The Effects of Protein Foods on Levodopa
Levodopa belongs to a class of drugs used to treat neurodegenerative diseases and is commonly prescribed for Parkinson’s disease. In patients taking levodopa, the type of protein eaten and the timing of meals that contain protein become important because a significant drug-nutrient interaction often causes decreased absorption, metabolism and excretion of the drug.
Levodopa
Levodopa is a derivative of the amino acid tyrosine and a psychoactive agent – it functions in the brain. It is important in the treatment of Parkinson’s because of its ability to cross through the blood-brain barrier that separates blood circulating throughout the body from the brain and prevents certain compounds from directly reaching the brain and central nervous system. Dopamine is deficient in the brains of people of Parkinson’s disease and cannot cross the blood-brain barrier. However, levodopa is able to cross this barrier and breakdown to dopamine.
- Levodopa is a derivative of the amino acid tyrosine and a psychoactive agent – it functions in the brain.
- Dopamine is deficient in the brains of people of Parkinson’s disease and cannot cross the blood-brain barrier.
Protein and Levodopa Compete for Absorption
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Dietary proteins are broken down into smaller molecules called amino acids. Once in the small intestine, they are transported across the small intestine into the bloodstream via specific carriers. Levodopa uses these same carriers to gain entry into the bloodstream. Managing dietary protein intake is effective in maximizing levodopa absorption to maximize its therapeutic benefits in patients with Parkinson's disease 2.
- Dietary proteins are broken down into smaller molecules called amino acids.
- Levodopa uses these same carriers to gain entry into the bloodstream.
Branched-Chain Amino Acids
Amino acids referred to as branched-chain, or BCAA, directly interfere with levodopa absorption. Leucine, isoleucine and valine are the three branched-chain amino acids that inhibit levodopa absorption more than other amino acids obtained from protein. Foods high in BCAAs include:
- red meat
- dairy
- chicken
- fish
- poultry
- eggs
Protein powders and whey supplements, a high-quality source of protein produced during the making of cheese, are also rich-sources of BCAAs.
Managing Levodopa and Protein Interactions
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Levodopa should be regimented with respect to meal times and patients should have a tightly controlled dietary protein intake. Limiting meat products and avoiding whey-based protein supplements often decreases interference. One nutritional therapy strategy involves limiting protein intake during the day and having the majority of protein in the evening or right before bed. Patients may also benefit from a high-carbohydrate, low-protein diet.
- Levodopa should be regimented with respect to meal times and patients should have a tightly controlled dietary protein intake.
- One nutritional therapy strategy involves limiting protein intake during the day and having the majority of protein in the evening or right before bed.
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References
- Five Star Living: Eat Well, Stay Well with Parkinson’s Disease; Katherine Holden, R.D.; 2004
- “American Journal of Clinical Nutrition”; Effect of Daytime Protein Restriction on Nutrient Intakes of Free-living Parkinson’s Disease Patients; S. Pare, et al; 1992
- Parkinson's Foundation. Managing PD Mid-Strike: A Treatment Guide to Parkinson's Disease.
- Mao ZL, Modi NB. Dose-Response Analysis of the Effect of Carbidopa-Levodopa Extended-Release Capsules (IPX066) in Levodopa-Naive Patients With Parkinson Disease. J Clin Pharmacol. 2016;56(8):974-82. doi:10.1002/jcph.683
- Binde CD, Tvete IF, Gåsemyr J, Natvig B, Klemp M. A multiple treatment comparison meta-analysis of monoamine oxidase type B inhibitors for Parkinson's disease. Br J Clin Pharmacol. 2018;84(9):1917-1927. doi:10.1111/bcp.13651
- Fasano A, Ricciardi L, Lena F, Bentivoglio AR, Modugno N. Intrajejunal levodopa infusion in advanced Parkinson's disease: long-term effects on motor and non-motor symptoms and impact on patient's and caregiver's quality of life. Eur Rev Med Pharmacol Sci. 2012;16(1):79-89.
- Martinez-Martin P et al. EuroInf: a multicenter comparative observational study of apomorphine and levodopa infusion in Parkinson's disease. Movement Disorders. 2015 Apr;30(4):510-6.
- Pahwa R, Lyons KE. Levodopa-related wearing-off in Parkinson's disease: identification and management. Curr Med Res Opin. 2009 Apr;25(4):841-9.
- Stocchi F, Jenner P, Obeso JA. When do levodopa motor fluctuations first appear in Parkinson's disease? Eur Neurol. 2010;63(5):257-66.
- Tarsy D. (2017). Motor fluctuations and dyskinesia in Parkinson's disease. Hurtig HI, ed. UpToDate. Waltham, MA: UpToDate Inc.
Writer Bio
A registered dietitian and licensed dietitian/nutritionist, Brandy Williams began writing in 2007. Her publications can be found in peer-reviewed journals such as the "American Journal of Lifestyle Medicine" and "Public Health Nutrition." Williams holds a Master of Science in human nutrition and food from Louisiana State University.