HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Figures Only Full Text (PDF) Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Vinson, J. A Articles by Proch, J. Search for Related Content PubMed PubMed Citation Articles by Vinson, J. A Articles by Proch, J.

Dried Fruits: Excellent in Vitro and in Vivo Antioxidants

Chemistry Department, University of Scranton, Scranton, Pennsylvania

Address reprint requests to: Joe A Vinson, PhD, Professor, Chemistry Department, University of Scranton, Scranton, PA 18510. E-mail vinson{at}uofs.edu

	ABSTRACT

TOP FOOTNOTES ABSTRACT INTRODUCTION METHODS RESULTS CONCLUSION REFERENCES

 
Objective: The goal of this work is to determine the amount and quality of phenol antioxidants in dried fruits and compare them with the corresponding fresh fruits; to compare the nutrients in fresh and dried fruits; to determine if figs are a source of in vivo antioxidants when eaten.

Methods: Commercial samples of dried fruits and fresh fruits were compared in the in vitro studies using a colorimetric method to measure phenolic antioxidants. The quality of the antioxidants was measured by inhibition of lower density lipoprotein oxidation. Ten normal free-living subjects were tested in the human study. Fasting subjects were given 40 g of figs with or without a carbonated beverage and the plasma antioxidant capacity was measured for six hours using the trolox equivalent antioxidant capacity assay.

Results: Dates have the highest concentration of polyphenols among the dried fruits. Figs and dried plums have the best nutrient score among the dried fruits, and dates among the fresh fruits. Processing to produce the dried fruit significantly decreases the phenols in the fruits on a dry weight basis. Compared with vitamins C and E, dried fruits have superior quality antioxidants with figs and dried plums being the best. Fig antioxidants can enrich lipoproteins in plasma and protect them from subsequent oxidation. Figs produced a significant increase in plasma antioxidant capacity for 4 hours after consumption, and overcame the oxidative stress of consuming high fructose corn syrup in a carbonated soft drink.

Conclusion: Dried fruits and especially figs, are a convenient and superior source of some nutrients, but in the American diet amount to less than 1% of total fruit consumed. Figs are in vivo antioxidants after human consumption. The findings suggest that dried fruits should be a greater part of the diet as they are dense in phenol antioxidants and nutrients, most notably fiber.

Key words: fruits, figs, polyphenols, antioxidants

	INTRODUCTION

TOP FOOTNOTES ABSTRACT INTRODUCTION METHODS RESULTS CONCLUSION REFERENCES

 
Fruit and vegetable consumption have been shown by multiple epidemiology studies to reduce the risk of chronic diseases such as cancer [1], heart disease [2], and stroke [3]. A U.S. study showed that diabetes in women was inversely associated with fruit and vegetable consumption [4]. Additionally, there is an inverse relationship between fruit and vegetable intake and blood pressure [5]. The National Cancer Institute and the National Research Council recommend at least five servings of fruits and vegetables. Yet only 17% of 15,000 Americans surveyed in schools, work sites, churches, or nutrition clinics in 1999, ate the recommended number of servings [6]. Initially it was assumed that vitamins C, E, and the provitamin beta carotene were responsible for the health benefits of fruits and vegetables. Recent supplementation studies with pure vitamin E and beta carotene have cast doubt on this hypothesis. A 4-year study of vitamin E supplementation to more than 9,000 patients at high risk for cardiovascular disease produced no significant benefit [7]. An 8-year prospective study of more than 44,000 healthy men in the Health Professionals Follow-up Study, found no benefits of vitamin C or E for decreasing the risk of stroke [8].

Abundant evidence exists for a beneficial effect of phenol antioxidants (this includes monophenols and polyphenols) on heart disease and cancer. It is hypothesized that phenol antioxidants are the agents in fruits that are at least partly responsible for these protective effects. An early step in atherosclerotic lesion formation is oxidation of low (LDL) and very low (VLDL) density lipoproteins [9]. Oxidation of DNA is an important event in carcinogenesis. The consumption of a diet high in fruits has been shown to decrease oxidative damage of DNA bases in humans [10]. Fruit and vegetable components, polyphenolic antioxidants such as flavonoids, are protective for heart disease [11] and for stroke in the Netherlands’ Zutphen Study [12]. A Finnish study of 10,000 men and women over a 20-year period showed a decreased risk of lung cancer which was attributed to flavonoid intake [13]. The intake of apples, the major dietary source of flavonols in this population, was inversely associated with lung cancer incidence. This benefit was not due to the intake of the antioxidant vitamins. A diet rich in fruits and vegetables has recently been found favorably to affect serum antioxidant capacity and protect against lipid peroxidation [14]. Human consumption of 200 g of strawberries has been shown to increase the plasma antioxidant capacity [15]. This could not be explained solely by the vitamin C from the strawberries.

