How Refined Sugar Causes Anxiety and Why It's Neurotoxic

antianxiety anxiety free anxiety free with food corn syrup functional medicine healing high fructose refined sugar studies sugar sweetener Aug 05, 2021

Hippocrates, widely regarded as the father of medicine, once said: “Let your food be your medicine, and your medicine be your food.” Refined sugar is certainly not “medicine”; it is a chronic stressor that remodels our brains in negative ways. Although you may not die right away after eating it, it has been proven to deteriorate the brain and other bodily tissues, so I don’t believe we want to take its toxicity lightly. When I was doing research for my latest book Anxiety-Free with Food I discovered that refined sugar is in fact the top #1 worst food for anxiety, meaning it causes anxiety and is neurotoxic. 

#1. Refined Sugar

The top food that causes anxiety is refined sugar, which includes white table sugar, brown sugar, corn syrup, sucrose, fructose, and high-fructose corn syrup. When you have low levels of serotonin in the brain, you crave sugar.1 While you may feel good during your five-minute sugar high, you quickly experience a crash, which can be accompanied by anxiety.

There is an incredible amount of data showing how refined sugar deteriorates our health, including our mental health. One study found that consumption of added refined sugars, particularly high-fructose corn syrup and sucrose, negatively impacts your metabolism and the function of your hippocampus, and even causes neuroinflammation.2

In a study published in the journal Diabetologia, researchers reported that when blood glucose levels are elevated, levels of brain-derived neurotrophic factor (BDNF) decrease. BDNF is a protein that encourages the growth of neurons. Decreased BDNF is linked to dementia, depression, and even type 2 diabetes.3

Research has established a correlation between increased sugar intake and anxiety. A 2008 study showed that rodents that binged on sugar displayed instant anxiety, signs of dependence, and opiate-like withdrawal. The researchers suggested that sugar binges may “activate neural pathways in a manner similar to taking drugs of abuse.”4 One study called sugar “more rewarding and attractive” than cocaine!5

Sugary beverages have been associated with a higher risk of depression or depressive symptoms.6 Yet in Britain, adults consume approximately double, and in the U.S. triple, the recommended level of added sugar, with sweet foods and drinks contributing to three-quarters of their intake. Meanwhile, major depression is predicted to become the leading cause of disability in high-income countries by 2030.7

Some people, even experts, have been known to say, “All sugar is sugar.” I will wholeheartedly debate this; it’s common sense that eating a tablespoon of white sugar and eating a tablespoon of an apple result in quite different effects on the body. A 2009 study supports this, showing that rodents fed sucrose were more likely to show symptoms of anxiety than others fed high-antioxidant honey.8

Fructose has also been shown to compromise cognitive abilities like learning and memory. A study by researchers at the University of California, Los Angeles, revealed that six weeks of taking a fructose solution (similar to soda) caused rodents to forget their way out of a maze, whereas those that ate a nutritious diet or consumed a high-fructose diet that included omega-3 fatty acids found their way out faster. The high-sugar diet without omega-3 supplementation caused insulin resistance, which in turn damaged communications between the brain cells that fuel learning and memory formation! 9

High-fructose corn syrup is a low-cost sweetener you’ll find in everything from ketchup to candy and crackers. Consuming high-fructose corn syrup is the fastest way to develop obesity, anxiety, depression, and other health issues. It is involved in a vicious cycle, too: It begins when a cause like chronic stress and anxiety deplete the brain’s reserves of dopamine (not sleeping properly, eating a poor diet, or adrenal fatigue will do the same). This leads us to eat a quick sugary snack to boost our energy, making matters worse. We crash after eating the sugar, then crave more sugar. Reduced dopamine is associated with obesity because of how it contributes to compulsive eating. High-fructose corn syrup can impair dopamine function, and reduced dopamine function has been implicated in anxiety and compulsive behaviors.10

The saddest part is that foods with high-fructose corn syrup are being fed to children, impairing their brains’ ability to learn and remember. Soda is often made with high-fructose corn syrup or white sugar. Do whatever you need to do to phase soda out of your life. Try drinking kombucha instead for a sweet fizzy drink.

This information about sugar may seem familiar, but I invite you to consider doing something radical: Never eat refined sugar again. A commitment would mean it’s not part of the foundation of your diet. If you do end up eating it here and there, then so be it. (Make sure to boost your intake of omega-3s, as this may be protective against the effects of sugar.) But don’t go out of your way to pursue white sugar. Do not keep it in your home. There is no need for it. Cut refined sugar from your diet, and I promise you will start to feel better immediately. There is no place for it anymore in our world—especially when we’re feeling anxious.


