Protein Intake & PD Medication: Does Eating Protein Affect Levodopa Absorption?

Many people with PD take a levodopa/carbidopa combination drug to help control their motor symptoms. Levodopa is a precursor to dopamine that can reduce motor-related issues like tremor, rigidity, or impaired balance. Carbidopa helps prevent the breakdown of levodopa in the body before it gets to the brain. Although this drug combination can be helpful for many, it needs to be absorbed properly in order to do its job effectively. Diet, specifically protein intake, can impact how well levodopa is absorbed.

What is the connection between levodopa absorption and protein?

After it’s taken, levodopa needs to be broken down in the stomach and absorbed in the intestines. From there, the levodopa needs to get into the brain where it can do its job. At each step, levodopa uses special transporters or carriers to get it to the next part of its journey. However, amino acids also use these same transporters.

Amino acids are found in protein-containing foods. These include meat, dairy, eggs, poultry, and fish, among other sources. When a drug containing levodopa is taken at the same time, or very close to, a protein-rich meal, the amino acids in the protein will take over the transporters. The amino acids will basically out-compete the levodopa and get absorbed first. This means, it will take longer for the levodopa to be absorbed and may impact PD-related symptoms. It is often recommended to take levodopa-containing drugs 30 to 60 minutes before a protein-rich meal in order to avoid this competition and to make sure levodopa is absorbed in a reasonable time frame.^1-3

What does this mean for PD symptoms and treatment?

When a person initially starts taking levodopa, changes in the way it’s absorbed may not make a big difference in its ability to control symptoms. However, as PD progresses, consistent and adequate levodopa absorption becomes more important in controlling on/off fluctuations and motor-related issues.

In some cases, changing protein intake even slightly may make a big difference in how well levodopa can do its job. If a person starts noticing that their body is responding differently to the same dosage and schedule of drugs, it could indicate an issue with their diet. This is one of the reasons why working with your doctor or a dietician to determine your nutritional needs can make a difference in quality of life with PD.^1,3

How can I adjust my diet to make sure my levodopa is absorbed properly?

There are a few ways you can adjust your diet or protein intake to ensure your levodopa is being absorbed as best as possible. However, diet changes can impact PD and its symptoms, so consulting a doctor or dietician before making any significant changes is important. In addition to taking levodopa at least 30 minutes before meals, several of the following changes (under a healthcare professional’s supervision) may also help:^1-3

• Determining your actual protein needs: In the typical Western diet, we often eat much more protein than we actually need. Working with a healthcare professional to determine your true protein needs and cutting back on any excess may help improve levodopa absorption. If you do find yourself cutting back on protein, your diet can be supplemented with more fruits, vegetables, and whole grains to ensure you’re getting all of the calories and nutrition that you need.
• Splitting up protein evenly: When you do determine how much protein you need, splitting it up evenly over meals, rather than having one meal that is heavier in protein than others, may help maintain consistent levodopa absorption throughout the day.
• Eating most of your protein in the evening: Instead of splitting protein up evenly throughout the day, in some cases, your doctor or dietician may recommend eating most of your protein in the evening. This may mean having a high carb meal for breakfast and lunch, and a protein-containing meal only for dinner. While this may help control daytime symptoms for some, others may find protein-loading at the end of the day increases difficult to manage symptoms at nighttime.
• Following a higher-carb diet: Carbs (carbohydrates) have high levels of glucose in them. Glucose increases the amount of insulin in the blood which can also help amino acids and levodopa absorption. However, a professional’s input is needed before moving toward a higher-carb diet, since some health conditions (including diabetes and lung disease, among others) may get worse as a result.

As mentioned, decreasing or changing your protein intake can lead to an increase in some symptoms, including dyskinesia. It can also lead to unintended weight loss or malnutrition. Both of these can also lead to serious issues as well.³ Keeping open lines of communication with your doctor about your diet, or enlisting the help of a dietician may be beneficial in your PD journey and improve symptom control.