(RxWiki News) There are many reasons to eat a healthy diet low in saturated fat and simple carbs. For individuals with a genetic risk for Alzheimer’s disease, a healthy diet may also help protect their brains.
In a recent study a small group of older adults were split into two groups: one that ate a diet high in fat and simple carbs and one that ate a diet low in fat and simple carbs.
After four weeks, the people on the high-fat, high-carb diet had higher levels of plaque associated with an increased risk for Alzheimer’s disease.
While people on the low-fat, low-carb diet had lower levels of plaque.
"Eat a healthy diet with lots of veggies."
Angela J. Hanson, MD, from the Geriatric Research, Education and Clinical Centers, a division of the Department of Veterans Affairs, worked with a team of fellow scientists at the Veterans Affairs Puget Sound Health Care System to investigate the effects of diet on risk factors associated with Alzheimer’s disease.
Alzheimer’s disease is a form of dementia characterized by memory loss, slowed thinking, behavioral changes, disorientation and confusion, just to name a few symptoms.
Part of the development of Alzheimer’s disease involves a build-up of a certain type of plaque in the brain tissue, which gets in the way of the brain’s ability to function properly. Plaque is a protein that won’t dissolve.
Previous studies have also shown that there is a particular gene, known as APOE, which has been associated with a higher risk of developing Alzheimer’s disease.
The researchers in this clinical trial set out to test whether diets high in fat and carbs effected the biomarkers for the plaque associated with an increased risk for Alzheimer’s disease.
For this small trial, the researchers recruited 20 adults around 69 years of age who had no signs of Alzheimer’s disease, and 27 adults around 67 years of age who had mild symptoms of Alzheimer’s disease.
The participants were randomly assigned to one of two different diets based on high or low fat and carbohydrate consumption for four weeks.
The "high" group ate a diet high in saturated fat — 45 percent of calories from fat and more than 25 percent of those calories from saturated fat — and high in carbohydrates — 35 to 40 percent of calories from high glycemic carbs.
The "low" group ate a diet low in saturated fat — 25 percent of calories from fat and less than 7 percent of those calories from saturated fat, and 55 to 60 percent of calories from low glycemic carbohydrates.
Low glycemic carbohydrates refer to foods that contain slower-acting sugars like whole grains, vegetables, fruits, nuts and beans.
High glycemic index refers to foods that contain simple sugars, which can cause a person’s blood sugar to spike, such as white breads, candy, potatoes, corn and soda.
Unsaturated fats can be found in foods like olive oil, nuts, avocado and fish. Saturated fats can be found in foods like butter, cream, lard, cheese and ice cream.
The researchers tested brain and spinal fluid samples from the participants before they began their diets and again four weeks later.
At the start of this study, the participants with mild symptoms of Alzheimer’s disease had higher levels of the biomarker for the Alzheimer’s-related plaque in their brains and spinal fluid samples compared to the participants who had no signs of Alzheimer’s disease.
The test results showed that the levels of the biomarker for the Alzheimer's-related plaque in the brain and spinal fluid increased in people in the high-fat, high-carb diet group, whether they had mild Alzheimer’s symptoms or not.
The test results also showed that the levels of the biomarker for the Alzheimer's-related plaque in the brain and spinal fluid decreased in people in the low-fat, low-carb diet group, whether they had mild Alzheimer’s symptoms or not.
According to the study authors, previous animal studies have implicated diets high in saturated fat, cholesterol and simple sugars as playing a role in the origin of Alzheimer’s disease.
The study authors concluded that the findings of this trial might add to the growing body of evidence showing poor diet as a risk factor for developing Alzheimer’s disease, especially in people with the gene associated with an increased risk for Alzheimer’s disease.
This study was published in June in JAMA Neurology.
The Hartford Center of Excellence, the National Institute on Aging, the Nancy and Buster Alvord Endowment and the Department of Veterans Affairs provided funding for this trial. No conflicts of interest were reported.