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Potential Nutritional Benefits of Current Citrus Consumption

  • Physicians Association for Nutrition

Abstract and Figures

Citrus contains nutrients and phytochemicals that may be beneficial for health. We collected citrus production and consumption data and estimated the amount of these compounds that are consumed. We then compared the amounts of citrus and citrus-derived compounds used in studies that suggest a health benefit to the amounts typically found in citrus. Data is scarce, but suggests that citrus consumption might improve indices of antioxidant status, and possibly cardiovascular health and insulin sensitivity.
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Agriculture 2013, 3, 170-187; doi:10.3390/agriculture3010170
ISSN 2077-0472
Potential Nutritional Benefits of Current Citrus Consumption
Tami Turner 1 and Betty J. Burri 2,*
1 Department of Nutrition, University of California, Davis, One Shields Avenue, Davis, CA 95616,
USA; E-Mail:
2 Western Human Nutrition Research Center, ARS, USDA, 430 W Health Sciences Drive, Davis,
CA 95616, USA
* Author to whom correspondence should be addressed; E-Mail:;
Tel.: +1-530-752-4748; Fax: +1-530-752-4390.
Received: 30 November 2012; in revised form: 1 February 2013 / Accepted: 17 February 2013 /
Published: 19 March 2013
Abstract: Citrus contains nutrients and phytochemicals that may be beneficial for health.
We collected citrus production and consumption data and estimated the amount of these
compounds that are consumed. We then compared the amounts of citrus and citrus-derived
compounds used in studies that suggest a health benefit to the amounts typically found in
citrus. Data is scarce, but suggests that citrus consumption might improve indices of
antioxidant status, and possibly cardiovascular health and insulin sensitivity.
Keywords: citrus; vitamin C; vitamin A; carotenoid; flavonoid; limonoid; health; human
1. Introduction
Citrus is the largest genus in the family Rutaceae and is the most traded horticultural product in the
world [1]. Taxonomic identification is difficult because there are many spontaneous and commercial
hybrids, but citrus can be generally classified into the following categories: sweet oranges (most are C.
sinensis but also includes blood and acidless oranges), mandarins (such as Satsuma (C. unshi),
tangerines (C. tangerina, and reticulata), and clementines (C. clementine)), sour/bitter oranges (such as
Seville, C. aurantium), lemons (C. limon), limes (C. aurantifolia and latifolia), grapefruit (C. paradisi)
and pummelos (C. grandis), hybrids (e.g., tangelos, tangors, and limequats), and citrons (C. medica,
which has a rind that is used primarily for confectionary and is only commercially grown in limited
areas) [2].
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Diets rich in fruits and vegetables have been strongly associated with numerous health benefits and
lower risk of disease [3,4]. Citrus fruits contain a variety of vitamins, minerals, fiber, and
phytochemicals such as carotenoids, flavonoids, and limonoids, which appear to have biological
activities and health benefits. There is considerable evidence that citrus fruit have antioxidant and
antimutagenic properties and positive associations with bone, cardiovascular, and immune system
health [5].
2. Data Sources
Production and consumption data were used to estimate the amounts of nutrients and non-nutrient
components of citrus fruits that are consumed. Data for production and estimated consumption was
compiled from databases maintained by the U.S. Department of Agriculture (USDA) and the Food and
Agriculture Organization of the United Nations (FAO). U.S. data on the amount of nutrients in citrus
consumed/capita/day and the percentage of the total dietary nutrient intake from citrus was taken directly
from USDA data [6]. Nutrient and non-nutrient concentrations of citrus fruit were gathered from
published literature and from the USDA. Then nutrient concentration ranges reported in 100 g of citrus
were compared to the RDA or AI (based upon age and life stage) for that nutrient. We reviewed the
literature for health benefits of whole citrus fruits, for those nutrients and phytochemicals that are
derived primarily from citrus fruit or that are present in citrus varieties in high concentrations by
searching the electronic databases PubMed, Web of Science, and Agricola using keyword and phase
searches such as “citrus and health”, “citrus and cardiovas*”, “carotenoid and citrus”, “flavonoid and
citrus”, etc. The amounts of nutrients and phytochemicals typically reported in citrus fruit were
compared to the amount of citrus or citrus-derived nutrients used in studies that showed health benefits.
Barriers to citrus consumption and trends in the citrus industry were identified through online
government databases from the USDA Economic Research Service, National Agriculture Statistical
Service, and Economic Statistics and Market Information System, as well as from university extension
and citrus supplier websites.
3. Production and Consumption
In 2010, the production of citrus fruit worldwide was estimated as 122.5 million tonnes with
~8.7 million hectares harvested; oranges were 50%–62% of the total area harvested and total
production [7] (Figure 1). Worldwide, there has been a steady increase of estimated per capita
consumption of citrus over the last 30 years (Table 1). However, least developed countries located in
areas of Sub-Saharan Africa and Southeast Asia, which generally have the highest proportion of persons
with malnutrition and micronutrient deficiencies [8–10], also have the lowest consumption of citrus.
Despite the growth of the citrus industry in China [6,7], people in lower income countries of Africa and
Asia consume approximately one-fourth as much citrus as developed countries. In fact, populations in
least developed countries consume only 8 g/person/day, six times less than the world average. On the
other hand, with the high production of citrus in the U.S., Mexico, Brazil, and Spain it is not surprising
that North Americans have the highest estimated consumption/capita/day in the world followed by
South Americans and Europeans [11].
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Figure 1. World production of citrus by fruit type in 2010 [7].
Table 1. Estimated supply and consumption of citrus by region, per person per day, and the
percentage of citrus consumed that is oranges and mandarins 1979–2009 [11].
