Negative Effects of Sugar on the Brain

Table of ContentsView AllTable of ContentsReward ResponseAddictionMemoryMoodMental Capacity

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Table of Contents

Reward Response

Addiction

Memory

Mood

Mental Capacity

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Thebrainuses 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.

The effects of sugar on the brain can include:

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 anddiabetes. The behavioral and neurobiochemical characteristics of substance abuse and overeating are quite similar, and the idea of food addiction is gaining ground among scientists.

This article discusses the effects thatsugar has on the brain, including its impact on the reward response. It also covers how it affects memory, mood, and cognition.

Press Play for Advice On Creating a Healthy Relationship With FoodThis episode ofThe Verywell Mind Podcast, featuring “The Fitness Chef” Graeme Tomlinson, shares how to establish a healthier relationship with food. Click below to listen now.

Press Play for Advice On Creating a Healthy Relationship With Food

This episode ofThe Verywell Mind Podcast, featuring “The Fitness Chef” Graeme Tomlinson, shares how to establish a healthier relationship with food. Click below to listen now.

Sugar Impacts the Brain’s Reward Response

Reward Response:The reward response occurs when certain structures in the brain are activated in response to a reward, such as food, sex, or addictive drugs. Activating this pathway creates a connection between the activity and the feelings of pleasure, which increases the likelihood that the behavior will occur again.

Reward Response:

The reward response occurs when certain structures in the brain are activated in response to a reward, such as food, sex, or addictive drugs. Activating this pathway creates a connection between the activity and the feelings of pleasure, which increases the likelihood that the behavior will occur again.

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 than low-glycemic foods. Foods that cause a higher elevation in blood glucose produce a greater addictive drive in the brain.

The glycemic index is a way of classifying carbohydrate-containing foods to estimate how quickly they are digested and their potential for increasing blood sugar levels.The various types of carbohydrates are processed differently in the body, some causing rapid spikes and dips in blood sugar and others leading to slower, more gradual increases and declines.

High-Glycemic Foods

High-glycemic foods are those with a high value on the glycemic index. They are digested quickly and cause a rapid increase in blood glucose levels.

Examples of high-glycemic foods include:

Low-Glycemic Foods

Low-glycemic foods are those that have a low value on the glycemic index. Such food can help people control blood sugar levels and body weight and reduce the risk for health conditions such as heart disease and type 2 diabetes.

Examples of low-glycemic foods include:

Research published in theAmerican Journal of Clinical Nutritionused the glycemic index (GI)—a measure of how certain foods convert to sugar in the body—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 Causes Addiction-Like Responses

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 withaddiction.

Why Do I Crave Sugar and Sweets? 4 Potential Causes

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 publishedPLoS Onefound that sweet foods can be more addictive thancocaine.Though the research was performed on animals, investigators found that intense sweetness can surpass cocaine reward, even in drug-sensitized and -addicted individuals.

Sugar Has Effects on Memory

In addition to sugar’s negative effects on the brain, it also harms the entire body. Even a single instance of elevated glucose in the bloodstream can be harmful to the brain, resulting in:

Inflammation in the brain can contribute to further memory difficulties. A 2016 study published inBehavioral Brain Researchfound inflammatory markers 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.

In addition, research published in the journalNutrientsin 2015 found reducing sugar consumption and supplementing with omega-3 fatty acids and curcumin improves working memory.

Sugar Has Effects on Mood

Another serious effect of sugar on the brain its its impact on mood. Such effects may include:

The study, published in 2017 in the journalScientific Reports, found those with the highest level of sugar consumption were a 23% more likely to be diagnosed with a mental disorder than those with the lowest sugar intakes.

Sugar Intake Hinders 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:

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 of brain-derived neurotrophic factor (BDNF), a brain chemical essential for new memory formation and learning.Lower levels of BDNF are also linked to dementia andAlzheimer’s disease, according to a study published in the journalDiabetologia.

Causes and Risk Factors of Alzheimer’s Disease

A Word From Verywell

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.

