British Journal of Nutrition

Full Papers

Lycopene from heat-induced cis-isomer-rich tomato sauce is more bioavailable than from all-trans-rich tomato sauce in human subjects

Nuray Z. Unlua1, Torsten Bohna1, David M. Francisa2, Haikady N. Nagarajaa3, Steven K. Clintona4 and Steven J. Schwartza1 c1

a1 Department of Food Science and Technology, The Ohio State University, Columbus, 2015 Fyffe Road, OH 43210, USA

a2 Department of Horticulture and Crop Science, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691, USA

a3 Department of Statistics, The Ohio State University, 1958 Neil Avenue, Columbus, OH 43210, USA

a4 Department of Internal Medicine, Division of Hematology and Medical Oncology, The Ohio State University, 320 West 10th Avenue, Columbus, OH 43210, USA

Abstract

Lycopene is present mainly as cis-isomers in human serum and tissues whereas all-trans-lycopene predominates in tomato products, suggesting that all-trans-lycopene is isomerised in the body or is less bioavailable. The objectives of the present study were to develop processing conditions for tomatoes to obtain products with different cis-trans-lycopene isomer distribution and to assess their bioavailability. Healthy adult subjects (n 12) were recruited for this randomised cross-over trial. Each intervention was preceded by a 2-week washout period. Two tomato sauces, one rich in all-trans-lycopene (32·5 mg total lycopene/100 g sauce; 5 % cis-isomers), the other high in cis-lycopene (26·4 mg total lycopene/100 g sauce; 45 % cis-isomers), were produced by different heat-processing techniques. Each sauce (150 g) was served in a standardised meal at 08.00 hours after overnight fasting. Plasma TAG-rich lipoprotein fractions over 9.5 h following test-meal consumption as a measure of lycopene absorption were obtained and expressed as baseline-corrected area under the concentration v. time curves (AUC), using HPLC-electrochemical detection. AUC values adjusted for the amount lycopene consumed showed that total, total cis-, and all-trans-lycopene responses were significantly higher from the cis-isomer-rich sauce, compared with the all-trans-rich sauce, being 7·30 (sem 1·45) v. 4·74 (sem 1·08) nmol × h/l (P = 0·002), 3·80 (sem 0·76) v. 1·98 (sem 0·37) nmol × h/l (P = 0·0005) and 3·50 (sem 0·76) v. 2·76 (sem 0·76) nmol × h/l (P = 0·01), respectively. The present study demonstrates significant lycopene bioavailability from cis-lycopene-rich tomato sauce and highlights the importance of considering isomer-distribution for lycopene bioavailability. Furthermore, processing parameters can be controlled to alter isomer patterns of tomato products and influence lycopene bioavailability.

(Received October 18 2006)

(Revised January 03 2007)

(Accepted January 09 2007)

Correspondence:

c1 *Corresponding author: Dr Steven J. Schwartz, fax +1 614 292 4233, email schwartz.177@osu.edu

Footnotes

Abbreviations: AUC, area under the concentration v. time curve; OSU, Ohio State University; TRL, TAG-rich lipoprotein