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  • Eur J Nutr 42 : 338345 (2003)DOI 10.1007/s00394-003-0430-6 ORIGINAL CONTRIBUTION

    Orly LivnyRam ReifenItzhak LevyZecharia MadarRichard FaulksSue SouthonBetty Schwartz

    -carotene bioavailability from differentlyprocessed carrot meals in human ileostomyvolunteers

    EJN

    430

    Received: 8 January 2003Accepted: 7 May 2003

    O. Livny R. Reifen Z. Madar B. Schwartz, Ph.D. ()Institute of Biochemistry, Food Science and NutritionFaculty of Agricultural, Food and Environmental Quality SciencesThe Hebrew University of JerusalemRehovot 76100, IsraelTel.: +9 72-8/9 48-90 07Fax: +9 72-8/9 36-32 08E-Mail: bschwart@agri.huji.ac.il

    I. LevyDept. of Surgery CSoroka Medical Center and Ben-Gurion UniversityBeer-Sheva, Israel

    R. Faulks S. SouthonDept. of Nutrition, Diet, and HealthInstitute of Food ResearchNorwich Research ParkColney, Norfolk, UK

    Summary BackgroundCarotenoids contribute to the ben-eficial effects of fruits and vegeta-bles consumption; however, thebioavailability of these com-pounds from fresh or processedfoods is not well established. Aim ofthe study We evaluated thebioavailability of -carotene(15 mg) from a single meal com-posed of cooked, pureed carrotsand compared it to raw, choppedcarrots. Methods Test meals weregiven to overnight-fasted-ileostomy volunteers (n = 8) alongwith skimmed-milk yogurt con-taining 40 g of added sunflower oil.Blood and complete ileal effluentsamples were collected over a 24 hperiod. Samples were solvent-ex-tracted and the -carotene contentmeasured by HPLC. Results Kinet-ics of excretion of cis and trans -carotene were similar. More -carotene was absorbed from pureeas compared to raw carrots.Carotenoid mass-balance calcula-tions indicated that 65.17.4 % of

    the -carotene was absorbed fromcooked pureed carrot meals,vs. 41.47.4 % from raw, choppedcarrot meals. Gastrointestinal tran-sit parameters did not differ signif-icantly among the volunteers. Asexpected, the calculated lag phasewas five times longer for raw vs.cooked carrots. Mean t-end, t-1/2and rate of mass transit resulted insimilar values for both raw andcooked carrot meals. A moderateresponse in carotenoid plasma pro-file was observed for cooked carrottest meals. Conclusions Signifi-cantly more -carotene was ab-sorbed from meals containingcooked, pureed carrots than frommeals containing the raw vegetable.Moderate carotenoid plasma re-sponse was detected within 6 h fol-lowing the administration ofcooked processed carotenoid-con-taining single meal.

    Key words carotenoids -carotene ileostomy transittime

    Introduction

    Epidemiological studies have shown that a high veg-etable intake is associated with reduced risk of free rad-ical-mediated degenerative diseases, such as epithelialcancers [1], cardiovascular disease [2] and age-relatedeye diseases [35]. Among the major carotenoids (-carotene, -carotene, lycopene, lutein, zeaxanthin, -

    cryptoxanthin and -cryptoxanthin) absorbed by hu-mans and incorporated into their blood and tissues, -carotene has been studied most extensively [6].

    A significant positive correlation exists between theextent of vegetable intake and plasma concentration ofcarotenoids [79]. In addition, increased vegetable con-sumption results in increased plasma levels ofcarotenoids [1012].

    In studies in which -carotene was given as supple-

  • O. Livny et al. 339-carotene bioavailability from carrot meals

    ment, or in which -carotene was a constituent part offoods, all have shown plasma alterations that are highlyvariable in magnitude and duration, and include non-responders [13] to elevated levels that are still de-tectable 10 to 20 days post-dose [13, 14].

    The absorption of carotenoids from test meals is re-ported to range between 2 and 90 % depending on themeal and the model used to assess absorption [15]. Thebenefit obtained from a high intake of carotenoids fromfruits and vegetables is dependent on the bioavailabilityof these molecules, which is influenced by food type,mode of preparation and individual response [16].

    Plasma concentrations have been erroneously usedin the vast majority of the bioavailability nutritionalstudies to indicate the proportion of carotenoids that areavailable to the body. In addition, determination of ab-sorption of carotenoids has been carried out in humanvolunteers using a large number of methodologies, suchas, oral-fecal mass balance [17], chronic dosing [6,1820], acute dosing [16, 21], triglyceride-rich lipopro-tein carotenoid from acute dosing [22, 23], radioactivetracers [24, 25], stable-isotope tracers [2628], total gas-trointestinal washout (mass balance) method [29], andmore recently, the ileostomy mass-balance model [30].

    This last methodology provides a system to assess theextent of carotenoid absorption and has been recentlyused to determine the extent of carotenoid intake fromcooked spinach meals; however, it has not been tested onadditional vegetables.