12 SourcesVerywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Vlachos D, Malisova S, Lindberg FA, Karaniki G.Glycemic index (GI) or glycemic load (GL) and dietary interventions for optimizing postprandial hyperglycemia in patients with T2 diabetes: A review.Nutrients. 2020;12(6):1561. doi:10.3390/nu12061561Lennerz BS, Alsop DC, Holsen LM, et al.Effects of dietary glycemic index on brain regions related to reward and craving in men.Am J Clin Nutr.2013;98(3):641-647. doi:10.3945/ajcn.113.064113Alonso-Alonso M, Woods SC, Pelchat M, et al.Food reward system: current perspectives and future research needs.Nutr Rev. 2015;73(5):296-307. doi:10.1093/nutrit/nuv002Lenoir M, Serre F, Cantin L, Ahmed SH.Intense Sweetness Surpasses Cocaine Reward.PLoS ONE. 2007;2(8):e698. doi:10.1371/journal.pone.0000698Beilharz JE, Maniam J, Morris MJ.Short-term exposure to a diet high in fat and sugar, or liquid sugar, selectively impairs hippocampal-dependent memory, with differential impacts on inflammation.Behav Brain Res. 2016;306:1-7. doi:10.1016/j.bbr.2016.03.018Tran DMD, Westbrook RF.A high-fat high-sugar diet-induced impairment in place-recognition memory is reversible and training-dependent.Appetite. 2017;110:61-71. doi:10.1016/j.appet.2016.12.010Beilharz JE, Maniam J, Morris MJ.Diet-Induced Cognitive Deficits: The Role of Fat and Sugar, Potential Mechanisms and Nutritional Interventions.Nutrients. 2015;7(8):6719-6738. doi:10.3390/nu7085307Sommerfield AJ, Deary IJ, Frier BM.Acute Hyperglycemia Alters Mood State and Impairs Cognitive Performance in People With Type 2 Diabetes.Diabetes Care. 2004;27(10):2335-2340. doi:10.2337/diacare.27.10.2335Knüppel A, Shipley MJ, Llewellyn CH, Brunner EJ.Sugar intake from sweet food and beverages, common mental disorder and depression: prospective findings from the Whitehall II study.Sci Rep.2017;7(1):6287. doi:10.1038/s41598-017-05649-7Zilliox LA, Chadrasekaran K, Kwan JY, Russell JW.Diabetes and Cognitive Impairment.Curr Diab Rep.2016;16(9):87. doi:10.1007/s11892-016-0775-xMolteni R, Barnard RJ, Ying Z, Roberts CK, Gómez-Pinilla F.A High-Fat, Refined Sugar Diet Reduces Hippocampal Brain-Derived Neurotrophic Factor, Neuronal Plasticity, and Learning.Neuroscience. 2002;112(4):803-814. doi:10.1016/s0306-4522(02)00123-9Krabbe KS, Nielsen AR, Krogh-Madsen R, et al.Brain-derived neurotrophic factor (BDNF) and type 2 diabetes.Diabetologia. 2007;50(2):431-438. doi:10.1007/s00125-006-0537-4Additional ReadingAhmed SH, Guillem K, Vandaele Y.Sugar addiction: pushing the drug-sugar analogy to the limit. Curr Opin Clin Nutr Metab Care. 2013;16(4):434-439. doi:10.1097/MCO.0b013e328361c8b8Kodl CT, Seaquist ER.Cognitive dysfunction and diabetes mellitus.Endocr Rev.2008;29:494-511. doi:10.1210/er.2007-0034Poulose SM, Miller MG, Scott T, Shukitt-Hale B.Nutritional Factors Affecting Adult Neurogenesis and Cognitive Function.Adv Nutr. 2017;8(6):804-811. doi:10.3945/an.117.016261

