Why Leafy Greens Hold The Key to Gut Health - May 2016

Provided by Walter and Eliza Hall Institute – February 15, 2016

Researchers from Melbourne and the UK have made a critical discovery and solved a 50-year mystery about how bacteria feed on an unusual sugar molecule found in leafy green vegetables. It could hold the key to explaining how 'good' bacteria protect our gut and promote health.

This finding suggests that leafy greens are essential for feeding good gut bacteria and in turn limiting the ability of bad bacteria to colonise the gut by shutting them out of the prime 'real estate'.

What they discovered is a previously unknown enzyme used by bacteria, fungi and other organisms. Its name is sulfoquinovose (SQ for short) and it is an abundant sugar found in green vegetables.

Each year, leafy green vegetables - such as spinach - produce this sugar on an enormous scale globally, comparable to the world's total annual iron ore production.

Dr Goddard-Borger said the discovery could be exploited to cultivate the growth of 'good' gut bacteria. "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," he said.

"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.

So mum was right when she said, “eat your greens if you want to grow up big and strong”. Consumption of this specific molecule within leafy greens will prove to be an important factor in improving and maintaining healthy gut bacteria and good digestive health."

The 50-year mystery which was solved surrounded how sulphur - an element essential for life on Earth - was used and recycled by living organisms," he said. "What is remarkable is that the YihQ enzyme was hiding in plain sight and is produced by the humble bacterium E. coli, present in nearly every biologist's laboratory."

The discovery also provides crucial insights that may one day be exploited to develop an entirely new class of antibiotics, Dr Goddard-Borger said. "New antimicrobial strategies are desperately needed as more and more bacteria acquire resistance to existing classes of antibiotics."

"We think it will be possible to use these widespread enzymes to enable highly specific delivery of antibiotics to harmful forms of E. coli and other pathogens, such as Salmonella, responsible for food poisoning, while leaving the good gut bacteria untouched."

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