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These Are the 9 Worst Foods for Your Brain

While avocados, berries, and dark chocolate are brain-boosting superstars, these foods might sap your smarts.

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Vegetable oils

Any oil is healthier than a big slab of butter, right? Not so fast. Canola, sunflower, and soybean oils contain higher levels of omega-6, a fatty acid that promotes inflammation in your brain. And simply put, “inflammation is what makes a good brain go bad,” according to David Perlmutter, MD, a board-certified neurologist and #1 New York Times bestselling author. A 2017 study linked canola oil, in particular, with impaired memory and Alzheimer’s disease. While omega-6 fatty acids can have health benefits for your bones, skin, and hair, you might be better off with oils that contain anti-inflammatory omega-3s, such as olive oil. Here are more of the best foods for your brain.

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While the occasional tuna sandwich is no big deal, you might want to think twice before making it a regular part of your diet. Mercury—found in fish such as tuna, shark, or swordfish—is toxic to humans, and it can accumulate in and damage your brain when ingested in large doses. In fact, University of South Florida researchers discovered that people with high levels of mercury in their bloodstream showed a five percent drop in cognitive function. But you don’t have to banish seafood from your plate forever; just limit yourself to one serving of tuna a week. Salmon, sardines, and mackerel, on the other hand, are low in mercury and high in brain-healthy omega-3s. Memorize these healthy habits that can boost your brain.

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Fried foods

Donuts and fries aren’t just bad for your waistline; they can spell trouble for your noggin, too. In fact, the two side effects are related: “Filling up on the fried foods can easily contribute to weight gain, which can negatively impact the health of your brain,” Dr. Josh Axe, D.N.M., C.N.S., D.C., founder of Ancient Nutrition, told Reader’s Digest. In a study published in the Journal of Nutritional Sciencesubjects who ate diets high in fried foods also scored poorly on tests that evaluated learning, memory, and brain function. The researchers believe that eating fried foods contributes to inflammation and small brain size. So choose foods that are baked or grilled over breaded or battered, and make sure to incorporate these brain-boosting herbs while you’re at it.

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Sugar-sweetened beverages

Brainiacs, beware of soft drinks, fruit juice, energy drinks, and sweet tea. Why, you ask? “High amounts of sugars to our brain does cause neurological damage” because they trigger inflammation, according to Wesley Delbridge, RDN, national media spokesperson for the Academy of Nutrition and Dietetics. These sugary beverages also contain fructose, a type of simple sugar that can increase your dementia risk. All the more reason to start dialing back your soda addiction. Watch out for the clear signs you’re eating too much sugar.

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Trans fats

While manufacturers use trans fats to extend the shelf life and enhance the flavor of their food, it comes at the cost of your brain’s health, Delbridge said. Research has found that a higher intake of trans fats—found in processed foods like cake, cookies, and muffins—can cause plaque to build up in your brain, increasing your risk of cognitive disorders like Alzheimer’s disease. Swap the pre-packaged desserts for dark chocolate, and trade your microwave popcorn for air-popped popcorn, instead. You need to try these powerful eating habits to protect your brain from Alzheimer’s, too.

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Refined carbs

White bread, pasta, rice, cereal, and sugar are just a few of the carbs you should avoid if you want your brain to perform at 100 percent. “These foods are quickly absorbed into the bloodstream, spiking levels of both blood sugar and insulin,” Dr. Axe said. The higher your blood sugar, the greater your risk of developing diabetes, which has been linked to Alzheimer’s disease. Granted, not all carbs are created equal. Whole wheat bread, brown rice, quinoa, barley, and faro contain dietary fiber, which nurtures your gut bacteria and regulates inflammation—all good things for your brain health. Try even more of the best carbs for your health.

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There is a “sweet spot” for alcohol consumption, according to Dr. Perlmutter. While the occasional glass of red wine can actually be healthy, drinking in excess is toxic to your brain structure and function—no matter your age. To protect your cranium, keep your alcohol consumption in moderation; the official American Dietary Guidelines recommend one drink per day for women and two drinks per day for men.


Fast food

It almost goes without saying that fast food can sap your smarts. For starters, the high levels of saturated fat found in greasy burgers and fries can make it harder to fight off Alzheimer’s-causing plaque. All that sodium can also cause your blood pressure to skyrocket, contributing to long-term cognitive decline. You’ll feel the effects right away, too. Just one meal can block your brain’s ability to learn and create new memories, according to Ewan McNay, Ph.D., an assistant professor of behavioral neuroscience at the University at Albany. The next time you’re in the mood for a convenient meal, try one of these healthy fast food options at the most popular restaurants.

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Added and artificial sugars

Like sugary beverages, added and artificial sugars like aspartame can lead to impaired memory and cognitive decline. Unfortunately, around 90 percent of foods you find in the grocery store aisles are high in added sugar, according to Dr. Perlmutter. He advises shopping around the edges of the store, where most of the unprocessed (and low-sugar) foods are displayed. And when in doubt, check the list of ingredients on the side of the box; if sugar is listed as one of the first ingredients, “that’s a good indicator that the product is high in added sugar,” Kelly Pritchett, Ph.D., R.D., told Women’s Health. Delbridge recommends watching out for sneaky terms for sugar like “organic brown rice syrup,” too. On the other hand, these brain-boosting foods will keep you sharp.