"Scientists believe that carotenoids, the pigments that give the red, yellow, and orange colors to some fruits and vegetables, provide the cancer-preventive benefits in tomatoes, but we don't know exactly how it happens," said John Erdman, Professor Emeritus, Department of Food Science and Human Nutrition, Illinois University.
The researchers will use isotopic labeling of three tomato carotenoids with heavier than normal carbon atoms which will allow tracking of the tomato components' absorption and metabolism in the body.
“We use the tomato cell as a bio-factory to produce stable isotopically labeled tomato carotenoids for human metabolism trials,” Erdman told NutraIngredients-USA.com.
“This tool will allow us to examine tomato carotenoid absorption and metabolism using non-radioactive tracers. This will provide key information about the health aspects of the tomato carotenoids lycopene, phytoene and phytofluene.”
Currently it is not clear to what extent the tomato carotenoids contribute to chronic disease prevention and the tool promises to help scientists clarify absorption and metabolism of these bioactive compounds.
"We have two questions we'd like to answer. First, are the carotenoids themselves bioactive, 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?" said Erdman.
His previous animal studies have shown that whole tomato powder, which contains all of the fruit's nutritional components, is more effective against prostate cancer than lycopene alone.
Nancy Engelmann, a doctoral student in Erdman's laboratory who helped develop the new method, 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."
Engelmann optimized the amount of carotenoids in tomato cell cultures by treating already high-achieving tomato varieties with two plant enzyme blockers. The best performers were then chosen for culturing and carbon-13 labeling.
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.
Lycopene, phytoene, and phytofluene
Erdman added: "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."
The $400,000 NIH grant to be spread over three years was made to the University of Illinois and Ohio State University.
Usually occurring in older men, NCI estimates that there will be more than 217,000 new cases of prostate cancer in the US this year resulting in over 32,000 deaths.