How can some carbohydrates serve as brain food while others hurt your mental health? See why the oft-labled "evil" nutrient sometimes earns a bad rap

By Charlotte Hilton Andersen
August 11, 2015
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Low-carb, high-carb, no-carb, gluten-free, grain-free. When it comes to healthy eating, there's some serious carbohydrate confusion. And it's no wonder-it seems like every month there's a new study telling you carbs will kill you, quickly followed by one that says they're the cure to cancer. This week is no different. Two new studies about the effects of carbohydrates on our brains were released: One says carbs are the key to human intelligence; the other says carbs harm your mental health.

But all these findings may not be as opposite as they first seem. In fact, it's not about whether or not you should eat carbs, but rather what types you should eat. (See Carbs Without Cause: 8 Foods Worse than White Bread.) "Not all carbs are created equal," says Sherry Ross, M.D., an ob-gyn at Providence Saint John's Health Center in Santa Monica, CA, and an expert in women's nutrition, "especially when it comes to the brain."

The Benefits

Carbs are actually to thank for your smarts: A new study, published in The Quarterly Review of Biology combed through archaeological, anthropological, genetic, physiological, and anatomical data to figure out whether carbohydrate consumption was a key factor in our brain development over the last million years. Turns out, potatoes, grains, fruits, and other healthy starches may be the reason humans developed our trademark big brains in the first place, says lead author Karen Hardy, Ph.D., a researcher at Universitat Autònoma de Barcelona specializing in ancient nutrition.

But this isn't just a history lesson-starches are just as important to brain health today. "Starchy foods, or carbs, are the main energy source for the brain and the body," Hardy explains. "They should be included in the diet for maximum functioning of the brain and body." (Also essential: The 11 Best Foods for Your Brain.)

So What's with the Bad Reputation?

Carbs have such a bad rap because of the black sheep of the nutrient's family: processed foods. It's refined carbs, particularly processed junk foods, that are linked with everything from heart disease to diabetes (not to mention weight gain). And nowhere is this more apparent than in the brain, as shown by another new study published in the American Journal of Clinical Nutrition. Researchers from Columbia University Medical Center found that participants who ate the most refined carbohydrates were more likely to be depressed. How are they sure it's the processed foods to blame? Because the inverse was also true: Women who ate more dietary fiber, whole grains, vegetables, and fruit-all full of healthy, whole carbs-were less likely to be down in the dumps. (What you nosh on can have a profound impact on your emotions. Try these 6 Foods to Fix Your Mood.)

How to Eat Carbs

It's confusion such as this that leads many women to just cut out the nutrient group all together. But this move would be a mistake. "Unequivocally, our brains need carbohydrates to function," Ross says. "Over time, not getting enough carbs in your diet can increase problems with basic mental functioning." She cites a 2008 Tufts University study linking low-carb diets with memory problems and slowed reaction times-a phenomenon often jokingly referred to as "carb flu." However, subsequent research has shown the cognitive effects of the carb flu are short-lived in most adults, as the brain can adjust to using fat for fuel instead of glucose. (Same with your body. Find out The Truth About the Low-Carb High-Fat Diet.) Plus, carbs are particularly helpful for women's brains. "They are especially essential for pregnant and lactating mothers, most specifically for the health of their babies," Hardy says.

Both experts say to steer clear of processed simple carbs (like sugar and honey) and to be particularly wary of those masquerading as "health foods," like sugar-soaked cereals and granola bars. (One quick trick is to look at the label and avoid anything that has more grams of sugar than fiber or protein.) Instead, fill your plate with a variety of whole, unprocessed starches which will provide nutrients vital to brain health.

To do this, Hardy recommends following our ancient ancestors' lead, saying that, contrary to popular paleo diet theory, their diet wasn't low-carb. Instead, they feasted on nuts, seeds, vegetables, tubers, and even the inside of tree bark to get calories and nutrients. And while she doesn't recommend gnawing on bark, beans, nuts, and whole grains all provide folate and other B vitamins which, according to a study from Cambridge University, are critical to brain development and functioning. Alternatively, Ross points to the Mediterranean diet as a good modern example of how to balance carbs as part of a healthy diet. (Check out Mediterranean Diet: Eat Your Way Forever Young.)

So whether you're following a cavewoman diet, a Mediterranean diet, or simply a clean diet based around whole foods, there are a lot of options to get brain-healthy carbohydrates on your plate. And not only will your brain thank you, but so will your taste buds. Bring on the sweet potatoes!