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Five Food Groups to Avoid to Keep Your Brain Healthy by Annie Fenn, MD

Updated: Nov 14, 2019

In my last SOULFUL Insights post, I shared the foods that are most proven to protect the brain from Alzheimer’s disease and other dementias. Filling your plate with the 10 Brain Healthy Food Groups has been proven to reduce Alzheimer’s risk by more than half. It’s exciting news that we have solid scientific evidence that certain foods slow down the aging of our brains. But it’s just as important to know which foods we should avoid. Can certain foods actually give you Alzheimer’s? Let me explain. When the Mediterranean DASH Intervention for Neurodegenerative Delay (MIND) researchers set out to determine the most neuroprotective foods, they also looked at data on the foods thought to be harmful to the brain. We’ve known for years that eating certain foods will increase your risk for heart disease and diabetes, both of which will increase your risk for Alzheimer’s. Now studies also show that a steady diet of brain-unhealthy foods is an independent risk factor for Alzheimer’s.

What to eat to fend off Alzheimer’s: Recipes for Pan-Fried Carrots and Asparagus with Dukkah, Cilantro Chutney and Citrusy Salmon and Zoodle Packets at Brain Health Kitchen.

Foods are considered to be harmful to the brain if they:

     1. Are high in saturated and trans fats. Eating more saturated and trans fats ups your odds of getting Alzheimer’s. In one of the most comprehensive studies to date, those who consumed more than 25 grams of fat a day tripled their risk of developing Alzheimer’s over a four-year period. That’s the amount of saturated fat in a typical fast-food hamburger and fries. If the diet was high in trans fats (more than two grams a day), the risk was three to five times greater. This doesn’t mean all fats are bad for the brain. But the brain-healthy diet favors healthy fats, such as the mono- and polyunsaturated fats found in olive oil, avocados, nuts and oily fish (salmon, mackerel, anchovies, sardines).

     2. Contain mostly simple sugars. Sugar and other simple carbohydrates in foods cause spikes in blood sugar that lead to inflammation of blood vessels and brain structures. Over time, eating sugary foods can lead to an unhealthy metabolic state in which the body becomes resistant to insulin. For years we have known that people with diabetes have a two- to four-fold increased risk of Alzheimer’s disease. Now, new data shows that even those with pre-diabetes (a borderline level on the fasting blood sugar test) are twice as likely to get Alzheimer’s. In fact, some experts refer to Alzheimer’s as Diabetes Type 3. The brains of Alzheimer’s victims are so resistant to insulin that they are no longer able to metabolize simple sugar and preferentially use fats for fueling the brain.

     3. Contain excessive salt. Too much salt in the diet can lead to cardiovascular disease, especially high blood pressure. High blood pressure, or hypertension, is a known risk factor for Alzheimer’s disease. A recent study showed those who maintained a healthy blood pressure at mid-life (systolic blood pressure < 130) have a reduced risk of Alzheimer’s disease decades later. Ridding the diet of excessive sodium, like that found in fried, packaged, processed and fast foods is an important tool for reducing Alzheimer’s risk.

     4. Create pathogenic compounds called advanced glycation end products (AGEs). What exactly are AGEs? AGEs are inflammatory substances in foods thought to be harmful to the brain. They result from processing food at high temperatures. Also called glycotoxins, AGEs are substances that crosslink proteins together, making tissues lose their elasticity. In blood vessels, this means the linings of arteries become stiff and prone to developing plaques. AGEs concentrate in key locations of Alzheimer’s victims’ brains such as the hippocampus, the brain’s filing cabinet for short-term memories.

Even though this burger is made from eggplant, not meat, its deep-fried preparation makes it very high in salt and AGEs.

Researchers have linked a high level of AGEs in the blood to an increased risk of many chronic diseases, such as diabetes, cardiovascular disease, kidney disease and Alzheimer’s.

The more a food is processed, the higher its AGE level. Fast, fried and processed foods have the highest AGE levels. Fatty spreads—butter, margarine, cream cheese and mayonnaise—are also very high in AGEs. Meats are inherently high in AGEs and become even more so when cooked over direct heat and slathered in sweet sauces. (Sorry, barbecue lovers!) Raw, minimally cooked, and fresh foods are the lowest in AGEs. Even commercially roasted nuts can rack up AGEs. It’s better to buy nuts raw and toast them yourself (as in these toasted pistachios in my Moroccan Forbidden Rice Salad).

For a comprehensive list of AGEs in foods, take a look at this study. If you want to indulge in AGE-full foods occasionally—like my favorite deep-fried falafel—be sure to eat a heap of fresh vegetables alongside. Eating leafy greens and vegetables can reduce the absorption of the food’s AGE content.