Region Item 1979 1989 1999 2009
World Total citrus supply tonnes 49,114,005 67,645,354 89,146,403 112,910,151
Total citrus g per capita/day 32 36 42 47
% of total that is oranges & mandarines 78 81 76 72
Least Total citrus supply tonnes 718,199 918,998 1,358,035 2,182,861
Developed Total citrus g per capita/day 6 6 7 8
Countries % of total that is oranges & mandarines 33 33 43 50
Africa Total citrus supply tonnes 4,371,141 5,955,141 8,312,179 10,988,040
Total citrus g per capita/day 26 28 31 32
% of total that is oranges & mandarines 50 54 52 50
Asia Total citrus supply tonnes 4,371,250 5,955,256 8,312,304 10,988,172
Total citrus g per capita/day 12 18 23 31
% of total that is oranges & mandarines 83 78 78 71
SE Asia Total citrus supply tonnes 991,627 1,695,364 3,008,770 4,947,774
Total citrus g per capita/day 7 10 16 24
% of total that is oranges & mandarines 100 100 81 83
Oceania Total citrus supply tonnes 515,315 569,112 547,564 548,025
Total citrus g per capita/day 73 71 60 52
% of total that is oranges & mandarines 84 86 90 88
Europe Total citrus supply tonnes 9,631,873 13,039,703 14,584,512 19,532,380
Total citrus g per capita/day 35 46 55 73
% of total that is oranges & mandarines 77 80 80 81
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Table 1. Cont.
Region Item 1979 1989 1999 2009
America Total citrus supply tonnes 13,292,610 14,506,257 14,141,748 13,928,358
Total citrus g per capita/day 144 143 125 112
% of total that is oranges & mandarines 81 81 82 79
America Total citrus supply tonnes 7,516,799 10,525,514 15,148,330 13,530,945
Total citrus g per capita/day 87 99 121 96
% of total that is oranges & mandarines 89 91 83 80
USA production (2011–2012) was 10.6 million tonnes, with 65% from Florida and 32% from
California. However, citrus production in the USA has been declining, apparently because of adverse
climate events such as hurricanes, freezes, and drought [12].
The types of citrus produced and consumed vary throughout the world (Table 1). About 80% of the
citrus grown are oranges and tangerines in most of the world, except for Africa (Table 1). The main
citrus crop produced in the USA is oranges, while Japanese consumers prefer tangerines. Most citrus are
produced in temperate climates, where they grow well. Harvest losses are moderate, at about 50% [6].
In the U.S., current consumption is estimated at 147 g/person/day, which is very high [13]. The total
estimated nutrients contributed by citrus/capita/day in the U.S. in 1970 and 2006 [6] are shown in
Table 2. In 2006, citrus contributed more of the dietary intake of all listed nutrients except fiber, which
was unchanged from 1970. Importantly, citrus provides about 25%–28% of vitamin C/capita/day.
However, citrus actually contributes a lower proportion of dietary carotenoids and folate in 2006 than in
1970. U.S. residents are now consuming more of these nutrients from other sources (e.g., fortified foods
or other fruits and vegetables). Currently, citrus contributes lesser but non-neglible amounts of vitamin
A (mostly derived from beta-cryptoxanthin), folate, fiber and carotenoids (Table 2).
Table 2. Total estimated nutrients contributed by current consumption of citrus and
estimated percentage of total dietary nutrients provided by citrus consumption/capita/day in
the U.S. in 1970 and 2006 [6].
Nutrient 1970 2006
Vitamin C
mg 26.4 32.8
% of dietary nutrients from citrus 24.9 27.6
Vitamin A
µg RAE 3.7 4.3
% of dietary nutrients from citrus 0.3 0.4
Folate (DFE)
µg 19.2 30.5
% of dietary nutrients from citrus 6.4 3.4
Dietary Fiber
g 0.6 0.6
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Table 2. Cont.
Nutrient 1970 2006
% of dietary nutrients from citrus 3.0 2.2
µg 7.7 8.2
% of dietary nutrients from citrus 1.5 1.2
4. Nutritional and Phytochemical Contents of Citrus
Citrus contains no fat, sodium or cholesterol. The average energy value of citrus is very low which
can be important for consumers concerned about obesity. Citrus contains large amounts of vitamin C and
appreciable amounts of carotenoids (some capable of converting to vitamin A), folate, and fiber. The
amount of selected nutrients are given in Table 3 along with the percentage of the recommended daily
allowance (RDA) or adequate intake (AI) [14] that is met when consuming 100 g of citrus fruit.
Table 3. The amount of nutrients and the percent of the recommended daily allowance or
adequate intake met from the consumption of 100 g of selected citrus fruit [15–18].
Vitamin C Vitamin A* Folate Fiber
Children under 9 y (%)
Persons 9+ y
Pregnant/lactating women
53–88 mg
17 µg
30 µg
2.4 g
Children under 9 y
Persons 9+ y
Pregnant/lactating women
31–61 mg
58 µg
13 µg
1.6 g
Children under 9 y
Persons 9+ y
Pregnant/lactating women
27–72 mg
46–144 µg
16 µg
1.8 g
Children under 9 y
Persons 9+ y
Pregnant/lactating women
29–61 mg
2–22 µg
11–16 µg
1.8–2.8 g
* assumes that 12 µg beta-carotene from food forms 1 µg vitamin A, and that 24 µg
beta-cryptoxanthin or alpha-carotene from food forms 1 µg vitamin A; percent of the recommended
intake met by consuming 100 g of food and is based upon the U.S. DRIs [14].
Of course, the nutritional and phytochemical contents of citrus vary widely depending upon growing
conditions, the variety of fruit, maturity, storage conditions, and on processing [5,19,20].
4.1. Vitamin C
Citrus is an excellent source of vitamin C. Most persons can achieve 100% of the RDA for vitamin C
by consuming moderate amounts of citrus fruit (Table 3). Vitamin C (ascorbic acid) is a water-soluble
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essential nutrient which acts as an antioxidant, is involved in iron metabolism, the biosynthesis of
carnitine, neurotransmitters, collagen and in the cross-linking of these fibers in bone, and is a cofactor in
various enzymatic and hormonal processes [14,21,22]. Vitamin C is also involved in the immune system
by stimulating white blood cell function [23]. Vitamin C can help reduce the risk of pre-eclampsia
during pregnancy [24], and in some studies vitamin C has been shown to lessen the severity and duration
of cold symptoms (reviewed in [23]). In vitro, ascorbic acid was observed to contribute 40%–54% of the
antioxidant potential of oranges, mandarins, and grapefruit [25].
