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    Diet Affects Markers of Alzheimer's Disease

    Low-Fat, Low-Glycemic-Index Diets Improve Markers for Alzheimer’s Disease, Study Suggests

    Tracking the Influence of Diet on Alzheimer’s continued...

    Researchers used blood tests to check insulin, glucose, and cholesterol levels.

    Researchers also performed spinal taps to analyze participants’ cerebrospinal fluid -- a clear, colorless liquid that bathes the brain and spinal cord.

    They measured beta-amyloid, the hormone insulin, a protein that helps in clearing out beta-amyloid called apolipoprotein E, and F2-isoprotanes, which are markers of oxidative damage caused by free radicals.

    Half of each group was then randomly assigned to one of two eating patterns.

    On the high-fat diet, participants got 45% of their daily calories from fat, including 25% from saturated fat, about 40% of calories came from high-glycemic-index carbohydrates, and about 20% were protein.

    On the low-fat diet, 25% of calories came from fat, with less than 7% from saturated fat, 55% to 60% of calories came from low-glycemic-index carbohydrates, and about 20% from protein.

    Study meals were delivered to participants twice each week.

    Dietary Changes May be More Helpful for Prevention Than for Treatment

    After one month on the diets, researchers repeated the original tests.

    In healthy adults, the high-fat diet increased levels of beta-amyloid and other markers of inflammation and damage in the spinal fluid, suggesting that the high amounts of unhealthy fats and wide swings in blood sugar and insulin may be moving the brain toward changes associated with Alzheimer’s.

    The low-fat diet, however, decreased those levels of beta-amyloid, insulin, and F2-isoprostanes and increased levels of apolipoprotein E, suggesting a protective effect.

    In adults who had already begun to have some memory and brain impairment, however, the results were more complex.

    Those on the high-fat diet saw little change in the Alzheimer’s biomarkers.

    “That’s possibly because they’ve already got a very pathological process going on,” Craft says, and she thinks her short study wasn’t going to make things much worse.

    Those who were on the low-fat diet saw increases in the levels of beta-amyloid in their spinal fluid.

    Researchers say other studies that have looked at changes in beta-amyloid as Alzheimer’s disease progresses have observed a tipping point, where levels rise until a critical level is reached and plaques begin to form. When that happens, the disease accelerates, more plaques form in the brain, and levels of beta-amyloid in spinal fluid drop.

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