Dietary glycemic index is inversely associated with the risk of Parkinson's disease: A case-control study in Japan

Objective: High glycemic index (GI) or glycemic load (GL) carbohydrates might be expected to decrease the risk of Parkinson's disease (PD) by an insulin-induced increase in brain dopamine We conducted a hospital-based case-control study in Japan to examine associations between dietary GI and GL and other dietary carbohydrate variables, including intake of available carbohydrate and dietary fiber, and PD Methods: Patients with PD diagnosed using the U K Parkinson's Disease Society Brain Bank criteria (n = 249) and controls without neurodegenerative diseases (n = 368) were recruited Dietary intake during the preceding month was assessed at the time of study recruitment using a validated, self-administered. semiquantitative, comprehensive diet history questionnaire. Results: After adjustment for potential dietary and non-dietary confounding factors. dietary Cl was significantly Inversely associated with the risk of PD. Multivariate odds ratios (95% confidence intervals) for PD in the first. second. third, and fourth quartiles of dietary GI were 1.00 (reference). 1.03 (0 64-1 66). 0 68 (0 4 1-1.15), and 0 61 (0 34-1.09). respectively (P for trend = 0 04) Conversely. 110 significant association was observed for other dietary carbohydrates, including dietary GL (P for trend = 0 77). available carbohydrate intake (P for trend = 0 28), or dietary fiber intake (P for trend = 0 73). Conclusion: This preliminary case-control study based on current dietary habits found an independent inverse relation between dietary GI and PD Considering the plausibility of the putative mechanism. further investigation using a case-control design with accurate assessment of past dietary habits or a prospective design is warranted. (C) 2010 Elsevier Inc All rights reserved