Studies in humans have also provided strong evidence for the antioxidant properties of citrus.
Drinking 500 mL/day of orange juice for two weeks (~250 mg ascorbic acid/day) increased plasma
vitamin C concentrations by 40%–64% and reduced oxidative markers (8-epi-PGF2α) in adults, with a
more pronounced effect in smokers [26]. In another study, a 47% reduction in plasma lipid peroxidation
in healthy adults was observed from the consumption of 8 ounces (~236 mL) of orange juice (~70 mg
vitamin C) every day for two weeks [27]. These data show that rapid improvement of vitamin C and
antioxidant status can be achieved by consuming reasonable amounts of citrus. Vitamin C deficiency is
not typically considered a problem in the U.S. or Canada [14], since U.S. residents consume about
72–102 mg/day of vitamin C from food, or 101–245 mg/day when supplements are included [28].
However, the prevalence of deficiency in the U.S., measured by serum ascorbic acid and indicated by the
NHANES III (1984–1994) and NHANES (2003–2004) data, was ~9%–13% and ~7.1%,
respectively [29]. Smokers, those who abuse drugs and alcohol, and those with diets low in fruits and
vegetables are at higher risk of having low vitamin C [14]. Also, prevalence of mild vitamin C deficiency
worldwide is probably fairly high [9], and data from undernourished women in developing countries
indicates breast milk levels to be inadequate (25 µg/L whereas the AI is 50 µg/L) (taken from [30]).
Regular consumption of citrus can also improve breast milk concentrations. In a study by
Daneel-Otterbech et al. [31], three servings or orange juice (~100 mg vitamin C/serving) for six weeks
doubled milk vitamin C concentrations (1 serving/week had no significant effect). Furthermore, there is
supporting evidence that more than 200 mg/day of vitamin C may be optimal for maximum health
benefits [32], and citrus may be the best food source for increasing vitamin C intake.
4.2. Carotenoids and Vitamin A
Citrus contains many carotenoids. Carotenoids are terpenes (tetraterpenoids) and are yellow and
orange pigments found ubiquitously in plants; over 600 carotenoids have been identified and about 50
are present in the human diet [33,34]. The most abundant carotenoids in the human diet, lutein,
zeaxanthin, lycopene, and the pro-vitamin A carotenoids, α- and β-carotene and β-cryptoxanthin, are
found in fruits and vegetables. Many functions and health benefits of carotenoids have been described:
they are antioxidants, have positive effects on the immune system [33,35–37], promote bone formation
and health [38,39], stimulate gap junction communication between cells [40], promote eye
health [41,42], and lower the risk of cancer [43–45]. Much data support beneficial health effects of
ingesting carotenoids; however, the only well-established health benefit of carotenoids in humans is the
ability of several to form vitamin A [14].
According to NHANES data (2009–2010), most people in the U.S. are not consuming enough
vitamin A from food, and only a small proportion of vitamin A is consumed as carotenoids (~20%–35%
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of the RDA for vitamin A) [28]. Worldwide, vitamin A deficiency is estimated to affect 209 million
women and children and is the leading cause of preventable blindness [8]. On the other hand, high
intakes of vitamin A from supplements or liver have been associated with negative health effects
including diarrhea, nausea, vomiting, headaches, bone abnormalities and osteoporosis, liver damage,
hair loss, and possibly birth defects [46,47]. Consuming even very large amounts of pro-vitamin A
carotenoids from food is safe [14].
Carotenoids in fruit are dissolved in the chromoplast as opposed to being bound to proteins in the
chloroplasts of dark-leafy green vegetables, and considerable evidence supports fruit carotenoids having
higher bioavailability [48,49]. Tangerines in particular can provide a substantial amount of the
pro-vitamin A carotenoid, β-cryptoxanthin, a carotenoid that appears to be a highly bioavailable source
of vitamin A [50,51]. In a recent study of breastfeeding women with low vitamin A status, the
consumption of tangerines (254 g or ~ 5.3 g/day β-cryptoxanthin) for 18 days maintained vitamin A
concentrations in breast milk and increased plasma and milk β-cryptoxanthin [52]. These results suggest
that the vitamin A contributed by tangerines might be more than twice as much than assumed, such that
100 g of tangerine would meet as much as 72% of the recommended daily intake of vitamin A for
children. Furthermore, estimates of production and consumption of tangerines specifically demonstrate
the capacity to provide significant amounts of vitamin A to populations experiencing vitamin A
deficiency if β-cryptoxanthin-rich varieties are selected for production and consumption [53].
4.3. Folate
As a coenzyme, folate participates in converting deoxyuridylic acid to thymidylic acid, in the
production of purines (formation of glycinamide ribonucleotide and 5-amino-4-imidazole carboxamide
ribonucleotide), and the interconversion of many amino acids; thus, folate is necessary for DNA
production, is involved in homocysteine regulation, and protein production primarily via methylation
transfer reactions [14]. Because DNA production is high during pregnancy, lack of folate is associated
with birth defects such as neural tube defects [54]. Lack of folate is also implicated in higher
homocysteine concentrations, which increase the risk of atherosclerosis and heart disease [14]. Citrus
can be a complementary source of dietary folate and can provide up to 10% to 20% of the RDA for adults
and children less than 9 years of age, respectively, with just 100 g. A study on commercial orange juices
in Europe found that the folate was 100% bioavailable and highly stable [55], and, in another study, the
consumption of orange juice (750 mL) daily for four weeks increased plasma folate concentrations in
adults by 18% [56].
