ANTIOXIDANT
POWERHOUSE

The colorful carotenoid lycopene beats out even beta carotene at
fighting free radicals.

By Marcia Zimmerman, M.Ed., C.N.

Pizza lovers rejoiced when Harvard scientists reported that tomato sauce, even on pizza, might protect against prostate cancer. Pizza is a medical food? There's more to the story.

So plentiful this time of year, luscious, ripe red tomatoes, along with watermelon, guava, strawberries and pink grapefruit, get their color from a pigment called lycopene. It turns out that lycopene - a member of the carotenoid family, which includes beta carotene - is a powerful scavenger of singlet oxygen free radicals.

In fact, lycopene beats out beta-carotene in free-radical quenching and it's slightly more abundant in the blood than beta-carotene. Lycopene is stored in the breast, color, liver, lungs, prostate gland, skin and testes and science is finding it to be a powerful ally in fighting free-radical-generated cancers.

ANTIOXIDANT PROTECTION

Recent research has uncovered the powerful antioxidant protection we get by eating lycopene-rich foods and taking supplements. Surprisingly, cooked tomato products (including tomato paste and tomato sauce, even on pizza) pack more bioavailable lycopene than the raw fruit. In one study lycopene absorption from cooked tomato paste was found to be nearly four times greater than that from fresh tomatoes. In addition, lycopene is best absorbed when some fats or oils are consumed along with it.

The human body is equipped with numerous antioxidant mechanisms for neutralizing free radicals. However, once we pass our late 20s, these protective mechanisms gradually decline and free radicals accumulate. That's the primary reason why we age and succumb to age-related conditions such as cancer and heart disease. Scientists have known for a long time that eating foods rich in carotenoids delays the onset of degenerative diseases by boosting the body's antioxidant capacity.

FIGHTING CANCER

Free radicals cause genetic damage that results in cellular transformations leading to cancer. A recent small study has shown that daily consumption of 7 mg of lycopene in tomato purée cut DNA damage in lymphocytes (white blood cells) in half, while significantly elevating serum lycopene levels. In an in vitro study reported in Anticancer Research, this carotenoid appears to improve the cellular differentiation that maintains normal metabolism, thus limiting the growth of cancer cells. Carotenoids, including lycopene, improve communication between cells, helping them resist damage from cancer-promoting agents.

A review of the scientific literature on lycopene's anticancer activities by Harvard's Edward Giovanannucci, MD, ScD, has show the most significant benefits in prostate, lung and stomach cancers. Lycopene may also be protective against cancers of the pancreas, colon, rectum, esophagus, oral cavity, breast and cervix.

Prostate Cancer. Dr. Giovannucci and his colleagues at Harvard and at Brigham and Women's Hospital gathered information from 47,894 participants in Boston's ongoing Health Professionals Study. They found a striking reduction in the occurrence of prostate cancer among men who ate the most cooked tomato products. Their conclusions from this study have been corroborated by subsequent studies.

Other investigators have studied the effects of lycopene on men who already have prostate cancer. Supplementation with lycopene (15 mg twice daily) reduced tumor size, biomarkers of cancerous growth and levels of prostate-specific antigen (PSA). (Elevated PSA levels are considered a marker for prostate disease, including cancer.) Lycopene may be useful as complementary therapy for those being treated for prostate cancer and supplementation is a convenient way to ensure consistent levels of intake.

Women's Cancers. In studies of cell growth, lycopene blocks membrane receptors that signal breast cancer cells to grow. The specific mechanism by which this occurs has been a topic of interest among scientists. In a study published in 2001, researchers in Israel found that lycopene blocks the progression of breast and endometrial cancer cells by a method similar in some ways, to that of tamoxifen.

