Low‐protein and protein‐redistribution diets for Parkinson's disease patients with motor fluctuations: A systematic review

Abstract

The American Academy of Neurology suggests advising the redistribution of daily protein meal content to every Parkinson's disease (PD) patient with motor fluctuations during levodopa treatment. However, no comprehensive evaluation of this complementary therapy has been performed. A systematic review of intervention studies investigating the neurologic outcome of low-protein (<0.8 g/kg of ideal weight/day) and protein-redistribution diets in patients with PD experiencing motor fluctuations during levodopa treatment. All studies (uncontrolled or randomized) investigating a low-protein and/or a protein-redistribution diet (LPD and PRD) and involving patients with PD with motor fluctuations were included, provided that sufficient information on dietary protein content and neurologic outcome measures was available. We identified 16 eligible studies, but they were markedly heterogeneous. There was not enough evidence to support the use of LPD. Response to PRD seemed very good. Acceptability appeared high upon introduction, but it seemed to progressively decrease over time. On average, PRD resulted in improved motor function, but also complications occurred. At the beginning, drop-outs were due to levodopa side effects rather than unsatisfactory benefits. Long-term adherence was more affected by changes in dietary habits than by diet-related side effects. Efficacy and benefits appeared to be higher when the intervention was proposed to subjects in the early stages of PD. PRD can be safely advised to fluctuating patients with PD, but those in whom benefits override the possible inconveniences still need to be identified. The long-term effects of PRD on nutritional status should be evaluated and true effectiveness in clinical practice should be reassessed, given the changes in levodopa formulations and the introduction of several adjuvants (levodopa degradation inhibitors and/or dopamine agonists).

Protein intake and the use of levodopa in patients with Parkinson's disease

“…Studies were conducted to evaluate the PD patients diet and the interference in the pharmacologic therapy (4,9,19,24,25). However, the number of different methodologies and the variety of sample populations do not provide any conclusive evidence to which is the best nutritional therapy for these patients in order to be able to relate the use of levodopa and other drugs (4,6,8,10,18).…”

“…After administration, levodopa is absorbed in the first portion of the small intestine by a saturable active transport mechanism which is also used by some aminoacids (1,5,10,18,19,23). Furthermore, the same aminoacids compete with the drug by active transport in the blood-brain barrier (5,25,26).…”

“…Even if these fluctuations can be unpredictable and spontaneous, they often become worse after meals (18). A great number of related studies argue that nutritional advice on protein intake can improve the levodopa kinetic profile, and therefore its therapeutic efficacy (1,9,10,18,19,24,29). The daily protein amount ingested and its distribution throughout the day are among the dietary recommendations found in the literature for reducing this influence.…”

“…In this study, 47% of patients consumed some food along with medicine. In the literature this practice is related to the need to prevent some symptoms such as nausea and discomfort (10). The use of low protein content products for renal patients is an alternative for patients who need to redistribute the protein consumption during the day (18,31).…”

“…For this purpose, drugs are used such as inhibitors of dopamine degradation, dopaminergic agonists (8), dopamine reuptake inhibitors and anticholinergic drugs (9), as well as a precursor of dopamine, L-DOPA (levodopa), which is the most frequently drug used in the PD treatment ( 8,10).…”