Researchers reveal tomatoes’ health benefits to gut microbes

According to a recent study, young pigs’ gut microbes were shifted toward a more desirable profile following two weeks of eating a tomato-rich diet.

The findings were reported in the journal Microbiology Spectrum. Following the observation of these results with a short-term intervention, the research team intends to conduct similar studies in humans, looking for health-related links between tomato consumption and changes in the human gut microbiome – the community of microorganisms living in the gastrointestinal tract.

“It’s possible that tomatoes impart benefits through their modulation of the gut microbiome,” said senior author Jessica Cooperstone, assistant professor of horticulture and crop science and food science and technology at The Ohio State University.

“Overall dietary patterns have been associated with differences in microbiome composition, but food-specific effects haven’t been studied very much,” Cooperstone said. “Ultimately we’d like to identify in humans what the role is of these particular microorganisms and how they might be contributing to potential health outcomes.”

The tomatoes used in the study were developed by Ohio State plant breeder, tomato geneticist, and co-author David Francis, and are the type typically found in canned tomato products.

“It’s possible that tomatoes impart benefits through their modulation of the gut microbiome,” said senior author Jessica Cooperstone, assistant professor of horticulture and crop science and food science and technology at The Ohio State University.

“Overall dietary patterns have been associated with differences in microbiome composition, but food-specific effects haven’t been studied very much,” Cooperstone said. “Ultimately we’d like to identify in humans what the role is of these particular microorganisms and how they might be contributing to potential health outcomes.”

The tomatoes used in the study were developed by Ohio State plant breeder, tomato geneticist, and co-author David Francis, and are the type typically found in canned tomato products.

Ten newly weaned control pigs were fed a conventional diet, and ten pigs were fed the usual diet with 10% of the meal made up of a freeze-dried tomato powder.

Both diets included the same amount of fibre, sugar, protein, fat, and calories. The control and study pig populations were kept separate, and the researchers who ran the study spent as little time as possible with the pigs – a series of precautions designed to ensure that any microbiome changes observed with the study diet could be attributed to chemical compounds in the tomatoes.

Microbial communities in the pigs’ stomachs were found in faecal samples collected before the trial began, as well as seven and fourteen days after the food was introduced.

The team used a technique called shotgun metagenomics to sequence all microbial DNA present in the samples. Results showed two main changes in the microbiomes of pigs fed the tomato-heavy diet – the diversity of microbe species in their guts increased, and the concentrations of two types of bacteria common in the mammal microbiome shifted to a more favorable profile.

This higher ratio of the phyla Bacteroidota (formerly known as Bacteriodetes) compared to Bacillota (formerly known as Firmicutes) present in the microbiome has been found to be linked with positive health outcomes, while other studies have linked this ratio in reverse, of higher Bacillota compared to Bacteroidota, to obesity.

Tomatoes account for about 22 per cent of vegetable intake in Western diets, and previous research has associated consumption of tomatoes with reduced risk for the development of various conditions that include cardiovascular disease and some cancers.

But tomatoes’ impact on the gut microbiome is still a mystery, and Cooperstone said these findings in pigs – whose gastrointestinal tract is more similar than rodents’ to the human GI system – suggest it’s an avenue worth exploring.

“This was our first investigation as to how tomato consumption might affect the microbiome, and we’ve characterized which microbes are present, and how their relative abundance has changed with this tomato intervention,” she said.

“To really understand the mechanisms, we need to do more of this kind of work in the long term in humans. We also want to understand the complex interplay – how does consuming these foods change the composition of what microbes are present, and functionally, what does that do?

“A better understanding could lead to more evidence-based dietary recommendations for long-term health.”