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.