Oral administration of L-dopa is currently the most effective way to treat the cerebral dopamine deficiency which causes Parkinson's disease. Unfortunately, many patients with advanced Parkinson's disease develop an unstable pattern of response to L-dopa because of fluctuating delivery of the drug to the brain. Diet contributes to this problem through its adverse effects on L-dopa pharmacokinetics. This article reviews dietary strategies to improve responsiveness to pharmaceutical L-dopa treatment and the potential use of food as a source of L-dopa. Nutritional factors concerning weight loss and energy balance in Parkinson's disease are also discussed. A set of dietary guidelines is developed to assist clinical nutritionists and neurologists in the practical management of patients with Parkinson's disease.