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
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
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.