Grains, Carbohydrates, and the Brain

Fueling the body and brain for optimal performance and cognitive functioning is one guiding principle in the U.S. Dietary Guidelines for Americans. Luckily, diets that optimize health for the body also optimize it for the brain and mental health.

Adherence to diets such as the Mediterranean diet, Dietary Approaches to Stop Hypertension (DASH), and USDA’s MyPlate is associated with lower risk of cognitive decline and dementia and Alzheimer’s disease (Gu et al., 2010; Solfrizzi et al., 2011; Gilette et al., 2013). Analysis of dietary patterns from around the world underscores these associations. Further, they show that such diets for the middle-aged are associated with less depression, work stress or anxiety, and improved mood (Suzuki et al., 2013). These dietary recommendations include 45% to 60% of calories from carbohydrates and  balanced amounts of heart- and brain-healthy foods. Those foods include lean meats and fish, fish oils and other healthy oils, nuts and legumes, low-fat dairy, vegetables and fruits, and a mix of whole and enriched grains.

Despite these proven health benefits, only 3% to 8% of Americans manage to achieve these recommendations. Yes, changes in our diets are warranted, but experts advocate and nutrition policies support that dietary patterns include more whole grains and fruits and vegetables, not fewer.

Several allegations have been made about our current diet with its emphasis on carbohydrates and grains (Perlmutter & Loberg, 2013; Davis, 2013). One is that early hominids ate the so-called “Paleo diet” and did not consume grains as hunter-gatherers. However, this can be discredited on two counts. First, foods not eaten by a population group certainly would not be chosen for domestication (Tanno & Willcox, 2006). Second, archeological evidence obtained using stable isotope determinations of charred cereals and pulses from Neolithic sites across Europe show that the contribution of these foods to early diets has been underestimated (Bogaard et al., 2013; Wynn et al., 2013).

Another claim is that grains, especially wheat, have changed dramatically in the last 50 years through plant breeding and genetic modification. Some authors go so far as to aver that today’s wheat gluten is not just problematic, but “toxic.” First, no genetically modified wheat is legally sold anywhere on the planet, so this could not be a problem. Second, while plant breeding does try to increase proteins that carry desirable traits, it cannot generate proteins that are absent in the DNA of the parent wheat plants. Thus the notion that proteins resulting from wheat breeding are unique or toxic is unsubstantiated.

Another assertion is that carbohydrate especially from wheat and other grain foods is linked to a number of brain woes including dementia, Alzheimer’s and Parkinson’s disease, depression, and ADHD. This is partially based on the fact that those with diabetes, insulin resistance, or abnormal glucose tolerance show elevated markers of inflammation, a shrinking of certain brain regions such as the hippocampus, greater brain plaque formation, and double the risk of dementia. However, this does not mean that those with normal glucose tolerance or diets with the right mix of carbohydrates and nutrient-rich foods will have such impacts. Nor are there data showing that dietary carbohydrate is the sole cause for such abnormalities. In fact excess intake of calories, fat, and carbohydrate, especially as part of a poor diet, can be factors in these conditions and excess inflammation. Obesity and chronic disease increase inflammation as do excess calories and poor diet (Moreira et al., 2012; Kalupahana et al., 2011; McCrimmon et al., 2012).

There is general agreement that excess circulating glucose is problematic in all areas of the body including the brain. Hyperglycemia, hypoglycemia, elevated glycosylated hemoglobin, and impaired insulin signaling are associated with a decline in brain function. Yet the brain’s access to a steady glucose supply can improve mental performance and behavior among children (Bellisle et al. and Micha et al., 2002).

The net-net is that dietary balance of nutrients, without the exclusion of grains,  keeps the brain and body performing optimally (Alzoubi et al., 2013; Bourre, 2006). For brain health, minimize advice that eliminates healthful foods and entire food groups, and DASH to a diet that meets the recommendations put forward in the Dietary Guidelines. 

Julie Jones, Ph.D., CFS, Contributing Editor
Distinguished Scholar and Professor
Emerita of Food & Nutrition, St. Catherine
University, St. Paul, Minn.
[email protected]

Marianne Smith Edge, R.D., Contributing Editor
Senior Vice President, Nutrition and Food
Safety, International Food Information
Council, Washington, D.C.
[email protected]