This is the polenta Napoleon at the Walnut Grille, a new restaurant in Newton that features vegetarian, vegan and gluten-free items. Dina Rudick/Globe Staff
Can what you eat actually affect how well your brain ages? That’s been a subject of heated debate as some scientists race to identify gene mutations linked to Alzheimer’s disease while others hone in on nutrients that appear to protect against dementia and keep our brains sharp through the years.
Vegetarian activist Dr. Neal Barnard, a clinical researcher and adjunct professor at the George Washington University School of Medicine, believes the balance tips more towards our diet than our genes. Over a vegan lunch of a summer salad with tempeh (recipe below), grilled eggplant sandwiches, and fruit kabobs, Barnard explained the principles of his new book Power Foods for the Brain and why he believes avoiding all animal products—as well as fortified breakfast cereals and vegetable oil—will help protect the brain from developing dementia.
Few nutritionists would argue with the basic tenets of Barnard’s eating plan: Consume a diet based on fruits, vegetables, legumes, nuts, and whole grains. He also advocates for regular exercise and adequate sleep to prevent brain diseases and rapid aging.
Where Barnard and his staff at the non-profit Washington-based research group Physicians for Responsible Medicine part ways with the public health establishment is in their vegan approach to eating. Meat, chicken, fish, dairy products, and most oils aren’t considered brain foods.
First off, animal products contain saturated fat which “has been pretty strongly linked to Alzheimer’s risk,” Barnard tells me. “There’s no good reason to eat it.” Saturated fat raises artery-damaging cholesterol, and research suggests it contributes to the formation of beta amyloid plaques that gunk up the brain and are associated with Alzheimer’s disease.
That makes sense to me, but why should I avoid my fat-free Greek yogurt or egg white omelettes that contain no saturated fat? Barnard has a weaker case to make against those since research can’t draw a clear connection between animal protein and long term memory loss.
He did, though, make an intriguing argument against the over-fortification of foods, especially cereals supplemented with minerals like copper and iron. “Very few of us are deficient in these minerals, and many of us have too much,” he said. An aging study conducted by Chicago researchers found elderly people with the highest risk of cognitive problems had the greatest intakes of copper, while other research has found both copper and iron in beta-amyloid plaques.
Just how much these minerals contribute to Alzheimer’s risk remains unknown, but Barnard was quick to point out that while the body may get too much iron from red meat and fortification, the iron found in spinach and other leafy greens is in a different form that’s only absorbed by the body if our iron stores are running low.
Limiting omega-6 fats like corn and vegetable oil is also key for brain health, Barnard contends, because these fats compete with and negate the effects of beneficial omega-3 fats—such as fish oil, walnuts, and flaxseed—that promote good blood flow to the brain.
Barnard excludes fish for good brain health because he thinks we can get enough omega-3 fats from vegetarian sources and because fatty fish is often contaminated with mercury, which is also toxic to the brain.
So which foods will actually help you shore up your brain’s defenses against aging? The book is careful not to single out a few magic bullet foods that will ward-off memory loss—none exist—but it does emphasize the following dietary principles.
1. Make a power plate at every meal. One quarter the plate should be filled with fruits, one quarter with grains, one quarter with legumes, and one quarter with vegetables.
2. Do colorful combinations of foods. Combining sweet potatoes with kale or oranges with apples will ensure that you get a variety of vitamins and other plant chemicals that work synergistically to promote good brain health. If some of the vegetables are too bitter for your taste, the book recommends spritzing them with lemon juice or apple cider vinegar to bring in some sour notes. I also loved the fresh mint they added to the fruit kabobs.
3. Get creative with legumes. Vegans use these are their main source of protein, so think hummus, tofu, tempeh, as well as beans, lentils and peas.
4. Learn to prepare foods without oil. The book recommends dry sauteeing vegetables. I’m assuming over low heat, so they won’t burn. You can also cook vegetables and grains in vegetable broth for added flavor or—if you must—spray on a little olive oil from a diffuser.
5. Don’t forget the nuts and seeds. Sprinkle nuts and seeds on your salads, grains, and morning oatmeal to get omega-3 fats and vitamin E, both beneficial for the brain.
6. Skip all supplements, except one containing a B-12. Vegetarians often lack B12—essential for proper brain function—in their diets since it’s found mainly in animal products like beef, turkey, and pork. so the book recommends taking a daily supplement.
Brain Power Food Recipe
½ red onion, diced
1 Mexican gray squash or zucchini, diced
1 cucumber, peeled and diced
2 small tomatoes, diced (and seeded if you like)
¼ cup sliced red cabbage
2 stalks celery, sliced
Kernels from 2 ears corn (about 1 ½ cups)
Pinch of sea salt
Juice of 1 small lime (about 1 tablespoon)
Optional: 2 tablespoons chopped fresh cilantro; 1 cup rinsed cooked or canned red beans or 1 cup sautéed tempeh; 1 cup sliced Swiss chard leaves
Mix all ingredients together in a large bowl and allow the salad to marinate for at least 30 minutes but preferably 2 hours.
Jason Wyrick. Adapted from “Power Foods for the Brain”