May/June 1998
By C. Leigh Broadhurst, Ph.D.,and James A. Duke, Ph.D.
Tomato products may lower the risk of prostate
cancer
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CAROTENOIDS are just about everywhere you look,
at least in the natural world. These chemicals produce red,
yellow, orange, and sometimes purple colors in plants and
microorganisms, which use them to protect themselves against
damaging sun rays, aid in photosynthesis, and stabilize cell
membranes.
In animals (including humans), some carotenoids help cells
communicate, facilitate cell growth, and protect the body from
ultraviolet radiation and cancer. In the commercial realm, we use
carotenoids to color foods, pharmaceuticals, and cosmetics.
Carotenoids include carotenes, lutein, and lycopene. The body
can convert some carotenes, most notably beta-carotene, into
vitamin A, a reaction that occurs either in the liver or the
intestines. Vitamin A is vital for good vision, healthy skin, bone
growth, and other body functions.
Carotenoids, including lycopene, can only be absorbed properly
when eaten with some form of fat, since fat dissolves them and
carries them through the body. Additionally, foods that contain
carotenoids may need to be cooked, pureed, or finely chopped. This
is especially true when the carotenoid is lycopene, which is found
in calendula (Calendula officinalis), watermelon, tomato, guava,
red grapefruit, bitter melon (Momordica charantia), carrot, rose
hips, and apricot.
The pros of pizza
Some studies suggest that lycopene protects against coronary
artery disease and colon, breast, and prostate cancer. In fact,
researchers have shown that lycopene accumulates in the prostate
gland. A statistical study, spanning six years and published in
1995, focused on the diets of nearly 50,000 American men. The data
show a relationship between lycopene-rich foods and a lower risk of
prostate cancer. Of forty-six foods, only four showed a significant
connection to lower prostate cancer risk: tomato sauce, tomatoes,
pizza with tomato sauce, and strawberries. All of the tomato
products are primary sources of lycopene (the strawberries are
not). The study recommends increased vegetable and fruit
consumption, especially of tomato-based products that have been
cooked and concentrated into paste or sauce.
Studies such as this one only highlight statistical
associations; they don’t prove that something prevents or cures a
disease. “Proving” requires that humans take part in controlled
research studies and that these studies can be duplicated.
Clinical clues
To date, controlled studies indicate that carotenoids work
synergistically with one another and other phytochemicals. In other
words, they perform better when they team up. Just how carotenoids
work together is open to debate, however, and studies have produced
varying results.