More than 4000 phenol compounds (flavonoids, monophenols and polyphenols) are found in vascular plants [16]. Phenols found in plants have been considered anti nutrients due to their potential to "tie up" nutrients such as copper and iron and especially proteins, and prevent them from being absorbed. Their function in the plant is to prevent free radical damage to proteins, carbohydrates, lipids and DNA caused by UV light from the sun. We have shown that phenols, especially those with multiple phenolic groups, are better antioxidants than the well-known antioxidant vitamins [17]. Fruits also possess these high quality antioxidants as measured by the oxidation of LDL + VLDL, an in vitro model of the initiation of atherosclerosis [18]. In fact, fruits have significantly higher quality phenol antioxidants than vegetables [18].

We hypothesize that the higher quantity and quality of antioxidants in fruits, are responsible for the generally greater benefit of fruits compared with vegetables in epidemiology studies. Since dried fruits are a more concentrated form of fruit, we have investigated the quantity and quality of the antioxidants in these fruits.

	METHODS

TOP FOOTNOTES ABSTRACT INTRODUCTION METHODS RESULTS CONCLUSION REFERENCES

 
Measurement of Quantity and Quality of Antioxidants
Three to five samples of each of the fresh and dried fruits (apricots, cranberries, dates, figs, raisins, and pitted prunes aka dried plums) were obtained from local supermarkets. Fresh figs and dates (not usually consumed by the public) were obtained direct from the grower. Fresh Mission and Calimyrna figs were analyzed on the day of receipt from DeBenedetto Farms (Fresno, CA). Fresh Deglit Noor and Zahidi dates were kindly supplied by California Redi-Date (Thermal, CA) and Leja Farms (Coachella, CA). Dried figs of the same variety were provided by the California Fig Advisory Board (Fresno, CA). We used our sample preparation and analysis method already described for fruits [18]. This involved cleaning, weighing, cutting and freeze-drying. This was followed by weighing and then dissolving the lyophilyzate in methanol/water to extract the free phenols. Another sample was dissolved in 50% methanol/50% water/1.2M hydrochloric acid, in order to extract the free and glycosylated phenols and hydrolyze the glycosylated phenols, to give an extract for total phenol analysis. Extracts from sulfite-containing fruits were treated with acetaldehyde before analysis. The quantity of free and total phenols in the fruit extracts was then analyzed by an oxidation-reduction colorimetric assay using the Folin-Ciocalteu reagent [Sigma Chemical Co., St. Louis, MO], with catechin as the standard, and measurement at 750 nm after reaction for 10 minutes.

The quality of the phenol antioxidants in the extracts was measured by determining the IC₅₀ (the concentration to inhibit the oxidation by 50%) of the pooled free phenol extracts for each fruit. Fruit extracts were added at phenol concentrations ranging from 0.2 to 2 µM (as measured by the Folin assay) to a fixed protein concentration of human LDL+VLDL that was isolated by heparin-agarose affinity column [19]. This was followed by oxidation with cupric ions at physiological pH and temperature under standardized conditions. The oxidation mixture was reacted with thiobarbituric acid and the products measured by fluorometry in butanol. A native sample without cupric ions and a blank sample without an antioxidant were also analyzed. All samples were analyzed in duplicate. IC₅₀ was determined graphically from the sigmoidal-shaped curve of antioxidant concentration (µM) vs. % inhibition. For comparison purposes the reciprocal 1/IC₅₀ was used so that the higher number corresponds to better quality antioxidants. This method has recently been described in detail [19].

