Drinking a specially formulated tomato-soy juice rich in plant compounds linked to health benefits reduced several markers of inflammation in adults with obesity after just four weeks, according to new research.
The findings suggest the beverage could serve as a functional food capable of helping control chronic inflammation, a process that contributes to many long-term health conditions.
Researchers found that the juice, which contains high levels of lycopene and soy isoflavones, significantly lowered blood concentrations of three proteins associated with systemic inflammation when compared with a control tomato juice that lacked those compounds.
“The idea is, can we use food-based interventions to modulate inflammation?” said lead author Jessica Cooperstone, associate professor of horticulture and crop science at The Ohio State University. “And can we test this in a rigorous way so that we can really see this is affecting inflammation, versus just saying something is anti-inflammatory?”
Building on these results and other supporting evidence, Cooperstone and colleagues have secured funding from the National Institute of Diabetes and Digestive and Kidney Diseases for a pilot clinical trial investigating whether the same tomato-soy juice can reduce inflammation in people with pancreatitis.
The study was recently published in the journal Molecular Nutrition & Food Research.
Why Tomatoes and Soy?
Lycopene is a carotenoid responsible for the red color of tomatoes and certain other fruits and vegetables. Soy isoflavones belong to a group of compounds called flavonoids and can mimic some actions of the hormone estrogen. Both are naturally occurring phytochemicals that play important roles in plant health.
The tomato-soy juice used in the study was developed years ago by Ohio State researchers after earlier studies suggested that diets rich in tomato products or soy were associated with a lower risk of prostate cancer. The juice was made using tomatoes specially bred to contain elevated levels of lycopene and was fortified with soy isoflavone extract.
Subsequent research at Ohio State found that increased consumption of the juice was linked to lower prostate-specific antigen levels in some men with prostate cancer. Other studies have also indicated that tomatoes and soy, either separately or together, may influence inflammatory and metabolic processes connected to obesity and other chronic diseases.
“There’s been enough compelling evidence that compounds from tomatoes and soy might be modulating inflammation that we decided to test this in people,” Cooperstone said.
Human Trial Reveals Reduced Inflammation
The study involved 12 healthy adults with obesity. Participants drank two 6-ounce cans of the tomato-soy juice each day for four weeks. Following a washout period, they consumed a low-carotenoid tomato juice for another four weeks.
“The hypothesis is that it’s the lycopene from the tomatoes and the isoflavones from the soy that’s inducing the effect, so we didn’t want to have a control that’s just water,” Cooperstone said.
Researchers collected blood samples before and after each four-week period and measured cytokines, which are inflammatory proteins produced by the immune system.
Only the tomato-soy juice produced significant reductions in three cytokines: Interleukin (IL)-5, IL-12p70 and granulocyte-macrophage colony-stimulating factor (GM-CSF). Researchers also observed a decrease in tumor necrosis factor alpha (TNF-a), though that change did not reach statistical significance.
Changes Seen Beyond Inflammatory Markers
The team also examined participants’ urine samples before and after each phase of the study to look for shifts in metabolites, the molecules produced when the body breaks down nutrients and carries out essential biological processes.
Some metabolite changes appeared after consumption of both the tomato-soy juice and the control tomato juice, indicating that tomatoes may produce biological effects even without high levels of lycopene.
However, changes related to soy isoflavone metabolites stood out in participants who consumed the tomato-soy juice. While researchers say more study is needed, these results provide additional evidence that the beverage is influencing human biology in measurable ways.
“This is probably a function of the fact that there’s more to our intervention agents than just these two compounds,” Cooperstone said. “Ultimately, we want to have a better understanding of how the foods that we eat are relating to our health. And when we really want to be sure, we need to test them in clinical trials. And that’s what we’re doing here.”