12 Sources

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Vlachos D, Malisova S, Lindberg FA, Karaniki G.Glycemic index (GI) or glycemic load (GL) and dietary interventions for optimizing postprandial hyperglycemia in patients with T2 diabetes: A review.Nutrients. 2020;12(6):1561. doi:10.3390/nu12061561Lennerz BS, Alsop DC, Holsen LM, et al.Effects of dietary glycemic index on brain regions related to reward and craving in men.Am J Clin Nutr.2013;98(3):641-647. doi:10.3945/ajcn.113.064113Alonso-Alonso M, Woods SC, Pelchat M, et al.Food reward system: current perspectives and future research needs.Nutr Rev. 2015;73(5):296-307. doi:10.1093/nutrit/nuv002Lenoir M, Serre F, Cantin L, Ahmed SH.Intense Sweetness Surpasses Cocaine Reward.PLoS ONE. 2007;2(8):e698. doi:10.1371/journal.pone.0000698Beilharz JE, Maniam J, Morris MJ.Short-term exposure to a diet high in fat and sugar, or liquid sugar, selectively impairs hippocampal-dependent memory, with differential impacts on inflammation.Behav Brain Res. 2016;306:1-7. doi:10.1016/j.bbr.2016.03.018Tran DMD, Westbrook RF.A high-fat high-sugar diet-induced impairment in place-recognition memory is reversible and training-dependent.Appetite. 2017;110:61-71. doi:10.1016/j.appet.2016.12.010Beilharz JE, Maniam J, Morris MJ.Diet-Induced Cognitive Deficits: The Role of Fat and Sugar, Potential Mechanisms and Nutritional Interventions.Nutrients. 2015;7(8):6719-6738. doi:10.3390/nu7085307Sommerfield AJ, Deary IJ, Frier BM.Acute Hyperglycemia Alters Mood State and Impairs Cognitive Performance in People With Type 2 Diabetes.Diabetes Care. 2004;27(10):2335-2340. doi:10.2337/diacare.27.10.2335Knüppel A, Shipley MJ, Llewellyn CH, Brunner EJ.Sugar intake from sweet food and beverages, common mental disorder and depression: prospective findings from the Whitehall II study.Sci Rep.2017;7(1):6287. doi:10.1038/s41598-017-05649-7Zilliox LA, Chadrasekaran K, Kwan JY, Russell JW.Diabetes and Cognitive Impairment.Curr Diab Rep.2016;16(9):87. doi:10.1007/s11892-016-0775-xMolteni R, Barnard RJ, Ying Z, Roberts CK, Gómez-Pinilla F.A High-Fat, Refined Sugar Diet Reduces Hippocampal Brain-Derived Neurotrophic Factor, Neuronal Plasticity, and Learning.Neuroscience. 2002;112(4):803-814. doi:10.1016/s0306-4522(02)00123-9Krabbe KS, Nielsen AR, Krogh-Madsen R, et al.Brain-derived neurotrophic factor (BDNF) and type 2 diabetes.Diabetologia. 2007;50(2):431-438. doi:10.1007/s00125-006-0537-4Additional ReadingAhmed SH, Guillem K, Vandaele Y.Sugar addiction: pushing the drug-sugar analogy to the limit. Curr Opin Clin Nutr Metab Care. 2013;16(4):434-439. doi:10.1097/MCO.0b013e328361c8b8Kodl CT, Seaquist ER.Cognitive dysfunction and diabetes mellitus.Endocr Rev.2008;29:494-511. doi:10.1210/er.2007-0034Poulose SM, Miller MG, Scott T, Shukitt-Hale B.Nutritional Factors Affecting Adult Neurogenesis and Cognitive Function.Adv Nutr. 2017;8(6):804-811. doi:10.3945/an.117.016261

Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

Vlachos D, Malisova S, Lindberg FA, Karaniki G.Glycemic index (GI) or glycemic load (GL) and dietary interventions for optimizing postprandial hyperglycemia in patients with T2 diabetes: A review.Nutrients. 2020;12(6):1561. doi:10.3390/nu12061561Lennerz BS, Alsop DC, Holsen LM, et al.Effects of dietary glycemic index on brain regions related to reward and craving in men.Am J Clin Nutr.2013;98(3):641-647. doi:10.3945/ajcn.113.064113Alonso-Alonso M, Woods SC, Pelchat M, et al.Food reward system: current perspectives and future research needs.Nutr Rev. 2015;73(5):296-307. doi:10.1093/nutrit/nuv002Lenoir M, Serre F, Cantin L, Ahmed SH.Intense Sweetness Surpasses Cocaine Reward.PLoS ONE. 2007;2(8):e698. doi:10.1371/journal.pone.0000698Beilharz JE, Maniam J, Morris MJ.Short-term exposure to a diet high in fat and sugar, or liquid sugar, selectively impairs hippocampal-dependent memory, with differential impacts on inflammation.Behav Brain Res. 2016;306:1-7. doi:10.1016/j.bbr.2016.03.018Tran DMD, Westbrook RF.A high-fat high-sugar diet-induced impairment in place-recognition memory is reversible and training-dependent.Appetite. 2017;110:61-71. doi:10.1016/j.appet.2016.12.010Beilharz JE, Maniam J, Morris MJ.Diet-Induced Cognitive Deficits: The Role of Fat and Sugar, Potential Mechanisms and Nutritional Interventions.Nutrients. 2015;7(8):6719-6738. doi:10.3390/nu7085307Sommerfield AJ, Deary IJ, Frier BM.Acute Hyperglycemia Alters Mood State and Impairs Cognitive Performance in People With Type 2 Diabetes.Diabetes Care. 2004;27(10):2335-2340. doi:10.2337/diacare.27.10.2335Knüppel A, Shipley MJ, Llewellyn CH, Brunner EJ.Sugar intake from sweet food and beverages, common mental disorder and depression: prospective findings from the Whitehall II study.Sci Rep.2017;7(1):6287. doi:10.1038/s41598-017-05649-7Zilliox LA, Chadrasekaran K, Kwan JY, Russell JW.Diabetes and Cognitive Impairment.Curr Diab Rep.2016;16(9):87. doi:10.1007/s11892-016-0775-xMolteni R, Barnard RJ, Ying Z, Roberts CK, Gómez-Pinilla F.A High-Fat, Refined Sugar Diet Reduces Hippocampal Brain-Derived Neurotrophic Factor, Neuronal Plasticity, and Learning.Neuroscience. 2002;112(4):803-814. doi:10.1016/s0306-4522(02)00123-9Krabbe KS, Nielsen AR, Krogh-Madsen R, et al.Brain-derived neurotrophic factor (BDNF) and type 2 diabetes.Diabetologia. 2007;50(2):431-438. doi:10.1007/s00125-006-0537-4

