Nutrition is essential in supporting proper development, health, and function of the nervous system and the brain. Dietary factors, including carbohydrates, play a role in neuronal function and plasticity. It is well known that glucose is the main energy source for the human brain. In fact, brain tissue contains approximately 20 percent more glucose than arterial plasma. It is not surprising that the blood-brain barrier tightly regulates the availability of nutrients and other compounds to and from the brain. While epidemiological (observational) studies have suggested some nutrients may influence cognition and brain function, clinical trials have failed to identify any specific dietary component with a causal role. In fact, transport of many nutrients and other molecules across the blood brain barrier is regulated by transporters that may limit drastic changes in availability of nutrients to the brain regardless of how much is consumed. While some researches have observed that dietary fructose intake may be associated with changes in problem solving or cognitive decline, it is essential to remember that correlations identified in observational studies are not necessarily causal. To date, studies have not confirmed differences in availability of different monosaccharides such as fructose and glucose due to changes in intake.
Research Study Summaries
Observational Findings Linking Intake of Sugar Containing Beverage Do Not Accurately Represent Americans’ Risk For Preclinical Alzheimer’s Disease
While a recent study alleges estimated intake of sugar containing beverages is associated with markers of preclinical Alzheimer’s disease, the observational nature of the study and other important limitations temper any significance of the findings. In the study, “Sugary beverage intake and preclinical Alzheimer’s disease in the community”, Pase et al., analyzed data from a […]
A recent study entitled “The human brain produces fructose from glucose” published in JCI Insight sought to examine whether peripheral hyperglycemia can drive intracerebral production of fructose through the polyol pathway [glucose –(aldose reductase)à sorbitol –(sorbitol dehydrogenase)à fructose] in an exploratory study. Researchers at Yale selected 4 male and 4 female participants (mean: age 28.8, […]
The review article, “The emerging role of dietary fructose in obesity and cognitive decline” by Lakhan and Kirchgessner has serious limitations.
A study published in Journal of Psychopharmacology found consuming fructose may result in comparable cognitive abilities as glucose without raising blood sugar levels as much as glucose.
Brain functional magnetic resonance imaging response to glucose and fructose infusions in human
In a recent paper, Stephan et al. speculated that high fructose intake is a risk factor for dementia and that increasing consumption of fructose in the U.S. population could lead to greater dementia risk. Their premise is weakened, however, by outdated references to fructose intake and functional properties, and by a reliance on supporting evidence gathered under extreme experimental conditions unrelated to typical human fructose exposure.