CIMMYT series on carbohydrates, wheat, grains, and health: Role of carbohydrates and grains in nutrition and neurological disorders: Headache, attention deficit hyperactivity disorder, and depression

Claims made in the popular press allege that grain-based foods, and the carbohydrates (CHOs) they contain, cause or worsen various neurological disorders, including headache, attention deficit hyperactivity disorder (ADHD), and depression. This article reviews the scientific literature to assess the role of these foods in nutrition and their impact on headache, ADHD, and depression. The bulk of the scientific literature shows that nearly all grain-based products are listed as nonoffending foods and are not thought to increase the risk of most types of headaches. When grain-based foods, and their CHOs, are consumed as part of balanced dietary patterns that emphasize an optimal mix of whole and refined grains, such as DASH (Dietary Approaches to Stop Hypertension) or Mediterranean Diets, they are associated with reduced headache risk. Although there are a number of food triggers for headache, grain-based foods are not listed as likely triggers. Evidence linking specific grain-based foods to headache is either lacking or extremely weak. However, excess weight, poor blood sugar control, and grain allergies or intolerances may increase risk. ADHD is a brain disorder that has many etiologies. Diet and food additives are suggested causes of ADHD, and elimination diets have been proposed as one strategy to decrease risk. However, study results are inconsistent, and controlled studies with gluten have failed to show that its elimination impacts ADHD. If anything, ingestion of grain-based foods as part of a healthy dietary pattern appears to reduce risk and improve symptoms. Abnormal glucose control may increase behavioral issues, and some small studies have shown that low-glycemic cereals or diets may be helpful in controlling behavior. However, low intakes of dietary fiber and n-3 fatty acids, unbalanced diets with frequent ingestion of indulgent foods, and disordered eating patterns are all associated with ADHD. Balanced dietary patterns are associated with reduced risk of depression. However, intake of CHOs or grain-based foods as part of high-fat, high-sugar food patterns are associated with the onset of symptoms of depression. Study results relating glycemic index or load and depression are mixed, but higher dietary fiber intake is consistently associated with reduced risk. Balanced dietary patterns incorporating a mix of grains and adequate dietary fiber have the most data supporting a positive relationship with all of these conditions. Brain health greatly depends on mitigation of oxidative stress and inflammation. The vitamins, minerals, and phytochemicals in grains provide many antioxidants and dietary fiber, in the diet. Scientific literature reporting findings that grains, grain-based foods, and their CHO components either cause or exacerbate any of these conditions is lacking.