Tomato Nutrient Lycopene Helps Fight Prostate Cancer
by Dr Gail Valentine
In a recent study, researchers led by Omer Kucuk, MD from the Karmanos Cancer Institute in Detroit gave the antioxidant lycopene to 30 men who were about to undergo surgical removal of their cancerous prostate glands.1 The phytonutrient lycopene, found in tomatoes, is a member of the carotene group. It has been previously shown in studies to help prevent cellular damage and abnormal cellular growth. And now a double-blinded study presents the first direct evidence that lycopene, which makes tomatoes red, may protect men against prostate cancer by shrinking tumors and slowing cancerous spread.
Lycopene has been previously shown in studies to help prevent cellular damage and abnormal cellular growth.
Three weeks prior to scheduled prostate surgery, the subjects were given either lycopene at 15 mg twice daily (30 mg/day) or a placebo. Remarkably, when the cancerous tissue specimens were examined after surgery, the cancers were found to have regressed for the lycopene users, but not for the placebo users. Upon examination, the cancer-affected tissue of the lycopene users was significantly less likely to extend to the edges of the prostate gland. Furthermore, the specimens from the lycopene users were more often correlated with pre-cancerous prostate cells. When compared microscopically, these cells were visually less atypical than the cells from the specimen samples of placebo users, which appeared more abnormal.
Pizza May Be Better Than We Think
The nutrient lycopene first came to the public's attention several years ago when a large cohort study of nearly 48,000 health care professionals was undertaken. Using responses to a food-frequency questionnaire, the dietary intake of the participants was assessed for a one year period and analyzed in relation to prostate cancer.2 The subjects were qualified by being free of cancer. In the follow-up questionnaire, conducted over a six year period, the incidence of prostate cancer was tabulated and matched against the dietary composition of carotenoids such as beta carotene, alpha-carotene, lutein, beta-cryptoxanthin, and lycopene. The researchers found only one clear association between the incidence of prostate cancer and dietary composition, and the dietary component was lycopene. Lycopene was discovered to be significant in its inverse relationship to prostate cancer. In other words, the more lycopene consumed, the less the incidence of prostate cancer.
Lycopene is offered in superior prostate function formulations, available for men who want all the advantages of the latest research. Besides lycopene, multiple other nutrients for enhanced prostate function include saw palmetto, pygeum and garlic extracts, S-allyl L-cysteine, beta carotene, mixed tocopherols and tocotrienols, Vitamin D and zinc.
Some may simply want to supplement their lycopene intake in greater amounts or as a singular supplement.
Computations found that those subjects who had at least 10 weekly servings of tomato-based foods were up to 45% less likely to develop prostate cancer. Of the foods eaten, in ascending order, tomatoes, tomato sauce, and pizza were found to be the most important lycopene sources. Apparently, cooked tomatoes increased lycopene bioavailability. And the presence of cheese (in the pizza) enhanced bioavailability even more so, because lycopene is fat soluble.
The more lycopene consumed, the less the incidence of prostate cancer.
Tomato's Dramatic Immune Function Role
In a prior study, a research team headed by Dr Patrizia Riso of the University of Milan, in conjunction with the Institute of Food Research, in Norwich, U.K., investigated the antioxidant activity of lycopene in 10 women whose intakes were randomized to either a diet of tomato puree or a tomato free diet.3 They hypothesized that lycopene might be shown to protect lymphocyte DNA from oxidative damage. Lymphocytes are cells which are instrumental in immune function. After 21 days, plasma lycopene concentrations increased significantly in women who ate the tomato puree diet but lycopene levels declined in the others who had no tomatoes in their diet.
Researchers used hydrogen peroxide to induce oxidative damage of lymphocyte DNA. They found that subjects, after 21 days of the tomato diet, experienced 33% to 42% more protection than placebo subjects. The researchers conjectured that the lycopene was likely to be responsible.
The more tomato or lycopene eaten, the less cancer incidence. This evidence was strongest for prostate, lung and stomach cancers.