Sneaky Sugar

It is important to check ingredient labels to see what type of sugar is in a food. (In fact, it’s never wise to eat anything these days without checking its ingredient label first.) Watch out for these names for sugar on the ingredient label:


Sneaky sugars include:

  • These ingredients with the word “sugar,” e.g., brown sugar, beet sugar, raw sugar, white sugar, white granulated sugar, organic white sugar. Excluding coconut sugar.
  • These ingredients with the word  “syrup,” e.g., corn syrup, high fructose corn syrup, golden syrup. Excluding maple syrup.
  • Any ingredient ending in “-ose,” e.g., fructose, glucose, maltose, sucrose dextrose, galactose, lactose, maltose, mannose, saccharose
  • Evaporated cane juice
  • Molasses
  • Caramel
  • Corn Sweetener
  • Muscovado (cane sugar that contains molasses)
  • Turbinado sugar (another type of cane sugar)
  • Treacle (uncrystallized syrup made during the refining of sugar)
  • Panela or raspadora (another type of cane sugar)

Sucrose, fructose, and glucose are not “bad,” per se. In fact, you’ll find these compounds naturally occurring in many fruits and vegetables. However, if you see these names on a product list, that means that the ingredient has been extremely refined and extracted. The only time you want to consume sucrose, glucose, or fructose is in its natural state.


This is an excerpt from my book Anxiety-Free with Food, out now,



  1. Q. Inam, et al., “Effects of Sugar Rich Diet on Brain Serotonin, Hyperphagia and Anxiety in Animal Model of Both Genders,” Pakistan Journal of Pharmaceutical Sciences, vol. 29, no. 3 (May 2016), pp. 757–63, PMID: 27166525.
  2. T.M. Hsu, et al., “Effects of Sucrose and High Fructose Corn Syrup Consumption on Spatial Memory Function and Hippocampal Neuroinflammation in Adolescent Rats,” Hippocampus, vol. 25, no. 2 (2015), pp. 227–39, doi: 10.1002/hipo.22368.
  3. K.S. Krabbe, et al., “Brain-derived Neurotrophic Factor (BDNF) and Type 2 Diabetes,” Diabetologia, vol. 50 (February 2007), pp. 431–8, doi: 10.1007/s00125-006-0537-4.
  4. N.M. Avena, et al., “After Daily Bingeing on a Sucrose Solution, Food Deprivation Induces Anxiety and Accumbens Dopamine/Acetylcholine Imbalance,” Physiology and Behavior, vol. 94, no. 3 (June 9, 2008), pp. 309–15, doi: 10.1016/j.physbeh.2008.01.008.
  5. S.H. Ahmed, K. Guillem, and Y. Vandaele, “Sugar Addiction: Pushing the Drug-Sugar Analogy to the Limit,” Current Opinion in Clinical Nutrition and Metabolic Care, vol. 16, no. 4 (July 2013), pp. 434–9, doi: 10.1097/MCO.0b013e328361c8b8.
  6. Q. Huang, et al., “Linking What We Eat to Our Mood: A Review of Diet, Dietary Antioxidants, and Depression,” Antioxidants, vol. 8, no. 9 (September 5, 2019), p. 376, doi: 10.3390/antiox8090376.
  7. A. Knüppel, et al., “Sugar Intake from Sweet Food and Beverages, Common Mental Disorder and Depression: Prospective Findings from the Whitehall II Study,” Scientific Reports, vol. 7 (July 27, 2017), p. 6287, doi: 10.1038/s41598-017-05649-7.
  8. L.M. Chepulis, et al., “The Effects of Long-Term Honey, Sucrose or Sugar-Free Diets on Memory and Anxiety in Rats,” Physiology and Behavior, vol. 97, nos. 3–4 (June 22, 2009), pp. 359–68, doi: 10.1016/j.physbeh.2009.03.001.
  9. G. Koleva, “Binging on Sugar Weakens Memory, UCLA Study Shows,” Forbes (accessed May 6, 2020),
  10. A.M. Meyers, D. Mourra, and J.A. Beeler, “High Fructose Corn Syrup Induces Metabolic Dysregulation and Altered Dopamine Signaling in the Absence of Obesity,” PLoS One, vol. 12, no. 12 (December 29, 2017), p. e0190206, doi: 10.1371/journal.pone.0190206.


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