Review
European Journal of Clinical Nutrition (2007) 61, 295–303. doi:10.1038/sj.ejcn.1602510; published online 16 August 2006
Tomatoes versus lycopene in oxidative stress and carcinogenesis: conclusions from clinical trials
- 1Medical Pathology, UCDavis Health System, Sacramento, CA, USA
- 2Department of Nutrition & Food Sciences, Texas Woman's University, Denton, TX, USA
Correspondence: Dr V Imrhan, Texas Woman's University, Box 425888, Denton, TX 76204, USA. E-mail: vimrhan@twu.edu
Received 11 November 2005; Revised 8 May 2006; Accepted 13 June 2006; Published online 16 August 2006.
Abstract
Objective:
To review the effects of tomato product supplementation, containing lycopene, on biomarkers of oxidative stress and carcinogenesis in human clinical trials.
Results:
Supplementation of tomato products, containing lycopene, has been shown to lower biomarkers of oxidative stress and carcinogenesis in healthy and type II diabetic patients, and prostate cancer patients, respectively. Processed tomato products like tomato juice, tomato paste, tomato puree, tomato ketchup and tomato oleoresin have been shown to provide bioavailable sources of lycopene, with consequent increases in plasma lycopene levels versus baseline. Dietary fats enhance this process and should be consumed together with food sources of lycopene. The mechanisms of action involve protection of plasma lipoproteins, lymphocyte DNA and serum proteins against oxidative damage, and anticarcinogenic effects, including reduction of prostate-specific antigen, upregulation of connexin expression and overall decrease in prostate tumor aggressiveness. There is limited in vivo data on the health benefits of lycopene alone. Most of the clinical trials with tomato products suggest a synergistic action of lycopene with other nutrients, in lowering biomarkers of oxidative stress and carcinogenesis.
Conclusions:
Consumption of processed tomato products, containing lycopene, is of significant health benefit and can be attributed to a combination of naturally occurring nutrients in tomatoes. Lycopene, the main tomato carotenoid, contributes to this effect, but its role per se remains to be investigated.
Sponsorship:
This study was supported by Human Nutrition Fund, Texas. AB wrote the first draft which was finalized by VI. VI also designed Figure 1.
Keywords:
tomatoes, lycopene, oxidative stress, DNA, lipoproteins, prostate cancer
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