a better choice to con-
trol blood glucose and could expect a lower GI than other date
varieties that contain no sucrose at all. Moreover, it may also
reduce the digestion of other carbohydrates consumed along
with DF and reduce glucose absorption and level in the blood.
This would help to lower the GI of a high GI diet and utilize
high GI food items in a more beneficial way. Presently, there
are only few preliminary studies to show this effect. Ahmed
et al., 1991 demonstrated that a combo meal of dates and Saudi
breakfast had an intermediate GI between dates and Saudi break-
fast alone (Ahmed, 1998) and Miller et al. (2003) showed that
a mixed meal of dates and yogurt had a lower GI than dates
alone.
Numerous studies have demonstrated abnormalities in the
micronutrient status of patients with DM and some studies in-
dicated that deficiency in certain minerals was correlated with
the presence of diabetic complications. Therefore, micronutri-
ents have been investigated as potential preventive and treatment
strategies for both Type 1 and Type 2 diabetes and for common
complications of diabetes. DF is rich in minerals involved in glu-
cose metabolism (Table 6) and may be potentially beneficial for
the prevention of diabetes. These minerals include Mg, which
is essential for energy-dependent transport systems, glycolysis,
oxidative energy metabolism, and release of insulin, Zn which
is intimately involved in insulin synthesis, secretion, and signal-
ing, Cr which enhances insulin action, and Mn and Cu, which are
found to alter glucose homeostasis when deficient (Reviewed in
Mooradian and Morley, 1987). An important mineral is Se which
has been shown to have insulin-mimetic action (Mooradian and
Morley, 1987; Stapleton, 2000). It stimulates glucose uptake,
regulate glycolysis, gluconeogenesis, fatty acid synthesis, and
pentose phosphate pathway. Therefore, regular consumption of
DF would maintain physiological levels of these minerals in the
body and may prevent the development of diabetes in the healthy
population as well as the progression or control of diabetes in
patients who are deficient in these minerals.
Diabetes is characterized by increased oxidative stress due
to hyperglycemia that leads to micro- and macrovascular com-
plications. Therefore, use of antioxidants is considered to be
preventive and a treatment strategy for diabetes alone or in com-
bination with other treatment strategies (Dembinska-Kiec et al.,
2008). As mentioned above, DF has strong antioxidant activity.
The antioxidant effect of dates is attributed to mainly the phe-
nolic compounds as well as carotenoids present in it. They have
been shown to inhibit ROS production by inhibiting several ROS
producing enzymes and by chelating trace metals and inhibiting
phospholipases A2 and C (Manach et al., 2005). Several studies
have demonstrated significant decrease of α- and γ-tocopherol,
β- and α-carotene, lycopene, β-cryptoxanthin, lutein, zeaxan-
thin, retinol, as well as ascorbic acid in the course of diabetes
(Polidori et al., 2000). DF contains significant amounts of many
of these antioxidants and its consumption would restore the
antioxidant capacity of the body. DF may also enhance the en-
dogenous antioxidant enzyme activity by providing metal ions
in the form of dietary minerals such as Se, Zn, Mg, etc., that
function as cofactors in many antioxidant enzymes.
In a recent study it was reported that oral consumption of
fructose elevates plasma urate levels and increases the plasma
antioxidant capacity in humans without an increase in plasma
ascorbate (Lotito and Frei, 2004; 2006). This increase in urate
levels has been correlated with an increase in antioxidant capac-
ity after consumption of flavanoid rich fruit like apple, which
contains reasonably high amounts of fructose (Lotito and Frei,
2004; 2006). It may be possible that consumption of fructose rich
DF will increase plasma antioxidant capacity by transiently in-
creasing the plasma urate levels. The increase in plasma antioxi-
dant capacities would thus attenuate the deleterious effects of re-
ducing sugars on the cellular macromolecules, such as glycation
DATE FRUITS: AN EMERGING MEDICINAL FOOD 263
of proteins, lipid oxidation, etc. However, further experimenta-
tions in this direction are required to clarify this notion.
Evidence is also emerging that dietary phytoestrogens play
a beneficial role in diabetes. Isoflavones and lignans appear
to act through various mechanisms that modulate pancreatic
insulin secretion or through antioxidative actions. They may
also act via estrogen receptor-mediated mechanisms (Bha-
thena and Velasquez, 2002). Recently it has been shown that
genistein and daidzein play important roles in the regulation
of glucose homeostasis in type 1 diabetic mice by down-
regulating glucose-6-phosphatase, phosphoenolpyruvate car-
boxykinase, fatty acid beta-oxidation and carnitine palmitoyl-
transferase activities, while up-regulating malic enzyme and
glucose-6-phosphate dehydrogenase activities in liver and pre-
serving pancreatic β-cells (Choi et al., 2008). Genistein and
daidzein also improve plasma triglyceride and free fatty acid
concentrations. It may be presumed that high amounts of phy-
toesterogens contained in DF may potentially help to maintain
normal glucose metabolism in both healthy populations as well
as in diabetic patients.
