New research from Karolinska Institutet in Sweden suggests that certain gut bacteria can transform compounds found in vegetables and other plant foods into molecules that may help protect the cardiovascular and metabolic systems.
Eating vegetables may do more than provide vitamins, minerals and fiber. New research from Karolinska Institutet in Sweden suggests that certain gut bacteria can transform compounds found in vegetables and other plant foods into molecules that may help protect the cardiovascular and metabolic systems.
The study, published in the journal Cell, identified a previously unknown way that the gut microbiome may influence health. Researchers found that gut bacteria can combine dietary nitrate and nonheme iron, the form of iron found primarily in plant foods, to produce molecules called dinitrosyl iron complexes, or DNICs.
Nitrate is naturally abundant in vegetables such as beets, spinach, arugula and lettuce. Nonheme iron is found in foods including beans, whole grains and green vegetables. According to the researchers, gut bacteria can use these dietary components to produce DNICs, which are then absorbed into the bloodstream and transported to organs throughout the body, particularly the liver and kidneys.
The discovery provides another example of how the foods we eat and the microorganisms living in our digestive tract can work together to produce compounds that may influence our health.
The researchers conducted experiments involving mice, human samples, cells and bacteria. Using advanced analytical techniques, they detected DNICs in various tissues and found that the compounds were completely absent in germ-free mice. This suggests that gut bacteria are essential for producing DNICs.
"Our results show that gut bacteria can convert components in food into biologically active molecules that influence important bodily functions," says Andrei L. Kleschyov, senior researcher at the Department of Physiology and Pharmacology at Karolinska Institutet.
The researchers then increased DNIC levels in an animal model of cardiovascular and metabolic disease. They did this either by providing nitrate and iron supplements or by administering synthetically produced DNIC and said the results were encouraging.
"Among other things, we observed lower blood pressure and improved vascular function, better blood sugar control and reduced fat accumulation in the liver," says Mattias Carlström, professor of cardiorenal physiology at Karolinska Institutet. "The results help to explain why a diet rich in vegetables, which contain both nitrate and iron, is linked to a lower risk of several diseases."
The findings add to growing evidence that the health benefits of food cannot always be explained simply by the nutrients listed on a nutrition label.
The body does not necessarily use every nutrient in exactly the same way. Instead, some dietary compounds can be transformed by the trillions of microorganisms living in the digestive tract. These microbial reactions can produce entirely new compounds that may affect organs and biological processes throughout the body.
In this case, researchers believe that the interaction between dietary nitrate, plant-based iron and specific gut bacteria may create DNICs that contribute to cardiovascular and metabolic health.
This may also help explain why diets rich in vegetables have consistently been associated with better health outcomes. Vegetables provide a combination of nutrients and plant compounds while also supplying raw materials that the gut microbiome can transform.
While the findings are promising, it is important to recognize that more work needs to be done as much of the research was conducted using experimental models rather than human clinical trials. Researchers do not yet know whether the same process occurs to the same extent in humans or whether increasing DNIC levels would provide meaningful protection against disease.
The next step is to develop reliable methods for measuring DNICs in people and determine how these compounds are produced, transported through the body and used by different tissues.
Researchers also want to determine whether diet or changes in the gut microbiome can influence DNIC levels. If so, this could eventually provide new insight into how dietary patterns and gut health might work together to reduce the risk of cardiovascular and metabolic disease.
For now, the research offers another reason to appreciate the complex relationship between the foods we eat and the microorganisms living inside us. What happens in the gut may be far more important to overall health than we once realized.