To illustrate the ability of phenols from fruits to incorporate in LDL+VLDL in plasma and protect these lipoproteins from subsequent oxidation was measured in Mission figs. Plasma was spiked with the water extract of Mission figs (25–100 µM phenols) along with a control, and equilibrated for one hour at 37°C. The LDL+VLDL was isolated by affinity column and oxidized with cupric ions under standard conditions as described previously. The kinetics of conjugated diene formation was determined at 234 nm and the lag time (where the initial slow oxidation line converges with the rapid oxidation line) was measured [19]. The longer the lag time compared to the control, the greater the amount of lipoprotein-bound antioxidants present from the fig.

Human Study
Ten normal subjects (5 males and 5 females, aged 25 to 58) participated in the study with informed consent. They were non-smoking individuals not taking any prescription medicine or vitamin supplements. After an overnight fast, they consumed either 240 ml of Sprite^TM alone (control), or with 40 g (one serving size) of dried Mission and Calimyrna figs in a random crossover design. Venipuncture was conducted at 0, 1, 2, 4, and 6 hours after consumption. Lunch was eaten after the 4-hour draw and consisted of a plain low-fat bagel and 240 ml of Sprite^TM. Plasma was stored at –70°C until assay for antioxidant activity using the trolox equivalent antioxidant capacity (TEAC) kit from Randox Laboratories (San Diego, CA) with trolox as the standard [20]. Statistical comparisons used a paired t-test with p < 0.05 considered significant.

	RESULTS

TOP FOOTNOTES ABSTRACT INTRODUCTION METHODS RESULTS CONCLUSION REFERENCES

 
Quantity and Quality of Antioxidants
We compared 6 fresh fruits with their corresponding dried versions with respect to nutrients for a serving size of the fruit. Data is taken from the U.S. Department of Agriculture [21] and displayed in Table 1. The lower the nutrient score, the better the source of nutrients. The best nutrient score of the fresh fruits belonged to dates, which in fact had the best nutrient score of all the fruits. The nutrient score was significantly better for the dried fruits compared to the fresh varieties (p < 0.001 by a chi-square test). Apricots and figs had the best nutrient scores among the dried fruits.

View larger version (15K): [in this window] [in a new window]   Fig. 1. Comparison of quantity of total polyphenols in fresh and the corresponding dried fruit on a dry weight basis.

View larger version (16K): [in this window] [in a new window]   Fig. 2. Comparison of quality of antioxidants of vitamins and dried fruits (mean ± standard deviation). Dried fruit extracts from several sources of dates and raisins were pooled prior to assay.

View larger version (13K): [in this window] [in a new window]   Fig. 3. Lipoprotein-bound antioxidant activity of fig phenols after spiking in plasma at different concentrations and determination of the lag time of LDL+VLDL oxidation.

View larger version (15K): [in this window] [in a new window]   Fig. 4. The average change in plasma antioxidant capacity after consumption of either control (SpriteTM) or figs and SpriteTM (mean ± standard error of the mean) for 10 subjects, * p < 0.01 by a paired t-test.

	DISCUSSION

Dates have the highest concentration of total phenols among the dried fruits, and cranberries have the highest based on free phenols. The extremely high levels may be due to the extreme temperatures and greater exposure to sunlight for dates compared to the other fruits, i.e. an adaptive response of the plant. The % free phenols increased after drying, averaging 49.6% for fresh and 59.7% for dried but the difference was not significant. It is interesting to compare the dried plum and raisin data using our Folin assay, to that previously published using another method for antioxidant activity of foods, namely the oxygen radical absorbance capacity (ORAC) method. They found that dried plums had twice the amount of free antioxidants compared to raisins [24]. Our method found that dried plums had 2.5 times more free phenol antioxidants than raisins. We found fresh dates at 2546 mg/100 g are also much higher in total phenols than cranberries which have the highest total phenols among the fresh fruits, 678 mg/100 g [18]. Dates are also higher than kidney beans which have the highest phenols of the vegetables, 923 mg/100 g [25]. Dried fruits were significantly higher in total phenols than 20 fresh fruits, 815 vs. 173 mg/100 g, respectively, p < 0.005 [18].

Processing was examined with the data in Fig. 1. Figs are the only fruit for which we had samples of both fresh and dried fruit from the same orchard. On a dry weight basis and compared to the fresh fruit, the dried fig lost 87% of total phenols. All 6 fruits averaged an 84% decline in total phenols as a result of drying, which was a significant decrease, p < 0.02 by the student’s t test. Based on dry weight, prunes [23] and raisins [26] also showed a decrease in some individual phenols during the processing of the fresh fruit. It appears that some of the polyphenols in the fresh fruit are destroyed and converted to non-antioxidant forms during the drying process [23, 27]. Compared on a fresh weight basis processing produced a 90% increase in free polyphenols (p < 0.05) as a result of the loss of water. There was an 11% increase in total polyphenols as a result of drying.