Another potential factor that may help to prevent the devel-
opment of diabetes or its progression is the dietary fiber, which
is present in large amounts in DF compared to any other com-
monly consumed fruits. Therefore, consumption of DF rich in
dietary fiber would contribute to a number of metabolic effects,
which include improvement of insulin sensitivity, modulation
of the secretion of certain gut hormones, and effects on various
metabolic and inflammatory markers that are associated with
the metabolic syndrome (Weickert and Pfeiffer, 2008).
Date Fruit: A Potential Medical Nutritional Therapy for
Cardio- and Cerebro-Vascular Diseases
The phytochemical and nutritional composition of DF and
some of the preliminary experimental evidence clearly identify
the potential use of DF against cardio- and cerebro-vascular
diseases (CCVD). DF may play a significant role in block-
ing the events that occur during the initiation and progres-
sion of (CCVD) primarily by reducing hypertension, hyperc-
holesterolemia, and oxidation of lipoproteins, enhancing serum
antioxidant status, alleviating the harmful effects of oxidative
stress and probably inflammation on the vascular system.
Hypertension is a major risk factor for the development of
cardio- and cerebro-vascular diseases. Although the cause of hy-
pertension is still unknown, it has been demonstrated clinically
that lowering hypertension by different means could signifi-
cantly reduce the development, progression, and mortality due
to the diseases such as stroke or heart diseases (Pinto et al.,
2004). DF has been used for centuries as an anti-hypertensive
food and medicine in eastern Africa as well as in the Middle
East. However, only recently the beneficial health effects of DF
have been demonstrated at least in some in vitro and animal ex-
periments. Furthermore, based on the nutritional composition,
DF may also have potential protective effects on many of the
conditions that lead to hypertension.
Renin-angiotensin system is an important regulatory mech-
anism that governs blood pressure in the human body. Renin is
released by the kidney in response to hypotension, decreased
sodium concentration in the distal tubule, decreased blood vol-
ume or renal sympathetic nerve stimulation. Renin cleaves the
liver-derived angiotensinogen into angiotensin I. Angiotensin I
is then converted to angiotensin II by the angiotensin-converting
enzyme (ACE) in the pulmonary circulation as well as in the
endothelium of blood vessels in many parts of the body. Thus,
blocking the formation of angiotensin II through ACE inhibition
is an important treatment strategy to reduce blood pressure and
many ACE inhibitory agents are currently being used to treat
hypertension. In a recent study, DF sugars have been reported to
have potent ACE inhibitory activity. The total phenolic content
and antioxidant activity was found to be proportional to the ACE
inhibitory activity of DF and also the inhibition of ACE strongly
correlated with the α-amylase and α-glucosidase inhibitory ac-
tivities. Among the palm sugars tested DF sugar had the highest
ACE inhibitory activity. ACE inhibitory activity of leaf extracts
of other date palm species has also been demonstrated (Braga
et al., 2007).
Dietary minerals play an important role in maintaining the
blood pressure. High sodium together with a low potassium in-
take causes a rise in blood pressure and increases the risk of
cardio- and cerebro-vascular disease, renal disease, and bone
demineralization (Macdonald and Struthers 2004; He and Mac-
Gregor 2008). Sodium retention decreases the synthesis of nitric
oxide, an arteriolar vasodilator, and increases the plasma level
of dimethyl-L-arginine, an endogenous inhibitor of nitric oxide
production (Fujiwara et al., 2000). Evidence from epidemio-
logical studies, animal experiments, and treatment trials has
shown that an increase in potassium intake has beneficial ef-
fects on human health. The best way of increasing potassium
intake is to increase the consumption of fruit and vegetables,
which in itself have other beneficial effects on health (antiox-
idants, folic acid, other minerals like Mg, Ca, etc.) indepen-
dent of potassium intake (He and MacGregor, 2008). A diet
rich in potassium increases in serum potassium as well, even
within the physiologic range, causing endothelium-dependent
vasodilatation by hyperpolarizing the endothelial cell through
stimulation of the sodium pump and opening potassium chan-
nels (Haddy et al., 2006). DF is an excellent dietary source of
potassium with very low sodium content. Consumption of ten
dates would provide more than 700 mg of potassium which
corresponds to 15–20% of daily RDA/AI. Regular consump-
tion of DF would thus provide sufficient amounts of potas-
sium needed to maintain the electrolyte balance within the body
and may prevent the development and progression of hyper-
tension. Other major elements that have been shown to protect
from hypertension are Mg and Ca. These two minerals occur
in DF at very high concentrations. Magnesium may lower BP
by acting like a natural calcium channel blocker. Magnesium
is also a cofactor for the -6-desaturase enzyme, which is the
264 P. K. VAYALIL
rate-limiting step for the conversion of linoleic acid, a precursor
of prostaglandin E. Prostaglandin is a vasodilator and platelet
inhibitor. Magnesium also regulates blood pressure by regulat-
ing intracellular calcium, sodium, potassium, and pH as well as
left ventricular mass, insulin sensitivity, and arterial compliance.