4.4. Fiber
Dietary fiber is the edible carbohydrate and lignin in plants that is not digested and absorbed in the
small intestine; fibers can promote laxation, satiety, reduce the uptake and/ or reabsorption of glucose,
fat, cholesterol, and bile acids thus reducing cardiovascular disease risk and possibly decreasing food
intake and promoting healthy intestinal fermentation [57,58]. The main fiber in citrus is pectin, a soluble
fiber, which makes up 65%–70% of the total fiber content [59]. Pectin is more completely fermented in
the gut by microflora than foods rich in cellulose like cereals and fermentation produces various
substrates including short-chain fatty acids that can be absorbed and provide energy [14,58]. There is
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conflicting data on whether fiber may interfere with the absorption of other nutrients; however, most
studies on pectin/ nutrition interactions did not show a decrease in nutrient bioavailability except when
large doses of pectin (12 g and 0.15 g/kg body weight) were concomitantly consumed [60,61]. Thus, it
has been concluded that a diet rich in dietary fiber will not cause adverse effects in healthy people [14].
The average U.S. adult consumes only ~57% of the RDA for fiber [28]. Because the RDA for fiber is
not being met by many adults and dietary fiber can reduce the risk of chronic diseases, citrus can make a
valuable contribution to meeting daily fiber goals. Lowering of cholesterol in particular by citrus,
however, may depend upon the amount, degree of esterification, molecular weight, and viscosity of the
fiber/pectin consumed [58,62] but may be significant with dietary intake that is achievable (2.2–9 g
pectin for 30 days) (in[57]).
4.5. Flavonoids and Limonoids
Flavonoids are polyphenolic compounds widely distributed in plants and are pigments responsible for
fruit and flower coloration [63] and involved in defense against UV radiation or aggression from
pathogens [64]. Flavonoids are divided into multiple classes of compounds such as flavones, flavanones,
isoflavones, flavonols, flavanols, flavan-3-ols (tannins, catechins), anthocyanidins, aurones, chalcones,
and coumarins [65–67]. Citrus is the major source of flavanones from food [65]; the most predominant
and widely studied flavanones in citrus are hesperetin (aka hesperidin) (predominant in oranges) and
naringenin (predominant in grapefruit) [63,67,68]. Of the edible parts, the membranous segments of
citrus fruit have the highest content of many bioactive compounds making high-pulp juices more
recommended for consumption [5]. Although the peels and seeds are often discarded, they generally
have different flavonoid composition than the edible fruit [63] making citrus byproducts a good source
of flavonoid extracts. Furthermore, the peels and seeds can contain the highest amounts of flavonoids;
for example the albedo (pith) of an orange can have up to five times higher flavanone content than
orange juice [64].
The health benefits of citrus flavonoids have been generally studied using individual extracted
compounds instead of whole foods, but these studies have had promising results. Flavonoids extracted
from citrus have been shown to act as antioxidants and anti-inflammatory agents, to reduce cholesterol
and triglycerides [69,70], and improve bone health [70,71] in experimental animals.
Their effects in humans are more controversial, because there is large intra- and inter-variability in
absorption, metabolism, and reported effects of flavonoids. Furthermore, the solubility of flavonoids is
often low and effected by microbiota in the gut [67,72,73]. Thus, the amount of flavanones from whole
citrus fruits may be very different than those that have beneficial effects in studies of animal models
using extracts. Nevertheless, in a study in adults with metabolic syndrome, the consumption of 500 mg
hesperitin/day as a supplement for three weeks resulted in improved brachial artery flow-mediated
dilation and reduced markers of inflammation (C-reactive protein, serum amyloid A protein, soluble
E-selectin) [74]; for comparison 236 mL (~ 8 oz) of orange juice contains ~39–62 mg of hesperitin [66].
Observational data indicate that dietary intake of flavanones (primarily hesperitin) is estimated at 15.4 to
69.54 mg/day in people from European countries (EPIC study) [75] and 17 to 24 mg flavonoids/day in
people from Finland [76], the UK [77], and the U.S. [78]. Higher intakes of flavonoids found in citrus
were associated with lower cardiovascular disease risk, asthma [76], and higher bone mineral
Agriculture 2013, 3 178
density [77]. Although observational evidence may be correlating health benefits to increased fruit and
vegetable intake rather than specifically to flavonoid intake, the data from cell culture, animal studies,
and limited human studies that associate citrus flavanones to positive health outcomes is encouraging.
The bitter taste in citrus can be attributed to limonoids. Limonoids are terpenes and occur only in
plants of the Rutaceae (citrus) and Meliaceae (neem, mahogany) families [79]. The most abundant
limonoids in citrus are glycosides of limonin and nomilin [79,80]. Citrus can contain 150–300 mg of
limonoids in 100 g of fruit whereas the peels and flesh solids can contain 500 mg per 100 g fruit. In
animal and human cell lines, limonoids have been shown to help reduce or inhibit proliferation of cancer
of the pancreas, stomach, colon, and breast; in animal studies, limonoids also reduced skin
tumors [81–83]. There is evidence of antiviral and antibacterial, properties of limonoids [84–86]. Most
studies on limonoids have used extracted compounds rather than citrus as a whole food making
translation of the dose used in cell culture and animal studies to intake in humans difficult; however,
with high concentrations of limonoids in citrus, it may be highly participatory in providing the health
benefits described.
5. Evidence of Health Benefits of Whole Citrus Fruits
The data on individual compounds contained in citrus shows that these can be related to antioxidant
activity and health outcomes such as diabetes [87,88]. However, much of the data can be difficult to
place in context of whole foods. Although many of the nutrients and phytochemicals found in citrus may
exert positive health outcomes, the combination of these compounds in a whole fruit may have
synergistic or antagonistic effects. Evidence is building that citrus fruits as whole foods, not just
extracted individual compounds, may provide a plethora of health benefits. In an in vitro comparison
study of common fruit, lemons exerted very high antioxidant and antiproliferative activities; lemons and
grapefruit also decreased proliferation of human liver cancer cells in a dose-dependent manner [89]. In
humans, the antioxidant effects of orange juice have been observed with as little as 8 ounces (236 mL)
consumed for two weeks [27]. Even in the presence of a high-fat diet or high-fat/ carbohydrate meal,
orange juice (containing either 500 mg of vitamin C or 300 kcal (probably ~630 mL) reduced the acute
effects of oxidative and inflammatory stress [90,91].