Antioxidant quality is a measure of the effectiveness of the antioxidant(s) present as a pure compound or a mixture. A comparison of antioxidant quality is shown in Fig. 2 and is measured by 1/IC₅₀. The higher the value, the better the quality. Phenol antioxidants’ quality in the dried fruits was compared to the antioxidant vitamins in Fig. 2 and found to be significantly higher, p < 0.02. Also quality seems to improve during the drying process. The IC₅₀ for fresh cranberries, green grapes and plums are 1.16, 1.32, and 1.42, respectively. For dried cranberries, raisins and dried plums, the values are 2.38, 3.45, and 4.38, respectively. This is a significant difference, p < 0.05. Quality of antioxidants is an important factor since following consumption of fruits polyphenols are usually present in plasma at concentrations not exceeding 10 µM. The average IC₅₀ was 0.3 µM for the dried fruits in Fig. 2. Thus the polyphenols from dried fruits can be potent antioxidants at physiological concentrations.

In the plasma spiking study the fig phenols caused an increase in the lag-time in an almost linear manner as shown in Fig. 3. This was also seen with pure polyphenols and beverages. [28]. From data in Fig. 3, the concentration of fig phenols to increase the lag time 50% compared to the control was calculated to be 143 µM. This value is similar to that found for dried plum juice, 111 µM [28]. The ability to bind lipoproteins is one of the mechanisms by which supplementation of vitamin E is hypothesized to decrease the risk of heart disease [29], and by which consuming polyphenols may be beneficial with respect to reducing the risk of heart disease.

In the human study, plasma antioxidant capacity was measured by TEAC. As seen in Fig. 4, the Sprite^TM caused a temporal decrease in antioxidant capacity which reached its lowest level at 1 hour after consumption of the soft drink. Figs produced a significant increase in plasma antioxidant capacity for 4 hours after consumption, and overcame the oxidative stress of consuming high fructose corn syrup in a carbonated soft drink. This increase cannot be attributed to vitamin C since less than 2 mg of the vitamin are found in the dried figs [21]. Although we did not measure glucose, this time corresponds to the maximum plasma glucose as seen for a glucose tolerance test [30]. Post-prandial hyperglycemia has been shown to produce oxidative stress in vivo [30, 31]. Thus the high fructose corn syrup in Sprite^TM (38 g of carbohydrates/12 oz), or by analogy any soft drink containing sugar, is a pro-oxidant, causing a temporary oxidative stress that lasts for 4 hours after drinking. In fact, up to 4 hours after consumption, there is a significant negative correlation between the control and fig antioxidant capacity (Pearson correlation coefficient –0.9999, p < 0.01), suggesting the same kinetics for both the oxidative stress (prooxidant) from the soft drink and the antioxidant effect from consuming the figs. The antioxidant effect of the figs overcame the oxidative stress of the sugars in the soft drink and the net effect was an increase in antioxidant capacity.

In a previous study, the largest increase in plasma antioxidant capacity (TEAC) after drinking one serving of green tea by normal subjects compared to the baseline was 4% [32]. In our study after eating figs the TEAC increase was 9% (Fig. 4). A fairer calculation would be the difference between the TEAC for figs plus Sprite^TM vs. Sprite^TM alone at 1 hour. This calculates as an 18% increase. Thus figs produce a much greater increase in plasma antioxidant capacity than green tea. In a pilot study with a single subject, 8 fig bars (Fig Newtons^TM) were consumed, and produced a maximal increase in plasma TEAC of 5%. Besides figs, the only other dried fruit to demonstrate human in vivo antioxidant activity was raisins from white grapes [33]. In this [33]. In this study subjects consumed 3 g/kg (about 5 servings) of raisins for a week and the fasting plasma antioxidant capacity increased 8%.

