More Vegetables May Help Reduce Fatty Liver as Gut Bacteria Produce a Key Molecule

Vegetables may provide more than the nutrients the body absorbs directly. Researchers in Sweden have identified a molecule that gut bacteria can produce from compounds found in vegetables and legumes, then pass into tissues beyond the intestines.

The team from Karolinska Institutet found that bacteria use dietary nitrate and non-heme iron to form dinitrosyl iron complexes, known as DNICs. Nitrate occurs in foods such as beetroot, spinach, arugula and lettuce. Non-heme iron is found in beans, whole grains and green vegetables.

The researchers detected DNICs in the tissues of ordinary mice, but not in germ-free mice. Experiments with mouse and human fecal samples also showed similar DNIC production. The findings point to gut bacteria as an important part of this previously underexplored metabolic pathway.

In another mouse experiment, raising DNIC levels was associated with lower blood pressure, improved blood vessel function, better blood sugar control and less fat accumulation in the liver. A human liver-cell model also showed that DNIC reduced fat buildup caused by fatty acids.

The findings do not establish that eating more vegetables prevents heart disease or diabetes. The clearest health effects came from mouse disease models, while the human evidence involved laboratory material such as fecal samples and liver cells. Researchers still need to determine how DNIC forms and moves through the human body, and whether it produces similar benefits. They also want to test whether diet or changes in gut bacteria can alter DNIC production.