Tomatoes are of interest as one such specific food because they are a common source of nutrients for many around the world. They are the second most commonly consumed vegetable and are an important specialty crop across the United States. Over 12 million metric tons of tomatoes are produced in the United States each year, with Americans consuming about 30 pounds per person in 2018 . Tomatoes are a rich source of essential nutrients (e.g., vitamins A and C), fiber, and phytochemicals (e.g., lycopene, flavonoids, and phenolic acids). Tomato consumption has been linked to protection against various chronic diseases , though causality about the mechanism of action is not well understood.
Diets rich in fruits and vegetables have been shown to exert positive effects on the gut microbiome.
Two weeks of eating a diet heavy in tomatoes increased the diversity of gut microbes and altered gut bacteria toward a more favorable profile in young pigs, researchers found.
After observing these results with a short-term intervention, the research team plans to progress to similar studies in people, looking for health-related links between tomatoes in the diet and changes to the human gut microbiome, the community of microorganisms living in the gastrointestinal tract.
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 recently weaned control pigs were fed a standard diet and 10 pigs were fed the standard diet fine-tuned so that 10% of the food consisted of a freeze-dried powder made from the tomatoes.
Fiber, sugar, protein, fat and calories were identical for both diets. The control and study pig populations lived separately, and researchers running the study minimized their time spent with the pigs — a series of precautions designed to ensure that any microbiome changes seen with the study diet could be attributed to chemical compounds in the tomatoes.
Microbial communities in the pigs’ guts were detected in fecal samples taken before the study began and then seven and 14 days after the diet was introduced.
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% 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.
To really understand the mechanisms, it is necessary to do more of this kind of work in the long term in humans. A better understanding could lead to more evidence-based dietary recommendations for long-term health.
Mallory L. Goggans, Emma A. Bilbrey, Cristian D. Quiroz-Moreno, David M. Francis, Sheila K. Jacobi, Jasna Kovac, Jessica L. Cooperstone (November 8 , 2022). Short-Term Tomato Consumption Alters the Pig Gut Microbiome toward a More Favorable Profile. Microbiology Spectrum. Retrieved from : https://journals.asm.org/doi/10.1128/spectrum.02506-22
Photo by Avin CP on Unsplash.