Diet and Alzheimer's Disease Risk
The research involved 1,691 people aged 65 and older with no signs of dementia when they entered the study. All filled out detailed questionnaires that asked about what foods they ate over the past year.
The researchers studied various foods in the lab including nuts, fish, salad dressing, poultry, tomatoes, cruciferous, dark, green leafy vegetables, fruits, low and high-fat dairy, red meat, organtic meat, and butter to determine which were rich in nutrients such as omega-3 fatty acids and vitamin E that have been linked to a lower risk of Alzheimer's disease and which were low in nutrients such as saturated fatty acids that have been linked to a greater risk.
Based on the amounts of each nutrient in each food, "we discovered an Alzheimer's-disease-protective dietary pattern that was characterized by healthy eating which included a high consumption of nuts, fish, salad dressing, poultry, tomatoes, cruciferous, dark, and green leafy vegetables and fruits, and low in high-fat dairy, red meat, organ meat, and butter," according to researcher Nikolaos Scarmeas, MD, associate professor of neurology at Columbia University in New York. "Foods are not consumed in isolation, so studying the dietary pattern may offer substantial advantage."
The analysis was adjusted for a variety of factors that could potentially explain the association, including age, physical activity, body mass index, smoking status and caloric intake.
The study articipants were then divided into three groups according to how well they adhered to a heart-healthy diet over the past year. Over the next four years, 211 of the participants were diagnosed with Alzheimer's disease. Results showed that those in the top third were 38% less likely to develop Alzheimer's disease four years later than those in the lowest third.
The fact that the researchers followed healthy people over time and that the analysis was adjusted to take into account factors such as physical activity that may also lower the risk of Alzheimer's disease gives it strength, says Craig Blackstone, MD, PhD, of the National Institute of Neurological Disorders and Stroke in Bethesda MD.