Calcium works in combination with other ions such as sodium,
potassium, and magnesium to provide an ionic balance to the
vascular membrane, vasodilatation, and resulting reduced BP.
Hypercholesterolemia is a major risk factor for the develop-
ment of CCVD. Recently, hypocholesterolemic effects of DF
has been reported (Alsaif et al., 2007). In this study, hamsters
were fed with chow alone or chow with 1% cholesterol supple-
mented with and without date pulp (1:1 w/w). Supplementation
of DF to high cholesterol fed hamsters significantly reduced
cholesterol-induced increases in the organ weights, total plasma
cholesterol, triglycerides and LDL cholesterol levels, and ele-
vated HDL cholesterol in the plasma. Feeding dates alone did not
affect the organ weights or plasma or tissue lipid levels. This
study thus suggests that DF supplementation may potentially
modulate cholesterol absorption or metabolism and prevent the
onset of atherosclerosis and coronary heart disease (CHD).
There may be several mechanisms to explain the hypocholes-
terolemic effects of DF. First, DF contains very low amounts of
fat. Second, as DF is a fiber rich diet, it may have significant
hypocholesterolemic activity by three potential mechanisms: a)
dietary fiber reduces the absorption of cholesterol and reab-
sorption of bile acids in the intestinal lumen, b) dietary fiber
is associated with reduced insulin secretion because of its low
glycemic effect on blood glucose, and c) fermentation of di-
etary fiber produces a series of short-chain fatty acids that may
inhibit hepatic cholesterol biosynthesis. Third, the phytochem-
icals such as phytosterols and phytoestrogens present in DF
might significantly reduce hypercholesterolemia. They also in-
hibit intestinal cholesterol absorption by displacing cholesterol
from micellar binding and thereby lowering the cholesterol lev-
els (John et al., 2007). β-sitosterol inhibits cholesterol synthesis
by inhibiting HMG-CoA reductase gene expression (Field et al.,
1997). The pronounced cholesterol lowering effect of stigmas-
terol has been demonstrated in animals (Batta et al., 2006) and
sitosterol in humans (Temme et al., 2002). Many phytoestro-
gens that are found in DF have also been shown to be hypoc-
holestrolemic. Ovariectomized rats fed with the isolated pure
isoflavone glucosides of daidzin or glycitin showed significantly
lesser plasma total cholesterol and triglyceride concentrations
compared with casein-fed rats (Uesugi et al., 2001). Plasma
triglyceride was significantly reduced in Sprague–Dawley rats
fed a mixture of synthetic daidzein and genistein compared with
those fed with casein (Demonty et al., 2002). Hamsters fed pure
synthetic daidzein had lower plasma total cholesterol and non-
HDL cholesterol compared with those fed casein alone (Song
et al., 2003).
Oxidized low-density lipoproteins appear to play a signif-
icant role in atherogenesis. In fact, circulating oxidized LDL
concentrations have been recognized as a risk factor for car-
diovascular disease. Dietary factors could be associated with a
lower risk of CVD through a reduction of the atherogenicity of
LDL particles through limited oxidation. In addition to several
reports demonstrating the antioxidant and free radical scaveng-
ing activity of dates and its fractions, Vinson et al. (2005) have
demonstrated that DF polyphenols are strong inhibitors of LDL-
VLDL oxidation in vitro.