    Mass-balance techniques in ileostomy patients [30]have been shown to provide useful absorption datawhile avoiding the confounding influence of the largeintestinal microflora. Even though some residual micro-bial activity remains (colonization of the terminal ileumin ileostomy patients), this activity is not thought tocause any significant loss during transit.

    The purpose of this study was to characterize the ab-sorption and disposal of -carotene in ileostomy sub-jects fed a single portion (equivalent to 15 mgcarotenoids) of raw carrots compared to a single portionof cooked carrots.

    Subjects and methods

    Ethics

    The study protocol was approved by the Ethics Commit-tee for human studies of the Israeli Ministry of Health,and the experimental work was carried out in accor-dance with the Declaration of Helsinki (1989). Informedwritten consent was obtained from each volunteer.

    Volunteers

    Eight volunteers (3875 years) were recruited for thisstudy, which was conducted in Soroka Medical Center.The weight range of the volunteers was 52 to 77 kg and amean BMI of 20.5 kg/m2 (range 18.525.2). The subjectshad undergone ileostomy surgery at least 2.5 years pre-vious to the experiment. They were free of intestinal dis-ease and otherwise healthy, as determined by medicalhistories, blood chemistry tests, lipidogram and com-plete blood count and urine analyses, which were allwithin normal limits.

    Study protocol

    The volunteers avoided consumption of food itemsknown to contain large amounts of carotenoids (a listwas provided) and recorded their habitual diet for 3 daysprior to the test day. The volunteers fasted from 19:00 hthe day before the test but were free to drink water. At08:00 h on the test day (fasted, t = 0) blood samples weretaken,participants then changed the stomal effluent col-lection bag and ate a breakfast containing fat-free yogurtto which 40 g of sunflower oil was added, homogenizedin a low speed blender, and the carotenoid-containingtest meal in the form of ground raw carrots or cookedpureed carrot. Each test meal contained an equivalent of15 mg trans -carotene. Volunteers were provided withcarotenoid-free midday (12:0012:30 h) consisting offat-free chicken breast meat or tofu-based meal accom-panied by potato puree and light refreshments. Theevening meals consisted of sandwich with low fat cot-tage cheese, three slices of bread and tea or coffee. Ve-nous blood samples were collected via antecubital can-nula into 10-ml heparin tubes every 2 h up to 12 h andthe last sample was collected after 24 h. Plasma was sep-arated by centrifugation (5 min, 5000 x g) and frozen at80 C. Stomal effluents were collected into pre-weighedbags every 2 h up to 12 h and the last sample was col-lected after 24 h.

    Analytical methods

    The carotenoid extraction method from effluent andserum samples was evaluated by introducing the inter-nal standard -apo-8-carotenal into the effluent orserum. This internal standard was prepared by dissolv-ing -apo-8-carotenal to a concentration of 0.7 g/ml inhexane. One ml of the internal standard was added to ef-fluent or serum before extraction. The mean percent ofrecovery was 91 % (range 8794).

    Plasma samples (500 l) were treated with sodiumdodecyl sulfate (0.5 ml, 10 mmol/l) and ethanol (1 ml) toprecipitate plasma proteins. The carotenoids were ex-

  • 340 European Journal of Nutrition, Vol. 42, Number 6 (2003) Steinkopff Verlag 2003

    tracted three times by the addition of hexane (2 ml), andthe pooled hexane fraction was dried with a stream ofnitrogen gas. The dry residue was dissolved indichloromethane (100 l) before adding 400 l of ace-tonitrile/methanol (79:21). The carotenoids were mea-sured by HPLC [30]. Effluent samples (2 g) were placedin 50-ml screw-top glass centrifuge tubes and 20 ml ofacetone added. The effluent was thoroughly dispersedusing a small ultra-turrax, the mixture was centrifuged(800 x g, 10 min) to pellet the solids and the supernatantwas transferred to a 100-ml volumetric flask. The pelletwas resuspended in 20 ml acetone and the process re-peated 3 more times. The acetone extract was brought to100 ml, thoroughly mixed and a filtered sub-sample(20 ml) stored at 20 C. A sub-sample (1 ml) of the fil-tered acetone extract was dried under N2, resuspendedin HPLC mobile phase, diluted if needed, and assayed byHPLC as above.

    HPLC analysis

    Samples were injected by using a JASCO Autosampler(model AS-95010; JASCO, Tokyo, Japan) onto a C18, RP(Vydac 201 TP 45) column fitted with a C18 guard col-umn and biocompatible frits. Samples were eluted iso-cratically in the HPLC mobile phase at a flow rate of1.2 ml/min with a model LC-1150 pump (GBC, ScientificEquipment, Victoria, Australia), a multiwave program-mable detector (model MD 910, JASCO) and a BorwinPDA version 1.50 system controller (JASCO).Carotenoids were identified and quantified at 450 nmusing known standards