It's undeniable that what you eat affects brain health both in the short and long terms. We know that foods high in omega-3 fats, vitamin B12, zinc, magnesium, and iron (all key components of the almighty Mediterranean diet), can boost your mood in the short term, provide energy, and also ward off cognitive decline later in life. But where carbs fit into the equation is less clear. Here, three experts—a functional neurology expert, an expert in nutritional biochemistry, and a registered dietitian all shine light on the carbs-brain health connection, both short- and long-term.
Carbohydrates and cognitive decline
The basics of carbs and brains: glucose—a type of carbohydrate—is your brain's preferred energy source. Your brain needs some amount of carbs to properly function. But then things quickly get more complicated. "Simple carbs, like bread, pasta, soda, or juice, are absorbed quicker in the body, which means they can provide a quick boost of energy, but it also [can cause] a blood sugar imbalance, since those levels will go up and then down instead of staying steady," says functional neurology expert Titus Chiu, MS, DC. If a person's blood sugar levels are consistently spiking and crashing (say, by eating a diet high in simple, processed sugars and carbohydrates), this sustained imbalance can lead to health problems like metabolic syndrome and diabetes.
What does this have to do with the brain, you ask? In the short term, the rise and fall in blood sugar can lead to brain fog. In the long term, Dr. Chiu says researchers believe there is a type of diabetes—called Type 3 diabetes—that is linked to Alzheimer's disease and cognitive decline. "[Type 3 diabetes] relates directly to brain health in relation to carbs because it occurs when brain cells become sensitive to insulin," he says. "Simple carbs affect blood sugar levels and insulin response." Essentially, a diet high in processed, simple carbohydrates can potentially impair brain health.
On the other hand, complex carbs, such as oats, lentils, quinoa, and beans, are linked to benefitting brain health. The reason for this, Dr. Chiu explains, is that unlike simple carbs, complex carbs stabilize blood sugar levels thanks to their fiber and phytonutrient content, which keeps mood and energy stable in the short term and promotes healthy brain function in the long run.
It's really easy to read that news and decide to shun carbs forever. But all the experts we spoke to emphasize that carbs should not be demonized. "What you have to think about is, what are the other nutrients—or lack thereof—in the foods you're eating," says Dr. Chiu. "If you're eating fruit for example, fruits are very nutrient-dense—full of fiber, antioxidants, and other nutrients that we know are good for brain health—so the effects of eating a piece of fruit are going to be a lot different than eating processed food, which has carbs but likely no other nutrients."
Cyrus Khambatta, Ph.D, a nutritional biochemistry expert, agrees. "Carbohydrate propaganda has many believing that all carbs are bad for health, but lentils, beans, and whole grains are all sources of carbs and also foods that are linked to improving overall health, the brain included," he says.
A note about keto
While many keto fans claim that their increased mental clarity is the result of carbohydrate restriction, Dr. Khambatta disagrees. "It's because they've replaced low-nutrient foods like breads, pasta, and cookies with higher-nutrient foods. It's not that they've cut carbs," argues Dr. Khambatta. "If you replace the same low-nutrient foods with nutrient-rich complex carb sources, you'll likely experience the same benefits."
Plus, the jury's out on any definitive long-term benefits of keto for brain health. "The ketogenic diet was originally recommended to people with epilepsy who experienced seizures and it was successful in treating that. But as far as longterm brain health for the average healthy person, we just don't know yet," says registered dietitian Maya Feller, RD. "When people tell me they're cutting carbs, the big question I ask them is, 'Okay, but what are you replacing them with?' Because while we don't know how eliminating carbs completely affects brain health longterm, we do know certain foods that are linked to good brain health—like leafy greens—and foods that aren't."
Check out the video below to see what a registered dietitian thinks of the ketogenic diet:
So what's the verdict on all of this? When it comes to carbs and brain health, all experts agree that the biggest connection comes down to carbs affecting blood sugar levels, which in turn can affect brain health both short- and long-term. With this in mind, the question shouldn't be carbs or no carbs, but the type you add to your plate. (Complex carbohydrates FTW!) And, as always, it's important to think of the whole food, not just one element of it. If the snack you're reaching for is full of fiber and vitamins, it's a good bet that it's going to benefit your entire body, brain included. If not, well that's another story.
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