In a recent review of the epidemiological literature, tomato consumption was found to have an inverse relation to various cancers in 57 of 72 studies. This inverse relation was statistically significant in 35 of the 57 studies in which it occurred.4 In other words, the more tomato or lycopene eaten, the less cancer incidence. This evidence was strongest for prostate, lung and stomach cancers. Yet, epidemiological studies do not constitute proof, but do support a strong suspicion that something is true. There were many other compounds in food thought to be causal.
Studies Find Lycopene Lessened Risk for Prostate Cancer
However, with the Karmanos study, at last there is good reason to focus on lycopene. Dr Omer Kucuk and his colleagues at the Karmanos Cancer Institute found that the size of the cancerous tumors in the lycopene-treated group were smaller, and the cancer cells were more likely to be confined to the prostate. The cancer cells had not spread to surrounding tissues or lymph nodes, nor spread even within the prostate. Moreover, blood tests measuring PSA (prostate specific antigen) levels declined overall in those receiving lycopene tomato extract. PSA testing is the most frequently used test for detecting prostate cancer and higher PSA levels are consistent with higher risk for prostate cancer. In the study, PSA levels fell 20% between the start of treatment and surgery in the lycopene patients. PSA levels were unchanged in the placebo group. Also important, the tumors of those consuming the naturally derived phytonutrient lycopene showed signs of actual regression as well as decreased malignancy.
Subjects who had at least 10 weekly servings of tomato-based foods (and especially pizza) were up to 45% less likely to develop prostate cancer.
Quoting Dr Kucuk, "To our knowledge, this is the first report from a randomized prospective clinical trial showing the efficacy of a lycopene supplement against prostate cancer. Previous reports were largely epidemiological studies showing an association between consumption of tomato products and decreased risk of prostate cancer. Furthermore, our findings suggest that lycopene as tomato extract may not only help prevent prostate cancer, but also may be useful in treating prostate cancer."5
Dr. Frank Rauscher of the Wistar Institute in Philadelphia added, "The results are significant. It's remarkable that lycopene may have both therapeutic and preventative value."
"Our findings suggest that lycopene as tomato extract may not only help prevent prostate cancer, but also may be useful in treating prostate cancer."
"If this is real, I would expect to see a decrease in the relapse rate and increased survival in these patients taking lycopene," Kucuk said.
Pizza in a Capsule
The supplement used and given in capsules in the study was a specially cultivated tomato extract designed for optimal lycopene delivery. It is extremely concentrated. The actual amount of lycopene found in two capsules containing 15 mg each is equivalent to about a pound of tomatoes. However, because of poor absorbability from raw tomatoes, you might have to eat two or three pounds per day to raise serum concentrations to the levels of the study. Or one heck of a lot of pizza, every day! But with the availability of tomato-extracted lycopene in supplement form you can now think of an alternative; namely, a heck of a lot of pizza in a capsule.
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- Kucuk, O., et al. Lycopene supplementation in men with localized prostate cancer (PCa) modulates grade and volume of prostatic intraepithelial neplasia (PIN) and tumor, level of serum PSA and biomarkers of cell growth, differentiation and apoptasis. Meeting of the American Association for Cancer Research. Philadelphia. April 1999.
- Giovannucci E, Ascherio A, Rimm EB, Stampfer MJ, Colditz GA, Willett WC. Intake of carotenoids and retinol in relation to risk of prostate cancer. J Natl Cancer Inst.1995 Dec 6;87(23):1767-76.
- Riso P, Pinder A, Santangelo A, Porrini M. Does tomato consumption effectively increase the resistance of lymphocyte DNA to oxidative damage? Am J Clin Nutr.1999 Apr;69(4):712-718.
- Giovannucci E. Tomatoes, tomato-based products, lycopene, and cancer: review of the epidemiologic literature. J Natl Cancer Inst.1999 Feb 17;91(4):317-31.
- Reuters Healthline. April 12, 1999 Web posted at: 1:00 PM EDT (1700 GMT)