In addition, low blood levels of vitamin A and carotenoids have long been associated with occurrence of cervical dysplasia and cervical cancer. A dietary study at the University of Pennsylvania School of Medicine compared the blood levels of vitamin A and lycopene of African American women who had cervical dysplasia or cancer to blood levels of those who had no symptoms of dysplasia. Researchers found that women who consumed the greatest amount of lycopene were one-third less likely to have dysplasia than as women consuming the lowest amounts. As for vitamin A, those with the highest consumption were one-fourth as likely to have symptoms as women with the lowest consumption. Investigators concluded that lycopene (and vitamin A to a lesser degree) may play a protective role in the early stages of cervical carcinogenesis.

CARDIOVASCULAR DISEASE

While a diet rich in fruits and vegetables has been shown to reduce the risk of cardiovascular disease (CVD), finding exactly which dietary components are most protective has proven difficult. Researchers at the University of North Carolina, Chapel Hill, recently reviewed studies to determine how lycopene helps protect against CVD. Protective effects of lycopene appear to come from its lowering of unhealthy LDL degradation within tissues. In vitro studies of human cells grown in a lycopene-rich medium, have show a 73 percent reduction in cholesterol synthesis and a 34 percent rise in rates of LDL degradation. A small follow-up study with six people who took daily lycopene supplements (60 mg) for three months found a 14 percent reduction in LDL cholesterol with no change in healthy HDL cholesterol levels. Other investigators say this equates to a 30 to 40 percent reduction in risk of heart attack.

Atherosclerosis is a degenerative process where plaque builds up in arteries, narrowing the blood vessel diameter and impeding blood flow. White blood cells or monocytes adhere to vessel walls as atherosclerotic lesions develop. Carotenoids appear to reduce monocyte's sticking and lycopene is the most effective antiadhesion carotenoid, reducing adhesion up to 25 percent.

Hypertension is another major factor in the development of CVD. To discover if lycopene could lower blood pressure, doctors gave 20 people with mild hypertension a tomato oleoresin supplement containing 15 mg of lycopene daily for 8 weeks. Results show a 9-mm average reduction in systolic (top number) and 7-mm reduction in diastolic (bottom number) blood pressure following lycopene supplementation. Adding a lycopene supplement to conventional antihypertensive therapy may help control the condition, researchers note.

THE BOTTOM LINE

"The consistently lower risk of cancer for a variety of anatomic sites that is associated with higher consumption of tomatoes and tomato-based products adds further support for current dietary recommendations to increase fruit and vegetable consumption," says Dr, Giovannucci, at Harvard Medical School. However, for those who experience acid indigestion when consuming large amounts of whole tomato products - or anyone who wants a consistent intake of this carotenoid - lycopene supplements are available in natural products stores. Because supplements are prepared from tomato seed oil, they are less acidic than the fruit. Look for soft-gel capsules (Recommended daily dosage is 5 to 15 mg.)§

Selected Sources
♦ "Absorption of Lycopene from Single or Daily Portions of Raw and Processed Tomato" by M. Porrini et al, Br J Nutr, 1998   ♦ "Dietary Intake and Blood Levels of Lycopene: Association with Cervical Dysplasia among Non-Hispanic Black Women by P. A. Kantesky et al. Nutr Cancer, 1998  ♦ "Lower Prostate Cancer Risk in Men with Elevated Plasma Lycopene Levele . . ." by P. H. Gann et al., Cancer Res, 1999  ♦ "Lycopene and Cardiovascular Disease" by Lenore Arab and Susan Steck, Am J Clin Nutr, 2000  ♦ "Lycopene Inhibition of Cell Cycle Progression in Breast and Endometrial Cancer Cells . . ." by Amit Nahum et al., Oncogene, 2002  ♦ "Phase II Randomized Clinical Trial of Lycopene Supplementation before Radical Prostatectomy" by G. Kucuk et al., Cancer Epidemiol Biomarkers Prev, 2001  ♦ "Tomato Lycopene and Low Density Lipoprotein Oxidation: a Human Dietary Intervention Study" by S. Agarwal and A. V. Rao, Lipids, 1998 

Copyright©, 2001 by The Zimmerman Group, Inc. All rights reserved. Except as permitted under the Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher.

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