Brain Food

Neurology Now
March/April 2008
Volume 4(2)
p 18–19,23–25

Abstract

Eating Mediterranean-style may protect brain cells, slow degeneration, and add a few years to your life.

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The Mediterranean region is home to abundant fruits and vegetables, aromatic herbs and spices, high-quality grapes, lean meats, many species of fish, and heart-friendly olive oil. So it's no wonder that following a Mediterranean-style diet is linked with a lower risk of disease and a longer life when compared with the typical American diet. In fact, studies suggest that eating Mediterranean lowers blood pressure, reduces inflammation in the body, and protects against chronic conditions ranging from cancer to stroke.

“Many of these conditions are also linked with Alzheimer's disease,” claims Nikolaos Scarmeas, M.D., M.Sc., assistant professor of neurology at Columbia University Medical Center in New York, NY. In a study of nearly 1,300 Japanese-American men published in the journal Stroke in 2006, for example, the risk of Alzheimer's disease was 65 percent lower in those who had been treated for hypertension than in those whose blood pressure was untreated. And since following a Mediterranean diet helps lower blood pressure, Dr. Scarmeas suspects it would also alter the onset and progression of Alzheimer's disease.

He may be right. In two separate studies, Dr. Scarmeas and his team of researchers found that following a Mediterranean diet not only protected against Alzheimer's but also enabled patients who have the disease to live an average of four years longer. The more closely subjects adhered to the diet, the greater the benefit.

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“Until now, most of the neurological research has focused on individual food components like fruits, vegetables, and certain vitamins,” says Dr. Scarmeas. “But it could be that these individual elements have a dynamic synergy, so two or three of them together may be more effective than the sum of the individual components.”

Interestingly, the diet's positive impact on overall health and longevity actually makes it difficult to pinpoint a precise connection to Alzheimer's disease. “The conjoint impact on both reduction in Alzheimer's disease incidence and mortality suggests that the Mediterranean diet may have nothing to do with Alzheimer's disease, but is part of a general pattern of healthy behavior that impacts all aspects of health, including Alzheimer's disease, heart disease, and mortality,” says David Knopman, M.D., professor of neurology at the Mayo Clinic in New York, NY.

While more studies need to be done, all indications are that going Mediterranean might tack on a few years to your life. Here's a breakdown of the key foods that can help.

Fish

How Much: Shoot for three to four ounces, two or three times a week, says Christine Gerbstadt, M.D., R.D., national spokesperson for the American Dietetic Association.

Why: Fish is a rich source of omega-3 fatty acids, the nutritional powerhouses responsible for lowering blood pressure and preventing blood clots (much like aspirin, but without the side effects). In one study published in the Journal of the American Medical Association in 2001, researchers tracked roughly 79,000 women for 14 years and found that those who ate fish at least twice a week had a 51 percent lower risk of ischemic stroke than those who ate fish less than once a month. And researchers at the University of California in Irvine determined that a certain type of omega-3 fatty acid, DHA, interferes with the formation of brain lesions that lead to Alzheimer's. The study also found that DHA might help prevent the onset of the disease.

Why are omega-3s (DHA, EPA, and ALA) such a hot topic? “They reduce inflammation in the arterial walls and keep blood flowing to the brain,” says Dr. Gerbstadt. “The less inflammation, the less plaque formation.”

Another potential omega-3 benefit: improved mood. Omega-3s make cell membranes more fluid so they can communicate with one another more effectively. That means feel-good neurotransmitters like serotonin and dopamine can get in and out of the cell more easily, translating to better mood.

Best Sources: Omega-3s, and specifically DHA, can be found in salmon, tuna, and other cold-water fish. Like salmon? Go for wild. They contain more omega-3s than farmed. If you're concerned about mercury, stay away from very large predator fish like shark, swordfish, king mackerel, and tilefish. The Environmental Protection Agency provides advice at epa.gov/waterscience/fishadvice/advice.html .

Fruits and Vegetables

How Much: Aim for nine or more servings every day, says Dr. Gerbstadt.