Elevation of homocysteine is implicated in multiple medi-
cal conditions, including classical homocystinuria, a variety of
remethylation disorders, and most recently in coronary artery
disease. The biggest threat to the life and health of patients with
classical homocystinuria is vascular or thromboembolic com-
plications. Betaine is a methyl donor agent that is beneficial in
lowering homocysteine through the remethylation of methion-
ine. Betaine therapy alone has been shown to prevent vascular
events in homocystinuria and may have clinical benefits in other
hyperhomocysteinemic disorders when used as adjunctive ther-
apy. As DF is rich in betaine and choline, it may be helpful in
reducing or preventing vascular complication due to improper
homocysteine metabolism.
Date Fruit: A Potential Cancer Preventive Diet
Experimental evidence and the phytochemical composition
suggest that DF may have potential health benefits against many
types of cancers. Despite high importance of DF in the human
diet, only a few studies have been reported elucidating the po-
tential cancer preventive activity. The first link to the potential
cancer preventive effects of DF was reported by Mills et al.
(1989) in a cohort study of diet, lifestyle, and prostate cancer
risk of approximately 14,000 Seventh-day Adventist men. In
this study they found during the 6-year follow-up period that in-
creased consumption of beans, lentils and peas, tomatoes, raisin,
dates, and other dried fruit were all associated with significantly
decreased prostate cancer risk. Moreover, the decreased risk
of prostate cancer was not related to exposure to vegetarian
lifestyle during the childhood suggesting the potential use of
dates in the prevention of prostate cancer. However, no further
experimental studies were performed yet to clarify the potential
of DF as a prostate cancer chemopreventive agent.
We first provided the experimental evidence for the chemo-
preventive activity of DF against chemical carcinogens by
demonstrating its antimutagenic activity in Salmonella tester
strains (Vayalil, 2002). We showed that fresh aqueous extract of
DF inhibited benzo(a)pyrene (B (a)p)-induced mutagenicity in
Salmonella tester strains TA-98 and TA-100 in a dose-dependent
manner. The concentrations of fresh extract required for 50%
inhibition of formation of His+colonies in TA 98 and A 100
were 3.6 mg and 4.3 mg/plate, respectively. The antimutagenic
activities of the DF extract may be related to their antioxi-
dant properties. It also appears that the extract may function
as an antimutagen in the B(a)p assay by preventing the cy-
tochrome P-450 enzyme-system-mediated metabolic activation
of the pro-mutagen to its mutagenic form. This was further sup-
ported by the observation that the date fruit pulp did not inhibit
DATE FRUITS: AN EMERGING MEDICINAL FOOD 265
mutagenesis induced by direct acting mutagens (does not require
metabolic activation to become mutagenic) such as sodium azide
with TA 100 tester strain (unpublished data).
Excessive production of reactive oxygen species and other
reactive radical species generated from toxic chemicals may
lead to the formation of highly reactive oxidation products and
activation of carcinogens that may lead to genetic aberrations
and cancer. Therefore, antioxidants are considered as potent
chemopreventive agents. Like many other fruits, DF also has
strong antioxidant activity. DF can scavenge free radicals as
well as prevent oxidation of macromolecules which may in turn
block the various stages of carcinogenesis (Vayalil, 2002). DF
may have an in vivo antioxidant activity attributed to many
components present in DF that may either directly scavenge
the free radicals (vitamins and phytochemicals) or activate the
endogenous antioxidant defense system (phytochemicals) by
activating the genes of antioxidant enzymes or providing mineral
cofactors such as Mg, Mn, Zn, Cu, or Se or vitamins for their
optimal activity.
Dietary fibers can act as direct scavengers of exogenous
and endogenous mutagens. Dietary fibers are also supposed to
act as anti-mutagens in the intestinal tract by increasing fecal
mass through their water-binding capacity, therefore diluting
mutagen concentrations and increasing fecal transit time (Fer-
guson, 1994). Date fruits are rich is fiber compared to other
fruits commonly consumed by humans. Furthermore, water or
ethanolic extracts of DF has been demonstrated to increase
the gastrointestinal transit in mice from 4 to 24% in a dose-
dependent manner compared to the untreated control mice.
Although the mechanism of enhanced gastrointestinal transit
is unknown, it has been postulated to be contributed by the
dietary fiber present in DF (Al-Qarawi et al., 2003). There-
fore, being a fiber rich food and increase gastrointestinal tran-
sit, consumption of DF may offer cancer preventive activity
in vivo.
Recently, the antitumor activity of a glucan isolated from
DF has been tested on the allogenic solid Sarcoma-180 in mice
(Ishurd and Kennedy, 2005). DF glucans inhibited tumor growth
in a dose dependent manner, with an optimum activity at l.0
mg/kg. Moreover, significant antitumor activity occurred dur-
ing the later stages of tumor development suggesting an in-
direct mode of action of these glucans. The same group has
also demonstrated that prophylactic treatment of mice with DF
glucans eleven days prior to tumor inoculation had a similar ef-
fect as simultaneous administration of glucan with tumor cells.