Evidence for improved cardiovascular health biomarkers and insulin sensitivity have also been
observed in some but not all studies consuming citrus. In obese children, consumption of mandarin juice
(500 mL/day for 1 month) reduced biomarkers of oxidative stress, increased antioxidants (vitamin E, C,
and glutathione), reduced blood pressure, and lowered insulin or improved insulin resistance
homoeostasis [92]. In hypercholesterolemic adults, 750 mL, but not 250 or 500 mL, of orange juice daily
for four weeks increased HDL and decreased LDL/HDL ratios as well as increased plasma folate and
vitamin C concentrations [56]. However, mildly hypercholesterolemic adults consuming a moderate
volume of orange juice (480 mL/day for 10 weeks), did not have an improvement in plasma lipid profiles
unless the orange juice was fortified with plant sterols (2 g/day) [93]. Also in a small study of healthy
adults where 236 mL of orange juice was incorporated into habitual diets three times a day for three
weeks, cholesterol concentrations were unaffected [94].
Fat and weight gain was inhibited by feeding mice blood orange juice (ad libitum in place of water)
for three months with a high-fat diet, and enhanced insulin sensitivity, decreased serum triglycerides,
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total cholesterol, alanine aminotransferase, and reduced liver steatogenisis were observed [95,96].
Evidence of an anitobesity effect of citrus in humans, however, is lacking.
Thus, the evidence for health benefits of whole citrus fruits is sparse, but promising. In summary, the
amount of citrus needed to provide health benefits is quite variable but appears to be within reasonably
consumable amounts. One to three glasses of orange juice a day appears to provide improvement in
antioxidant, cardiovascular, and insulin sensitivity biomarkers as well as increase vitamin C
concentrations in plasma and breast milk. Two large tangerines a day may provide a substantial amount
of carotenoids and improve vitamin A concentrations. Contributions to folate, fiber, and phytochemicals
in the diet from citrus could also be beneficial, but the amount needed to obtain the health benefits
observed in studies is uncertain. Extracted compounds from citrus from peels and seeds that are
generally discarded, such as pectin, flavonoids, and limonoids, may also be beneficial to health, but the
amounts needed to have an effect are also uncertain.
Many nutrients and phytochemicals are degraded when exposed to light, oxygen, and during
extracting procedures [33,97,98]. Thus, whole citrus consumption may provide increased nutritional
benefits compared to supplements and sometimes even juices. For example, oranges often contain
higher amounts of carotenoids and fiber than orange juice [15]. On the other hand, many compounds
such as folate may have limited bioavailability from food [14] or, as in flavonoids, are not present in
concentrations in food as high as those used in studies suggesting a health benefit (see section 4.5). Thus,
depending on the compound, juices, extracts, or supplements may be a more abundant or bioavailable
source of the phytonutrient than whole foods [88]. However, while specific nutritional inadequacies may
require the consumption of supplements in certain groups, it is generally recommended that most
nutrients be obtained primarily from whole foods rather than from supplements [99]. Overall, the
compounds in citrus, whether obtained from whole foods, extracts, or supplements, appear to have
positive health benefits.
6. Barriers of Increasing Citrus Intake and Recommendations
In some areas, such as the U.S., production and consumption of citrus fruit (per capita/day) has
declined. In addition, the production of processed citrus in the U.S. (7.3–7.7 million tonnes in 2012 and
10.5–12.7 million tonnes in 1999) [100,101] and its consumption in top markets (U.S., European Union)
has declined [102]. Lower production can be attributed to citrus diseases and fewer new plantings due to
low prices in the past, and lower consumption because of greater competition from other fruits now
available due to improved logistics in transportation and in packaging [1,103]. Although consumption
data should be interpreted with caution because it is restricted to the availability of data and is a
reflection of availability of food for consumption rather than actual intake, as with most commodities,
price and accessibility heavily influence citrus consumption. The price of citrus at the consumer level is
multifaceted and influenced heavily on complex trade matrices, thus there have been calls for reforms in
the citrus industry for promotion of long-term relationships along the supply lines to consumers allowing
the “share of risk of price and yield variability and costs of marketing promotion, and on-going
R&D” [1]. Increasing domestic production, improving current yields, and investing in transportation,
storage, and production infrastructure, especially in developing countries, may improve accessibility,
which can influence price. Agriculturalists, governments, and industry can provide assistance in
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increasing production and trade and provide information to improve citrus varieties. For example, some
nutrients and phytochemicals can be increased by not only selecting for nutrient-rich varieties of citrus,
but also by manipulating external conditions and harvesting times. Vitamin C can be increased by
increasing potassium and maintaining adequate zinc, magnesium, and copper in the soil, and can be
negatively affected by elevated nitrogen from fertilizer; growth and storage in cooler temperatures, and
growth in direct sunlight can also increase and retain vitamin C in citrus as well as the type of rootstock
the citrus is grafted on [18].
Another barrier is a dearth of knowledge about the nutrient content, bioavailability, and potential
health benefits of citrus varieties grown in tropical areas. Currently most research and development has
been done using common citrus fruits grown in temperate climates, such as oranges, lemons, and
mandarins. Encouraging research on lesser known citrus varieties, and developing citrus varieties
capable of expanding into new environs might increase consumption in low income countries that
currently lack sufficient domestic citrus production and extend the potential health benefits of citrus to
these populations. Finally, promoting the nutritional and health benefits of citrus may correspondingly
encourage consumption.
References and Notes
1. Fresh Citrus Report. Available online:
report (accessed on 14 October 2012).
2. Ortiz, J.M. Botany. In Citrus: The Genus Citrus; Dugo, G., Di Giacomo, A., Eds.; Taylor and
Francis: New York, NY, USA, 2002; pp. 16–35.
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... Very fragrant and sweet, Clementine fruits are eaten fresh or used for the preparation of syrups, juices, jams, and in many pastry recipes for the preparation of cakes and pies, or to obtain ice creams, sorbets, and jellies. This citrus fruit has been recognized by many authors as source of countless bioactive compounds with health-promoting properties for humans, such as vitamins (in particular, C), carotenoids, flavonoids, and phenolic acids [1,2]. However, post-harvest operations, such as peeling and cutting, can significantly affect the shelf life, as they favor metabolic processes that cause a sudden qualitative decay [3]. ...
