How Tomatoes Cut Prostate Cancer Risk

The University of Illinois scientists, who suggested that eating tomatoes reduces risk of prostate cancer, have developed a tool that may help trace the metabolism of tomato carotenoids in the human body.

"Scientists believe that carotenoids-the pigments that give the red, yellow, and orange colours to some fruits and vegetables-provide the cancer-preventive benefits in tomatoes, but we don't know exactly how it happens," said John W. Erdman, of the University of Illinois.

The researchers will use isotopic labeling of three tomato carotenoids with heavier carbon atoms than are commonly seen in nature, which will allow tracking of the tomato components' absorption and metabolism in the body, he said.

"We have two questions we'd like to answer. First, are the carotenoids themselves bio-active, or are their metabolic or oxidative products responsible for their benefits? Second, is lycopene alone responsible for the tomato's benefits, or are other carotenoids also important?" he said.

"Lycopene, which gives the fruit its red color, has received a lot of attention-it's even advertised as an ingredient in multivitamin supplements, but two little-known colorless carotenoids, phytoene and phytofluene, probably also have benefits," said Nancy Engelmann, of the Erdman's laboratory.

The scientists grew tomato cells with non-radioactive carbon-13 sugars, yielding carbon molecules that are heavier than the 12-carbon molecules that exist elsewhere, Erdman said.

"These heavy carbon molecules are then incorporated into the carotenoids in the tomato cell cultures. The result is that researchers will be able to track the activity of lycopene, phytoene, and phytofluene and their metabolites," he said.