Protein intake, nitrogen balance and nutritional status in patients with Parkinson's disease; time for a change?

Objective: to evaluate protein intake, nitrogen balance and nutritional status of clinically stable patients with Parkinson’s disease (PD). Methods: a cross-sectional study of PD patients Hoehn-Yahr scale stage 1-3 and subjects with no neurologic disease (controls) matched for age and gender. All participants underwent a diet history interview, anthropometric measurements, bioelectrical impedance and food record over three non-consecutive days, including a weekend. A 24-hour urine collection and fasting venous blood sampling were collected from the participants for evaluation of creatinine clearance, creatinine height index and the nitrogen balance. Results: the mean age of PD patients was 58.9 ± 12.8 year compared to 54.7 ± 12.6 year of the controls, P = 0.34. One third of PD group had symptoms of dysphagia and ingested less water and fibers when compared to controls. Calf circumference was small in PD group (35.5 ± 2.8 vs. 38.4 ± 3.5 cm, P = 0.012). Intake of nitrogen was significantly lower and nitrogen balance was negative in PD patients (-1.8 ± 3.9 vs. 1.1 ± 4.2 controls, P = 0.06). The antioxidants folate and vitamin E were consumed in small amounts in both groups, although significantly less in PD patients (P = 0.04 and 0.03, respectively). Discussion: daily intakes of protein of approximately 1.1 g/kg by clinically stable PD patients may not be enough to ensure a neutral calorie-nitrogen balance and muscle tissue conservation. Larger studies are necessary to provide a more comprehensive picture of PD patients’ metabolic status.