Leafy Greens, Your Intestinal Health and Fighting Salmonella

Sugar molecule sulfoquinovose (SQ) in leafy greens feeds gut good bacteria


Not all bacteria are bad for you. In the case of your intestinal health, some bacteria are vitally important.

Researchers from Melbourne, Australia and the United Kingdom have discovered leafy greens are critical for feeding the good bacteria in your gut. An unusual sugar molecule in the greens promotes the growth of good bacteria.

The gut microbiome is a term used to describe the trillions of bacteria in the human intestinal system. More than 1,000 species of bacteria colonize the gut, according to a January 2015 article in Clinica Chimica Acta.

Gut bacteria influence obesity, inflammatory diseases (i.e. ulcerative colitis) and immune diseases (i.e. rheumatoid arthritis).

Antibiotics can disturb the balance of the gut microbiome. This leads to an overgrowth of bad bacteria.

The new research indicates that proper feeding of good bacteria by eating leafy greens limits the ability of bad bacteria to grow in the gut. The leafy greens contain an unusual sugar called sulfoquinovose (SQ).

Lead author Ethan Goddard-Borger, PhD, commented in a press release, "Every time we eat leafy green vegetables we consume significant amounts of SQ sugars, which are used as an energy source by good gut bacteria.”

Dr. Goddard-Borger and colleagues discovered an enzyme called YihQ. Bacteria use YihQ to absorb and metabolize SQ as food. The researchers theorized that when gut bacteria are properly fed with lots of SQ, they prevent overgrowth of harmful gut bacteria.

SQ is unusual because it is a sugar molecule that contains sulfur.

The new study also answers a 50-year-old mystery. Scientists have been unable to understand how sulfur was used and recycled by living organisms. That answer is the YihQ enzyme.

"Bacteria in the gut, such as crucial protective strains of E. coli, use SQ as a source of energy. E. coli provides a protective barrier that prevents growth and colonisation by bad bacteria, because the good bugs are taking up all the habitable real estate," Dr Goddard-Borger said in the press release. "Sulfur is critical for building proteins, the essential components of all living organisms. SQ is the only sugar molecule which contains sulfur, and 'digestion' of the molecule by bacteria releases sulfur into the environment, where it re-enters the global 'sulfur cycle' to be reused by other organisms."

Dr. Goddard-Borger think this research may help scientists develop new antibiotics that can target only harmful gut bacteria. This could help treat food poisoning caused by organisms like Salmonella.

The study was published in the February issue of Natural Chemical Biology.

Funding for the study was provided by the National Health and Medical Research Council and Australian Research Council. Additional funding was supplied by UK Biotechnology and Biological Sciences Research Council and the European Research Council.

Information on conflict of interest was not available.