Carbohydrates and their grain sources: A review on their relationships to brain health

Recent claims suggesting whole and refined grain-based foods should be omitted from the diet because the carbohydrates (CHOs) they contain negatively impact the brain's long-term health and functioning need to be evaluated in light of the scientific literature. This review reveals that grain- based foods are important sources of glucose for the brain, which preferentially uses glucose as a source of energy. The lipid-rich brain is very meta-bolically active and, therefore, requires a lot of energy. Further, CHO-rich foods such as whole grains contain a variety of antioxidant and bioactive compounds that counter oxidative stress and inflammation, helping to prevent damage to brain tissue and maintain optimal cognitive functioning. Such compounds become more important with aging because the brain becomes more susceptible to oxidative stress and inflammation-conditions that promote the development of neurological diseases and disorders. An overview of studies on the relationship between CHO-rich, grain-based foods and many different neurological conditions is presented. The body of scientific evidence shows that whole and refined grain-based foods contribute energy and needed glucose for brain metabolism and that whole grains have the potential to offer slow glucose release and the capacity to deliver vitamins, minerals, and phytonutrients that are important for brain health. Because refined grain-based foods often deliver rapidly available glucose and may contain fewer phytochemicals and nutrients and less fiber than whole grains, results described in the scientific literature on the effects of refined grains on cognitive health are mixed. For example, studies have found that too much refined grain, as well as too many calories or too much fat, in the diet can have adverse health effects. However, refined grains consumed as part of a balanced diet, including the minerals and vitamins contained in enriched and fortified grains, appear to contribute positively to cognitive capacity and brain health. The roles whole and refined grains and their CHOs play in brain metabolism and various neurological diseases and disorders when consumed as part of balanced dietary patterns (e.g., Mediterranean-style diets) and as part of unbalanced dietary patterns (e.g., typical Western diets) that include too many calories and grain-based desserts and too few fruits, vegetables, and whole grains are examined.