High Intake of Lycopene and Alpha-Carotene Lowers Risk By 20-25 Percent
October 11, 2000 – A new study conducted by a team of Harvard researchers links diets rich in tomato-based foods and carrots to reduced risk of lung cancer. Each year in the United States, over 150,000 men and women die of lung cancer — more than any other cancer.
“Our data suggest that lycopene is an important carotenoid for protection against lung cancer, especially in current smokers,” says Edward Giovannucci, M.D., Sc.D., of Harvard School of Public Health, and one of the study’s lead researchers.
The findings, reported in the October issue of the American Journal of Clinical Nutrition (AJCN), are the result of an analysis of over 124,000 men and women participating a ten-year period in the Health Professionals Follow Up Study and the Nurses Health Study. Researchers at the Harvard School of Public Health found that individuals consuming the highest amounts of two carotenoids in their diet, alpha-carotene and lycopene, had a 20-25% lower risk of lung cancer.
The Harvard findings provide additional support for the potential health benefits of vegetables such as processed tomato products and carrots. Previous studies examining the relationship between fruit and vegetable intake and the risk of lung cancer have generally found that fruits and vegetables have a protective effect. The latest study found specifically that foods containing lycopene and alpha carotene appear to provide protection against lung cancer.
Lycopene, the natural pigment that gives tomatoes their red color, is obtained predominantly from tomato-rich foods such as pasta sauces, tomato soups, tomato-based vegetable juice and ketchup which provide more than 85% of dietary lycopene in the American diet. Alpha-carotene is found in carrots and multi component foods such as tomato-based vegetable juice.
According to Dr. Giovannuci, “We also observed a stronger association with lycopene and lung cancer when we took into consideration forms of tomato-rich foods that enhanced the body’s ability to absorb and use lycopene. The body is better able to absorb and use the lycopene in cooked tomato products than raw tomatoes,” he said.
Dr. Giovannucci also pointed out that for non-smokers who have never smoked, high intakes of alpha-carotene were found to significantly lower the risk of lung cancer. It was Dr. Giovannucci who conducted an earlier review of 72 studies evaluating tomato and tomato product intake, blood lycopene levels and their association with cancer risk reduction. That study was published in the Journal of the National Cancer Institute (February 17, 1999) and concluded that intake of tomatoes and tomato-rich foods was associated with a lower risk of a variety of cancers, including prostate cancer.
In an editorial in AJCN commenting on the new Harvard study, Dr. David Heber, M.D., Ph.D., Director of the Center for Human Nutrition at the University of California at Los Angeles, points out that “a significant reduction in cancer risk was noted in association with an increased intake of lycopene, even in smokers. Interestingly, smoking alters the concentration of most carotenoids, including beta-carotene, but not lycopene.”
In a separate interview, Dr. Heber emphasized that “while smoking cessation remains the most important strategy for preventing lung cancer, lycopene may have a special role in lung cancer prevention. Based on these observations, I would recommend that men and women interested in reducing their risk of cancer eat at least five servings of tomato products per week,” stated Dr. Heber. “As little as six ounces of tomato-based vegetable juice or an eight ounce serving of tomato soup have been shown to help elevate blood lycopene levels,” he said.
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