Dried fruits are not commonly eaten in the US diet. In 2000 only 2.3 lb/year (corresponding to a mere 3 g/day) of the 6 dried fruits combined, were consumed. This compares with 126 lb/year of fresh fruits and 152 lb/year of processed fruit [34]. Currently we Americans are not following the 5 A Day plan recommended by the National Cancer Institute. In 1999, the mean intake, calculated from 7 study centers and 15,060 subjects were 3.6 servings of fruits and vegetables, with only 1.5 servings/day of fruit [6]. Dried fruits are an excellent source of fiber, nutrients, and complex carbohydrates and thus a good choice for a snack. For example, eating dried fruits produced a significantly lower insulin response than consuming processed snacks containing sugar such as chocolate candy, or cola along with potato chips [35].

There have been a large number of beneficial studies indicating that increased consumption of fruits and vegetables decreases the risk of many cancers. Most of the decreased risk has been attributed to the vegetables rather than the fruits. However an inverse association with lung cancer has been shown for fruit consumption but not vegetables [36]. The benefits of consuming dried fried are difficult to determine by observational studies due to the low consumption of dried fruit. Two recent case-controlled epidemiology studies in the US found no association of prostate cancer risk and fruit consumption [37, 38]. This was confirmed in two additional studies; a Dutch study and an American study, which in contrast found an inverse association of this cancer with dried fruit consumption [39, 40]. Potent in vitro supressors of cancer cell proliferation have been found in a fraction isolated from figs [41].

	CONCLUSION

TOP FOOTNOTES ABSTRACT INTRODUCTION METHODS RESULTS CONCLUSION REFERENCES

 
Dried fruits have a greater nutrient density, greater fiber content, increased shelf life, and significantly greater phenol antioxidant content compared to fresh fruits. The quality of the antioxidants in the processed dried fruit is the same as in the corresponding fresh fruit. Phenols in dried fruit may be important antioxidants as demonstrated by the in vivo antioxidant effect from eating a serving size of figs. Therefore, more dried fruits should be recommended to be added to the diet by dieticians and nutritionists.

	FOOTNOTES

TOP FOOTNOTES ABSTRACT INTRODUCTION METHODS RESULTS CONCLUSION REFERENCES

 
Financial Information: There is no current financial interest from this work. The work was funded in part by a grant from the California Fig Advisory Board.

Received June 23, 2003. Accepted March 3, 2004.

	REFERENCES

TOP FOOTNOTES ABSTRACT INTRODUCTION METHODS RESULTS CONCLUSION REFERENCES

 