Therefore, they postulated the potential involvement of immune
system in the anticancer activity of glucans.
Activation of the immune system is another approach for
cancer prevention. The immune system recognizes the aberrant
or transformed cells and eliminates them before they could es-
tablish a tumor colony. DF has been shown in mice to enhance
humoral and cellular immunity in mice (Puri et al., 2000). Seven
days of continuous treatment of DF extract stimulated the anti-
body titer and plaque forming cells by 3-fold which correlates
with humoral immunity, and macrophage migration index by
80% representing the cellular immunity, compared to untreated
control BALB/c mice.
In a recent study, treatment of DF has been shown to stim-
ulate significantly IFN-γmRNA expression in cells obtained
from Peyer’s patch compared to other dried fruits such as prune
or figs. Administration of DF extract to mice specifically stim-
ulated IFN-γCD4+cells, IFN-γCD49b+and IL-12+CD11b+
cells in the spleen which represent Th1 immune response. There-
fore, it has been proposed to be an effective immunomodula-
tor and that these effects are attributed to the polyphenols and
polysaccharides present in DF (Karasawa et al. 2011).
DF contains many phytochemical compounds that have been
shown to have significant chemopreventive and anticancer activ-
ity. These components include phytoesterogens such as genis-
tein, glycitein, daidzein; phenolic acids such as gallic and fer-
ulic acids; and other polyphenolic compounds including tannins,
anthocyanins, flavonoids, phytosterols, etc. A variety of mech-
anisms have been identified that relate to the cancer preventive
and anticancer properties of these phytochemicals and have been
reviewed extensively (Surh, 2003). Therefore, being a staple diet
and consumed by the people on a daily basis, it may be specu-
lated that DF would have potential cancer preventive properties
and have great potential as a medicinal food for the prevention
of cancer that needs extensive testing in the laboratory.
Date Fruit: A Potent Medicinal Food against Bacterial
and Fungal Infections
The decoction of DF or DF in combination with other herbs
has been used in the folk-lore to treat bronchitis, cough, and
other infections. The antimicrobial effect of DF can be explained
based on the in vitro and in vivo data available in the scientific lit-
erature. DF has been to shown to have direct antibacterial effects
on Bacillus subtilis,Staphylococcus aureus,Salmonella typhi,
and Pseudomonas aeruginosa (Sallal and Ashkenani, 1989). A
20% Barhi date variety extract inhibited the growth of these
bacteria almost completely in the nutrient growth medium. DF
extracts also inhibited B. subtilis spore germination almost com-
pletely suggesting the presence of components with potential
antibacterial effect.
The effect of date DF extracts on Streptococcus pyogenes
was also studied both in vivo and in vitro. It was found that in-
cubation with date fruit extract effectively inhibited the growth
of S.pyogenes. DF also neutralized the hemolytic activity of the
streptococcal exotoxin, streptolysin O. The erythrocytes taken
from DF fed volunteers showed resistance to hemolytic activ-
ity of streptolysin O; however, date intake did not affect the
titer of antistreptolysin O antibodies. It was suggested that the
inhibitory substance may be steroidal in nature and the neu-
tralization property occurs through erythrocyte membrane sta-
bilization and inhibition of streptolysin O enzyme.
DF extracts also have been demonstrated to induce direct
antifungal activity in vitro (Sallal et al., 1996; Shraideh et al.,
1998). Addition of 5% DF extract inhibited the growth and
266 P. K. VAYALIL
germ-tube formation and caused extensive leakage of cytoplas-
mic contents from Candida albicans in culture. This inhibitory
effect has been demonstrated to be comparable to that of the
known antifungal drugs. Further ultrastructural studies demon-
strated that DF extract damages the integrity of cell membranes
and induces aggregation of the cytoplasmic contents and de-
tachment of plasmalemma from the cell wall (Shraideh et al.,
1998).
To establish the use of DF for the control of Candida infec-
tions, the adherence of three Candida species to human buccal
epithelial cells (BEC) following treatment with date extract as
well as the effect of a mouth rinse with date extract on the ad-
hesion of yeast to BEC was studied (Abu-Elteen, 2000). All
the Candida species tested had a significantly low adherence to
BEC after both short- and long-term periods of yeast exposure
to various concentrations of date extract. Pre-incubation of BEC
with date extract also produced similar inhibition of adherence
of Candida. Moreover, the adherence of yeast to BEC was sig-
nificantly reduced when BEC’s were collected immediately or
5–20 min after an oral rinse with 10% date extract.
