What Sugar Does to Your Brain

Everyone likes a sweet treat now and then. We’re sort of wired that way. After all, sugar, or glucose, is the primary energy source for every cell in your body. This goes doubly for your brain, which uses twice as much energy as your other cells.1 So when you eat something sweet, your brain responds with positive reinforcement, lighting up reward pathways and releasing happy chemicals like dopamine and serotonin.2 This is why you get that notorious “sugar high.”

Once upon a time, our ancestors had to forage for ripe, sweet fruits to get that rush. But today, sugar is everywhere. It’s added to most drinks and found in 75% of our processed and packaged foods.3 Most of us aren’t even aware of how often we’re eating sugar. In fact, the CDC estimates that the average American consumes 27.5 teaspoons, or 440 calories, of added sugar every day -- almost a quarter of our daily calorie count.

This means we’re constantly triggering a chemical rush in our brains. Unfortunately, too much of a good thing is not so good. We become habituated to the sugar rush, and then desensitized. As the body and brain develop a tolerance to sugar, their ability to metabolize the sugar becomes impaired.1 So you crave more, but it works less. And when your brain can’t use sugar as well, it may not function as it should. Here are some of the ways that too much sugar can affect your brain:

1. Sugar Can Be Addictive

Studies show that a sugar high activates the same reward circuits in the brain that get triggered by other addictive behaviors, like drugs or gambling.4,5 After the surge of feel-good hormones, the high is followed by a crash, with a deficit of dopamine and serotonin that leaves you feeling low and moody. (This yo-yo effect is especially pronounced when we eat refined, processed sugar, which is absorbed into the bloodstream much more quickly than the naturally-occurring sugars in fruit and grains.)

The crash triggers another craving, prompting a vicious cycle.4 Over time, with repetition, this cycle can alter your brain’s reward circuits and weaken your self-control.6 The dopamine receptors in the brain become less responsive through over-excitation, so that it takes more and more to give you that dopamine hit. It’s not hard to see how this is like a drug. One study found that sugar can be even more addictive than cocaine.7 Going off sugar can even result in symptoms of physical and psychological withdrawal.2 

2. Sugar Can Affect Your Mood

When your blood sugar is on the spike-and-crash roller coaster, you may experience feelings of irritability, anxiety, sadness, and fatigue. But the long-term effects of this cycle are worse. Too much sugar consumption overstimulates the serotonin and dopamine pathways in the brain. This can lead to a depletion of these important neurotransmitters, which are crucial for maintaining a balanced, happy mood.3

Not surprisingly, a high sugar diet is linked with greater risk of depression. One study found that those who consumed the most sugar were 23% more likely to be diagnosed with a mood disorder than those with the lowest sugar consumption.8 

3. Sugar Can Impair Memory and Learning

When you eat sugar, your body releases insulin to help regulate your blood sugar levels. But if your body is pumping out insulin all the time, it eventually becomes less responsive to it, and your ability to metabolize glucose becomes impaired. This is known as insulin resistance, and it's a precondition for diabetes. It’s also linked with low levels of BDNF (brain-derived nootropic factor), an important brain chemical for memory and learning.1

Your brain needs insulin to help strengthen synaptic connections between brain cells, which is what allows you to form memories. If your brain can’t properly take up insulin, cognitive function slows down.3 One recent study showed that just two months on a high sugar diet reduced BDNF levels in the brain and impaired synaptic plasticity, resulting in impaired memory and learning performance.9

4. Sugar Raises Risk of Cognitive Decline

We’ve seen how insulin resistance in the brain can impair cognitive function, and it’s not hard to see how this can have a dangerous cumulative effect over time. One recent large-scale study showed that higher blood sugar levels are associated with much faster rates of cognitive decline.10 In fact, insulin resistance, low BDNF levels, and diabetes have all been linked with dementia and Alzheimer’s in recent research.3,11,12 Alzheimer’s has even been called “type 3 diabetes” because of this link.