1. Block G, Patterson B, Subar A: Fruit, vegetables, and cancer prevention: a review of the epidemiological evidence.Nutr Cancer18 :1 –29,1992 .[Medline]
2. Rimm EB, Ascherio A, Giovanucci E, Speigelman D, Stampfer MJ, Willett WC: Vegetable, fruit and cereal fiber intake and risk of coronary heart disease among men.JAMA275 :447 –451,1996 .[Abstract/Free Full Text]
3. Joshipura KJ, Ascherio A, Manson, JE, Stampfer MJ, Rimm EB, Speizer FE, Hennekens CH, Spiegelman D, Willett WC: Fruit and vegetable intake in relation to risk of ischemic stroke.J Am Med Assoc82 :1233 –1239,1999 .
4. Ford ES, Mokdad AH: Fruit and vegetable consumption and diabetes mellitus incidence among U.S. adults.Prev Med32 :33 –39,2001 .[Medline]
5. Ascherio A, Stamper MJ, Colditz GA, Willett WC, McKinlay, J: Nutrient intakes and blood pressure in normotensive males.Int J Epidemiol20 :886 –891,1991 .[Abstract/Free Full Text]
6. Thompson B, Demark-Whanefried W, Taylor G, McClelland JW, Stables G, Havas S, Feng Z, Topor M, Heimendinger J, Reynolds KD, Cohen N: Baseline fruit and vegetable intake among adults in seven 5 A Day study centers located in diverse geographic areas.J Am Diet Assoc99 :1241 –1248,1999 .[Medline]
7. Yusuf S, Dagenais G, Pogue J, Bosch J, Sleight P: Vitamin E supplementation and cardiovascular events in high-risk patients. The Heart Outcomes Prevention Study Investigators.N Engl J Med342 :154 –160,2000 .[Abstract/Free Full Text]
8. Ascherio A, Rimm EB, Hernan MA, Giovannucci E, Kawachi I, Stampfer MJ, Willett WC: Relation of consumption of vitamin E, vitamin C, and carotenoids to risk for stroke among men in the United States.Ann Intern Med130 :963 –970,1999 .[Abstract/Free Full Text]
9. Steinberg D, Parathasarathy S, Carew TE, Khoo JC, Witzum, JL: Beyond cholesterol; modification of low-density lipoprotein that increases its atherogenicity.New Engl J Med320 :915 –924,1989 .[Medline]
10. Djuric Z, Depper JB, Uhley V, Smith D, Lababidi S, Martino S, Heilbrun LK: Oxidative DNA damage levels in blood from women at high risk for breast cancer are associated with dietary intakes of meats, vegetables, and fruits.J Am Diet Assoc98 :524 –528,1998 .[Medline]
11. Hertog MGL, Feskens EJM, Hollman PCH, Katan MB, Kromhout D: Dietary antioxidant flavonoids and risk of coronary heart disease: the Zutphen Elderly Study.Lancet342 :1007 –1011,1993 .[Medline]
12. Keli SO, Hertog MG, Feskens EJ, Kromhout D: Dietary flavonoids, antioxidant vitamins, and incidence of stroke: the Zutphen study.Arch Intern Med156 :637 –642,1996 .[Abstract/Free Full Text]
13. Knekt P, Jarvinen R, Seppanen R, Hellovaara M, Teppo L, Pukkala E, Aroma A. Dietary flavonoids and the risk of lung cancer and other malignant neoplasms.Am J Epidemiol146 :223 –230,1997 .[Abstract/Free Full Text]
14. Miller ER 3rd, Appel LJ, Risby TH: Effect of dietary patterns on measures of lipid peroxidation: results from a randomized clinical trial.Circulation98 :2390 –2395,1998 .[Abstract/Free Full Text]
15. Cao G, Russell RM, Lischner N, Prior RL: Serum antioxidant capacity is increased by consumption of strawberries, spinach, red wine or vitamin C in elderly women.J Nutr128 :2383 –2390,1998 .[Abstract/Free Full Text]
16. Middleton E, Kandaswami C: The impact of plant flavonoids on mammalian biology: implications for immunity, inflammation and cancer. In Harborne JB (ed):"The Flavonoids: Advances in Research since 1986." London: Chapman and Hall, pp619 –652,1994 .
17. Vinson JA, Dabbagh YA, Serry MM, Jang J: Plant flavonoids, especially tea flavonols, are powerful antioxidants using an in vitro oxidation model for heart disease.J Agric Food Chem43 :2800 –2802,1995 .
18. Vinson JA, Su X, Zubik L, Bose P: Phenol antioxidant quantity and quality in foods: fruits.J Agric Food Chem49 :5315 –5321,2001 .[Medline]
19. Vinson JA, Proch J, Bose P: Determination of the quantity and quality of polyphenol antioxidants in foods and beverages.Methods Enzymol335 :103 –114,2001 .[Medline]
20. Rice-Evans CA, Miller NJ, Bolwell PG, Bramley PM, Pridham JB: The relative antioxidant activities of plant-derived polyphenolic flavonoids.Free Radic Res22 :375 –383,1995 .[Medline]
21. US Department of Agriculture, Agricultural Research Service, USDA Nutrient Database for Standard Reference, Release 15, 2002 Nutrient Data Laboratory Home Page, http://www.nal.usda.gov/fnic/foodcomp.