Why: Fruits and vegetables are loaded with antioxidants. Ever leave a cut apple on the countertop and watch it shrivel up and turn brown? That's oxidation, and when it happens in your body—as it does every day—it can damage your cells and organs. “As we age, our protective mechanisms don't work as well when we get an oxidant hit,” says James Joseph, Ph.D., director of the neuroscience lab at USDA's Human Nutrition Research Center on Aging at Tufts University in Boston, MA. “How do you know when you're not handling oxidative stress as well? You get wrinkles,” says Dr. Joseph. Just like the apple.

Antioxidants act as the body's natural defense system, helping neutralize unstable molecules called free radicals that can damage cells. They also repair the cell damage associated with neurodegenerative conditions. A study published in the American Academy of Neurology's journal Neurology in 2006 of almost 2,000 men and women over the age of 65 found that those who ate more than two servings of vegetables each day showed 40 percent less mental decline on cognitive tests than those who reported eating little or no vegetables. And when British researchers pooled eight studies that included more than 250,000 people, they found that those who reported eating at least five servings of fruits and vegetables a day had a 26 percent lower risk of stroke than those who ate less than three servings daily.

But these studies aren't without criticism. “Diet is a function of a broader set of behaviors by people—health-related behaviors—of which diet may be a proxy but not the cause of the improved outcomes,” says Dr. Knopman. “Observational studies cannot establish causality and should not be made into public health dictums.”

In other words, there is no definitive research yet establishing a clear link. As of right now, the idea that a Mediterranean diet lowers the risk for neurological conditions is mostly theory. But it is based on a body of proven research that following a Mediterranean diet dramatically reduces the risk of cardiovascular conditions, including cardiac arrest and stroke—and on the common knowledge that what's good for the heart is also good for the brain.

Experts claim eating eight to 10 fruits and vegetables a day as part of a low-fat diet can lower blood pressure almost as much as most blood pressure medications. “A person who lowers their blood pressure even a few millimeters has made a real impact,” claims Dr. Gerbstadt. “The more fruits and vegetables you can eat, the better, but go with vegetables over fruit for health benefits and weight control.”

Best Sources: Researchers claim the most beneficial vegetables are the green leafy variety, including spinach, kale, and collard greens, most likely because they're loaded with antioxidants such as vitamins C, E, A, and selenium. In terms of fruits, go for color—try blueberries, blackberries, and strawberries. A study published in the May 2005 issue of the Journal of Experimental Neurology found that rats fed diets enriched with spinach and blueberries lost fewer brain cells after a stroke and recovered significantly more than rats that weren't eating the spinach- and blueberry-enriched diets.

Olive Oil

How Much: Two to three tablespoons daily can improve health, but at 119 calories per tablespoon, it's better to go easy on this Mediterranean staple, says Dr. Gerbstadt.

Why: Olive oil is very high in compounds called phenols, which act as powerful antioxidants. It's also made up largely of healthful monounsaturated fat. A study published in the Archives of Internal Medicine in 2000 found that among people with high blood pressure, those who were given olive oil significantly lowered their blood pressure compared to those who were given sunflower oil (a typical oil used in Western diets). What's more, the olive oil group lowered their need for blood pressure meds by a whopping 48 percent.

Best Sources: Not all olive oil is created equal. Extra virgin varieties go through less refining and processing and thus retain the most nutrients.

Red Wine

How Much: Shoot for a glass a day if you're a woman; two if you're a man, says Ralph Felder, M.D., director of cardiac nutrition at Banner Good Samaritan Medical Center in Phoenix, AZ, and co-author of The Bonus Years Diet (GP Putnam's Sons New York, 2007).

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Why: Red wine contains chemicals called polyphenols that reduce cholesterol, prevent blood clots, and lower blood pressure. The latest research suggests that polyphenols may also inhibit inflammation—the culprit at the crux of many chronic diseases, including Alzheimer's.

One particular polyphenol called resveratrol is a powerful anti-aging substance, experts claim. “Resveratrol makes the individual blood cells less sticky and thus thins out the blood, which prevents dangerous blood clots,” says Dr. Felder. “When blood clots form and become lodged in the smaller vessels of the heart or brain, they prevent oxygen from reaching these vital organs, and that can cause a heart attack or stroke.”

In fact, a study published in the Journal of Agricultural and Food Chemistry in 2006 found that resveratrol improves blood flow to the brain by 30 percent, which reduces the risk of stroke. Other studies have shown that this antioxidant extended the lives of fruit flies by 30 percent.

