The Negative Impact of Sugar on the Brain

The Negative Impact of Sugar on the Brain Brain Health Brain Food Print Negative Impact of Sugar on the Brain By Joel Fuhrman, MD facebook twitter Joel Fuhrman, MD, is a board-certified physician focused on nutrition and natural healing. Hes a New York Times best-selling author and TEDx speaker. Learn about our editorial policy Joel Fuhrman, MD Medically reviewed by Medically reviewed by Steven Gans, MD on July 13, 2017 Steven Gans, MD is board-certified in psychiatry and is an active supervisor, teacher, and mentor at Massachusetts General Hospital. Learn about our Medical Review Board Steven Gans, MD Updated on February 03, 2020 Andrijana Kostova / Stocksy United More in Brain Health Brain Food Mental Exercises Healthy Aging In This Article Table of Contents Expand Reward Response Sugar Addiction Memory Mood Mental Capacity View All Back To Top The brain uses more energy than any other organ in the human body and glucose is its primary source of fuel. But what happens when the brain is exposed to an excessive amount of sugars in the standard American diet? In this case, more is definitely not better. In the brain, excess sugar impairs both our cognitive skills and our self-control. For many people, having a little sugar stimulates a craving for more. Sugar has drug-like effects in the reward center of the brain. Scientists have proposed that sweet foodsâ€"along with salty and fatty foodsâ€"can produce addiction-like effects in the human brain, driving the loss of self-control, overeating, and subsequent weight gain. In early humans, this stimulus helped lead them to calorie-rich foods, which aided survival when food was scarce. But now this primitive drive contributes to our epidemics of obesity and diabetes. The behavioral and neurobiochemical characteristics of substance abuse and overeating are quite similar, and the idea of food addiction is gaining ground among scientists. Reward Response In humans, high-glycemic foods have been found to activate regions of the brain associated with the reward response and provoke more intense feelings of hunger compared to low-glycemic foods. Foods that cause a higher elevation in blood glucose produce a greater addictive drive in the brain. Research published in the  American Journal of Clinical Nutrition used the glycemic index (GI)â€"a measure of how certain foods convert to sugar in the bodyâ€"to test this process and found eating a high-GI meal elicited greater  brain  activity in regions  involved in eating behavior,  reward, and  craving. Sugar Addiction Additional studies on brain activity have provided evidence supporting the idea that overeating alters our brain’s reward system, which then further drives overeating. This same process is thought to underlie the tolerance associated with addiction. Is Sugar Really, Truly Addictive? Over time, greater amounts of the substance are required to reach the same level of reward. Studies imply that overeating results in a diminished reward response and a progressively worsening addiction to low-nutrient foods rich in sugar, salt, and fat. A study published  PLoS One found that sweet foods can be more addictive than cocaine. Though the research was performed on animals, investigators found that intense  sweetness  can surpass  cocaine  reward, even in drug-sensitized and -addicted individuals.   Memory Throughout the body, excess sugar is harmful. Even a single instance of elevated glucose in the bloodstream can be harmful to the brain, resulting in slowed cognitive function and deficits in memory and attention. Some research suggests high sugar consumption causes inflammation in the brain, leading to memory difficulties. A 2016 study published in Behavioral Brain Research found inflammatory markers were present in the hippocampus of rats fed a high sugar diet, but not in those fed a standard diet. The good news, however, is this inflammatory damage from sugar may not be permanent. A 2017 study in the journal  Appetite found that the memory damage caused by sugar consumption can be reversed by following a low-sugar, low-GI diet. In addition, research published in the journal Nutrients in 2015 found reducing sugar consumption and supplementing with omega-3 fatty acids and curcumin improves working memory. Mood Sugar also affects mood. In healthy young people, the ability to process emotion is compromised with elevated blood glucose, according to a brain imaging study. Another study published in Diabetes Care found that people with type 2 diabetes reported increased feelings of sadness and anxiety during acute hyperglycemia (elevated blood sugar). One of the largest studies to link sugar with depressionâ€"an analysis of dietary consumption and mood of 23,245 individuals enrolled in the Whitehall II studyâ€"found higher rates of sugar consumption was associated with a greater incidence of depression. The study, published in 2017 in the journal  Scientific Reports, found those with the highest level of sugar consumption were a 23 percent more likely to be diagnosed with a mental disorder than those with the lowest sugar intakes. Mental Capacity Elevated blood glucose harms blood vessels. Blood vessel damage is the major cause of the vascular complications of diabetes, leading to other problems, such as damage to blood vessels in the brain and eyes causing retinopathy. Studies of long-term diabetics show progressive brain damage leading to deficits in learning, memory, motor speed, and other cognitive functions. Frequent exposure to high glucose levels diminishes mental capacity, as higher HbA1c levels have been associated with a greater degree of brain shrinkage. Even in those without diabetes, higher sugar consumption is associated with lower scores on tests of cognitive function. These effects are thought to be due to a combination of hyperglycemia, hypertension, insulin resistance, and elevated cholesterol. Additional research shows that a diet high in added sugar reduces the production brain-derived neurotrophic factor (BDNF), a brain chemical essential for new memory formation and learning. Lower levels of BDNF are also linked to dementia and Alzheimers disease, according to a study published in the journal Diabetologia. A Word From Verywell As the research shows, any sugar added in our food is dangerous. We can avoid these dangers by satisfying our sweet tooth with fresh fruit in place of refined sugars. Eating fresh fruit provides the satisfying sweetness of sugar-laden treats with the added bonus of the fruit’s fiber, antioxidants, and phytochemicals that curtail the surge of sugar in the bloodstream and block its negative effects.