Four Weeks of Tomato-Soy Juice Lowered Inflammation in Adults with Obesity

Key Takeaways:

• In a four-week study, a tomato-soy juice rich in lycopene and soy isoflavones significantly reduced three blood markers of systemic inflammation in healthy adults with obesity, while a control tomato juice lacking those compounds did not.
  
• The researchers chose a low-carotenoid tomato juice as the comparison drink, rather than water, so they could isolate the effects of the lycopene and isoflavones rather than the effects of tomato juice in general.
  
• Building on these results and supporting animal data, the team has secured federal funding for a pilot clinical trial examining whether the same juice can ease inflammation in people living with pancreatitis.
  
  
  

A food-based approach to inflammation

Drinking a tomato-soy juice packed with plant compounds previously shown in animal studies to support health lowered pro-inflammatory proteins in healthy adults with obesity after four weeks, according to a new study. The researchers say the findings point to the juice’s potential as a functional food that could help rein in the persistent, unchecked inflammation that underpins a wide range of chronic conditions.

The juice was formulated to deliver high levels of two plant-based compounds, lycopene and soy isoflavones, both of which earlier research suggests have antioxidant and anti-inflammatory properties. Measured against a control tomato juice that lacked these compounds, the tomato-soy juice produced a significant drop in the blood levels of three proteins that serve as 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?”

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

What is in the juice

Lycopene is a carotenoid, the class of pigments responsible for the colours of tomatoes and various other vegetables. Soy isoflavones are flavonoids that mimic the action of the hormone oestrogen. Both are phytochemicals, naturally occurring compounds that help plants thrive.

Years ago, drawing on studies that linked diets rich in either tomato products or soy with a reduced risk of prostate cancer, Ohio State researchers developed the tomato-soy juice. It was made using tomatoes bred to contain a high concentration of lycopene – varieties also developed and grown at Ohio State – and then enriched with a soy isoflavone extract.

Subsequent research at the university connected a higher intake of the tomato-soy juice with reduced prostate-specific antigen levels in some men with prostate cancer. Studies conducted elsewhere have likewise suggested that tomatoes and soy, whether eaten separately or together, can influence inflammatory and metabolic pathways tied 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.

How the study was carried out

For the new study, 12 healthy adults with obesity drank two 6-ounce cans of the tomato-soy juice every day for four weeks. Following a washout period, the same participants then consumed the low-carotenoid control tomato juice for a further four weeks.

The choice of comparison drink was deliberate. Rather than pitting the juice against plain water, the team selected a tomato juice stripped of the key compounds so that any difference could be attributed to those compounds specifically.

“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.

What the blood tests showed

Before and after each four-week period, the researchers collected blood samples and tested them for cytokines, the pro-inflammatory proteins produced by the immune system. Only the tomato-soy juice produced significant reductions, and it did so in three cytokines: interleukin (IL)-5, IL-12p70 and granulocyte-macrophage colony-stimulating factor (GM-CSF). The juice was also associated with a downward trend in tumour necrosis factor alpha (TNF-a), although that particular change did not reach statistical significance.

Clues from the urine analysis

The team also examined participants’ urine before and after each trial period, looking for changes in metabolites. Metabolites are the molecular products of the biochemical reactions that break down nutrients to generate energy and carry out other essential functions in the body.

The analysis revealed that both the tomato-soy juice and the control tomato juice prompted some of the same shifts in metabolite profiles, indicating that certain tomato-driven effects occurred even in the absence of lycopene. Among the changes specifically induced by the tomato-soy juice, shifts in soy isoflavone metabolites stood out. The researchers note that, while more investigation is warranted, these changes offer further evidence that the food-based intervention is acting on 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.”

Next steps: a pancreatitis trial

On the strength of these results and additional data, Cooperstone and her colleagues have received funding from the National Institute of Diabetes and Digestive and Kidney Diseases for a pilot clinical trial. That trial will test whether consuming the same tomato-soy juice reduces inflammation in people living with pancreatitis.

The team has also gathered evidence from an animal model suggesting that the tomato-soy juice can lessen both inflammation and the severity of chronic pancreatitis. Those findings support the central prediction behind the new clinical trial, namely that the intervention could improve outcomes for people with the condition.

“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.

Funding and contributors

The 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, along with Jenna Miller, Emma Bilbrey, David Francis and Thomas Mace, all 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 principal investigators on that trial.

Source: Eureka Alert!