A drawing of some gut microbes

Targeting bacteria in the gut could increase effectiveness of levodopa

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New research from Harvard University suggests changes to the gut could improve how a common Parkinson's medication works.

The study demonstrates that by altering levels of bacteria in the gut the delivery of levodopa into the brain could be improved and side effects reduced.

A delivery problem

Levodopa is one of the main drugs used to treat Parkinson's symptoms. It works by boosting dopamine levels in the brain.

In order to reach the brain, levodopa is absorbed into the bloodstream via the gut. On this journey, some levodopa gets converted into dopamine, causing side effects such as nausea, and limiting the drug’s effectiveness. The drug carbidopa is given alongside levodopa to help combat this, but it’s not 100% effective.

We already know that bacteria in the gut play a role in Parkinson's and that some bacteria and proteins found in the gut can break down levodopa. Indeed, recent research has found that specific intestinal bacteria known to break down levodopa are found at higher levels in people with Parkinson's who require larger doses of the medication.

A promising discovery

In order to reduce the amount of medication being broken down in the gut, the Harvard scientists turned to mice and a molecule called alpha-fluoromethyltyrosine (AFMT). In mice, this molecule was able to block the bacteria in the gut from breaking down levodopa, increasing its concentration in the blood.

Dr Lynn Duffy, Senior Scientific Content Writer at Parkinson's UK, says:

"Research is developing our understanding of how the gut plays a role in the onset and progression of Parkinson's. And it is clear there is still much to learn.

"This research is at an early stage, but it shows that by targeting levodopa break down it may be possible to improve symptoms, reduce side effects or maybe reduce the number of tablets many people with Parkinson's must take every day. However, levodopa cannot slow or stop the progression of Parkinson's, so at the same time as improving the medications we have, it is vital we support research developing new and better treatments."

Find out more

The bacteria in the gut could play a key role in the treatment of Parkinson's