The good news is that you can undo the damage that sugar does to your brain by reducing your sugar intake. Try to cut back on foods and drinks with added refined sugar, and get more of your sugar from whole foods like fruit and grains. These have a more complex carbohydrate structure that’s metabolized more slowly, so your blood sugar doesn’t spike and crash so dramatically. They also come with a lot of nutrients and antioxidants, and do a better job of satisfying your appetite.

Studies show that it is possible to reverse memory damage by following a low-sugar diet.13 It’s also a good idea to get more brain-protective nutrients in your diet, such as omega-3 fatty acids and turmeric curcumin. Omega-3 fatty acids are essential for healthy brain function, particularly DHA, which supports learning and memory and protects the brain against oxidative stress.14 Curcumin, the primary active compound in turmeric, also has antioxidant benefits and has been shown to improve memory and mood in those with mild cognitive decline.15 They even work better together: curcumin has been shown to help boost DHA levels in the brain.16

Omega-3s are mostly found in fish like salmon and tuna, while turmeric is a spice most commonly found in curry. If these aren’t a regular part of your diet, it’s a good idea to supplement. Research has shown that reducing sugar in your diet while also supplementing with omega-3s and curcumin can improve your working memory.17 NATURELO offers both an Omega-3 Fish Oil supplement and a Vegan DHA supplement from algae, as well as a Turmeric Curcumin supplement to support your brain health.

References:

1. DiSalvo, David. “What EatingToo Much Sugar Does to Your Brain.” Psychology Today, Apr 2012.

2. Lewis, Jordan Gaines. “What happens to your brain when you give up sugar.” Chicago Tribune, Mar 2015.

3. Gregoire, Carolyn. “This is What Sugar Does to Your Brain.” Huffpost, Apr 2015.

4. Migliore, Lauren. “A Bittersweet Truth: The Neuroscience of Sugar and Addiction.” Brain World Magazine, Feb 2020.

5. Belinda S Lennerz, David C Alsop, Laura M Holsen, Emily Stern, Rafael Rojas, Cara B Ebbeling, Jill M Goldstein, David S Ludwig. “Effects of dietary glycemic index on brain regions related to reward and craving in men.” The American Journal of Clinical Nutrition, Volume 98, Issue 3, September 2013, Pages 641–647, https://doi.org/10.3945/ajcn.113.064113

6. Miguel Alonso-Alonso, Stephen C. Woods, Marcia Pelchat, Patricia Sue Grigson, Eric Stice, Sadaf Farooqi, Chor San Khoo, Richard D. Mattes, Gary K. Beauchamp. “Food reward system: current perspectives and future research needs.Nutrition Reviews, Volume 73, Issue 5, May 2015, Pages 296–307, https://doi.org/10.1093/nutrit/nuv002

7. 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

8. 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

9. 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

10. Zheng, F., Yan, L., Yang, Z. et al. “HbA1c, diabetes and cognitive decline: the English Longitudinal Study of Ageing.” Diabetologia 61, 839–848 (2018). https://doi.org/10.1007/s00125-017-4541-7

11. 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

12. American Academy of Neurology. "Diabetes may significantly increase the risk of dementia." ScienceDaily. ScienceDaily, 20 September 2011. <www.sciencedaily.com/releases/2011/09/110919163947.htm>.

13. 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

14. University of California - Los Angeles. "Scientists Learn How Food Affects The Brain: Omega 3 Especially Important." ScienceDaily. ScienceDaily, 11 July 2008. <www.sciencedaily.com/releases/2008/07/080709161922.htm>.

15.  Kan, Deborah. “Could a Daily Dose of Curcumin Improve Your Memory?” Being Patient, Sep 2018.

16. Wu, Aiguo et al. “Curcumin boosts DHA in the brain: Implications for the prevention of anxiety disorders.Biochimica et biophysica acta vol. 1852,5 (2015): 951-61. doi:10.1016/j.bbadis.2014.12.005

17. 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