Is Cutting Carbs Bad For Your Brain? A Neuroscientist Explains

Today, as many as one in three Americans avoids gluten—a protein found in wheat, barley, and rye—thereby eliminating grains and cereals from the diet. They might be trying to lose weight, boost energy, or even treat medical conditions like arthritis, asthma, multiple sclerosis, schizophrenia, and now more recently: dementia.

Caveat that indeed about 1 percent of the population suffers from Celiac disease (a gluten allergy), and they should continue to avoid gluten. And while estimates vary, another 6 percent of people may have determinable gluten sensitivities, and they should be careful around gluten as well. But for the other 93 percent of us, a gluten-free diet is not only unnecessary but can do more harm than good.

First off, the witch hunt against gluten has led many people to go on low-carb diets. Since fiber comes mostly from grains (besides vegetables and legumes), low-carb diets can be alarmingly low in fiber as well. Among scientists, there is strong consensus that a diet rich in carbohydrates and fiber is crucial for brain health and Alzheimer’s prevention. And while there is nothing yet proved about how gluten can cause dementia, there are conclusive studies demonstrating that the absence of fiber can harm our brains. Fiber deficiencies harm our guts and therefore the population of friendly bacteria in those guts (the microbiome). Given the established connection between gut health and brain health—a topic all its own—a low-fiber diet risks negative long-term effects on the brain, causing brain fog, confusion, and even depression and anxiety.

And let's look at epidemiology: A large body of literature on centenarians (those who are 100 years old or older) shows that they often follow high-carb diets. That’s a strong clue that the relationship between healthy carbs and fiber and the diet and longevity is a largely beneficial one. When we study centenarian diets in detail, we note that over 80 percent of calories in their diet comes from vegetables, fruit, legumes, and complex carbohydrates, such as whole grains, brown rice, oats, and sweet potatoes. These foods are packed with brain supportive nutrients—from B vitamins to a bounty of antioxidants and minerals. They are also a good source of glucose, the main energy source for the brain. Combined with high fiber content to stabilize blood sugar levels, these foods enhance your metabolism, support healthy digestion, and boost the immune system.

In the end, eliminating gluten and other grains from the diet may well compromise the adequate intake of fiber, healthy carbs, and other brain-essential nutrients. Organic whole-grain foods should be an important component of the diet, especially for anyone reasonably concerned with preventing neurological diseases like Alzheimer’s.

If you have Celiac disease or are—like about 6 percent of the population, sensitive to gluten—focus on gluten-free grains like rice, amaranth, buckwheat, millet, quinoa, sorghum, and teff. Gluten-free products are often processed junk foods with high sugar and fat content, mixed with artificial coloring and unhealthy additives. There are many poisons that we introduce into our body and brain, but for the vast majority of us, gluten is not likely to be "the one." That said, if you are about to reach for a cupcake, hold on. Let me suggest three rules to eating carbs:

This piece is adapted from Brain Food: The Surprising Science of Eating for Cognitive Power, to be published on March 6th, 2018 by Avery/ Penguin Random House.