Healthy eating lowers your risk of diabetes, hypertension, and heart disease, but it's not yet clear if that's true for Alzheimer's disease as well.
"I can't write a prescription for broccoli and say this will help-yet," says Sam Gandy MD, PhD, the associate director of the Mount Sinai Medical Center Alzheimer's Disease Research Center, in New York City.
(The National Institutes of Health recently said there is insufficient evidence that food, diet, or lifestyle will prevent Alzheimer's disease.)
It's not a lost cause though. Here are 9 foods that researchers think will keep your whole body-including your brain-healthy.
Oil-based salad dressings
"The data support eating foods that are high in vitamin E and this includes healthy vegetable oil-based salad dressings, seeds and nuts, peanut butter, and whole grains," says Martha Clare Morris, ScD, director of the section on nutrition and nutritional epidemiology in the Department of Internal Medicine at Rush University, in Chicago.
The benefit has been seen with vitamin-E rich foods, but not supplements, she says.
A potent antioxidant, vitamin E may help protect neurons or nerve cells. In Alzheimer's disease, neurons in certain parts of the brain start to die, which jump-starts the cascade of events leading to cognitive deterioration.
Salmon, mackerel, tuna, and other fish are rich in heart-healthy omega-3 fatty acids, including docosahexaenoic acid (DHA).
"In the brain, DHA seems to be very important for the normal functioning of neurons," Morris says.
Another plus: Eating more fish often means eating less red meat and other forms of protein that are high in artery-clogging saturated fats.
Dark green leafy vegetables
Kale, collard greens, spinach, and broccoli are good sources of vitamin E and folate, Morris says.
For example, one cup of raw spinach has 15% of your daily intake of vitamin E, and 1/2 a cup of cooked spinach has 25% of your daily intake.
Exactly how folate may protect the brain is unclear, but it may be by lowering levels of an amino acid known as homocysteine in the blood. High levels of homocysteine may trigger the death of nerve cells in the brain, but folic acid helps break down homocysteine levels.
High homocysteine levels have also been linked to an increased risk for heart disease.
This creamy treat is also a rich source of the antioxidant vitamin E.
Research by Morris and her colleague suggests that foods rich in vitamin E-including avocado, which is also high in the antioxidant powerhouse vitamin C-are associated with a lower risk of developing Alzheimer's.
Health.com: 8 avocado recipes (besides guacamole)
Seeds, including sunflower seeds, are also good sources of vitamin E.
One ounce of dry-roasted sunflower seeds contains 30% of your recommended daily intake. Sprinkle them on top of your salad to give your brain a boost.
Peanuts and peanut butter
Although both are high in fat, peanuts and peanut butter tend to be a source of healthy fats. And they are also packed with vitamin E.
Both foods may help keep the heart and brain healthy and functioning properly. Other good choices are almonds and hazelnuts.
"There has been some very good research that diets that are high in healthy fats, low in saturated fat and trans fats, and rich in whole grains, green leafy vegetables, and nuts are good for the brain and the heart," says Maria C. Carrillo, PhD, senior director of medical and scientific relations at the Chicago-based Alzheimer's Association.
Health.com: What can you make with peanut butter?
Studies have shown that people who consume moderate amounts of red wine and other types of alcohol may be at reduced risk for Alzheimer's disease, but it may be that there is something else that tipplers do or don't do that affects their risk of developing Alzheimer's, Carrillo says.
"People who drink alcohol or eat healthy may be healthier in other aspects of their life, so it is difficult to disentangle whether it's the healthy diet that protects them versus other healthy behaviors."
The latest research presented at the National Meeting of the American Chemical Society in Boston found that blueberries, strawberries, and acai berries may help put the brakes on age-related cognitive decline by preserving the brain's natural "housekeeper" mechanism, which wanes with age.
This mechanism helps get rid of toxic proteins associated with age-related memory loss.
Fiber-rich whole grains are an integral part of the Mediterranean diet, which is also loaded with fruits, vegetables, nuts and seeds, olive oil, and wine.
Research out of Columbia University Medical Center in New York City shows that this diet may be linked to lower risk of the mild cognitive impairment that can progress to Alzheimer's disease.
"We don't eat foods or nutrients in isolation, we eat in combination with other foods so there is value in dietary patterns," says Nikolaos Scarmeas, MD, an associate professor of neurology at Columbia University, who conducted the studies.
This type of diet may reduce inflammation, oxidative stress, and other vascular risk factors such as high blood pressure-all of which may have a role in increasing risk for brain and heart diseases.
Okay you can't eat it, but research suggests that regular exercise is as important, if not more so, as what you eat when it comes to memory-saving lifestyle changes.
Experts all stress that getting regular exercise is also an important part of the equation when it comes to staving off many diseases, including Alzheimer's.
The bottom line?
"We can't go out and say, 'Eat these things and you are protected from Alzheimer's,' but there is almost no downside to increasing your physical activity and consuming a diet rich in whole grains, vegetables, fish, healthy oils, nuts, and seeds," Morris says.