Tomato-soy juice lowers inflammation in adults with obesity

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Tomato-soy juice lowers inflammation in adults with obesity

Study hints at potential for a 'functional food' that improves health

Drinking tomato-soy juice loaded with compounds shown in animal studies to promote health lowered pro-inflammatory proteins in healthy adults with obesity after four weeks, a new study found.

The findings hint at the juice's promise as a functional food that may help curb the unchecked inflammation that characterizes a range of chronic conditions, researchers say.

The tomato-soy juice contained high levels of the plant-based compounds lycopene and soy isoflavones, both believed to have antioxidant and anti-inflammatory properties based on previous research. Compared to a control tomato juice lacking these compounds, the tomato-soy juice significantly lowered blood levels of three proteins that are markers of systemic inflammation.

"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?"

Based on these results and additional data, Cooperstone and colleagues have received National Institute of Diabetes and Digestive and Kidney Diseases funding for a pilot clinical trial testing whether consuming the same tomato-soy juice reduces inflammation in patients with pancreatitis.

The study was published recently in the journal Molecular Nutrition & Food Research.

Lycopene is a carotenoid that gives tomatoes and other vegetables their colors, and soy isoflavones are flavonoids that mimic the action of the hormone estrogen. Both are phytochemicals that help plants thrive.

Years ago, based on studies showing an association between diets high in either tomato products or soy and a lowered risk for prostate cancer, Ohio State researchers developed the tomato-soy juice made with tomatoes containing a high concentration of lycopene - also developed and grown at Ohio State - and enriched with soy isoflavone extract.

Later research at the university linked higher intake of the tomato-soy juice to reduced prostate-specific antigen levels in some men with prostate cancer, and studies elsewhere have suggested that tomatoes and soy, consumed separately or combined, can affect inflammatory and metabolic pathways related to obesity and other chronic illnesses.

"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.

In the new study, 12 healthy adults with obesity consumed two 6-ounce cans of tomato-soy juice every day for four weeks. After a washout period, they consumed the low-carotenoid control tomato juice for 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 took blood samples testing for cytokines - pro-inflammatory proteins produced by the immune system - before and after each four-week trial period. Only the tomato-soy juice resulted in significant reductions in three cytokines: Interleukin (IL)-5, IL-12p70 and granulocyte-macrophage colony-stimulating factor (GM-CSF), as well as showing a downward trend in tumor necrosis factor alpha (TNF-a) that was not statistically significant.

The team also analyzed participants' urine before and after each trial period for changes in metabolites, the molecular products of biochemical reactions that break down nutrients to produce energy and perform other essential functions.

The findings showed that both the tomato-soy and control tomato juice led to some shared changes in the metabolite profiles, meaning some tomato-driven effects occurred in the absence of lycopene. Soy isoflavone metabolite shifts stood out among the changes induced by the tomato-soy juice. While further investigation is warranted, the changes provide additional evidence that this food-based intervention is affecting human biology.

"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."

She and colleagues have also found evidence in an animal model that the soy-tomato juice can reduce inflammation and the severity of chronic pancreatitis - data supporting the prediction in the current clinical trial that the intervention could improve outcomes for patients with pancreatitis.

"Care for patients with pancreatitis is palliative, focused on controlling pain and GI symptoms. Our hypothesis is that the tomato-soy juice may serve as an intervention to decrease inflammation and hopefully increase patients' quality of life," Cooperstone said.

This work was supported by the U.S. Department of Agriculture, the National Institutes of Health, the Lisa and Dan Wampler Endowed Fellowship for Foods and Health Research, and the Foods for Health Initiative at Ohio State.

Co-authors include first author Maria Sholola, Jenna Miller, Emma Bilbrey, David Francis and Thomas Mace of Ohio State, and Janet Navotny of the USDA. Mace is the lead principal investigator on the pancreatitis trial. Cooperstone, Philip Hart and Kristen Roberts of Ohio State are also PIs on the trial.

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