Dietary Glycemic Load and Plasma Amyloid-beta Biomarkers of Alzheimer's Disease

Previous studies have highlighted links between a high-glycemic-load (GL) diet and Alzheimer's disease in apolipoprotein E epsilon 4 (APOE4) carriers. However, the impact of high-GL diet on plasma amyloid-beta (A beta), an Alzheimer's disease hallmark that can be detected decades before clinical symptomatology, is unknown. This study examined the association between plasma A beta peptides (A beta(40), A beta(42) concentration and A beta(42)/A beta(40) ratio) and GL. The influence of the GL of four meal types (breakfast, lunch, afternoon snack, and dinner) was also determined. From the prospective Three-City study, 377 participants with plasma A beta measurements, and who completed the Food Frequency Questionnaire, were selected. The association between plasma A beta and GL was tested using an adjusted linear regression model. Lunch GL was associated with a lower plasma A beta(42) concentration (beta = -2.2 [CI = -4.27,-0.12], p = 0.038) and lower A beta(42)/A beta(40) ratio (beta = -0.009 [CI = -0.0172, -0.0007], p = 0.034) in the model adjusted for center, age, sex, education level, APOE4 status, energy intake, serum creatinine, total cholesterol, and Mediterranean-like diet. No significant association was found with the GL of the other meal types. These results suggest that dietary GL may independently modulate the plasma A beta of the APOE4 status. The mechanism underlying diet, metabolic response, and A beta peptide regulation must be elucidated.