... An initial increase in TPC and TFC was observed, followed by the maintenance of these constant values at the end of their shelf life. Several authors report that this phenomenon is mainly due to the activity of the enzyme PAL that, following the peeling operation, catalyzes the synthesis reactions of new phenolic compounds [1,[40][41][42]. However, this rise could be followed by rapid decay if strategies to contain the oxidation of newly formed compounds do not fit. ...
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Conventional and innovative preservation treatments were compared to extend the shelf life of ready-to-eat Clementine (Citrus x Clementina) segments. The aim of this research was to find an environmentally friendly packaging typology for this fruit while preserving quality and meeting the needs of the consumer in terms of practicality of use and food safety. The experimental plan envisaged both the use of conventional storage techniques, such as modified atmosphere packaging (O2 5%, CO2 5%, and N2 90%), and the use of innovative storage techniques, such as an alginate-based (1.5%) edible coating. Quality changes were monitored by evaluating several indexes, such as color, texture, weight loss, respiration rate, pH, solid soluble content, bioactive compounds, antioxidant activity, organic acids, and microbiological contamination for 21 days at 4 °C. Moreover, a panel of judges assessed the sensory characteristics. Ready-to-eat Clementine segments, produced with edible coatings, possessed better sensory and textural properties and similar physic-chemical characteristics than those packaged in a modified atmosphere. The coating favored the creation of a controlled environment with low oxygen stress, which resulted in a reduction in enzymatic activity and oxidation for 20 days of storage at 4 °C. The results suggest that an edible coating could be a sustainable alternative to a modified atmosphere for the shelf life extension of ready-to-eat Clementine segments.
... Citrus fruits and juices represent one such dietary component that may be of interest to measure for population monitoring and/or nutritional epidemiological studies due to their high content of essential nutrients such as vitamin C, folate, and fiber, as well as other bioactive phytochemicals that may confer health benefits in humans (reviewed in [27] and [28]). Some epidemiological evidence supports a negative association between consumption of citrus fruit and/or the flavonoids present in them and inflammatory markers in women [29] and ischemic stroke in men [30], and randomized clinical trials have suggested a beneficial effect of orange juice consumption on endothelial function [31][32][33]. ...
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Proline betaine (Pro-B) has been identified as a biomarker of dietary citrus intake, yet gaps remain in its validation as a quantitative predictor of intake during various physiological states. This study quantified sources of within-individual variation (WIV) in urinary Pro-B concentration during pregnancy and assessed its correlation with the reported usual intake of citrus fruit and juice. Pro-B concentrations were determined by 1H-NMR spectroscopy in spot and 24-h urine specimens (n = 255) collected throughout pregnancy from women participating in the MARBLES cohort study. Adjusted linear or log mixed effects models quantified WIV and tested potential temporal predictors of continuous or elevated Pro-B concentration. Pearson or Spearman correlations assessed the relationship between averaged repeated biomarker measures and usual citrus intake reported by food frequency questionnaires. The proportion of variance in urinary Pro-B attributable to WIV ranged from 0.69 to 0.74 in unadjusted and adjusted models. Citrus season was a significant predictor of Pro-B in most analyses (e.g., adjusted β [95% CI]: 0.52 [0.16, 0.88] for non-normalized Pro-B), while gestational age predicted only non-normalized Pro-B (adjusted β [95% CI]: −0.093 [−0.18, −0.0038]). Moderate correlations (rs of 0.40 to 0.42) were found between reported usual citrus intake and averaged repeated biomarker measurements, which were stronger compared to using a single measurement. Given the high degree of WIV observed in urinary Pro-B, multiple samples per participant are likely needed to assess associations between citrus consumption and health outcomes.
... grandis)). Three kinds of citrus produced in India (Mandarin (Kinnow, Nagpur, Coorg, and Khasi), Sweet orange (Mosambi, Jaffa, Malta, and Satgudi), and lime/lemon) have gained focus for cultivation and commercialization (Turner and Burri, 2013). The average production of mandarin is 6.4 million metric tons, lemon is 3.7 million metric tons and sweet orange is 3.53 million metric tons in India during the year 2021 (Statista, 2022). ...
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The peel which is the primary waste of citrus fruit processing is usually discarded. But these peels are good source of pectin, phenols, flavonoids, and limonene. The peel can be used to extract essential oil that can be used in food system. The present study aimed to extraction and analyse the chemical composition of citrus peel essential oil by hydrodistillation and soxhlet methodThe optimum condition for essential oil extraction by hydrodistillation method was standardized and the oil extraction was efficient at 95 °C. The extraction time was 3 hours with solid solvent ratio of 1:10 (g sample/mL of water). d-Limonene is the major compound present in all three citrus peel essential oils extracted by both the methods followed by β myrcene, α pinene, β pinene, and γ terpinene. Essential oil from fresh citrus peel contains many other compounds such as neral, caryophyllene, β bisbolene, etc. These bioactive volatile compounds are responsible for the antioxidant and antimicrobial properties of the essential oil.
... Citrus, a member of the Rutaceae family and the Aurantioideae subfamily, is one of the most significant fruit crops. Citrus reticulata, Citrus sinensis, Citrus limon, Citrus aurantium, and Citrus paradisi are among the citrus species grown for commercial purposes (Turner and Burri, 2013). China, Brazil, India, Mexico and United States of America are the top countries that produce citrus fruits (Marti et al., 2009). ...
