The Parkinson Association of the Rockies has created a new segment on our bi-weekly enews called, “Ask the Parkinson’s Expert”. Every enews we ask the community to submit a question they may have for a Parkinson’s doctor, a selected question will then be answered and featured on the next enews.

All questions are confidential. Not all questions can be answered, so please notify your physician for immediate attention.

Q: What factors influence the interference of dietary protein with carbi-DOPA/levo-DOPA? Fiber or fat content of the meal? Rate of ingestion? Other?

A: This is an important question because most people aren’t counseled about the effect that dietary protein can have on the absorption of levodopa from the gut. People can be effectively wasting a dose of levodopa if they take it at the same time as a high-protein meal – as most of the medicine will just end up going straight through them! Levodopa is an amino acid, and amino acids are the “building blocks” of proteins. There are transport channels in the gut that let amino acids enter into the blood stream and later get to the brain. For levodopa to get to the brain, it needs to enter through these transport channels, but it can’t do so if they’re all taken up by the other amino acids from the bacon and eggs you had for breakfast!  High protein foods include not only meat (chicken, beef, pork, fish), but also dairy (milk, eggs, yogurt and cheese), beans and nuts.

Other dietary factors don’t affect this protein transport channel issue directly, but they can slow down or speed up the absorption of levodopa in other ways. If the pill is taken with or just after a meal, it will take longer to exit the stomach and get to the intestines.   It takes between 1 to 3 hours for food to exit the stomach. It wouldn’t really matter how quickly the meal was ingested, as it all ends up in the stomach and is slowly metered out to the small intestines over that 1-3 hour period. A pill would exit the stomach faster if it was taken on its own, without food. High-fat meals slow down stomach emptying even more, so it would take even longer for the levodopa to exit the stomach. Alternatively, a high-fiber diet helps keep the GI tract moving and avoids constipation in general, so this could help make sure that the levodopa gets to the intestines to be absorbed in a timely fashion. But you still wouldn’t want to take the levodopa at the same time as a meal, even if it was a high fiber meal, due to the stomach emptying issue.  

Ideally, levodopa should be taken 30-60 minutes before a meal, so it can exit the stomach quickly and be absorbed through the intestines without any competition. People with Parkinson’s should eat a high-fiber diet to keep the GI tract healthy and regular, ensuring a lot of fluid intake to keep that fiber moving through the gut!

– Dr. Samantha Holden, University of Colorado Hospital