Before we review the Five Brain-Unhealthy Food Groups, keep in mind that the MIND diet is not an elimination diet. It’s still okay to have an occasional salty or sweet treat—just limit your intake of these foods.

Five Brain-Unhealthy Food Groups

1. Red Meat. Fewer than three (3- to 5-ounce) servings each week. We know that the more red meat a person consumes, the greater their risk of cardiovascular disease. The same seems to be true for Alzheimer’s disease. Limit red meat to just a few servings each week. Seek out meat raised without antibiotics or hormones and fed only grass, preferably on a farm, not in a factory. Although the choice of meat is not proven to reduce Alzheimer’s risk—that study has not been done—grass-fed meat and wild game have more healthy omega-3s, and less of the inflammatory omega-6s fats.

2. Fried Food and Fast Food. Less than one serving each week. Not only do these foods rack up high levels of AGEs, but they also possess brain-unhealthy fats, sugars and excessive levels of salt. It’s okay to indulge in fried food as an occasional treat; just make sure the food is fried in olive or avocado oil, not inflammatory vegetable or seed oils. It is good news that the use of trans fats has been banned, but most restaurants still fry food in inexpensive, inflammatory oils.

My favorite indulgence is falafel; eating these fried, AGE-full chickpea fritters with leafy greens reduces absorption of AGEs.

3. Butter. Less than one tablespoon each day. This is a tough one for those of us who love butter. But butter is a potent source of brain-unfriendly fats; just one pat has four grams of total fat, mostly saturated. As you may recall from my last Soulful Insights, a brain-healthy diet uses olive oil as its primary cooking oil. With a little practice (and some good recipes), olive oil can be used instead of butter with great results. You don’t have to give up butter entirely; look for high-quality butter and use sparingly. Grass-fed butter, such as the European brands Kerrygold and Plugra, come from cows that are fed only grass. These brands have a higher level of brain-healthy omega-3s.

4. Cheese. Enjoy infrequently. Before you give up on the MIND diet (cutting back on butter can be hard enough), consider this: cheese is the primary source of saturated fat in Americans’ diets. Just one ounce of cheese—a one-inch cube—has more saturated fat (5.1 grams) than a serving of roast beef. As a cheese lover, I advise eating cheese like my Sicilian relatives: choose high-quality cheese that is naturally lower in fat (think Pecorino, Parmesan and feta.) In my family, we reserve nice cheeses for special occasions, like holidays and dinner parties, and avoid having a big bag of shredded cheddar or mozzarella always at the ready.

 5. Pastries and Sweets. Fewer than five servings each week. Pastries and sweets are full of unhealthy fats, refined sugars and salt. They are also high in calories with little nutritive value in return and contribute to unhealthy weight gain. This doesn’t mean you should never have another chocolate croissant! But reserve these for occasional treats, not everyday foods.

Most of what we eat should flood our brains with healthy fats, phytonutrients (found in fruits and vegetables), gut-healthy fiber and anti-inflammatory substances. In the MIND diet study, those who ate primarily from 10 brain-healthy food groups and largely avoided the five brain unhealthy ones had 53% less incidence of Alzheimer’s at the end of the 4.5-year study. Those who followed these guidelines half the time still had a significant reduction in risk—35%!

Want to learn more about the data behind certain foods and the brain? Read my interview with Dr. Martha Clare Morris, lead researcher of the MIND diet study, here. The MIND diet is currently being examined as a randomized, controlled trial. Stay tuned: the results will be published in 2021.

In the meantime, over at Brain Health Kitchen, I’ll be busy creating more delicious brain-healthy recipes for you.


Annie Fenn, MD

Annie Fenn is a board-certified physician, culinary instructor and trained chef. She practiced obstetrics and gynecology with a specialty in menopausal health for over 20 years in Jackson, Wyoming, where she lives.

Dr. Fenn switched gears in 2010 to practice medicine from a different angle—teaching her patients how to eat and cook with whole foods. After attending culinary school in Italy, Mexico and the Culinary Institute of America, she taught dozens of cooking classes in her community and wrote about food, health and sustainability for numerous media outlets. In 2017, she launched Brain Health Kitchen, the only cooking school of its kind to focus exclusively on preventing Alzheimer’s and dementia.

Dr. Fenn teaches cooking and gives talks throughout the U.S. and abroad about how to cook and eat to reduce Alzheimer’s risk. Along with a team of cognitive health specialists, she offers four Brain Works Boot Camps in Jackson Hole each year—seven-day immersion experiences in cutting-edge Alzheimer’s prevention. She creates recipes based on scientific data from the Mediterranean diet, the MIND diet, the study of Blue Zones centenarians and the large body of data about how lifestyle factors impact Alzheimer’s risk. She loves showing people how easy and delicious it can be to cook for brain health.

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