Patients with Parkinson’s Disease are treated with levodopa, which is converted into the neurotransmitter dopamine in the brain. In a study that was published on 18 January in Nature Communications, we show that gut bacteria can metabolise levodopa into dopamine. As dopamine cannot cross the blood-brain barrier, this means the bacteria can compromise the availability of the medication, even in the presence of inhibitors that should prevent the conversion of levodopa. Check it at: https://www.nature.com/articles/s41467-019-08294-y