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Are Processed Foods Bad for Your Brain?   

Eating lots of salty, sugary and high-fat snacks could impact your memory after midlife


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If you’re looking to keep your brain healthy as you age, you may want to lay off the packaged pastries for breakfast, frozen pizza for lunch and ice cream in the evening. Accumulating research suggests that a diet chock-full of highly processed foods could contribute to worsening brain health.

A study published May 22 in the journal Neurology found that adults 45 and older who recorded a higher intake of ultraprocessed foods — foods high in sugar, fat and salt, and low in protein and fiber — had a greater risk for cognitive decline and stroke, while those who kept to a minimally processed diet saw a decreased risk for both conditions. The association was especially pronounced among Black participants: Black adults who ate more ultraprocessed foods had a 15 percent increase in their risk of stroke.

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Researchers have also linked a steady diet of our favorite salty snacks, high-sugar treats and preservative-laden frozen dinners to an increased risk of dementia. Similar to this recent report, the authors of a study published in Neurology in 2022 discovered that replacing processed foods with minimally processed options was associated with a 19 percent lower risk of dementia.

What’s more, research presented at the 2022 Alzheimer’s Association International Conference found that people who consumed the highest amounts of ultraprocessed foods (more than 20 percent of their daily caloric intake) saw a faster decline in memory, planning and organizational skills over a span of several years, compared with those with lower consumption.

“There are a lot of studies that have already shown that eating [healthy] is good for your heart, but we’re starting to see trends that eating a heart-healthy diet may also be good for your brain,” says Rebecca Edelmayer, senior director of scientific engagement for the Alzheimer’s Association.

An earlier report from AARP’s Global Council on Brain Health reached a similar conclusion — that what you eat impacts the health of your brain and that foods high in salt, sugar, excess calories and saturated fats don’t do it any favors. Still, an analysis of national data published in BMJ Open found that ultraprocessed foods represent more than half (58 percent) of all calories in the U.S. diet.

The food-brain relationship

Many foods that line the grocery store shelves are considered processed. For example, bagged salads go through minimal processing; so do cans of beans and boxes of frozen vegetables.

But the types of foods that these studies looked at “really go through a significant industrial process and contain large quantities of fats, sugars, salt, artificial flavors and colors, even stabilizers and preservatives,” Edelmayer says.

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Most live in the center aisles of the grocery store, not the fresh and refrigerated sections along the perimeter. And when it comes to their potential impact on brain health, it’s important to remember that “the whole body is interconnected,” says Stephanie Kim Nothelle, M.D., a geriatrician and assistant professor of medicine at Johns Hopkins Medicine, who was not involved in either study.

The brain is a highly vascular organ, Nothelle explains, and everything we eat gets absorbed into the bloodstream. “And so if you’re eating something that’s really high in fat, or really high in salt, or really high in sugar, those things are going to be distributed throughout the body and have effects everywhere, including the brain,” Nothelle says.

Research shows that people with certain health conditions that can be influenced by a bad diet — heart disease, high blood pressure and diabetes, for example — are more likely to experience cognitive decline as they age. These are also risk factors for stroke.

Another thing to consider: It may not be what you’re eating when you devour a packaged snack but what you’re not eating when you choose that highly processed option over, say, a piece of fruit, points out Paul Jacques, a senior scientist at the Jean Mayer USDA Human Nutrition Research Center on Aging and a professor at the Friedman School of Nutrition Science and Policy at Tufts University.

“There’s a lot of things in [whole] foods — a lot of phytochemicals, polyphenols — that have been associated with brain health that aren’t going to be found in most ultraprocessed foods,” he says. These brain-boosting compounds are “hard to avoid” if you’re eating a mostly plant-based, Mediterranean-style diet. You can find them in berries, onions, apples, leafy greens, nuts and seeds. Fish is another food that research has shown may benefit the brain.

“The important thing [to think about] is what are the ultraprocessed foods replacing,” Jacques says. “It’s really looking at your overall diet and seeing what’s in it.” And know that a handful of blueberries once a week won’t offset a steady stream of fast food, he adds.

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Healthy habits can help your brain

It’s hard to avoid ultraprocessed foods; they’re stocked in nearly every store, and there’s no denying their convenience. Plus, for many people, access to fresh, healthy food isn’t always an option. But if you’re looking to cut down on the amount of highly processed foods you’re eating, Nothelle says to choose single-ingredient foods when you can, like an apple, a chicken breast or a bowl of whole grains.

“You know what is in them, versus some packaged product where when you look at the back, the ingredient list is like 100 different items long, half [of them] you can’t even pronounce or don’t know what they are,” she says.

Also, don’t overthink it. If you stick to a diet that’s good for your heart, the latest research suggests your brain will also reap the benefits. “Sometimes people drive themselves crazy about this sort of stuff, but hopefully having a balanced perspective will help,” Nothelle says.

The Alzheimer’s Association’s Edelmayer says the mounting research linking diet and brain health strengthens the notion that there are everyday things individuals can do to reduce their risk of dementia — and that’s “exciting,” she adds. The Centers for Disease Control and Prevention says nearly 40 percent of Alzheimer’s disease and related dementias may be prevented or delayed with the adoption of certain habits, like a healthy diet and regular exercise.

“There will be some more research that’s needed to come up with the most sustainable and evidence-supported strategy for individuals, but I think when we look at the future of treatment for Alzheimer’s disease and other dementias, it’s going to include strategies like ... the incorporation of healthy habits into one’s lifestyle but also the ability to have access to really powerful medicines to effectively treat Alzheimer’s and other dementias,” Edelmayer says.

Only one medication has received full federal approval for the treatment of Alzheimer’s disease, which is the most common form of dementia; a second one is being considered, and several potential therapies are being studied in clinical trials.

Editor’s Note: This story, originally published Aug. 10, 2022, has been updated to include new information.

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