Vlachos D, Malisova S, Lindberg FA, Karaniki G.Glycemic index (GI) or glycemic load (GL) and dietary interventions for optimizing postprandial hyperglycemia in patients with T2 diabetes: A review.Nutrients. 2020;12(6):1561. doi:10.3390/nu12061561

Lennerz BS, Alsop DC, Holsen LM, et al.Effects of dietary glycemic index on brain regions related to reward and craving in men.Am J Clin Nutr.2013;98(3):641-647. doi:10.3945/ajcn.113.064113

Alonso-Alonso M, Woods SC, Pelchat M, et al.Food reward system: current perspectives and future research needs.Nutr Rev. 2015;73(5):296-307. doi:10.1093/nutrit/nuv002

Lenoir M, Serre F, Cantin L, Ahmed SH.Intense Sweetness Surpasses Cocaine Reward.PLoS ONE. 2007;2(8):e698. doi:10.1371/journal.pone.0000698

Beilharz JE, Maniam J, Morris MJ.Short-term exposure to a diet high in fat and sugar, or liquid sugar, selectively impairs hippocampal-dependent memory, with differential impacts on inflammation.Behav Brain Res. 2016;306:1-7. doi:10.1016/j.bbr.2016.03.018

Tran DMD, Westbrook RF.A high-fat high-sugar diet-induced impairment in place-recognition memory is reversible and training-dependent.Appetite. 2017;110:61-71. doi:10.1016/j.appet.2016.12.010

Beilharz JE, Maniam J, Morris MJ.Diet-Induced Cognitive Deficits: The Role of Fat and Sugar, Potential Mechanisms and Nutritional Interventions.Nutrients. 2015;7(8):6719-6738. doi:10.3390/nu7085307

Sommerfield AJ, Deary IJ, Frier BM.Acute Hyperglycemia Alters Mood State and Impairs Cognitive Performance in People With Type 2 Diabetes.Diabetes Care. 2004;27(10):2335-2340. doi:10.2337/diacare.27.10.2335

Knüppel A, Shipley MJ, Llewellyn CH, Brunner EJ.Sugar intake from sweet food and beverages, common mental disorder and depression: prospective findings from the Whitehall II study.Sci Rep.2017;7(1):6287. doi:10.1038/s41598-017-05649-7

Zilliox LA, Chadrasekaran K, Kwan JY, Russell JW.Diabetes and Cognitive Impairment.Curr Diab Rep.2016;16(9):87. doi:10.1007/s11892-016-0775-x

Molteni R, Barnard RJ, Ying Z, Roberts CK, Gómez-Pinilla F.A High-Fat, Refined Sugar Diet Reduces Hippocampal Brain-Derived Neurotrophic Factor, Neuronal Plasticity, and Learning.Neuroscience. 2002;112(4):803-814. doi:10.1016/s0306-4522(02)00123-9

Krabbe KS, Nielsen AR, Krogh-Madsen R, et al.Brain-derived neurotrophic factor (BDNF) and type 2 diabetes.Diabetologia. 2007;50(2):431-438. doi:10.1007/s00125-006-0537-4

Ahmed SH, Guillem K, Vandaele Y.Sugar addiction: pushing the drug-sugar analogy to the limit. Curr Opin Clin Nutr Metab Care. 2013;16(4):434-439. doi:10.1097/MCO.0b013e328361c8b8Kodl CT, Seaquist ER.Cognitive dysfunction and diabetes mellitus.Endocr Rev.2008;29:494-511. doi:10.1210/er.2007-0034Poulose SM, Miller MG, Scott T, Shukitt-Hale B.Nutritional Factors Affecting Adult Neurogenesis and Cognitive Function.Adv Nutr. 2017;8(6):804-811. doi:10.3945/an.117.016261

Ahmed SH, Guillem K, Vandaele Y.Sugar addiction: pushing the drug-sugar analogy to the limit. Curr Opin Clin Nutr Metab Care. 2013;16(4):434-439. doi:10.1097/MCO.0b013e328361c8b8

Kodl CT, Seaquist ER.Cognitive dysfunction and diabetes mellitus.Endocr Rev.2008;29:494-511. doi:10.1210/er.2007-0034

Poulose SM, Miller MG, Scott T, Shukitt-Hale B.Nutritional Factors Affecting Adult Neurogenesis and Cognitive Function.Adv Nutr. 2017;8(6):804-811. doi:10.3945/an.117.016261

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