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Introduction Nutritional content in citrus fruit is enormous. Citrus grandis (L.) Osbeck is underutilised citrus crop that receives little attention due to the lack of knowledge regarding its nutritional value. Citrus waste disposal poses a problem due to economic and environmental factors. Methods The metabolites flavonoids, phenols and antioxidant capacity in the dropped fruits of the underutilised citrus species pomelo ( Citrus grandis (L.) Osbeck) were examined. Results and discussion Hesperidin varied from 1.22 to 2.83% and 1.08 to 1.16% from 10 mm to 14 mm whereas naringin dominates in fruits measuring 10 mm and 12mm with 60.61%, 60.77%, and 47.76%, 45.87% in freeze dried (FD) and hot air oven dried (HAOD) samples. According to the results of the antioxidant assays, the highest concentrations of ABTS azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) and DPPH (2, 2-diphenyl-1-picrylhydrazyl radical) were found in freeze dried samples, ranging from 9.679 to 10.416 mmol L ⁻¹ Trolox and 14.825 to 16.432 mmol L ⁻¹ Trolox, respectively. However, the Ferric Reducing Antioxidant Power (FRAP) assay revealed higher content in samples of both FD and HAOD that were 10mm in size (4.578 mmol L ⁻¹ Trolox and 3.730 mmol L ⁻¹ Trolox). Total phenol content was measured, and the highest concentrations were found in fruits with a diameter between 10 mm and 18 mm. It ranged from 48.479 to 54.498 mg GAE L ⁻¹ in FD samples and from 45.757 to 51.159 mg GAE L ⁻¹ in HAOD samples. The smallest fruits, or those that were still in the immature stage, had the highest content. It was found that when the immature dropped fruits were dried by HAOD, the content decreased. At p<0.01 and p<0.05, there was a significant positive correlation between the flavonoids, antioxidants, and total phenols. The results showed that the immature dropped immature fruits of lesser known underutilised citrus sp. Citrus grandis can act as potential source of flavonoids, total phenol concentration, and antioxidant potential. Freeze drying can be recommended to recover the most bioactive substances from physiologically dropped fruits of Citrus grandis for use in the pharmaceutical and nutraceutical sectors. This study will help in reducing the environmental impact caused due to citrus dropped fruits and its responsible management.
... There is considerable evidence that citrus fruit has antioxidant and antimutagenic properties and a positive association with the health of bones, cardiovascular and immune systems (Codoňer-Franch and Valls-Bellés, 2010). Citrus consumption might improve indices of antioxidant status, and possibly cardiovascular health and insulin sensitivity (Turner and Burri, 2013). ...
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Pruning and fertilization are factors that can determine the production and quality of citrus. The objective of this study was to determine the effect of pruning intensity and fertilizer doses of N (nitrogen), P (phosporus), and K (potassium) on citrus production and quality. The study was carried out in a citrus orchard in Central Java, Indonesia, over the course of two seasons, 2016-17 and 2017-18. The experiment was conducted as a two-factorial, completely randomized block design where the first factor was pruning intensity, namely 0, 5, 10, and 15 % of the total number of branches per tree while the second factor was doses of N, P, and K fertilizers, namely 0, 2, and 4 % of the weight of harvested citrus fruit in the previous season. The result showed that increasing doses of N, P, K fertilizers from 0 to 4 % increased fruit-set, harvested fruits, fruit size, content of vitamin C, sugar, and soluble solid. The highest fruit-set, weight of harvested fruits, and content of vitamin C were achieved by pruning intensity of 10 %.
PURPOSE: Nowadays, herbal medicine offers many solutions to deal with respiratory, viral and, bacterial infections. More and more people are turning to natural antioxidants, so finding new drugs is a current goal of health and medical researchers. Medicinal plants traditional to different regions of the world (Lavandula angustifolia Mill., Mentha piperita Lin., Rosa damascena Mill., Azadirachta indica (neem oil)) contain a wide variety of bioactive compounds that have proven beneficial effects on human health. There is ample evidence that polyphenols, flavonoids, and vitamins counteract and neutralize genetic and environmental stressors, especially oxidative stress, which is closely related to the initiation of many diseases. Here we review the possible uses of the aromatic medicinal plants cited above.
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Citrus limon is among the species of the genus Citrus that dominates the world market. It is highly nutritious for humans as it contains twice the amount of the suggested daily intake of ascorbic acid and is also a good source of phenolic compounds, carotenoids, and other bioactive compounds. This study aimed to identify the optimal extraction procedures and parameters to obtain the maximum quantity of bioactive components from lemon peel by-products. Various extraction techniques, including stirring, ultrasound, and pulsed electric field, were evaluated, along with factors such as extraction time, temperature, and solvent composition. The results revealed that simple stirring for 150 min at 20 °C proved to be the most effective and practical method. The ideal solvent mixture consisted of 75% ethanol and 25% water, highlighting the crucial role of solvent composition in maximizing extraction efficiency. Among the extracted compounds were phenolics, ascorbic acid, and carotenoids. Under optimum extraction conditions, the extract was found to contain high total phenolic content (TPC) (51.2 mg of gallic acid equivalents, GAE/g dry weight), total flavonoid content (TFC) (7.1 mg of rutin equivalents, RtE/g dry weight), amounts of ascorbic acid (3.7 mg/g dry weight), and total carotenoids content (TCC) (64.9 μg of β-carotene equivalents, CtE/g). Notably, the extracts demonstrated potent antioxidant properties (128.9 μmol of ascorbic acid equivalents, AAE/g; and 30.3 μmol of AAE/g as evidenced by FRAP and DPPH assays, respectively), making it a promising ingredient for functional foods and cosmetics. The study’s implications lie in promoting sustainable practices by converting lemon peel into valuable resources and supporting human health and wellness through the consumption of natural antioxidants.
The leaves, flowers and fruit peels of Banzhair lime trees are rich in essential oils (EOs), which are characterized by odor, antiseptic and antimicrobial properties. Arid regions (ARR) are characterized by stress properties that have a negative impact on the production of Banzhair lime EOs. Trans-cinnamic acid (t-CA) is an antioxidant substance that has an anti-bad effect when plants are exposed to stress. The aim of this investigation was to reduce the harmful effect of stress factors on Banzhair lime trees by adapting them to ARR through t-CA. Various EOs were analyzed by GC and GC/MS. The major compound of leaf and peel EOs was limonene, while geranial was in flower EO. The major chemical group in leaf and flower EOs was oxygenated monoterpenes, while it was monoterpene hydrocarbons in peel EO. Trees exposed to 40 mg/L t-CA acid resulted in the maximum contents of leaf (0.5%, w/w), flower (0.2%, w/w) and (0.3%, w/w) peel essential oils. Leaf EO obtained from trees subjected to 20 mg/L t-CA resulted in the greatest value of limonene, while flower EO produced from trees treated with t-CA at 40 mg/L resulted in the highest value of geranial. This trial recommends the cultivation of Banzhair lime trees in ARR under the application of t-CA to improve the productivity of their EOs.