Although several active components in DF have been iden-
tified, the components that mediate direct antimicrobial effects
unknown. Both currently known and unidentified phytochemi-
cals present in DF may be involved in the anti-microbial activity.
Another potential mechanism that contributes to the prevention
of infection in humans may be the immunostimulatory activ-
ity of DF (Puri et al., 2000). As described above, DF extracts
stimulate both humoral and cellular immunity in mice that may
potentially help to protect against various infections and be use-
ful for the prophylactic treatment of infections.
Other Potential Health Benefits
Date fruits have also been reported to have several other
health benefits. However, these studies are preliminary and re-
quire further investigations, both experimental and clinical, to
further validate its effects and derive the mechanism of actions
of date fruits.
Laxative
The laxative property of DF has been demonstrated by quan-
tifying their effect on gastrointestinal transit in mice. Compared
with the control, the animals that received DF extracts emptied
more of their gastrointestinal content which ranged from 4 to
22% (Al-Qarawi et al., 2003).
Antiinflamatory Activity in Adjuvant Arthritis Model
The antiinflammatory potential of DF was demonstrated
quite recently (Mohamed and Al-Okbi, 2004). It has been
demonstrated that oral administration of methanolic or aqueous
extracts of edible portion of DFs suppressed the inflammation in
the foot induced by the adjuvant. Moreover, DF administration
reduced ESR and plasma fibrinogen that was elevated after ad-
juvant administration. Administration of DF extracts produced
significant increase in body weight gain and food efficiency ratio
compared to the adjuvant treated controls.
Protective Effects against Chemical Induced Toxicity
Recently, the effect of extract of the flesh of DF was in-
vestigated on gentamicin-induced nephrotoxicity in rats (Al-
Qarawi et al., 2008). Gentamycin treatment significantly ele-
vated plasma creatinine and urea and caused significant necro-
sis of the renal proximal tubules. DF extract (50% w/w) effec-
tively reduced plasma creatinine and urea levels and reduced
the extent of renal damage induced by gentamycin. Antioxi-
dants present in DF have been suggested to protect the animals
from gentamycin-induced nephrotoxicity.
The same group has also reported that DF extracts ameliorate
CCl4–induced hepatotoxicity (Al-Qarawi et al., 2004). They
showed that DF extracts reduced hepatotoxicity by demonstrat-
ing significant reduction in aspartate aminotransferase (AST),
alanine aminotransferase (ALT), alkaline phosphatase (ALP),
and bilirubin concentration after CCl4administration compared
to its DF untreated controls. The ameliorative activity of aqueous
extract of the flesh of dates on thioacetamide-induced hepato-
toxicity was also studied in rats. Treatment with aqueous extract
of date flesh significantly reduced liver cirrhosis by demonstrat-
ing significant reduction in thioacetamide-induced elevation in
plasma bilirubin AST, ALT, lactate dehydrogenase (LDH), γ
glutamyl transferase (GGT), and ALP (Ahmed et al., 2008).
Neuro-Protective Effects
Recently, the neuro-protective effect of aqueous extract of
DF in rats has been investigated. Pretreatment of the animals
with DF at a dose of 250 mg/kg significantly decreased neural
death of CA1 hippocampal neurons induced by focal cerebral
ischemia compared to the control group (Majid et al., 2008).
Anti-Ulcer Effect
DF was also tested for its beneficial effects in a rat model
of ethanol-induced gastric ulceration. Aqueous and ethanolic
extracts of DF ameliorated the severity of gastric ulceration
and decreased ethanol-induced plasma gastrin levels and the
concentrations of histamine and mucin in gastric mucosa (Al-
Qarawi et al., 2005).
Date Fruit for Deficiency Diseases
Diets in developing countries generally lack many nutrients,
including energy due to inadequate intake of food. Mineral and
vitamin deficiencies are also very common in the developing
world due to reduced intake or lack of a nutritious diet. From
the nutritional point of view, DF is an energy rich food and a
source of a variety of nutrients that are essential to maintain
DATE FRUITS: AN EMERGING MEDICINAL FOOD 267
human health. Consumption of DF would contribute signifi-
cantly to the daily requirement of many of these components
such as carbohydrates and minerals (Fe, Mg, Ca, Zn, P, Cu,
Se, I, etc.) and a reasonable source of vitamins (niacin, B6,
folate, etc). Therefore, daily consumption DF may be a good
alternative for the treatment of deficiency related diseases such
as anemia, goiter, rickets, osteomalacia, etc. Moreover, DF will
be a nutritional therapy for osteoporosis, arthritis, and other
diseases related to bone metabolism, multiple sclerosis, cancer,
cataracts, age spots, etc., by supplementing minerals such as Ca,
Cu, Se, P, etc., for the body’s needs.
