Lycopene: A potent antioxidant

Lycopene, one of 600 carotenoids, is found in fruits and vegetables. It is one of the prominent carotenoids of tomato that gives it a red color. Unlike most carotenoids, it is not readily available in vegetables other than tomatoes. 80% of lycopene consumed in the United States is derived from tomato products. Pink grapefruit, fresh papaya, raw guava, watermelon, dried apricots and pureed rosehips all contain only traces of this nutrient.

Its chemical structure contributes to the beneficial effect as a free radical scavenger and antioxidant agent in living cells. In decades after 1970, there has been an accumulation of evidence in support of fruit and vegetable diet for a lower risk of many cancers. Of all the carotenoids, lycopene is one of the most potent antioxidants.

The lycopene content of tomatoes varies considerably with variety and ripening stage of tomatoes. Lycopene concentrations in the red strains are 50 mg/kg whereas yellow varieties have only 5 mg/kg.

Unlike other fruits and vegetables where nutritional content such as vitamin C is diminished upon cooking, processing of tomatoes with heat increases the concentration of bioavailable lycopene. For instance, tomato paste contains four times more bioavailable lycopene than fresh tomatoes.

Use Of Lycopene And Prostate Cancer Risk:

Greek scientists compared the dietary habits of 320 men with prostate cancer to 246 normal patients as a control. They found that consumption of cooked tomatoes was inversely proportional to cancer risk.

The findings from the Health Professionals Follow-Up Study (HPFS) from 1986 through 1992, suggest that frequent intake of tomato products or lycopene, a carotenoid from tomatoes, is associated with reduced risk of prostate cancer. The data is provided and analyzed by researchers of Harvard Medical School.

University of California based researchers investigated the role of lycopene and other carotenoids – retinol and tocopherol on the risk of prostate cancer. The study included 65 patients with prostate cancer and 132 cancer-free controls from 1993 to 1997. Plasma levels of carotenoids, retinol, and tocopherols were measured by high performance liquid chromatography. This study demonstrated the inverse associations between lycopene and other carotenoids and prostate cancer.

Researchers from University of Illinois, Chicago explored the potential of lycopene to prevent prostate cancer. The National Foundation for Cancer Research awarded a $300,000 grant to Phyllis Bowen, the professor in department of Human Nutrition and Dietetics. This research was closely supported by department of pharmacognosy and medicinal chemistry.

The team gave prostate cancer patients either lycopene pills or a placebo for three weeks prior to biopsy or surgery of prostate cancer. They tried to determine whether lycopene is taken by prostate cells and its preventive effect on DNA damage and on white blood cells.

They demonstrated that lycopene is readily absorbed into the prostates of men with prostate cancer and is associated with decreases in prostate-specific antigen and DNA damage to cells in prostate tissue.

Dosage Of Lycopene:

It is taken normally in the dosage of 15-50 mg per day and is well tolerated in this dosage. No adverse effects had been reported with significantly higher dosage.

Research Resources:

1) Tomatoes GE. Tomato-based products, lycopene, and cancer: Review of the epidemiologic literature. J Natl Cancer Inst 91:317–331, 1999.

2) Edward Giovannucci, Eric B. Rimm, Yan Liu, Meir J. Stampfer, Walter C. Willett
Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA; Departments of Nutrition and Epidemiology, Harvard School of Public Health, Boston.

3) Qing-Yi Lu, Jui-Chun Hung, David Heber, Vay Liang W. Go, Victor E. Reuter, Carlos Cordon-Cardo, Howard I. Scher, James R. Marshall and Zuo-Feng Zhang
Center for Human Nutrition, University of California at Los Angeles School of Medicine; Arizona Cancer Center, Tucson, Arizona; Memorial Sloan-Kettering Cancer Center, New York;

4) Craig W. Hadley, Elizabeth C. Miller, Steven J. Schwartz and Steven K. Clinton
Department of Food Science and Technology; Division of Hematology and Oncology, and Division of Hematology and Oncology, The James Cancer Hospital and Solove Research Institute, The Ohio State University, Columbus, Ohio 43210

5) Kolonel L, Hankin H, Whittemore A, 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 Prev 9:795–804, 2000.