If you aspire to have a brain like Socrates, eat like a Greek.

The Mediterranean-style diet, full of vegetables, fruits, olive oil, moderate amounts of whole grains, fish, poultry, and nuts is neuroprotective; in other words, it’s good for your noggin. In fact, a variation of the Mediterranean diet called the MIND diet intervention, which also limits sodium and processed foods, has been shown to slow brain aging by 7.5 years and reduce your risk of developing Alzheimer’s disease.

“Food is like a pharmaceutical compound that affects the brain,” says Fernando Gomez-Pinilla, PhD, a UCLA professor of integrative biology and physiology. And depending upon what you’re eating, that can either help or harm your cognitive ability. For example: “Eating a high-fructose diet over the long term alters your brain’s ability to learn and remember information,” says Gomez-Pinilla. “But adding omega-3 fatty acids to your meals can help minimize the damage.”

So, while you’re angling to get more fatty fish into your diet, burn some neurons conjuring up ways to eliminate these worst foods for your brain health below. And while you’re at it, erase these 11 Worst Frozen Foods from your grocery list as well.

French fries
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Foods fried in partially hydrogenated oils like French fries, chicken nuggets, battered fish, mozzarella sticks, wontons, and onion rings, contain some of the highest amounts of trans fatty acids. Trans fats are manufactured hydrogenated vegetable oils that stay solid at room temperature, so they won’t spoil. Trans fatty acids raise your bad cholesterol and lower the good stuff, boosting your heart disease risk; studies show they’re also harmful to the brain. A 10-year Japanese study involving 1,600 elderly people who did not have dementia found that those with the highest levels of industrial trans fats in their blood were up to 75% more likely to develop Alzheimer’s disease or dementia by the end of the trial.

Trans fat-laden fried foods showed up regularly in a dietary survey of 1,018 people who were also given a memory test by researchers at the University of California, San Diego School of Medicine. Their study published in PLOS ONE found that young men with the highest intake of trans fats performed the worst on a test of word recall. “Trans fats were most strongly linked to worse memory in men during their high productivity years,” said Beatrice A Golomb, MD, a professor of medicine at UC San Diego School of Medicine. “As I tell patients, while trans fats increase the shelf life of foods, they reduce the shelf life of people.” Did you know that french fries also happen to fall on the list of The 7 Foods Most Likely to Make You Gain Weight?

Hot cocoa with marshmallows
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You’re aware of the health benefits of the flavanols found in dark chocolate. But you may not know that some chocolates, cocoa powders, cacao nibs, and even dark chocolates may contain neurotoxic heavy metals. A study of cocoa trees in Peru found that certain tree varieties pull high levels of cadmium from the soil that end up in chocolate bars and cocoa powder. In an analysis of chocolate products currently on the market, ConsumerLab.com found that some chocolate bars contained toxic levels of cadmium. “There’s a limit to how much cadmium you should get,” says Tod Cooperman, MD, president of ConsumerLab.com. While the United States has set no federal guidelines on cadmium in foods, California recommends limiting consumption to 4.1 micrograms per day. “I wouldn’t have more than one cup of cocoa per day,” Cooperman says. You can find a review of the tested chocolate products at ConsumerLab.com.

If you’re looking to thread the needle between reaping the benefits of chocolate while avoiding the bad, stick to no more than one serving of chocolate per day.

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soda
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Drinking sugar-sweetened beverages can be detrimental to your mental capacity. They are loaded with refined sugars like high fructose corn syrup (HFCS), which has been shown to promote inflammation and oxidative stress. “Unfortunately, just like an expensive car, your brain can be damaged if you ingest anything other than premium fuel,” writes Eva Selhub, MD, in the Harvard Health Blog. “Multiple studies have found a correlation between a diet high in refined sugars and impaired brain function—and even a worsening of symptoms of mood disorders, such as depression,” writes Dr. Selhub, who is a clinical associate of the Benson Henry Institute for Mind-Body Medicine at Massachusetts General Hospital in Boston. In studies on rats, researchers found that a short-term diet high in refined sugars changed more than 200 sequenced genes (that are comparable to those in humans) in the hippocampus, a brain area crucial to memory. Support your brain health and replace soda with any of these 13 Healthy Foods That Boost Your Memory, According to Nutritionists.

beer cheers
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You may have noticed, in other people of course, that booze can impair judgment and make otherwise intelligent people do and say stupid things. But, seriously, heavy alcohol consumption can cause significant cognitive dysfunction. In fact, studies have shown that long-term alcohol dependence can reduce the volume of your gray and white matter. In other words, it can shrink your brain. In work published in the journal Alcohol Research — Clinical Reviews doctors using functional magnetic resonance imaging tested chronic alcoholics who had abstained from drinking for at least five days and discovered deficits in areas of the brain involved in verbal learning, processing speed, attention, problem-solving, and impulsivity.

But like most foods and drinks that affect your body, quantity often determines if you suffer a cost or gain a benefit. Recently a large, nationally representative study published in JAMA gave social drinkers something to toast: a few drinks may be good for preserving, not pickling, your brain. The University of Georgia analysis examined data on the more than 19,000 participants involved the decade-long Health and Retirement Study. Compared with never drinkers, low to moderate drinkers were less likely to experience a decline in mental status and such cognitive abilities as word recall and vocabulary. If you’re not a drinker and thinking you should start, “don’t,” say the researchers. But if you’re curious, the optimal number of drinks per week was between 10 and 14, according to corresponding study author Changwei Li, MD, PhD, MPH, of the department of epidemiology and biostatistics at the University of Georgia College of Public Health.

soda in glasses
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Artificially sweetened beverages don’t contain sugar but, as we’ve reported in the past, they do have negative health effects, namely weight gain and an increased risk of type 2 diabetes. A 2019 study in the American Heart Association’s journal Stroke points to another potential problem, this one involving the brain. The researchers analyzed data on over 81,000 women and, after adjusting for common stroke risk factors, found that women who consumed 24 or more ounces of artificially sweetened beverages per day were 23% more likely to have a stroke than those who drank less than 12 ounces weekly. For more, don’t miss Dangerous Side Effects of Drinking Soda Every Day, According to Science.