Diet is considered by some experts to be one of the most clinically accessible, modifiable risk factors for Alzheimer's, and, in conjunction with other lifestyle factors like exercise, sleep and stress, could potentially lower the risk of developing the disease. Whether there could be an "ideal" diet to reduce the risk of Alzheimer's is therefore something experts are keen to further investigate. In August, scientists at Bond University, Australia, published a study in the journal Frontiers in Nutrition outlining some of the potential mechanisms that suggest the food a person eats may be associated with a higher or lower risk of developing Alzheimer's.
They determined that certain diets can negatively impact a number of key biological pathways in the body and result in chronic neuroinflammation, insulin resistance, metabolic dysregulation, oxidative stress and impact blood-brain barrier integrity and the gut microbiome, all of which could affect a person's brain health. This in turn suggests certain diets could support those pathways, which may in turn potentially reduce risk. For example, the Bond University experts pointed to the Mediterranean diet—a diet mostly made up of fresh fruit and vegetables, healthy fats like olive oil, and whole grains—as one which positively impacted the gut microbiome and also was associated with slower global cognitive decline.
Other diets like the DASH diet—a diet designed for those with high blood pressure, focusing on fresh fruit and vegetables, lean protein and low sodium—and the MIND diet—which combines elements of the Mediterranean and DASH diets for brain health—have also been associated with a reduced risk of Alzheimer's disease, according to the Bond University researchers. "Although the brain represents only a small proportion of body weight, it has very high energy requirements and depends heavily on peripheral metabolism to provide its fuel," Suzanne Craft, director of the Alzheimer’s Disease Research Center at Wake Forest University, told Newsweek. "A healthy dietary pattern can therefore influence the brain both directly, by supplying essential nutrients, and indirectly, by improving metabolic, vascular, and inflammatory processes throughout the body." Researchers are still investigating what foods, if any, reduce Alzheimer’s disease risk or progression.
As a general guideline, the MIND diet is a "useful model," Craft said, as it combines the elements of the Mediterranean and DASH diets and "emphasizes vegetables—particularly leafy greens—berries, whole grains, beans, nuts, fish, poultry, and olive oil, while limiting foods high in saturated fat and highly processed foods." Dr. Russell Swerdlow, director of the University of Kansas Alzheimer's Disease Research Center, told Newsweek that it also seems to be "reasonable to speculate the best diet is one that does not harm your metabolism." "The brain is a privileged organ," he said. "The rest of the body essentially exists to keep it in a state of metabolic equilibrium." "So, while diet can have a big impact on other parts of the body, such as the health of the liver, or how much fat we store in our adipose tissue, the impact on the brain is somewhat attenuated because a healthy body is already working to keep the brain in a stable environment," he added.
The brain depends on healthy fats to maintain cell membranes and support connections between brain cells, and key sources include olive oil, nuts, seeds, avocados, and fatty fish, Craft said. She added that fruits and vegetables provide vitamins, minerals, antioxidants, and other compounds that support brain and vascular health, while having adequate protein—such as from fish, poultry, beans and legumes, and plant proteins like tofu—is also important, as is fiber for gastrointestinal health and a healthy gut microbiome, which can be found in beans and legumes, vegetables, fruits, and whole grains. "These foods may support brain health through several complementary mechanisms," Craft said.
"They can help reduce chronic inflammation, support healthy glucose and lipid metabolism, and promote cardiovascular and cerebrovascular health—all of which are closely related to brain health." However, Craft said that rather than "focusing on individual 'brain foods,' it is more useful to think about the overall dietary pattern." For example, a brain-healthy diet includes "adequate amounts of unsaturated fats, particularly monounsaturated fats and omega-3 polyunsaturated fats," she said. While certain diets have been associated with a reduced Alzheimer's risk, "correlation does not establish causality and more research is needed," Swerdlow said. Hussein Yassine, director of the Center for Personalized Brain Health at the University of Southern California, told Newsweek "I would be careful not to conflate association with causation," though he added that it is "plausible that diet in concert with other factors such as exercise, sleep, stress reduction and other factors work together to reduce Alzheimer's disease risk." "The field so far lacks a definitive study that confidently establishes what everyone is hoping for—that we can control our Alzheimer’s destiny by controlling what we eat," Swerdlow added.
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