22. Sanz ML, del Castillo MD, Corzo N, Olano A: Formation of Amadori compounds in dehydrated fruits.J Agric Food Chem49 :5228 –5231,2001 .[Medline]
23. Donovan JL, Meyer AS, Waterhouse AL: Phenolic Composition and Antioxidant Activity of Prunes and Prune Juice (Prunus domestica).J Agric Food Chem46 :1247 –1252,1998 .
24. PruneTec,"Prunes test highest in important health-sustaining compounds," Pleasanton, CA, California Prune Board, April,1999 .
25. Vinson JA, Hao Y, Su X, Zubik LS: Phenol antioxidant quantity and quality in foods: vegetables.J Agric Food Chem46 :3630 –3634,1998 .
26. Karadeniz F, Durst RW, Wrolstad RE: Polyphenolic composition of raisins.J Agric Food Chem48 :5343 –5350,2000 .[Medline]
27. Ferreira D, Guyot S, Marnet N, Delgadillo I, Renard CM, Colmbra MA: Composition of phenolic compounds in Portuguese pear and changes after sun-drying.J Agric Food Chem50 :4537 –4544,2000 .
28. Vinson JA, Jang J, Yang J, Dabbagh Y, Liang X, Serry M, Proch J, Cai S: Vitamins and especially flavonoids in common beverages are powerful in vitro antioxidants which enrich lower density lipoproteins and increase their oxidative resistance after ex vivo spiking in human plasma.J Agric Food Chem47 :2502 –2504,1999 .[Medline]
29. Jialal IC, Fuller CJ, Huet BA: The effect of alpha-tocopherol supplementation on LDL oxidation: a dose-response study.Atheroscler Thromb Vasc Biol15 :190 –198,1995 .[Abstract/Free Full Text]
30. Guven M, Onaran I, Ulutin T, Sultuybek G, Hatemi H: Effect of acute hyperglycemia on potassium (86Rb+) permeability and plasma lipid peroxidation in subjects with normal glucose tolerance.J Endocrinol Invest7 :549 –553,2001 .
31. Lebovitz HE: Effect of the postprandial state on nontraditional risk factors.Am J Cardiol88 :20H –5H,2001 .[Medline]
32. Serafini M, Ghiselli A, Ferro-Luzzi A: In vivo antioxidant effect of green and black tea in man.Eur J Clin Nutr50 :28 –32,1996 .[Medline]
33. Durak I, Karaca L, Cimen MB, Kacmaz M, Avci A, Gubat G, Ozturk HS: Dried white grapes enhance blood antioxidant potential.Nutr Metab Cardiovasc Dis12 :204 –205,2002 .[Medline]
34. Putnam JJ, Allshouse JE:"Statistical Bulletin No. 965" U. S. Department of Agriculture, Economic Research Service, Washington, DC: U.S. Government Printing Office,1999 .
35. Oettle GJ, Emmett PM, Heaton KW: Glucose and insulin responses to manufactured and whole-food snacks.Am J Clin Nutr45 :86 –91,1987 .[Abstract/Free Full Text]
36. Miller AB et al.: Fruits and vegetables and lung cancer: Findings from the European Prospective Investigation into Cancer and Nutrition.Int J Cancer10 :269 –276,2004 .
37. Cohen JH, Kristal AR, Stanford JL: Fruit and vegetable intakes and prostate cancer risk.J Natl Cancer Inst5 :61 –68,2000 .
38. Kolonel LN, Hankin JH, Whittemore AS, Wu AH, Gallagher RP, Wilkens LR, John EM, Howe GR, Dreon DM, West DW, Paffenbarger RS Jr: Vegetables, fruits, legumes and prostate cancer: a multiethnic case-control study.Cancer Epidemiol Biomarkers Prev9 :795 –804,2000 .[Abstract/Free Full Text]
39. Schuurman AG, Goldbohm RA, Dorant E, van den Brandt PA: Vegetable and fruit consumption and prostate cancer risk: a cohort study in The Netherlands.Cancer Epidemiol Biomarkers Prev7 :673 –680,1998 .[Abstract]
40. Mills PK, Beeson WL, Phillips RL, Fraser GE: Cohort study of diet, lifestyle, and prostate cancer in Adventist men.Cancer1 :598 –604,1989 .
41. Rubnov S, Kashman Y, Rabinowitz R, Schlesinger M, Mechoulam R: Suppressors of cancer cell proliferation from fig (Ficus carica) resin: isolation and structure elucidation.J Nat Prod64 :993 –996,2001 .[Medline]

This article has been cited by other articles:

				A. Amoros, M.T. Pretel, M.S. Almansa, M.A. Botella, P.J. Zapata, and M. Serrano Antioxidant and Nutritional Properties of Date Fruit from Elche Grove as Affected by Maturation and Phenotypic Variability of Date Palm Food Science and Technology International, February 1, 2009; 15(1): 65 - 72. [Abstract] [PDF]

This Article Abstract Figures Only Full Text (PDF) Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Vinson, J. A Articles by Proch, J. Search for Related Content PubMed PubMed Citation Articles by Vinson, J. A Articles by Proch, J.