Best Sources: Red wines pack a heavier health punch than whites since polyphenols are more concentrated in grape skins (reds contain more material from the skins). Among red wine varietals, Pinot Noir may be the best pick since it typically contains the highest concentrations of resveratrol. As a delicate, thin-skinned grape, Pinot Noir is a prime candidate for mildew, which causes the vines to build up a natural defense—and this defense is resveratrol. (If you can't drink alcohol, grape juice is a good substitute. There's less resveratrol, but you'll still get an antioxidant kick.)

But perhaps the most important dietary step you can take to stave off disease—neurological and others—is to keep excess pounds at bay. A study published in the Annals of Internal Medicine in 2002 of more than 20,000 male health professionals found the risk of stroke was 30 percent higher in overweight men and twice as high in those who were obese as in normal-weight men.

“Overweight and obese persons have more inflammation in their bodies,” says Dr. Gerbstadt. The more calories you eat, the more the body generates free radicals. Eating nutrient-dense foods that are low in calories—many of which are featured in the Mediterranean diet—can help keep you lean and healthy.

Rosemary and Turmeric: Anti-Alzheimer's Spices?

When it comes to kicking up the flavor of an otherwise drab dish, herbs and spices are a natural fix. But emerging research reveals that—like fruits and vegetables—some spices have powerful disease-fighting potential, even surpassing that of vitamin supplements. Two of note:

TURMERIC Used medicinally for more than 5,000 years, turmeric has antioxidant, anti-inflammatory, and cholesterol-lowering properties—all three of which are thought to be involved in the onset of Alzheimer's disease. A major source of the anti-inflammatory curcumin (the chemical responsible for the spice's yellow color), turmeric helps combat inflammation deep within the brain's tissue and thwart the development of plaques in the brain, which contribute to the disease.

ROSEMARY Rosemary contains several compounds that prevent the breakdown of acetylcholine, an important neurotransmitter in the brain necessary for memory and healthy brain function. In fact, one Alzheimer's drug, Aricept, works similarly, by interfering with acetylcholine breakdown.

Tuna Sicilian Style

Adapted and updated from Modern Italian Cooking by Biba Caggiano (Simon & Schuster, 1987)

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(Serves 4)

INGREDIENTS

2 cups canned plum tomatoes with their juices

½ cup all-purpose unbleached flour

2 pounds tuna steaks, about ¾-inch thick

4 tablespoons olive oil

1 small onion, thinly sliced

2 garlic cloves, finely chopped

½ teaspoon anchovy paste

1 cup dry white wine

¼ kosher salt

pinch cayenne pepper

½ cup black olives, halved

1 tablespoon capers, rinsed and dried

1 tablespoon chopped fresh parsley

DIRECTIONS

Press the tomatoes through a food mill or sieve to remove the seeds. Set aside.

Spread the flour on a piece of aluminum foil. Coat the fish lightly with the flour. Heat the oil in a large skillet over medium heat. Add the fish and cook for 2 to 3 minutes per side, until the fish is lightly browned. Transfer the fish to a plate.

Add the onion to the skillet and saut over medium heat until the onion is pale yellow, 4 to 5 minutes. Add the garlic and anchovy paste and stir to blend with the onion. Cook 1 minute longer. Add the wine and stir, scraping up any browned bits in the skillet. When the wine has evaporated, add the strained tomatoes. Season with salt and cayenne pepper and cook the sauce over low heat, uncovered, for 8 to 10 minutes.

Return the fish to the skillet and add the black olives and capers. Cover the skillet and cook for 5 minutes longer over low heat. Stir in the parsley. Serve the fish topped by a few tablespoons of its own sauce.

Nutrition Analysis

(per serving)

Antioxidant-Rich Foods

Vitamin C citrus fruits, strawberries, green leafy vegetables, raw cabbage, green peppers, potatoes, broccoli, melon.

Vitamin A carrots, squash, sweet potatoes, tomatoes, kale, collard greens, peaches, apricots, cantaloupe.

Vitamin E nuts, seeds, wheat germ, whole grains, vegetable oil, fish-liver oil, green leafy vegetables.

Selenium garlic, eggs, chicken, grains, red meat, fish, shellfish.

Lycopene pink grapefruit, guava, watermelon, rosehips, tomatoes.

Polyphenols tea, berries, grapes, turmeric, sesame seeds, artichokes.

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