HEALTH BENEFITS OF DATE FRUITS IN HUMAN
SUBJECTS
In vitro and animal studies on the antioxidant activity and
anti-hypocholesterolemic effect of DFs have been further sub-
stantiated in healthy subjects in an interesting study by Rock
et al. (2009). They have shown that in human subjects a con-
sumption of 100 g/day of DF, Hallawi or Medjool, for 4-weeks
did not alter their body mass index, glucose or total cholesterol,
VLDL, LDL, or HDL levels in the serum. However, serum
triacylglycerol and VLDL was significantly reduced after con-
sumption of DFs. They have also shown that Hallawi dates
reduced the oxidative stress by 33% as measured by different
methods. This was further supported by elevation of antioxidant
enzymes in the serum such as paraoxonase 1 arylesterase.
CONCLUSION
Based on the available evidence from the literature, we are
beginning to learn and admire the potential health benefits of
DF. DF is a fruit of high nutrient value compared to any other
fruits commonly consumed by man. Even though DF is a sugar
packed fruit (dried or fresh), consumption of certain varieties
of DF’s do not induce any metabolic and inflammatory markers
that are associated with metabolic syndrome and related diseases
and the effect is comparable to that of other fruits. This refutes
the misconception that dates are similar to candies and its daily
consumption would develop chronic diseases. However, further
animal and clinical research in these areas would confirm and
promote DF as a potential nutritional therapeutic diet for infants,
adults, and patients with metabolic syndrome and against the
development of related diseases such as diabetes, CHD, stroke,
etc.
DF is not only beneficial to the people of industrialized na-
tions but, many qualities associated with DF also make them
an appropriate food source for the people living in the poverty-
stricken parts of the world. First, DF is comparatively inexpen-
sive to produce and store, because, unlike other fruits, it can
be stored for months after harvest without further preservation.
Second, it is an energy-rich food containing high concentra-
tions of carbohydrates and several essential nutrients (miner-
als, amino acids, and vitamins) required to maintain human
health. Moreover, DF is considered as a staple food like wheat,
rice, etc., which are mainly consumed to meet the daily en-
ergy requirement. Accordingly, DF consumption may serve as
a single food source providing the benefits of both fruit and
cereals to meet the daily nutritional requirements. Therefore,
DF consumption would be a good alternative for the malnour-
ished infants and adults for their basic nutritional requirements
and to fight against deficiency related diseases and infections
which is an endemic in the poor nations of the world. There-
fore, DF may be considered as a gift of nature to the people
not only living in the hot arid regions but also other parts of the
world for general nutrition and a potential emerging medicinal
food.
ACKNOWLEDGMENT
The author acknowledges Mark B. Cope for critical reading,
for valuable suggestions, and for editing the manuscript.
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... Dates too possess numerous medicinal abilities such as anti-bacterial, anti-fungal, anti-tumor, anti-ulcer, and immuno-modulatory possessions. An action of antioxidant about Date palm cultivars has been credited to phenolic mixes [5,12,13,14]. Traditional harvesting techniques and processing of dates were observed in the studied area. Farmers are not given advancement, awareness, and key attention from the stakeholders, policymakers, and non-governmental as well as governmental bodies. ...
... Dates are extremely nutritious food with innumerable health benefits. The fate of Dates as an emergent "healthy" food has been studied by several authors [12,18]. Seeds are the main waste of marketable handling. ...
... As a medicinal food [12] Flavonoid sulfates During maturing and large volume of procyanidin/tannin at khalal stage [51] 43 volatile compounds Noticed in Tunisian Dates at various maturity phases [52] Phenolic compounds (antioxidants) ...
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Background: Food processing is fundamental to extend the shelf-life of food products. During the processing, several parts of food are wasted. FAO indicated that about one-third of the world's food production for human consumption was lost or wasted, and food waste is an environmental, economic, and social problem. Fruits and vegetables are the food groups with the highest amount of food waste, both in food processing and in consumption stage. However, those by-products constitute a potential source of bioactive compounds, with powerful biological activities. Scope and Approach: This paper carries out a comprehensive review of the scientific literature, on the main active compounds of some fruits and vegetable by-products, their biological activities, and potential uses. This study highlights the importance of food safety assessment of by-products to ensure human health. Key Findings and Conclusions: The cherry, plum, date and artichoke by-products presented high antioxidant and antimicrobial activity, which makes them sustainable natural high-added value compounds to be reincorporated into the food supply chain, to improve functionality as well as to extend the shelf-life of food products, within the framework of the circular economy.
