Tomatoes and broccoli are two vegetables known for their cancer-fighting properties. But when used together, they are more effective in shrinking prostate tumors than they are used separately, the new research stressed.

"When tomatoes and broccoli are eaten together, we see an additive effect. We think it's because different bioactive compounds in each food work on different anti-cancer pathways," said John Erdman, professor in food science and human Nutrition at the University of Illinois.

In the study, Erdman and his doctoral student Kirstie Canene-Adams fed a diet with 10 percent tomato powder and 10 percent broccoli powder to laboratory rats that had been implanted with prostate cancer cells. The powders were made from whole foods.

As control, other rats in the study received either tomato or broccoli powder alone; or a lycopene supplement, or finasteride, a drug prescribed for men with enlarged prostates.

Another group of rats was castrated.

Lycopene is the red pigment found in tomatoes that is believed to be the effective cancer-preventive agent.   The researchers used it to see how the isolated tomato compound would act differently from the powder from whole tomatoes.

Broccoli and other cruciferous vegetables are known to have sulfur compounds, a group of the cancer-fighting agents that enhance certain detoxification enzymes in the human body. Dr. Elizabeth Jeffery, a colleague of John’s at the University has found that these enzymes are responsible for the degradation of carcinogens or the cancer causing agents.

After 22 weeks of treatment starting one month prior to receiving tumor cells, rats on the diet with the tomato/broccoli combo had their tumors shrunk to a greater degree than other groups of rats whereas rats castrated experienced comparable results.

Specifically, “lycopene at 23 or 224 nmol/g of the diet insignificantly reduced tumor weights by 7% or 18%, respectively, whereas tomato reduced tumor weight by 34%. Broccoli decreased tumor weights by 42% whereas the 10:10 combination caused a 52% decrease,” the researchers write in their report.

In comparison, castration reduced prostate weights, tumor areas, and tumor weight by 62% whereas finasteride reduced tumor are or weight, but had no effect on tumor area or weight.

Biopsies confirmed that tumor cells in the tomato/broccoli rats were not proliferating as rapidly as those on other diets, according to the study.   The tomato/broccoli combo also increased apoptosis of cells, promoting deaths of cancer cells.

“Older men with slow-growing prostate cancer who have chosen watchful waiting over chemotherapy and radiation should seriously consider altering their diets to include more tomatoes and broccoli," said Canene-Adams.

To get these effects in men, 1.4 cups of raw broccoli and 2.5 cups of fresh tomato or equivalent amounts of tomato sauce or tomato paste should be consumed daily, according to Canene-Adams.

The results of the study showed eating tomatoes is more beneficial than eating a lycopene supplement, suggesting that eating whole foods is better than taking supplements, Erdman said.

In addition, “Cooked tomatoes may be better than raw tomatoes. Chopping and heating make the cancer-fighting constituents of tomatoes and broccoli more bioavailable," he added.

John’s team conducted a study earlier and found that the tomato powder, tomato carotenoids phytofluene, and lycopene reduced testosterone levels in men.   The study was published in the December 2006 issue of the Journal of Nutrition.  

Evidence has been reported that most prostate cancers are hormone-sensitive. Reducing the male hormone would inhibit growth of prostate cancer.

The results indicate that one's diet plays an important role in risk of prostate cancer and other types of cancer.  

Dr. Dean Ornish, president and founder of the nonprofit Preventive Medicine Research Institute in Sausalito, California, as well as Clinical Professor of Medicine at the University of California, San Francisco,  published a research article in the Sept. 2005 issue of The Journal of Urology saying that his dietary and lifestyle program works for prostate cancer patients.

In his study, a group of patients with prostate cancar who chose not to undergo conventional treatment were assigned a vegan diet (all veggies and no dairy) and antioxidant supplements.   Also they were instructed to do aerobic exercise and stress management.

After 12 months, prostate specific antigen (PSA) was found much lower in the treated group than the group who were not treated with the former decreased by 4 percent and the latter increased by 6 percent.

When serum samples from the groups were applied to prostate cancer cell lines, the cells treated with the serum from people who were not on the program grew eight times faster than those cells treated with serum from men who underwent the program.

Overall evidence shows that a healthy dietary practice may likely get prostate cancer under control if not cured.

Sources:

Combinations of Tomato and Broccoli Enhance Antitumor Activity in Dunning R3327-H Prostate Adenocarcinomas
Cancer Res first published on January 9, 2007 as doi:10.1158/0008-5472.CAN-06-3462 [Abstract] [PDF]
Authors of the tomato/broccoli study are Kirstie Canene-Adams, Brian L. Lindshield, Elizabeth H. Jeffery, and John W. Erdman Jr. at the University of Illinois and Shihua Wang and Steven K. Clinton of The Ohio State University. The study was funded by the American Institute for Cancer Research and the U.S. Department of Agriculture.
 

Title: Serum Testosterone Is Reduced Following Short-Term Phytofluene, Lycopene, or Tomato Powder Consumption in F344 Rats
2006 American Society for Nutrition J. Nutr. 136:2813-2819, November 2006
Authors: Jessica K. Campbell, Chad K. Stroud, Manabu T. Nakamura, Mary Ann Lila and John W. Erdman, Jr.^* Division of Nutritional Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801
Funding was provided by the National Institutes of Health's National Cancer Institute.
 

Can Diet Really Control Prostate Cancer?
Mark Scholz, MD and Ralph Blum
PCRI Insights February 2006 vol. 9, no. 1