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Recent studies have documented a number of health benefits associated with the consumption of citrus. These fruits are predominantly composed of water and have a very low energy density. However, they are some of the most important nutrient-dense foods available. In effect, citrus fruits contain a range of key nutrients such as vitamin C, folate, dietary fiber, minerals (potassium) and phytochemicals, which confer them the health-promoting properties. In recent years, there has been increasing interest in the anti-oxidant capacity of foods. Vitamin C is a major contributor to the anti-oxidant capacity of citrus. However, the major contribution of citrus anti-oxidant activity comes from the combination of phytochemicals and from their synergistic action with vitamin C. The major phytochemicals in citrus fruits are the terpenes and phenolic compounds, which possess anti-inflammatory and anti-carcinogenic activity. Carotenoids and limonoids are terpenes that are released in the processing of juices. Citrus is the main source of specific nutrients such as flavanones (hesperetin and naringenin, usually present as glycosides) and the carotenoid cryptoxanthin, which are not present in other fruits in significant quantities. Flavonoids also have a role in cardiovascular protection, inhibiting the formation of atheroma in many steps of its pathogenesis.
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For some classes of dietary polyphenols, there are now sufficient intervention studies to indicate the type and magnitude of effects among humans in vivo, on the basis of short-term changes in biomarkers. Isoflavones (genistein and daidzein, found in soy) have significant effects on bone health among postmenopausal women, together with some weak hormonal effects. Monomeric catechins (found at especially high concentrations in tea) have effects on plasma antioxidant biomarkers and energy metabolism. Procyanidins (oligomeric catechins found at high concentrations in red wine, grapes, cocoa, cranberries, apples, and some supplements such as Pycnogenol) have pronounced effects on the vascular system, including but not limited to plasma antioxidant activity. Quercetin (the main representative of the flavonol class, found at high concentrations in onions, apples, red wine, broccoli, tea, and Ginkgo biloba) influences some carcinogenesis markers and has small effects on plasma antioxidant biomarkers in vivo, although some studies failed to find this effect. Compared with the effects of polyphenols in vitro, the effects in vivo, although significant, are more limited. The reasons for this are 1) lack of validated in vivo biomarkers, especially in the area of carcinogenesis; 2) lack of long-term studies; and 3) lack of understanding or consideration of bioavailability in the in vitro studies, which are subsequently used for the design of in vivo experiments. It is time to rethink the design of in vitro and in vivo studies, so that these issues are carefully considered. The length of human intervention studies should be increased, to more closely reflect the long-term dietary consumption of polyphenols.
Conference Paper
Based on animal studies, epidemiologic studies and intervention trials, maternal folic acid is known to be protective for neural tube defects (NTD), primarily spina bifida and anencephalus. To reduce the risk of NTD, the U.S. Food and Drug Administration mandated that all enriched cereal grain products be fortified with folic acid as of January 1998. Recent data demonstrate that this public health action is associated with increased folate blood levels among U.S. women of childbearing age and that the national rate of spina bifida has decreased by 20%. Rates of anencephaly appear not to have declined. Epidemiologic data on use of folate and folate antagonists have also implicated folic acid in prevention of other birth defects such as facial clefts and cardiac and limb defects. Dietary folic acid is likely to be inadequate for maximal protection against NTD. Because about half of pregnancies in the U.S. are unplanned, according to the March of Dimes, birth defect prevention includes a recommended daily dose of 400 A,g synthetic folic acid for women of childbearing age. Uniform compliance is estimated to decrease the incidence of NTD by up to 70%. This could reduce the overall incidence from 2 to 0.6 per 1000 pregnancies and prevent disease in similar to2000 babies per year in the U.S. Four thousand micrograms of folic acid per day is recommended for women with previous pregnancies affected by NTD.
Polyphenols are abundant micronutrients in our diet, and evidence for their role in the prevention of degenerative diseases is emerging. Bioavailability differs greatly from one polyphenol to another, so that the most abundant polyphenols in our diet are not necessarily those leading to the highest concentrations of active metabolites in target tissues. Mean values for the maximal plasma concentration, the time to reach the maximal plasma concentration, the area under the plasma concentration-time curve, the elimination half-life, and the relative urinary excretion were calculated for 18 major polyphenols. We used data from 97 studies that investigated the kinetics and extent of polyphenol absorption among adults, after ingestion of a single dose of polyphenol provided as pure compound, plant extract, or whole food/beverage. The metabolites present in blood, resulting from digestive and hepatic activity, usually differ from the native compounds. The nature of the known metabolites is described when data are available. The plasma concentrations of total metabolites ranged from 0 to 4 mumol/L with an intake of 50 mg aglycone equivalents, and the relative urinary excretion ranged from 0.3% to 43% of the ingested dose, depending on the polyphenol. Gallic acid and isoflavones are the most well-absorbed polyphenols, followed by catechins, flavanones, and quercetin glucosides, but with different kinetics. The least well-absorbed polyphenols are the proanthocyanidins, the galloylated tea catechins, and the anthocyanins. Data are still too limited for assessment of hydroxycinnamic acids and other polyphenols. These data may be useful for the design and interpretation of intervention studies investigating the health effects of polyphenols.
Citrus limonoids are one of the two main types of compounds responsible for the bitter taste in citrus fruits. Nomilin and limonin are two most predominant limonoids found in Rutaceous plants such as lemon, lime, orange, and grapefruit. Recently, it has been discovered that citrus limonoids possess certain biological activities that may be useful as chemopreventive agents. This article probes the possible role of citrus limonoids in the inhibition of forestomach tumors, lung tumors and skin carcinogenesis.