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Fruits of the date palm (Phoenix dactylifera L. Arecaceae) are consumed in many regions of the world. This fruit has been traditionally used as oriental folk medicine for mothers after childbirth and invalids. In the present study, the protective effect of aqueous extract of date fruit (AE-DF) against hydrogen peroxide H2O2- induced cytotoxicity in HEPG-2, A172, U937 and PC12 cell lines was investigated. Cytotoxic effects were evaluated by XTT assay. The total antioxidant capacity of AE-DF was measured using the Randox kit. In addition, the protective effects of AE-DF against H2O 2 - induced apoptosis was investigated using DAPI staining. The total antioxidant capacity of AE-DF was 1.97±0.04 mmol Trolox equivalent/l. The results demonstrated that AE-DF inhibits H2O2- induced cell damage in a concentration dependent manner. The 0.1% AE-DF significantly inhibited the 1.47mM H2O2- induced damage, especially in the A172 cells (p<0.05 to 0.001). Moreover, 10% AE-DF completely inhibited 29.4mMH2O2-induced damage. At the same time, the growth of U937 cells significantly increased in the presence of 10% AE-DF compared to the control cells (p<0.01). Cells treated with 2.94 mM H2O 2 exhibited several apoptotic features, while those simultaneously exposed with H2O2 and AE-DF showed the complete inhibition of apoptotic features. These results suggest that date fruit may exert protective and proliferative effects against H2O2 - induced cytotoxicity.
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Date crop is of great economic importance in Egypt. Fruits of the date palm (Phoenix dactylifera L. family Palmae) Zaghlool are very commonly consumed in Egypt. The objective of this study was to evaluate the antioxidant activity of methanolic, petroleum ether and water extracts of the edible portion (flesh part) and seeds of date fruit in-vitro. Proximate analysis of the dry edible portion was carried out. Vitamin E, β-carotene and total phenolic contents of the edible portion of the fruits were also determined. Total phenolic content was found to be 1461 mg of gallic acid equivalent/100 g dry weight. Antioxidant activity of the different extracts of the edible portion of fruit according to the β-carotene bleaching method ranged from 9.28% to 75.96%. Antioxidant activity of petroleum ether seeds extract was 8.16%, while methanolic and water extracts of seeds were devoid of any activity. The present study showed that the antioxidant activity of the edible portion might be attributed to the presence of phenolic compounds and α-tocopherol.
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Background: We have previously reported that contrary to the popular belief, ingestion of dates does not adversely affect glucose tolerance compared to an isocaloric Saudi breakfast in normal subjects. Objective: Since Saudi people customarily consume dates prior to major meals, we considered it important to study the metabolic impact of the ingestion of combination of dates and a Saudi breakfast (a "combo meal"), and to compare its effect to those of date meal (DM) alone, Saudi breakfast (SBF) alone and oral glucose tolerance test (OGTT). Methods: Nine subjects, 4 males and 5 females, aged 26.7 ± 0.8 years (mean ± SEM) with a body mass index of 22.4 ± 0.5 were fed in random order : (a) a DM consisting of approximately 300 calories (CHO 74.5g, protein 3.7g and fats 0.66g), (b) a SBF consisting of 300 calories (CHO 35.6g, protein 13.16g and fats 11.9g), (c) a 75g glucose solution (OGTT) and (d) a combination ("Combo meal") of DM and SBF as in (a) and (b) above on 4 different days at least one week apart. Plasma glucose (G), insulin (I) and C-peptide (C) values were determined at -30, 0, and then every 30 minutes for 180 minutes. Glycemic indices (GI) for DM, SBF and the "combo meal" also were determined. Results: G area profiles after the "combo meal" were significantly (P=0.02) lower than those of OGTT but did not differ when compared to DM or SBF. I and C profile areas were significantly greater (p<0.05) following the "combo meal" than those following either the DM or SBF but did not differ those of the OGTT. GI of the "combo meal" was 65 and fell in between that for the DM (59) and SBF (79). Conclusion: Despite ingestion of twice as many calories as those contained either in DM or SBF, the "combo meal" does not appear to adversely influence the glucose tolerance in normal subjects; however this is accompanied by relative hyperinsulinemia, the consequences of which remain to be ascertained.